Commit 71cd3466ec

@@ -1,9 +1,22 @@
 const bits = @import("bits.zig");
 const Register = bits.Register;
 
-// Register windowing mechanism will take care of preserving registers
-// so no need to do it manually
-pub const callee_preserved_regs = [_]Register{};
+// There are no callee-preserved registers since the windowing
+// mechanism already takes care of them.
+// We still need to preserve %o0-%o5, %g1, %g4, and %g5 before calling
+// something, though, as those are shared with the callee and might be
+// thrashed by it.
+pub const caller_preserved_regs = [_]Register{ .o0, .o1, .o2, .o3, .o4, .o5, .g1, .g4, .g5 };
+
+// Try to allocate i, l, o, then g sets of registers, in order of priority.
+pub const allocatable_regs = [_]Register{
+    // zig fmt: off
+    .@"i0", .@"i1", .@"i2", .@"i3", .@"i4", .@"i5",
+      .l0,    .l1,    .l2,    .l3,    .l4,    .l5,    .l6,    .l7,
+      .o0,    .o1,    .o2,    .o3,    .o4,    .o5,
+              .g1,                    .g4,    .g5,
+    // zig fmt: on
+};
 
 pub const c_abi_int_param_regs_caller_view = [_]Register{ .o0, .o1, .o2, .o3, .o4, .o5 };
 pub const c_abi_int_param_regs_callee_view = [_]Register{ .@"i0", .@"i1", .@"i2", .@"i3", .@"i4", .@"i5" };

@@ -16,6 +16,8 @@ const Type = @import("../../type.zig").Type;
 const GenerateSymbolError = @import("../../codegen.zig").GenerateSymbolError;
 const FnResult = @import("../../codegen.zig").FnResult;
 const DebugInfoOutput = @import("../../codegen.zig").DebugInfoOutput;
+const RegisterManagerFn = @import("../../register_manager.zig").RegisterManager;
+const RegisterManager = RegisterManagerFn(Self, Register, &abi.allocatable_regs);
 
 const build_options = @import("build_options");
 
@@ -73,6 +75,8 @@ branch_stack: *std.ArrayList(Branch),
 // Key is the block instruction
 blocks: std.AutoHashMapUnmanaged(Air.Inst.Index, BlockData) = .{},
 
+register_manager: RegisterManager = .{},
+
 /// Maps offset to what is stored there.
 stack: std.AutoHashMapUnmanaged(u32, StackAllocation) = .{},
 
@@ -380,7 +384,6 @@ fn resolveCallingConventionValues(self: *Self, fn_ty: Type, is_caller: bool) !Ca
     return result;
 }
 
-/// Caller must call `CallMCValues.deinit`.
 fn gen(self: *Self) !void {
     const cc = self.fn_type.fnCallingConvention();
     if (cc != .Naked) {