Commit 8be8ebd698

Andrew Kelley <andrew@ziglang.org>
2020-07-06 08:10:44
stage2: skeleton codegen for x64 ADD
also rework Module to take advantage of the new hash map implementation.
1 parent ad2ed45
src-self-hosted/codegen.zig
@@ -46,7 +46,14 @@ pub fn generateSymbol(
             var mc_args = try std.ArrayList(Function.MCValue).initCapacity(bin_file.allocator, param_types.len);
             defer mc_args.deinit();
 
-            var next_stack_offset: u64 = 0;
+            var branch_stack = std.ArrayList(Function.Branch).init(bin_file.allocator);
+            defer {
+                assert(branch_stack.items.len == 1);
+                branch_stack.items[0].deinit(bin_file.allocator);
+                branch_stack.deinit();
+            }
+            const branch = try branch_stack.addOne();
+            branch.* = .{};
 
             switch (fn_type.fnCallingConvention()) {
                 .Naked => assert(mc_args.items.len == 0),
@@ -61,8 +68,8 @@ pub fn generateSymbol(
                                 switch (param_type.zigTypeTag()) {
                                     .Bool, .Int => {
                                         if (next_int_reg >= integer_registers.len) {
-                                            try mc_args.append(.{ .stack_offset = next_stack_offset });
-                                            next_stack_offset += param_type.abiSize(bin_file.options.target);
+                                            try mc_args.append(.{ .stack_offset = branch.next_stack_offset });
+                                            branch.next_stack_offset += @intCast(u32, param_type.abiSize(bin_file.options.target));
                                         } else {
                                             try mc_args.append(.{ .register = @enumToInt(integer_registers[next_int_reg]) });
                                             next_int_reg += 1;
@@ -100,23 +107,17 @@ pub fn generateSymbol(
             }
 
             var function = Function{
+                .gpa = bin_file.allocator,
                 .target = &bin_file.options.target,
                 .bin_file = bin_file,
                 .mod_fn = module_fn,
                 .code = code,
                 .err_msg = null,
                 .args = mc_args.items,
-                .branch_stack = .{},
+                .branch_stack = &branch_stack,
             };
-            defer {
-                assert(function.branch_stack.items.len == 1);
-                function.branch_stack.items[0].inst_table.deinit();
-                function.branch_stack.deinit(bin_file.allocator);
-            }
-            try function.branch_stack.append(bin_file.allocator, .{
-                .inst_table = std.AutoHashMap(*ir.Inst, Function.MCValue).init(bin_file.allocator),
-            });
 
+            branch.max_end_stack = branch.next_stack_offset;
             function.gen() catch |err| switch (err) {
                 error.CodegenFail => return Result{ .fail = function.err_msg.? },
                 else => |e| return e,
@@ -218,6 +219,7 @@ pub fn generateSymbol(
 }
 
 const Function = struct {
+    gpa: *Allocator,
     bin_file: *link.ElfFile,
     target: *const std.Target,
     mod_fn: *const Module.Fn,
@@ -232,10 +234,37 @@ const Function = struct {
     /// within different branches. Special consideration is needed when a branch
     /// joins with its parent, to make sure all instructions have the same MCValue
     /// across each runtime branch upon joining.
-    branch_stack: std.ArrayListUnmanaged(Branch),
+    branch_stack: *std.ArrayList(Branch),
 
     const Branch = struct {
-        inst_table: std.AutoHashMap(*ir.Inst, MCValue),
+        inst_table: std.AutoHashMapUnmanaged(*ir.Inst, MCValue) = .{},
+
+        /// The key is an enum value of an arch-specific register.
+        registers: std.AutoHashMapUnmanaged(usize, RegisterAllocation) = .{},
+
+        /// Maps offset to what is stored there.
+        stack: std.AutoHashMapUnmanaged(usize, StackAllocation) = .{},
+        /// Offset from the stack base, representing the end of the stack frame.
+        max_end_stack: u32 = 0,
+        /// Represents the current end stack offset. If there is no existing slot
+        /// to place a new stack allocation, it goes here, and then bumps `max_end_stack`.
+        next_stack_offset: u32 = 0,
+
+        fn deinit(self: *Branch, gpa: *Allocator) void {
+            self.inst_table.deinit(gpa);
+            self.registers.deinit(gpa);
+            self.stack.deinit(gpa);
+            self.* = undefined;
+        }
+    };
+
+    const RegisterAllocation = struct {
+        inst: *ir.Inst,
+    };
+
+    const StackAllocation = struct {
+        inst: *ir.Inst,
+        size: u32,
     };
 
     const MCValue = union(enum) {
@@ -256,6 +285,13 @@ const Function = struct {
         memory: u64,
         /// The value is one of the stack variables.
         stack_offset: u64,
+
+        fn isMemory(mcv: MCValue) bool {
+            return switch (mcv) {
+                .embedded_in_code, .memory, .stack_offset => true,
+                else => false,
+            };
+        }
     };
 
     fn gen(self: *Function) !void {
@@ -318,7 +354,7 @@ const Function = struct {
         const inst_table = &self.branch_stack.items[0].inst_table;
         for (self.mod_fn.analysis.success.instructions) |inst| {
             const new_inst = try self.genFuncInst(inst, arch);
-            try inst_table.putNoClobber(inst, new_inst);
+            try inst_table.putNoClobber(self.gpa, inst, new_inst);
         }
     }
 
@@ -344,19 +380,99 @@ const Function = struct {
     }
 
     fn genAdd(self: *Function, inst: *ir.Inst.Add, comptime arch: std.Target.Cpu.Arch) !MCValue {
-        const lhs = try self.resolveInst(inst.args.lhs);
-        const rhs = try self.resolveInst(inst.args.rhs);
+        // No side effects, so if it's unreferenced, do nothing.
+        if (inst.base.isUnused())
+            return MCValue.dead;
         switch (arch) {
-            .i386, .x86_64 => {
-                // const lhs_reg = try self.instAsReg(lhs);
-                // const rhs_reg = try self.instAsReg(rhs);
-                // const result = try self.allocateReg();
-
-                // try self.code.append(??);
+            .x86_64 => {
+                // Biggest encoding of ADD is 8 bytes.
+                try self.code.ensureCapacity(self.code.items.len + 8);
+
+                // In x86, ADD has 2 operands, destination and source.
+                // Either one, but not both, can be a memory operand.
+                // Source operand can be an immediate, 8 bits or 32 bits.
+                // So, if either one of the operands dies with this instruction, we can use it
+                // as the result MCValue.
+                var dst_mcv: MCValue = undefined;
+                var src_mcv: MCValue = undefined;
+                if (inst.base.operandDies(0)) {
+                    // LHS dies; use it as the destination.
+                    dst_mcv = try self.resolveInst(inst.args.lhs);
+                    // Both operands cannot be memory.
+                    if (dst_mcv.isMemory()) {
+                        src_mcv = try self.resolveInstImmOrReg(inst.args.rhs);
+                    } else {
+                        src_mcv = try self.resolveInst(inst.args.rhs);
+                    }
+                } else if (inst.base.operandDies(1)) {
+                    // RHS dies; use it as the destination.
+                    dst_mcv = try self.resolveInst(inst.args.rhs);
+                    // Both operands cannot be memory.
+                    if (dst_mcv.isMemory()) {
+                        src_mcv = try self.resolveInstImmOrReg(inst.args.lhs);
+                    } else {
+                        src_mcv = try self.resolveInst(inst.args.lhs);
+                    }
+                } else {
+                    const lhs = try self.resolveInst(inst.args.lhs);
+                    const rhs = try self.resolveInst(inst.args.rhs);
+                    if (lhs.isMemory()) {
+                        dst_mcv = try self.copyToNewRegister(inst.base.src, lhs);
+                        src_mcv = rhs;
+                    } else {
+                        dst_mcv = try self.copyToNewRegister(inst.base.src, rhs);
+                        src_mcv = lhs;
+                    }
+                }
+                // x86 ADD supports only signed 32-bit immediates at most. If the immediate
+                // value is larger than this, we put it in a register.
+                // A potential opportunity for future optimization here would be keeping track
+                // of the fact that the instruction is available both as an immediate
+                // and as a register.
+                switch (src_mcv) {
+                    .immediate => |imm| {
+                        if (imm > std.math.maxInt(u31)) {
+                            src_mcv = try self.copyToNewRegister(inst.base.src, src_mcv);
+                        }
+                    },
+                    else => {},
+                }
 
-                // lhs_reg.release();
-                // rhs_reg.release();
-                return self.fail(inst.base.src, "TODO implement register allocation", .{});
+                switch (dst_mcv) {
+                    .none => unreachable,
+                    .dead, .unreach, .immediate => unreachable,
+                    .register => |dst_reg_usize| {
+                        const dst_reg = @intToEnum(Reg(arch), @intCast(@TagType(Reg(arch)), dst_reg_usize));
+                        switch (src_mcv) {
+                            .none => unreachable,
+                            .dead, .unreach => unreachable,
+                            .register => |src_reg_usize| {
+                                const src_reg = @intToEnum(Reg(arch), @intCast(@TagType(Reg(arch)), src_reg_usize));
+                                self.rex(.{ .b = dst_reg.isExtended(), .r = src_reg.isExtended(), .w = dst_reg.size() == 64 });
+                                self.code.appendSliceAssumeCapacity(&[_]u8{ 0x1, 0xC0 | (@as(u8, src_reg.id() & 0b111) << 3) | @as(u8, dst_reg.id() & 0b111) });
+                            },
+                            .immediate => |imm| {
+                                const imm32 = @intCast(u31, imm); // We handle this case above.
+                                // 81 /0 id
+                                if (imm32 <= std.math.maxInt(u7)) {
+                                    self.rex(.{ .b = dst_reg.isExtended(), .w = dst_reg.size() == 64 });
+                                    self.code.appendSliceAssumeCapacity(&[_]u8{ 0x83, 0xC0 | @as(u8, dst_reg.id() & 0b111), @intCast(u8, imm32)});
+                                } else {
+                                    self.rex(.{ .r = dst_reg.isExtended(), .w = dst_reg.size() == 64 });
+                                    self.code.appendSliceAssumeCapacity(&[_]u8{ 0x81, 0xC0 | @as(u8, dst_reg.id() & 0b111) });
+                                    std.mem.writeIntLittle(u32, self.code.addManyAsArrayAssumeCapacity(4), imm32);
+                                }
+                            },
+                            .embedded_in_code, .memory, .stack_offset => {
+                                return self.fail(inst.base.src, "TODO implement x86 add source memory", .{});
+                            },
+                        }
+                    },
+                    .embedded_in_code, .memory, .stack_offset => {
+                        return self.fail(inst.base.src, "TODO implement x86 add destination memory", .{});
+                    },
+                }
+                return dst_mcv;
             },
             else => return self.fail(inst.base.src, "TODO implement add for {}", .{self.target.cpu.arch}),
         }
@@ -526,23 +642,23 @@ const Function = struct {
     /// resulting REX is meaningful, but will remain the same if it is not.
     /// * Deliberately inserting a "meaningless REX" requires explicit usage of
     /// 0x40, and cannot be done via this function.
-    fn REX(self: *Function, arg: struct { B: bool = false, W: bool = false, X: bool = false, R: bool = false }) !void {
+    fn rex(self: *Function, arg: struct { b: bool = false, w: bool = false, x: bool = false, r: bool = false }) void {
         //  From section 2.2.1.2 of the manual, REX is encoded as b0100WRXB.
         var value: u8 = 0x40;
-        if (arg.B) {
+        if (arg.b) {
             value |= 0x1;
         }
-        if (arg.X) {
+        if (arg.x) {
             value |= 0x2;
         }
-        if (arg.R) {
+        if (arg.r) {
             value |= 0x4;
         }
-        if (arg.W) {
+        if (arg.w) {
             value |= 0x8;
         }
         if (value != 0x40) {
-            try self.code.append(value);
+            self.code.appendAssumeCapacity(value);
         }
     }
 
@@ -570,11 +686,11 @@ const Function = struct {
                         // If we're accessing e.g. r8d, we need to use a REX prefix before the actual operation. Since
                         // this is a 32-bit operation, the W flag is set to zero. X is also zero, as we're not using a SIB.
                         // Both R and B are set, as we're extending, in effect, the register bits *and* the operand.
-                        try self.REX(.{ .R = reg.isExtended(), .B = reg.isExtended() });
+                        try self.code.ensureCapacity(self.code.items.len + 3);
+                        self.rex(.{ .r = reg.isExtended(), .b = reg.isExtended() });
                         const id = @as(u8, reg.id() & 0b111);
-                        return self.code.appendSlice(&[_]u8{
-                            0x31, 0xC0 | id << 3 | id,
-                        });
+                        self.code.appendSliceAssumeCapacity(&[_]u8{ 0x31, 0xC0 | id << 3 | id });
+                        return;
                     }
                     if (x <= std.math.maxInt(u32)) {
                         // Next best case: if we set the lower four bytes, the upper four will be zeroed.
@@ -607,9 +723,9 @@ const Function = struct {
                     // Since we always need a REX here, let's just check if we also need to set REX.B.
                     //
                     // In this case, the encoding of the REX byte is 0b0100100B
-
-                    try self.REX(.{ .W = true, .B = reg.isExtended() });
-                    try self.code.resize(self.code.items.len + 9);
+                    try self.code.ensureCapacity(self.code.items.len + 10);
+                    self.rex(.{ .w = true, .b = reg.isExtended() });
+                    self.code.items.len += 9;
                     self.code.items[self.code.items.len - 9] = 0xB8 | @as(u8, reg.id() & 0b111);
                     const imm_ptr = self.code.items[self.code.items.len - 8 ..][0..8];
                     mem.writeIntLittle(u64, imm_ptr, x);
@@ -620,13 +736,13 @@ const Function = struct {
                     }
                     // We need the offset from RIP in a signed i32 twos complement.
                     // The instruction is 7 bytes long and RIP points to the next instruction.
-                    //
+                    try self.code.ensureCapacity(self.code.items.len + 7);
                     // 64-bit LEA is encoded as REX.W 8D /r. If the register is extended, the REX byte is modified,
                     // but the operation size is unchanged. Since we're using a disp32, we want mode 0 and lower three
                     // bits as five.
                     // REX 0x8D 0b00RRR101, where RRR is the lower three bits of the id.
-                    try self.REX(.{ .W = true, .B = reg.isExtended() });
-                    try self.code.resize(self.code.items.len + 6);
+                    self.rex(.{ .w = true, .b = reg.isExtended() });
+                    self.code.items.len += 6;
                     const rip = self.code.items.len;
                     const big_offset = @intCast(i64, code_offset) - @intCast(i64, rip);
                     const offset = @intCast(i32, big_offset);
@@ -646,9 +762,10 @@ const Function = struct {
                     // If the *source* is extended, the B field must be 1.
                     // Since the register is being accessed directly, the R/M mode is three. The reg field (the middle
                     // three bits) contain the destination, and the R/M field (the lower three bits) contain the source.
-                    try self.REX(.{ .W = true, .R = reg.isExtended(), .B = src_reg.isExtended() });
+                    try self.code.ensureCapacity(self.code.items.len + 3);
+                    self.rex(.{ .w = true, .r = reg.isExtended(), .b = src_reg.isExtended() });
                     const R = 0xC0 | (@as(u8, reg.id() & 0b111) << 3) | @as(u8, src_reg.id() & 0b111);
-                    try self.code.appendSlice(&[_]u8{ 0x8B, R });
+                    self.code.appendSliceAssumeCapacity(&[_]u8{ 0x8B, R });
                 },
                 .memory => |x| {
                     if (reg.size() != 64) {
@@ -662,14 +779,14 @@ const Function = struct {
                         // The SIB must be 0x25, to indicate a disp32 with no scaled index.
                         // 0b00RRR100, where RRR is the lower three bits of the register ID.
                         // The instruction is thus eight bytes; REX 0x8B 0b00RRR100 0x25 followed by a four-byte disp32.
-                        try self.REX(.{ .W = true, .B = reg.isExtended() });
-                        try self.code.resize(self.code.items.len + 7);
-                        const r = 0x04 | (@as(u8, reg.id() & 0b111) << 3);
-                        self.code.items[self.code.items.len - 7] = 0x8B;
-                        self.code.items[self.code.items.len - 6] = r;
-                        self.code.items[self.code.items.len - 5] = 0x25;
-                        const imm_ptr = self.code.items[self.code.items.len - 4 ..][0..4];
-                        mem.writeIntLittle(u32, imm_ptr, @intCast(u32, x));
+                        try self.code.ensureCapacity(self.code.items.len + 8);
+                        self.rex(.{ .w = true, .b = reg.isExtended() });
+                        self.code.appendSliceAssumeCapacity(&[_]u8{
+                            0x8B,
+                            0x04 | (@as(u8, reg.id() & 0b111) << 3), // R
+                            0x25,
+                        });
+                        mem.writeIntLittle(u32, self.code.addManyAsArrayAssumeCapacity(4), @intCast(u32, x));
                     } else {
                         // If this is RAX, we can use a direct load; otherwise, we need to load the address, then indirectly load
                         // the value.
@@ -700,15 +817,15 @@ const Function = struct {
                             // Currently, we're only allowing 64-bit registers, so we need the `REX.W 8B /r` variant.
                             // TODO: determine whether to allow other sized registers, and if so, handle them properly.
                             // This operation requires three bytes: REX 0x8B R/M
-                            //
+                            try self.code.ensureCapacity(self.code.items.len + 3);
                             // For this operation, we want R/M mode *zero* (use register indirectly), and the two register
                             // values must match. Thus, it's 00ABCABC where ABC is the lower three bits of the register ID.
                             //
                             // Furthermore, if this is an extended register, both B and R must be set in the REX byte, as *both*
                             // register operands need to be marked as extended.
-                            try self.REX(.{ .W = true, .B = reg.isExtended(), .R = reg.isExtended() });
+                            self.rex(.{ .w = true, .b = reg.isExtended(), .r = reg.isExtended() });
                             const RM = (@as(u8, reg.id() & 0b111) << 3) | @truncate(u3, reg.id());
-                            try self.code.appendSlice(&[_]u8{ 0x8B, RM });
+                            self.code.appendSliceAssumeCapacity(&[_]u8{ 0x8B, RM });
                         }
                     }
                 },
@@ -731,36 +848,40 @@ const Function = struct {
     }
 
     fn resolveInst(self: *Function, inst: *ir.Inst) !MCValue {
-        if (self.inst_table.get(inst)) |mcv| {
-            return mcv;
-        }
         // Constants have static lifetimes, so they are always memoized in the outer most table.
         if (inst.cast(ir.Inst.Constant)) |const_inst| {
             const branch = &self.branch_stack.items[0];
-            const gop = try branch.inst_table.getOrPut(inst);
+            const gop = try branch.inst_table.getOrPut(self.gpa, inst);
             if (!gop.found_existing) {
                 const mcv = try self.genTypedValue(inst.src, .{ .ty = inst.ty, .val = const_inst.val });
-                try branch.inst_table.putNoClobber(inst, mcv);
-                gop.kv.value = mcv;
+                try branch.inst_table.putNoClobber(self.gpa, inst, mcv);
+                gop.entry.value = mcv;
                 return mcv;
             }
-            return gop.kv.value;
+            return gop.entry.value;
         }
 
         // Treat each stack item as a "layer" on top of the previous one.
         var i: usize = self.branch_stack.items.len;
         while (true) {
             i -= 1;
-            if (self.branch_stack.items[i].inst_table.getValue(inst)) |mcv| {
+            if (self.branch_stack.items[i].inst_table.get(inst)) |mcv| {
                 return mcv;
             }
         }
     }
 
+    fn resolveInstImmOrReg(self: *Function, inst: *ir.Inst) !MCValue {
+        return self.fail(inst.src, "TODO implement resolveInstImmOrReg", .{});
+    }
+
+    fn copyToNewRegister(self: *Function, src: usize, mcv: MCValue) !MCValue {
+        return self.fail(src, "TODO implement copyToNewRegister", .{});
+    }
+
     fn genTypedValue(self: *Function, src: usize, typed_value: TypedValue) !MCValue {
         const ptr_bits = self.target.cpu.arch.ptrBitWidth();
         const ptr_bytes: u64 = @divExact(ptr_bits, 8);
-        const allocator = self.code.allocator;
         switch (typed_value.ty.zigTypeTag()) {
             .Pointer => {
                 if (typed_value.val.cast(Value.Payload.DeclRef)) |payload| {
@@ -787,7 +908,7 @@ const Function = struct {
     fn fail(self: *Function, src: usize, comptime format: []const u8, args: var) error{ CodegenFail, OutOfMemory } {
         @setCold(true);
         assert(self.err_msg == null);
-        self.err_msg = try ErrorMsg.create(self.code.allocator, src, format, args);
+        self.err_msg = try ErrorMsg.create(self.bin_file.allocator, src, format, args);
         return error.CodegenFail;
     }
 };
src-self-hosted/ir.zig
@@ -2,6 +2,7 @@ const std = @import("std");
 const Value = @import("value.zig").Value;
 const Type = @import("type.zig").Type;
 const Module = @import("Module.zig");
+const assert = std.debug.assert;
 
 /// These are in-memory, analyzed instructions. See `zir.Inst` for the representation
 /// of instructions that correspond to the ZIR text format.
@@ -12,18 +13,28 @@ pub const Inst = struct {
     tag: Tag,
     /// Each bit represents the index of an `Inst` parameter in the `args` field.
     /// If a bit is set, it marks the end of the lifetime of the corresponding 
-    /// instruction parameter. For example, 0b00000101 means that the first and
+    /// instruction parameter. For example, 0b000_00101 means that the first and
     /// third `Inst` parameters' lifetimes end after this instruction, and will
     /// not have any more following references.
     /// The most significant bit being set means that the instruction itself is
     /// never referenced, in other words its lifetime ends as soon as it finishes.
-    /// If the byte is `0xff`, it means this is a special case and this data is
-    /// encoded elsewhere.
-    deaths: u8 = 0xff,
+    /// If bit 7 (0b1xxx_xxxx) is set, it means this instruction itself is unreferenced.
+    /// If bit 6 (0bx1xx_xxxx) is set, it means this is a special case and the
+    /// lifetimes of operands are encoded elsewhere.
+    deaths: u8 = undefined,
     ty: Type,
     /// Byte offset into the source.
     src: usize,
 
+    pub fn isUnused(self: Inst) bool {
+        return (self.deaths & 0b1000_0000) != 0;
+    }
+
+    pub fn operandDies(self: Inst, index: u3) bool {
+        assert(index < 6);
+        return @truncate(u1, self.deaths << index) != 0;
+    }
+
     pub const Tag = enum {
         add,
         arg,
@@ -240,4 +251,4 @@ pub const Inst = struct {
 
 pub const Body = struct {
     instructions: []*Inst,
-};
\ No newline at end of file
+};
src-self-hosted/link.zig
@@ -1007,7 +1007,7 @@ pub const ElfFile = struct {
             .appended => code_buffer.items,
             .fail => |em| {
                 decl.analysis = .codegen_failure;
-                _ = try module.failed_decls.put(decl, em);
+                _ = try module.failed_decls.put(module.gpa, decl, em);
                 return;
             },
         };
@@ -1093,7 +1093,7 @@ pub const ElfFile = struct {
         for (exports) |exp| {
             if (exp.options.section) |section_name| {
                 if (!mem.eql(u8, section_name, ".text")) {
-                    try module.failed_exports.ensureCapacity(module.failed_exports.items().len + 1);
+                    try module.failed_exports.ensureCapacity(module.gpa, module.failed_exports.items().len + 1);
                     module.failed_exports.putAssumeCapacityNoClobber(
                         exp,
                         try Module.ErrorMsg.create(self.allocator, 0, "Unimplemented: ExportOptions.section", .{}),
@@ -1111,7 +1111,7 @@ pub const ElfFile = struct {
                 },
                 .Weak => elf.STB_WEAK,
                 .LinkOnce => {
-                    try module.failed_exports.ensureCapacity(module.failed_exports.items().len + 1);
+                    try module.failed_exports.ensureCapacity(module.gpa, module.failed_exports.items().len + 1);
                     module.failed_exports.putAssumeCapacityNoClobber(
                         exp,
                         try Module.ErrorMsg.create(self.allocator, 0, "Unimplemented: GlobalLinkage.LinkOnce", .{}),
src-self-hosted/liveness.zig
@@ -123,7 +123,7 @@ fn analyzeInst(arena: *std.mem.Allocator, table: *std.AutoHashMap(*ir.Inst, void
             if (arg_index >= 6) {
                 @compileError("out of bits to mark deaths of operands");
             }
-            const prev = try table.put(@field(inst.args, field.name), {});
+            const prev = try table.fetchPut(@field(inst.args, field.name), {});
             if (prev == null) {
                 // Death.
                 inst.base.deaths |= 1 << arg_index;
@@ -131,4 +131,4 @@ fn analyzeInst(arena: *std.mem.Allocator, table: *std.AutoHashMap(*ir.Inst, void
             arg_index += 1;
         }
     }
-}
\ No newline at end of file
+}
src-self-hosted/main.zig
@@ -502,7 +502,7 @@ fn updateModule(gpa: *Allocator, module: *Module, zir_out_path: ?[]const u8) !vo
     const update_nanos = timer.read();
 
     var errors = try module.getAllErrorsAlloc();
-    defer errors.deinit(module.allocator);
+    defer errors.deinit(module.gpa);
 
     if (errors.list.len != 0) {
         for (errors.list) |full_err_msg| {
src-self-hosted/Module.zig
@@ -20,8 +20,8 @@ const ast = std.zig.ast;
 const trace = @import("tracy.zig").trace;
 const liveness = @import("liveness.zig");
 
-/// General-purpose allocator.
-allocator: *Allocator,
+/// General-purpose allocator. Used for both temporary and long-term storage.
+gpa: *Allocator,
 /// Pointer to externally managed resource.
 root_pkg: *Package,
 /// Module owns this resource.
@@ -33,7 +33,7 @@ bin_file_path: []const u8,
 /// It's rare for a decl to be exported, so we save memory by having a sparse map of
 /// Decl pointers to details about them being exported.
 /// The Export memory is owned by the `export_owners` table; the slice itself is owned by this table.
-decl_exports: std.AutoHashMap(*Decl, []*Export),
+decl_exports: std.AutoHashMapUnmanaged(*Decl, []*Export) = .{},
 /// We track which export is associated with the given symbol name for quick
 /// detection of symbol collisions.
 symbol_exports: std.StringHashMap(*Export),
@@ -41,9 +41,9 @@ symbol_exports: std.StringHashMap(*Export),
 /// is modified. Note that the key of this table is not the Decl being exported, but the Decl that
 /// is performing the export of another Decl.
 /// This table owns the Export memory.
-export_owners: std.AutoHashMap(*Decl, []*Export),
+export_owners: std.AutoHashMapUnmanaged(*Decl, []*Export) = .{},
 /// Maps fully qualified namespaced names to the Decl struct for them.
-decl_table: DeclTable,
+decl_table: std.HashMapUnmanaged(Scope.NameHash, *Decl, Scope.name_hash_hash, Scope.name_hash_eql, false) = .{},
 
 optimize_mode: std.builtin.Mode,
 link_error_flags: link.ElfFile.ErrorFlags = .{},
@@ -55,13 +55,13 @@ work_queue: std.fifo.LinearFifo(WorkItem, .Dynamic),
 /// The ErrorMsg memory is owned by the decl, using Module's allocator.
 /// Note that a Decl can succeed but the Fn it represents can fail. In this case,
 /// a Decl can have a failed_decls entry but have analysis status of success.
-failed_decls: std.AutoHashMap(*Decl, *ErrorMsg),
+failed_decls: std.AutoHashMapUnmanaged(*Decl, *ErrorMsg) = .{},
 /// Using a map here for consistency with the other fields here.
 /// The ErrorMsg memory is owned by the `Scope`, using Module's allocator.
-failed_files: std.AutoHashMap(*Scope, *ErrorMsg),
+failed_files: std.AutoHashMapUnmanaged(*Scope, *ErrorMsg) = .{},
 /// Using a map here for consistency with the other fields here.
 /// The ErrorMsg memory is owned by the `Export`, using Module's allocator.
-failed_exports: std.AutoHashMap(*Export, *ErrorMsg),
+failed_exports: std.AutoHashMapUnmanaged(*Export, *ErrorMsg) = .{},
 
 /// Incrementing integer used to compare against the corresponding Decl
 /// field to determine whether a Decl's status applies to an ongoing update, or a
@@ -76,8 +76,6 @@ deletion_set: std.ArrayListUnmanaged(*Decl) = .{},
 
 keep_source_files_loaded: bool,
 
-const DeclTable = std.HashMap(Scope.NameHash, *Decl, Scope.name_hash_hash, Scope.name_hash_eql, false);
-
 const WorkItem = union(enum) {
     /// Write the machine code for a Decl to the output file.
     codegen_decl: *Decl,
@@ -176,19 +174,23 @@ pub const Decl = struct {
 
     /// The shallow set of other decls whose typed_value could possibly change if this Decl's
     /// typed_value is modified.
-    dependants: ArrayListUnmanaged(*Decl) = ArrayListUnmanaged(*Decl){},
+    dependants: DepsTable = .{},
     /// The shallow set of other decls whose typed_value changing indicates that this Decl's
     /// typed_value may need to be regenerated.
-    dependencies: ArrayListUnmanaged(*Decl) = ArrayListUnmanaged(*Decl){},
+    dependencies: DepsTable = .{},
+
+    /// The reason this is not `std.AutoHashMapUnmanaged` is a workaround for
+    /// stage1 compiler giving me: `error: struct 'Module.Decl' depends on itself`
+    pub const DepsTable = std.HashMapUnmanaged(*Decl, void, std.hash_map.getAutoHashFn(*Decl), std.hash_map.getAutoEqlFn(*Decl), false);
 
-    pub fn destroy(self: *Decl, allocator: *Allocator) void {
-        allocator.free(mem.spanZ(self.name));
+    pub fn destroy(self: *Decl, gpa: *Allocator) void {
+        gpa.free(mem.spanZ(self.name));
         if (self.typedValueManaged()) |tvm| {
-            tvm.deinit(allocator);
+            tvm.deinit(gpa);
         }
-        self.dependants.deinit(allocator);
-        self.dependencies.deinit(allocator);
-        allocator.destroy(self);
+        self.dependants.deinit(gpa);
+        self.dependencies.deinit(gpa);
+        gpa.destroy(self);
     }
 
     pub fn src(self: Decl) usize {
@@ -247,23 +249,11 @@ pub const Decl = struct {
     }
 
     fn removeDependant(self: *Decl, other: *Decl) void {
-        for (self.dependants.items) |item, i| {
-            if (item == other) {
-                _ = self.dependants.swapRemove(i);
-                return;
-            }
-        }
-        unreachable;
+        self.dependants.removeAssertDiscard(other);
     }
 
     fn removeDependency(self: *Decl, other: *Decl) void {
-        for (self.dependencies.items) |item, i| {
-            if (item == other) {
-                _ = self.dependencies.swapRemove(i);
-                return;
-            }
-        }
-        unreachable;
+        self.dependencies.removeAssertDiscard(other);
     }
 };
 
@@ -390,10 +380,10 @@ pub const Scope = struct {
         }
     }
 
-    pub fn unload(base: *Scope, allocator: *Allocator) void {
+    pub fn unload(base: *Scope, gpa: *Allocator) void {
         switch (base.tag) {
-            .file => return @fieldParentPtr(File, "base", base).unload(allocator),
-            .zir_module => return @fieldParentPtr(ZIRModule, "base", base).unload(allocator),
+            .file => return @fieldParentPtr(File, "base", base).unload(gpa),
+            .zir_module => return @fieldParentPtr(ZIRModule, "base", base).unload(gpa),
             .block => unreachable,
             .gen_zir => unreachable,
             .decl => unreachable,
@@ -422,17 +412,17 @@ pub const Scope = struct {
     }
 
     /// Asserts the scope is a File or ZIRModule and deinitializes it, then deallocates it.
-    pub fn destroy(base: *Scope, allocator: *Allocator) void {
+    pub fn destroy(base: *Scope, gpa: *Allocator) void {
         switch (base.tag) {
             .file => {
                 const scope_file = @fieldParentPtr(File, "base", base);
-                scope_file.deinit(allocator);
-                allocator.destroy(scope_file);
+                scope_file.deinit(gpa);
+                gpa.destroy(scope_file);
             },
             .zir_module => {
                 const scope_zir_module = @fieldParentPtr(ZIRModule, "base", base);
-                scope_zir_module.deinit(allocator);
-                allocator.destroy(scope_zir_module);
+                scope_zir_module.deinit(gpa);
+                gpa.destroy(scope_zir_module);
             },
             .block => unreachable,
             .gen_zir => unreachable,
@@ -483,7 +473,7 @@ pub const Scope = struct {
         /// Direct children of the file.
         decls: ArrayListUnmanaged(*Decl),
 
-        pub fn unload(self: *File, allocator: *Allocator) void {
+        pub fn unload(self: *File, gpa: *Allocator) void {
             switch (self.status) {
                 .never_loaded,
                 .unloaded_parse_failure,
@@ -497,16 +487,16 @@ pub const Scope = struct {
             }
             switch (self.source) {
                 .bytes => |bytes| {
-                    allocator.free(bytes);
+                    gpa.free(bytes);
                     self.source = .{ .unloaded = {} };
                 },
                 .unloaded => {},
             }
         }
 
-        pub fn deinit(self: *File, allocator: *Allocator) void {
-            self.decls.deinit(allocator);
-            self.unload(allocator);
+        pub fn deinit(self: *File, gpa: *Allocator) void {
+            self.decls.deinit(gpa);
+            self.unload(gpa);
             self.* = undefined;
         }
 
@@ -528,7 +518,7 @@ pub const Scope = struct {
             switch (self.source) {
                 .unloaded => {
                     const source = try module.root_pkg.root_src_dir.readFileAllocOptions(
-                        module.allocator,
+                        module.gpa,
                         self.sub_file_path,
                         std.math.maxInt(u32),
                         1,
@@ -576,7 +566,7 @@ pub const Scope = struct {
         /// not this one.
         decls: ArrayListUnmanaged(*Decl),
 
-        pub fn unload(self: *ZIRModule, allocator: *Allocator) void {
+        pub fn unload(self: *ZIRModule, gpa: *Allocator) void {
             switch (self.status) {
                 .never_loaded,
                 .unloaded_parse_failure,
@@ -585,30 +575,30 @@ pub const Scope = struct {
                 => {},
 
                 .loaded_success => {
-                    self.contents.module.deinit(allocator);
-                    allocator.destroy(self.contents.module);
+                    self.contents.module.deinit(gpa);
+                    gpa.destroy(self.contents.module);
                     self.contents = .{ .not_available = {} };
                     self.status = .unloaded_success;
                 },
                 .loaded_sema_failure => {
-                    self.contents.module.deinit(allocator);
-                    allocator.destroy(self.contents.module);
+                    self.contents.module.deinit(gpa);
+                    gpa.destroy(self.contents.module);
                     self.contents = .{ .not_available = {} };
                     self.status = .unloaded_sema_failure;
                 },
             }
             switch (self.source) {
                 .bytes => |bytes| {
-                    allocator.free(bytes);
+                    gpa.free(bytes);
                     self.source = .{ .unloaded = {} };
                 },
                 .unloaded => {},
             }
         }
 
-        pub fn deinit(self: *ZIRModule, allocator: *Allocator) void {
-            self.decls.deinit(allocator);
-            self.unload(allocator);
+        pub fn deinit(self: *ZIRModule, gpa: *Allocator) void {
+            self.decls.deinit(gpa);
+            self.unload(gpa);
             self.* = undefined;
         }
 
@@ -630,7 +620,7 @@ pub const Scope = struct {
             switch (self.source) {
                 .unloaded => {
                     const source = try module.root_pkg.root_src_dir.readFileAllocOptions(
-                        module.allocator,
+                        module.gpa,
                         self.sub_file_path,
                         std.math.maxInt(u32),
                         1,
@@ -701,8 +691,8 @@ pub const AllErrors = struct {
         msg: []const u8,
     };
 
-    pub fn deinit(self: *AllErrors, allocator: *Allocator) void {
-        self.arena.promote(allocator).deinit();
+    pub fn deinit(self: *AllErrors, gpa: *Allocator) void {
+        self.arena.promote(gpa).deinit();
     }
 
     fn add(
@@ -772,20 +762,14 @@ pub fn init(gpa: *Allocator, options: InitOptions) !Module {
     };
 
     return Module{
-        .allocator = gpa,
+        .gpa = gpa,
         .root_pkg = options.root_pkg,
         .root_scope = root_scope,
         .bin_file_dir = bin_file_dir,
         .bin_file_path = options.bin_file_path,
         .bin_file = bin_file,
         .optimize_mode = options.optimize_mode,
-        .decl_table = DeclTable.init(gpa),
-        .decl_exports = std.AutoHashMap(*Decl, []*Export).init(gpa),
         .symbol_exports = std.StringHashMap(*Export).init(gpa),
-        .export_owners = std.AutoHashMap(*Decl, []*Export).init(gpa),
-        .failed_decls = std.AutoHashMap(*Decl, *ErrorMsg).init(gpa),
-        .failed_files = std.AutoHashMap(*Scope, *ErrorMsg).init(gpa),
-        .failed_exports = std.AutoHashMap(*Export, *ErrorMsg).init(gpa),
         .work_queue = std.fifo.LinearFifo(WorkItem, .Dynamic).init(gpa),
         .keep_source_files_loaded = options.keep_source_files_loaded,
     };
@@ -793,51 +777,51 @@ pub fn init(gpa: *Allocator, options: InitOptions) !Module {
 
 pub fn deinit(self: *Module) void {
     self.bin_file.deinit();
-    const allocator = self.allocator;
-    self.deletion_set.deinit(allocator);
+    const gpa = self.gpa;
+    self.deletion_set.deinit(gpa);
     self.work_queue.deinit();
 
     for (self.decl_table.items()) |entry| {
-        entry.value.destroy(allocator);
+        entry.value.destroy(gpa);
     }
-    self.decl_table.deinit();
+    self.decl_table.deinit(gpa);
 
     for (self.failed_decls.items()) |entry| {
-        entry.value.destroy(allocator);
+        entry.value.destroy(gpa);
     }
-    self.failed_decls.deinit();
+    self.failed_decls.deinit(gpa);
 
     for (self.failed_files.items()) |entry| {
-        entry.value.destroy(allocator);
+        entry.value.destroy(gpa);
     }
-    self.failed_files.deinit();
+    self.failed_files.deinit(gpa);
 
     for (self.failed_exports.items()) |entry| {
-        entry.value.destroy(allocator);
+        entry.value.destroy(gpa);
     }
-    self.failed_exports.deinit();
+    self.failed_exports.deinit(gpa);
 
     for (self.decl_exports.items()) |entry| {
         const export_list = entry.value;
-        allocator.free(export_list);
+        gpa.free(export_list);
     }
-    self.decl_exports.deinit();
+    self.decl_exports.deinit(gpa);
 
     for (self.export_owners.items()) |entry| {
-        freeExportList(allocator, entry.value);
+        freeExportList(gpa, entry.value);
     }
-    self.export_owners.deinit();
+    self.export_owners.deinit(gpa);
 
     self.symbol_exports.deinit();
-    self.root_scope.destroy(allocator);
+    self.root_scope.destroy(gpa);
     self.* = undefined;
 }
 
-fn freeExportList(allocator: *Allocator, export_list: []*Export) void {
+fn freeExportList(gpa: *Allocator, export_list: []*Export) void {
     for (export_list) |exp| {
-        allocator.destroy(exp);
+        gpa.destroy(exp);
     }
-    allocator.free(export_list);
+    gpa.free(export_list);
 }
 
 pub fn target(self: Module) std.Target {
@@ -855,7 +839,7 @@ pub fn update(self: *Module) !void {
     // Until then we simulate a full cache miss. Source files could have been loaded for any reason;
     // to force a refresh we unload now.
     if (self.root_scope.cast(Scope.File)) |zig_file| {
-        zig_file.unload(self.allocator);
+        zig_file.unload(self.gpa);
         self.analyzeRootSrcFile(zig_file) catch |err| switch (err) {
             error.AnalysisFail => {
                 assert(self.totalErrorCount() != 0);
@@ -863,7 +847,7 @@ pub fn update(self: *Module) !void {
             else => |e| return e,
         };
     } else if (self.root_scope.cast(Scope.ZIRModule)) |zir_module| {
-        zir_module.unload(self.allocator);
+        zir_module.unload(self.gpa);
         self.analyzeRootZIRModule(zir_module) catch |err| switch (err) {
             error.AnalysisFail => {
                 assert(self.totalErrorCount() != 0);
@@ -876,7 +860,7 @@ pub fn update(self: *Module) !void {
 
     // Process the deletion set.
     while (self.deletion_set.popOrNull()) |decl| {
-        if (decl.dependants.items.len != 0) {
+        if (decl.dependants.items().len != 0) {
             decl.deletion_flag = false;
             continue;
         }
@@ -889,7 +873,7 @@ pub fn update(self: *Module) !void {
     // to report error messages. Otherwise we unload all source files to save memory.
     if (self.totalErrorCount() == 0) {
         if (!self.keep_source_files_loaded) {
-            self.root_scope.unload(self.allocator);
+            self.root_scope.unload(self.gpa);
         }
         try self.bin_file.flush();
     }
@@ -915,10 +899,10 @@ pub fn totalErrorCount(self: *Module) usize {
 }
 
 pub fn getAllErrorsAlloc(self: *Module) !AllErrors {
-    var arena = std.heap.ArenaAllocator.init(self.allocator);
+    var arena = std.heap.ArenaAllocator.init(self.gpa);
     errdefer arena.deinit();
 
-    var errors = std.ArrayList(AllErrors.Message).init(self.allocator);
+    var errors = std.ArrayList(AllErrors.Message).init(self.gpa);
     defer errors.deinit();
 
     for (self.failed_files.items()) |entry| {
@@ -989,9 +973,9 @@ pub fn performAllTheWork(self: *Module) error{OutOfMemory}!void {
                     }
                     // Here we tack on additional allocations to the Decl's arena. The allocations are
                     // lifetime annotations in the ZIR.
-                    var decl_arena = decl.typed_value.most_recent.arena.?.promote(self.allocator);
+                    var decl_arena = decl.typed_value.most_recent.arena.?.promote(self.gpa);
                     defer decl.typed_value.most_recent.arena.?.* = decl_arena.state;
-                    try liveness.analyze(self.allocator, &decl_arena.allocator, payload.func.analysis.success);
+                    try liveness.analyze(self.gpa, &decl_arena.allocator, payload.func.analysis.success);
                 }
 
                 assert(decl.typed_value.most_recent.typed_value.ty.hasCodeGenBits());
@@ -1002,9 +986,9 @@ pub fn performAllTheWork(self: *Module) error{OutOfMemory}!void {
                         decl.analysis = .dependency_failure;
                     },
                     else => {
-                        try self.failed_decls.ensureCapacity(self.failed_decls.items().len + 1);
+                        try self.failed_decls.ensureCapacity(self.gpa, self.failed_decls.items().len + 1);
                         self.failed_decls.putAssumeCapacityNoClobber(decl, try ErrorMsg.create(
-                            self.allocator,
+                            self.gpa,
                             decl.src(),
                             "unable to codegen: {}",
                             .{@errorName(err)},
@@ -1048,16 +1032,17 @@ fn ensureDeclAnalyzed(self: *Module, decl: *Decl) InnerError!void {
             // prior to re-analysis.
             self.deleteDeclExports(decl);
             // Dependencies will be re-discovered, so we remove them here prior to re-analysis.
-            for (decl.dependencies.items) |dep| {
+            for (decl.dependencies.items()) |entry| {
+                const dep = entry.key;
                 dep.removeDependant(decl);
-                if (dep.dependants.items.len == 0 and !dep.deletion_flag) {
+                if (dep.dependants.items().len == 0 and !dep.deletion_flag) {
                     // We don't perform a deletion here, because this Decl or another one
                     // may end up referencing it before the update is complete.
                     dep.deletion_flag = true;
-                    try self.deletion_set.append(self.allocator, dep);
+                    try self.deletion_set.append(self.gpa, dep);
                 }
             }
-            decl.dependencies.shrink(self.allocator, 0);
+            decl.dependencies.clearRetainingCapacity();
 
             break :blk true;
         },
@@ -1072,9 +1057,9 @@ fn ensureDeclAnalyzed(self: *Module, decl: *Decl) InnerError!void {
             error.OutOfMemory => return error.OutOfMemory,
             error.AnalysisFail => return error.AnalysisFail,
             else => {
-                try self.failed_decls.ensureCapacity(self.failed_decls.items().len + 1);
+                try self.failed_decls.ensureCapacity(self.gpa, self.failed_decls.items().len + 1);
                 self.failed_decls.putAssumeCapacityNoClobber(decl, try ErrorMsg.create(
-                    self.allocator,
+                    self.gpa,
                     decl.src(),
                     "unable to analyze: {}",
                     .{@errorName(err)},
@@ -1088,7 +1073,8 @@ fn ensureDeclAnalyzed(self: *Module, decl: *Decl) InnerError!void {
         // We may need to chase the dependants and re-analyze them.
         // However, if the decl is a function, and the type is the same, we do not need to.
         if (type_changed or decl.typed_value.most_recent.typed_value.val.tag() != .function) {
-            for (decl.dependants.items) |dep| {
+            for (decl.dependants.items()) |entry| {
+                const dep = entry.key;
                 switch (dep.analysis) {
                     .unreferenced => unreachable,
                     .in_progress => unreachable,
@@ -1127,8 +1113,8 @@ fn astGenAndAnalyzeDecl(self: *Module, decl: *Decl) !bool {
             // to complete the Decl analysis.
             var fn_type_scope: Scope.GenZIR = .{
                 .decl = decl,
-                .arena = std.heap.ArenaAllocator.init(self.allocator),
-                .instructions = std.ArrayList(*zir.Inst).init(self.allocator),
+                .arena = std.heap.ArenaAllocator.init(self.gpa),
+                .instructions = std.ArrayList(*zir.Inst).init(self.gpa),
             };
             defer fn_type_scope.arena.deinit();
             defer fn_type_scope.instructions.deinit();
@@ -1178,7 +1164,7 @@ fn astGenAndAnalyzeDecl(self: *Module, decl: *Decl) !bool {
             _ = try self.addZIRInst(&fn_type_scope.base, fn_src, zir.Inst.Return, .{ .operand = fn_type_inst }, .{});
 
             // We need the memory for the Type to go into the arena for the Decl
-            var decl_arena = std.heap.ArenaAllocator.init(self.allocator);
+            var decl_arena = std.heap.ArenaAllocator.init(self.gpa);
             errdefer decl_arena.deinit();
             const decl_arena_state = try decl_arena.allocator.create(std.heap.ArenaAllocator.State);
 
@@ -1189,7 +1175,7 @@ fn astGenAndAnalyzeDecl(self: *Module, decl: *Decl) !bool {
                 .instructions = .{},
                 .arena = &decl_arena.allocator,
             };
-            defer block_scope.instructions.deinit(self.allocator);
+            defer block_scope.instructions.deinit(self.gpa);
 
             const fn_type = try self.analyzeBodyValueAsType(&block_scope, .{
                 .instructions = fn_type_scope.instructions.items,
@@ -1202,8 +1188,8 @@ fn astGenAndAnalyzeDecl(self: *Module, decl: *Decl) !bool {
                 // pass completes, and semantic analysis of it completes.
                 var gen_scope: Scope.GenZIR = .{
                     .decl = decl,
-                    .arena = std.heap.ArenaAllocator.init(self.allocator),
-                    .instructions = std.ArrayList(*zir.Inst).init(self.allocator),
+                    .arena = std.heap.ArenaAllocator.init(self.gpa),
+                    .instructions = std.ArrayList(*zir.Inst).init(self.gpa),
                 };
                 errdefer gen_scope.arena.deinit();
                 defer gen_scope.instructions.deinit();
@@ -1235,7 +1221,7 @@ fn astGenAndAnalyzeDecl(self: *Module, decl: *Decl) !bool {
                 prev_type_has_bits = tvm.typed_value.ty.hasCodeGenBits();
                 type_changed = !tvm.typed_value.ty.eql(fn_type);
 
-                tvm.deinit(self.allocator);
+                tvm.deinit(self.gpa);
             }
 
             decl_arena_state.* = decl_arena.state;
@@ -1626,40 +1612,31 @@ fn getSimplePrimitiveValue(name: []const u8) ?TypedValue {
 }
 
 fn declareDeclDependency(self: *Module, depender: *Decl, dependee: *Decl) !void {
-    try depender.dependencies.ensureCapacity(self.allocator, depender.dependencies.items.len + 1);
-    try dependee.dependants.ensureCapacity(self.allocator, dependee.dependants.items.len + 1);
-
-    for (depender.dependencies.items) |item| {
-        if (item == dependee) break; // Already in the set.
-    } else {
-        depender.dependencies.appendAssumeCapacity(dependee);
-    }
+    try depender.dependencies.ensureCapacity(self.gpa, depender.dependencies.items().len + 1);
+    try dependee.dependants.ensureCapacity(self.gpa, dependee.dependants.items().len + 1);
 
-    for (dependee.dependants.items) |item| {
-        if (item == depender) break; // Already in the set.
-    } else {
-        dependee.dependants.appendAssumeCapacity(depender);
-    }
+    depender.dependencies.putAssumeCapacity(dependee, {});
+    dependee.dependants.putAssumeCapacity(depender, {});
 }
 
 fn getSrcModule(self: *Module, root_scope: *Scope.ZIRModule) !*zir.Module {
     switch (root_scope.status) {
         .never_loaded, .unloaded_success => {
-            try self.failed_files.ensureCapacity(self.failed_files.items().len + 1);
+            try self.failed_files.ensureCapacity(self.gpa, self.failed_files.items().len + 1);
 
             const source = try root_scope.getSource(self);
 
             var keep_zir_module = false;
-            const zir_module = try self.allocator.create(zir.Module);
-            defer if (!keep_zir_module) self.allocator.destroy(zir_module);
+            const zir_module = try self.gpa.create(zir.Module);
+            defer if (!keep_zir_module) self.gpa.destroy(zir_module);
 
-            zir_module.* = try zir.parse(self.allocator, source);
-            defer if (!keep_zir_module) zir_module.deinit(self.allocator);
+            zir_module.* = try zir.parse(self.gpa, source);
+            defer if (!keep_zir_module) zir_module.deinit(self.gpa);
 
             if (zir_module.error_msg) |src_err_msg| {
                 self.failed_files.putAssumeCapacityNoClobber(
                     &root_scope.base,
-                    try ErrorMsg.create(self.allocator, src_err_msg.byte_offset, "{}", .{src_err_msg.msg}),
+                    try ErrorMsg.create(self.gpa, src_err_msg.byte_offset, "{}", .{src_err_msg.msg}),
                 );
                 root_scope.status = .unloaded_parse_failure;
                 return error.AnalysisFail;
@@ -1686,22 +1663,22 @@ fn getAstTree(self: *Module, root_scope: *Scope.File) !*ast.Tree {
 
     switch (root_scope.status) {
         .never_loaded, .unloaded_success => {
-            try self.failed_files.ensureCapacity(self.failed_files.items().len + 1);
+            try self.failed_files.ensureCapacity(self.gpa, self.failed_files.items().len + 1);
 
             const source = try root_scope.getSource(self);
 
             var keep_tree = false;
-            const tree = try std.zig.parse(self.allocator, source);
+            const tree = try std.zig.parse(self.gpa, source);
             defer if (!keep_tree) tree.deinit();
 
             if (tree.errors.len != 0) {
                 const parse_err = tree.errors[0];
 
-                var msg = std.ArrayList(u8).init(self.allocator);
+                var msg = std.ArrayList(u8).init(self.gpa);
                 defer msg.deinit();
 
                 try parse_err.render(tree.token_ids, msg.outStream());
-                const err_msg = try self.allocator.create(ErrorMsg);
+                const err_msg = try self.gpa.create(ErrorMsg);
                 err_msg.* = .{
                     .msg = msg.toOwnedSlice(),
                     .byte_offset = tree.token_locs[parse_err.loc()].start,
@@ -1732,11 +1709,11 @@ fn analyzeRootSrcFile(self: *Module, root_scope: *Scope.File) !void {
     const decls = tree.root_node.decls();
 
     try self.work_queue.ensureUnusedCapacity(decls.len);
-    try root_scope.decls.ensureCapacity(self.allocator, decls.len);
+    try root_scope.decls.ensureCapacity(self.gpa, decls.len);
 
     // Keep track of the decls that we expect to see in this file so that
     // we know which ones have been deleted.
-    var deleted_decls = std.AutoHashMap(*Decl, void).init(self.allocator);
+    var deleted_decls = std.AutoHashMap(*Decl, void).init(self.gpa);
     defer deleted_decls.deinit();
     try deleted_decls.ensureCapacity(root_scope.decls.items.len);
     for (root_scope.decls.items) |file_decl| {
@@ -1760,9 +1737,9 @@ fn analyzeRootSrcFile(self: *Module, root_scope: *Scope.File) !void {
                 decl.src_index = decl_i;
                 if (deleted_decls.remove(decl) == null) {
                     decl.analysis = .sema_failure;
-                    const err_msg = try ErrorMsg.create(self.allocator, tree.token_locs[name_tok].start, "redefinition of '{}'", .{decl.name});
-                    errdefer err_msg.destroy(self.allocator);
-                    try self.failed_decls.putNoClobber(decl, err_msg);
+                    const err_msg = try ErrorMsg.create(self.gpa, tree.token_locs[name_tok].start, "redefinition of '{}'", .{decl.name});
+                    errdefer err_msg.destroy(self.gpa);
+                    try self.failed_decls.putNoClobber(self.gpa, decl, err_msg);
                 } else {
                     if (!srcHashEql(decl.contents_hash, contents_hash)) {
                         try self.markOutdatedDecl(decl);
@@ -1796,14 +1773,14 @@ fn analyzeRootZIRModule(self: *Module, root_scope: *Scope.ZIRModule) !void {
     const src_module = try self.getSrcModule(root_scope);
 
     try self.work_queue.ensureUnusedCapacity(src_module.decls.len);
-    try root_scope.decls.ensureCapacity(self.allocator, src_module.decls.len);
+    try root_scope.decls.ensureCapacity(self.gpa, src_module.decls.len);
 
-    var exports_to_resolve = std.ArrayList(*zir.Decl).init(self.allocator);
+    var exports_to_resolve = std.ArrayList(*zir.Decl).init(self.gpa);
     defer exports_to_resolve.deinit();
 
     // Keep track of the decls that we expect to see in this file so that
     // we know which ones have been deleted.
-    var deleted_decls = std.AutoHashMap(*Decl, void).init(self.allocator);
+    var deleted_decls = std.AutoHashMap(*Decl, void).init(self.gpa);
     defer deleted_decls.deinit();
     try deleted_decls.ensureCapacity(self.decl_table.items().len);
     for (self.decl_table.items()) |entry| {
@@ -1845,7 +1822,7 @@ fn analyzeRootZIRModule(self: *Module, root_scope: *Scope.ZIRModule) !void {
 }
 
 fn deleteDecl(self: *Module, decl: *Decl) !void {
-    try self.deletion_set.ensureCapacity(self.allocator, self.deletion_set.items.len + decl.dependencies.items.len);
+    try self.deletion_set.ensureCapacity(self.gpa, self.deletion_set.items.len + decl.dependencies.items().len);
 
     // Remove from the namespace it resides in. In the case of an anonymous Decl it will
     // not be present in the set, and this does nothing.
@@ -1855,9 +1832,10 @@ fn deleteDecl(self: *Module, decl: *Decl) !void {
     const name_hash = decl.fullyQualifiedNameHash();
     self.decl_table.removeAssertDiscard(name_hash);
     // Remove itself from its dependencies, because we are about to destroy the decl pointer.
-    for (decl.dependencies.items) |dep| {
+    for (decl.dependencies.items()) |entry| {
+        const dep = entry.key;
         dep.removeDependant(decl);
-        if (dep.dependants.items.len == 0 and !dep.deletion_flag) {
+        if (dep.dependants.items().len == 0 and !dep.deletion_flag) {
             // We don't recursively perform a deletion here, because during the update,
             // another reference to it may turn up.
             dep.deletion_flag = true;
@@ -1865,7 +1843,8 @@ fn deleteDecl(self: *Module, decl: *Decl) !void {
         }
     }
     // Anything that depends on this deleted decl certainly needs to be re-analyzed.
-    for (decl.dependants.items) |dep| {
+    for (decl.dependants.items()) |entry| {
+        const dep = entry.key;
         dep.removeDependency(decl);
         if (dep.analysis != .outdated) {
             // TODO Move this failure possibility to the top of the function.
@@ -1873,11 +1852,11 @@ fn deleteDecl(self: *Module, decl: *Decl) !void {
         }
     }
     if (self.failed_decls.remove(decl)) |entry| {
-        entry.value.destroy(self.allocator);
+        entry.value.destroy(self.gpa);
     }
     self.deleteDeclExports(decl);
     self.bin_file.freeDecl(decl);
-    decl.destroy(self.allocator);
+    decl.destroy(self.gpa);
 }
 
 /// Delete all the Export objects that are caused by this Decl. Re-analysis of
@@ -1899,7 +1878,7 @@ fn deleteDeclExports(self: *Module, decl: *Decl) void {
                     i += 1;
                 }
             }
-            decl_exports_kv.value = self.allocator.shrink(list, new_len);
+            decl_exports_kv.value = self.gpa.shrink(list, new_len);
             if (new_len == 0) {
                 self.decl_exports.removeAssertDiscard(exp.exported_decl);
             }
@@ -1907,12 +1886,12 @@ fn deleteDeclExports(self: *Module, decl: *Decl) void {
 
         self.bin_file.deleteExport(exp.link);
         if (self.failed_exports.remove(exp)) |entry| {
-            entry.value.destroy(self.allocator);
+            entry.value.destroy(self.gpa);
         }
         _ = self.symbol_exports.remove(exp.options.name);
-        self.allocator.destroy(exp);
+        self.gpa.destroy(exp);
     }
-    self.allocator.free(kv.value);
+    self.gpa.free(kv.value);
 }
 
 fn analyzeFnBody(self: *Module, decl: *Decl, func: *Fn) !void {
@@ -1920,7 +1899,7 @@ fn analyzeFnBody(self: *Module, decl: *Decl, func: *Fn) !void {
     defer tracy.end();
 
     // Use the Decl's arena for function memory.
-    var arena = decl.typed_value.most_recent.arena.?.promote(self.allocator);
+    var arena = decl.typed_value.most_recent.arena.?.promote(self.gpa);
     defer decl.typed_value.most_recent.arena.?.* = arena.state;
     var inner_block: Scope.Block = .{
         .parent = null,
@@ -1929,10 +1908,10 @@ fn analyzeFnBody(self: *Module, decl: *Decl, func: *Fn) !void {
         .instructions = .{},
         .arena = &arena.allocator,
     };
-    defer inner_block.instructions.deinit(self.allocator);
+    defer inner_block.instructions.deinit(self.gpa);
 
     const fn_zir = func.analysis.queued;
-    defer fn_zir.arena.promote(self.allocator).deinit();
+    defer fn_zir.arena.promote(self.gpa).deinit();
     func.analysis = .{ .in_progress = {} };
     //std.debug.warn("set {} to in_progress\n", .{decl.name});
 
@@ -1947,7 +1926,7 @@ fn markOutdatedDecl(self: *Module, decl: *Decl) !void {
     //std.debug.warn("mark {} outdated\n", .{decl.name});
     try self.work_queue.writeItem(.{ .analyze_decl = decl });
     if (self.failed_decls.remove(decl)) |entry| {
-        entry.value.destroy(self.allocator);
+        entry.value.destroy(self.gpa);
     }
     decl.analysis = .outdated;
 }
@@ -1958,7 +1937,7 @@ fn allocateNewDecl(
     src_index: usize,
     contents_hash: std.zig.SrcHash,
 ) !*Decl {
-    const new_decl = try self.allocator.create(Decl);
+    const new_decl = try self.gpa.create(Decl);
     new_decl.* = .{
         .name = "",
         .scope = scope.namespace(),
@@ -1981,10 +1960,10 @@ fn createNewDecl(
     name_hash: Scope.NameHash,
     contents_hash: std.zig.SrcHash,
 ) !*Decl {
-    try self.decl_table.ensureCapacity(self.decl_table.items().len + 1);
+    try self.decl_table.ensureCapacity(self.gpa, self.decl_table.items().len + 1);
     const new_decl = try self.allocateNewDecl(scope, src_index, contents_hash);
-    errdefer self.allocator.destroy(new_decl);
-    new_decl.name = try mem.dupeZ(self.allocator, u8, decl_name);
+    errdefer self.gpa.destroy(new_decl);
+    new_decl.name = try mem.dupeZ(self.gpa, u8, decl_name);
     self.decl_table.putAssumeCapacityNoClobber(name_hash, new_decl);
     return new_decl;
 }
@@ -1992,7 +1971,7 @@ fn createNewDecl(
 fn analyzeZirDecl(self: *Module, decl: *Decl, src_decl: *zir.Decl) InnerError!bool {
     var decl_scope: Scope.DeclAnalysis = .{
         .decl = decl,
-        .arena = std.heap.ArenaAllocator.init(self.allocator),
+        .arena = std.heap.ArenaAllocator.init(self.gpa),
     };
     errdefer decl_scope.arena.deinit();
 
@@ -2008,7 +1987,7 @@ fn analyzeZirDecl(self: *Module, decl: *Decl, src_decl: *zir.Decl) InnerError!bo
         prev_type_has_bits = tvm.typed_value.ty.hasCodeGenBits();
         type_changed = !tvm.typed_value.ty.eql(typed_value.ty);
 
-        tvm.deinit(self.allocator);
+        tvm.deinit(self.gpa);
     }
 
     arena_state.* = decl_scope.arena.state;
@@ -2146,11 +2125,11 @@ fn analyzeExport(self: *Module, scope: *Scope, src: usize, symbol_name: []const
         else => return self.fail(scope, src, "unable to export type '{}'", .{typed_value.ty}),
     }
 
-    try self.decl_exports.ensureCapacity(self.decl_exports.items().len + 1);
-    try self.export_owners.ensureCapacity(self.export_owners.items().len + 1);
+    try self.decl_exports.ensureCapacity(self.gpa, self.decl_exports.items().len + 1);
+    try self.export_owners.ensureCapacity(self.gpa, self.export_owners.items().len + 1);
 
-    const new_export = try self.allocator.create(Export);
-    errdefer self.allocator.destroy(new_export);
+    const new_export = try self.gpa.create(Export);
+    errdefer self.gpa.destroy(new_export);
 
     const owner_decl = scope.decl().?;
 
@@ -2164,27 +2143,27 @@ fn analyzeExport(self: *Module, scope: *Scope, src: usize, symbol_name: []const
     };
 
     // Add to export_owners table.
-    const eo_gop = self.export_owners.getOrPut(owner_decl) catch unreachable;
+    const eo_gop = self.export_owners.getOrPut(self.gpa, owner_decl) catch unreachable;
     if (!eo_gop.found_existing) {
         eo_gop.entry.value = &[0]*Export{};
     }
-    eo_gop.entry.value = try self.allocator.realloc(eo_gop.entry.value, eo_gop.entry.value.len + 1);
+    eo_gop.entry.value = try self.gpa.realloc(eo_gop.entry.value, eo_gop.entry.value.len + 1);
     eo_gop.entry.value[eo_gop.entry.value.len - 1] = new_export;
-    errdefer eo_gop.entry.value = self.allocator.shrink(eo_gop.entry.value, eo_gop.entry.value.len - 1);
+    errdefer eo_gop.entry.value = self.gpa.shrink(eo_gop.entry.value, eo_gop.entry.value.len - 1);
 
     // Add to exported_decl table.
-    const de_gop = self.decl_exports.getOrPut(exported_decl) catch unreachable;
+    const de_gop = self.decl_exports.getOrPut(self.gpa, exported_decl) catch unreachable;
     if (!de_gop.found_existing) {
         de_gop.entry.value = &[0]*Export{};
     }
-    de_gop.entry.value = try self.allocator.realloc(de_gop.entry.value, de_gop.entry.value.len + 1);
+    de_gop.entry.value = try self.gpa.realloc(de_gop.entry.value, de_gop.entry.value.len + 1);
     de_gop.entry.value[de_gop.entry.value.len - 1] = new_export;
-    errdefer de_gop.entry.value = self.allocator.shrink(de_gop.entry.value, de_gop.entry.value.len - 1);
+    errdefer de_gop.entry.value = self.gpa.shrink(de_gop.entry.value, de_gop.entry.value.len - 1);
 
     if (self.symbol_exports.get(symbol_name)) |_| {
-        try self.failed_exports.ensureCapacity(self.failed_exports.items().len + 1);
+        try self.failed_exports.ensureCapacity(self.gpa, self.failed_exports.items().len + 1);
         self.failed_exports.putAssumeCapacityNoClobber(new_export, try ErrorMsg.create(
-            self.allocator,
+            self.gpa,
             src,
             "exported symbol collision: {}",
             .{symbol_name},
@@ -2198,9 +2177,9 @@ fn analyzeExport(self: *Module, scope: *Scope, src: usize, symbol_name: []const
     self.bin_file.updateDeclExports(self, exported_decl, de_gop.entry.value) catch |err| switch (err) {
         error.OutOfMemory => return error.OutOfMemory,
         else => {
-            try self.failed_exports.ensureCapacity(self.failed_exports.items().len + 1);
+            try self.failed_exports.ensureCapacity(self.gpa, self.failed_exports.items().len + 1);
             self.failed_exports.putAssumeCapacityNoClobber(new_export, try ErrorMsg.create(
-                self.allocator,
+                self.gpa,
                 src,
                 "unable to export: {}",
                 .{@errorName(err)},
@@ -2224,13 +2203,13 @@ fn addNewInstArgs(
 }
 
 fn newZIRInst(
-    allocator: *Allocator,
+    gpa: *Allocator,
     src: usize,
     comptime T: type,
     positionals: std.meta.fieldInfo(T, "positionals").field_type,
     kw_args: std.meta.fieldInfo(T, "kw_args").field_type,
 ) !*zir.Inst {
-    const inst = try allocator.create(T);
+    const inst = try gpa.create(T);
     inst.* = .{
         .base = .{
             .tag = T.base_tag,
@@ -2273,7 +2252,7 @@ fn addNewInst(self: *Module, block: *Scope.Block, src: usize, ty: Type, comptime
         },
         .args = undefined,
     };
-    try block.instructions.append(self.allocator, &inst.base);
+    try block.instructions.append(self.gpa, &inst.base);
     return inst;
 }
 
@@ -2433,7 +2412,7 @@ fn analyzeInst(self: *Module, scope: *Scope, old_inst: *zir.Inst) InnerError!*In
 fn analyzeInstStr(self: *Module, scope: *Scope, str_inst: *zir.Inst.Str) InnerError!*Inst {
     // The bytes references memory inside the ZIR module, which can get deallocated
     // after semantic analysis is complete. We need the memory to be in the new anonymous Decl's arena.
-    var new_decl_arena = std.heap.ArenaAllocator.init(self.allocator);
+    var new_decl_arena = std.heap.ArenaAllocator.init(self.gpa);
     const arena_bytes = try new_decl_arena.allocator.dupe(u8, str_inst.positionals.bytes);
 
     const ty_payload = try scope.arena().create(Type.Payload.Array_u8_Sentinel0);
@@ -2457,8 +2436,8 @@ fn createAnonymousDecl(
 ) !*Decl {
     const name_index = self.getNextAnonNameIndex();
     const scope_decl = scope.decl().?;
-    const name = try std.fmt.allocPrint(self.allocator, "{}${}", .{ scope_decl.name, name_index });
-    defer self.allocator.free(name);
+    const name = try std.fmt.allocPrint(self.gpa, "{}${}", .{ scope_decl.name, name_index });
+    defer self.gpa.free(name);
     const name_hash = scope.namespace().fullyQualifiedNameHash(name);
     const src_hash: std.zig.SrcHash = undefined;
     const new_decl = try self.createNewDecl(scope, name, scope_decl.src_index, name_hash, src_hash);
@@ -2554,8 +2533,8 @@ fn analyzeInstBlock(self: *Module, scope: *Scope, inst: *zir.Inst.Block) InnerEr
     };
     const label = &child_block.label.?;
 
-    defer child_block.instructions.deinit(self.allocator);
-    defer label.results.deinit(self.allocator);
+    defer child_block.instructions.deinit(self.gpa);
+    defer label.results.deinit(self.gpa);
 
     try self.analyzeBody(&child_block.base, inst.positionals.body);
 
@@ -2567,7 +2546,7 @@ fn analyzeInstBlock(self: *Module, scope: *Scope, inst: *zir.Inst.Block) InnerEr
         // No need to add the Block instruction; we can add the instructions to the parent block directly.
         // Blocks are terminated with a noreturn instruction which we do not want to include.
         const instrs = child_block.instructions.items;
-        try parent_block.instructions.appendSlice(self.allocator, instrs[0 .. instrs.len - 1]);
+        try parent_block.instructions.appendSlice(self.gpa, instrs[0 .. instrs.len - 1]);
         if (label.results.items.len == 1) {
             return label.results.items[0];
         } else {
@@ -2577,7 +2556,7 @@ fn analyzeInstBlock(self: *Module, scope: *Scope, inst: *zir.Inst.Block) InnerEr
 
     // Need to set the type and emit the Block instruction. This allows machine code generation
     // to emit a jump instruction to after the block when it encounters the break.
-    try parent_block.instructions.append(self.allocator, &block_inst.base);
+    try parent_block.instructions.append(self.gpa, &block_inst.base);
     block_inst.base.ty = try self.resolvePeerTypes(scope, label.results.items);
     block_inst.args.body = .{ .instructions = try parent_block.arena.dupe(*Inst, child_block.instructions.items) };
     return &block_inst.base;
@@ -2596,7 +2575,7 @@ fn analyzeInstBreakVoid(self: *Module, scope: *Scope, inst: *zir.Inst.BreakVoid)
     while (opt_block) |block| {
         if (block.label) |*label| {
             if (mem.eql(u8, label.name, label_name)) {
-                try label.results.append(self.allocator, void_inst);
+                try label.results.append(self.gpa, void_inst);
                 return self.constNoReturn(scope, inst.base.src);
             }
         }
@@ -2719,8 +2698,8 @@ fn analyzeInstCall(self: *Module, scope: *Scope, inst: *zir.Inst.Call) InnerErro
 
     // TODO handle function calls of generic functions
 
-    const fn_param_types = try self.allocator.alloc(Type, fn_params_len);
-    defer self.allocator.free(fn_param_types);
+    const fn_param_types = try self.gpa.alloc(Type, fn_params_len);
+    defer self.gpa.free(fn_param_types);
     func.ty.fnParamTypes(fn_param_types);
 
     const casted_args = try scope.arena().alloc(*Inst, fn_params_len);
@@ -2739,7 +2718,7 @@ fn analyzeInstCall(self: *Module, scope: *Scope, inst: *zir.Inst.Call) InnerErro
 fn analyzeInstFn(self: *Module, scope: *Scope, fn_inst: *zir.Inst.Fn) InnerError!*Inst {
     const fn_type = try self.resolveType(scope, fn_inst.positionals.fn_type);
     const fn_zir = blk: {
-        var fn_arena = std.heap.ArenaAllocator.init(self.allocator);
+        var fn_arena = std.heap.ArenaAllocator.init(self.gpa);
         errdefer fn_arena.deinit();
 
         const fn_zir = try scope.arena().create(Fn.ZIR);
@@ -3120,7 +3099,7 @@ fn analyzeInstCondBr(self: *Module, scope: *Scope, inst: *zir.Inst.CondBr) Inner
         .instructions = .{},
         .arena = parent_block.arena,
     };
-    defer true_block.instructions.deinit(self.allocator);
+    defer true_block.instructions.deinit(self.gpa);
     try self.analyzeBody(&true_block.base, inst.positionals.true_body);
 
     var false_block: Scope.Block = .{
@@ -3130,7 +3109,7 @@ fn analyzeInstCondBr(self: *Module, scope: *Scope, inst: *zir.Inst.CondBr) Inner
         .instructions = .{},
         .arena = parent_block.arena,
     };
-    defer false_block.instructions.deinit(self.allocator);
+    defer false_block.instructions.deinit(self.gpa);
     try self.analyzeBody(&false_block.base, inst.positionals.false_body);
 
     return self.addNewInstArgs(parent_block, inst.base.src, Type.initTag(.void), Inst.CondBr, Inst.Args(Inst.CondBr){
@@ -3284,7 +3263,7 @@ fn cmpNumeric(
             return self.constUndef(scope, src, Type.initTag(.bool));
         const is_unsigned = if (lhs_is_float) x: {
             var bigint_space: Value.BigIntSpace = undefined;
-            var bigint = try lhs_val.toBigInt(&bigint_space).toManaged(self.allocator);
+            var bigint = try lhs_val.toBigInt(&bigint_space).toManaged(self.gpa);
             defer bigint.deinit();
             const zcmp = lhs_val.orderAgainstZero();
             if (lhs_val.floatHasFraction()) {
@@ -3319,7 +3298,7 @@ fn cmpNumeric(
             return self.constUndef(scope, src, Type.initTag(.bool));
         const is_unsigned = if (rhs_is_float) x: {
             var bigint_space: Value.BigIntSpace = undefined;
-            var bigint = try rhs_val.toBigInt(&bigint_space).toManaged(self.allocator);
+            var bigint = try rhs_val.toBigInt(&bigint_space).toManaged(self.gpa);
             defer bigint.deinit();
             const zcmp = rhs_val.orderAgainstZero();
             if (rhs_val.floatHasFraction()) {
@@ -3457,7 +3436,7 @@ fn coerceArrayPtrToSlice(self: *Module, scope: *Scope, dest_type: Type, inst: *I
 
 fn fail(self: *Module, scope: *Scope, src: usize, comptime format: []const u8, args: var) InnerError {
     @setCold(true);
-    const err_msg = try ErrorMsg.create(self.allocator, src, format, args);
+    const err_msg = try ErrorMsg.create(self.gpa, src, format, args);
     return self.failWithOwnedErrorMsg(scope, src, err_msg);
 }
 
@@ -3487,9 +3466,9 @@ fn failNode(
 
 fn failWithOwnedErrorMsg(self: *Module, scope: *Scope, src: usize, err_msg: *ErrorMsg) InnerError {
     {
-        errdefer err_msg.destroy(self.allocator);
-        try self.failed_decls.ensureCapacity(self.failed_decls.items().len + 1);
-        try self.failed_files.ensureCapacity(self.failed_files.items().len + 1);
+        errdefer err_msg.destroy(self.gpa);
+        try self.failed_decls.ensureCapacity(self.gpa, self.failed_decls.items().len + 1);
+        try self.failed_files.ensureCapacity(self.gpa, self.failed_files.items().len + 1);
     }
     switch (scope.tag) {
         .decl => {
@@ -3542,28 +3521,28 @@ pub const ErrorMsg = struct {
     byte_offset: usize,
     msg: []const u8,
 
-    pub fn create(allocator: *Allocator, byte_offset: usize, comptime format: []const u8, args: var) !*ErrorMsg {
-        const self = try allocator.create(ErrorMsg);
-        errdefer allocator.destroy(self);
-        self.* = try init(allocator, byte_offset, format, args);
+    pub fn create(gpa: *Allocator, byte_offset: usize, comptime format: []const u8, args: var) !*ErrorMsg {
+        const self = try gpa.create(ErrorMsg);
+        errdefer gpa.destroy(self);
+        self.* = try init(gpa, byte_offset, format, args);
         return self;
     }
 
     /// Assumes the ErrorMsg struct and msg were both allocated with allocator.
-    pub fn destroy(self: *ErrorMsg, allocator: *Allocator) void {
-        self.deinit(allocator);
-        allocator.destroy(self);
+    pub fn destroy(self: *ErrorMsg, gpa: *Allocator) void {
+        self.deinit(gpa);
+        gpa.destroy(self);
     }
 
-    pub fn init(allocator: *Allocator, byte_offset: usize, comptime format: []const u8, args: var) !ErrorMsg {
+    pub fn init(gpa: *Allocator, byte_offset: usize, comptime format: []const u8, args: var) !ErrorMsg {
         return ErrorMsg{
             .byte_offset = byte_offset,
-            .msg = try std.fmt.allocPrint(allocator, format, args),
+            .msg = try std.fmt.allocPrint(gpa, format, args),
         };
     }
 
-    pub fn deinit(self: *ErrorMsg, allocator: *Allocator) void {
-        allocator.free(self.msg);
+    pub fn deinit(self: *ErrorMsg, gpa: *Allocator) void {
+        gpa.free(self.msg);
         self.* = undefined;
     }
 };