Commit 2bb795dc45

Andrew Kelley <andrew@ziglang.org>
2019-02-21 16:07:11
`@sliceToBytes` works at comptime
closes #262
1 parent db31c25
src/all_types.hpp
@@ -630,19 +630,6 @@ struct AstNodeUnwrapOptional {
     AstNode *expr;
 };
 
-enum CastOp {
-    CastOpNoCast, // signifies the function call expression is not a cast
-    CastOpNoop, // fn call expr is a cast, but does nothing
-    CastOpIntToFloat,
-    CastOpFloatToInt,
-    CastOpBoolToInt,
-    CastOpResizeSlice,
-    CastOpNumLitToConcrete,
-    CastOpErrSet,
-    CastOpBitCast,
-    CastOpPtrOfArrayToSlice,
-};
-
 struct AstNodeFnCallExpr {
     AstNode *fn_ref_expr;
     ZigList<AstNode *> params;
@@ -2142,6 +2129,7 @@ enum IrInstructionId {
     IrInstructionIdConst,
     IrInstructionIdReturn,
     IrInstructionIdCast,
+    IrInstructionIdResizeSlice,
     IrInstructionIdContainerInitList,
     IrInstructionIdContainerInitFields,
     IrInstructionIdStructInit,
@@ -2503,6 +2491,18 @@ struct IrInstructionReturn {
     IrInstruction *value;
 };
 
+enum CastOp {
+    CastOpNoCast, // signifies the function call expression is not a cast
+    CastOpNoop, // fn call expr is a cast, but does nothing
+    CastOpIntToFloat,
+    CastOpFloatToInt,
+    CastOpBoolToInt,
+    CastOpNumLitToConcrete,
+    CastOpErrSet,
+    CastOpBitCast,
+    CastOpPtrOfArrayToSlice,
+};
+
 // TODO get rid of this instruction, replace with instructions for each op code
 struct IrInstructionCast {
     IrInstruction base;
@@ -2513,6 +2513,13 @@ struct IrInstructionCast {
     LLVMValueRef tmp_ptr;
 };
 
+struct IrInstructionResizeSlice {
+    IrInstruction base;
+
+    IrInstruction *operand;
+    LLVMValueRef tmp_ptr;
+};
+
 struct IrInstructionContainerInitList {
     IrInstruction base;
 
src/codegen.cpp
@@ -2882,6 +2882,76 @@ static void add_error_range_check(CodeGen *g, ZigType *err_set_type, ZigType *in
     }
 }
 
+static LLVMValueRef ir_render_resize_slice(CodeGen *g, IrExecutable *executable,
+        IrInstructionResizeSlice *instruction)
+{
+    ZigType *actual_type = instruction->operand->value.type;
+    ZigType *wanted_type = instruction->base.value.type;
+    LLVMValueRef expr_val = ir_llvm_value(g, instruction->operand);
+    assert(expr_val);
+
+    assert(instruction->tmp_ptr);
+    assert(wanted_type->id == ZigTypeIdStruct);
+    assert(wanted_type->data.structure.is_slice);
+    assert(actual_type->id == ZigTypeIdStruct);
+    assert(actual_type->data.structure.is_slice);
+
+    ZigType *actual_pointer_type = actual_type->data.structure.fields[0].type_entry;
+    ZigType *actual_child_type = actual_pointer_type->data.pointer.child_type;
+    ZigType *wanted_pointer_type = wanted_type->data.structure.fields[0].type_entry;
+    ZigType *wanted_child_type = wanted_pointer_type->data.pointer.child_type;
+
+
+    size_t actual_ptr_index = actual_type->data.structure.fields[slice_ptr_index].gen_index;
+    size_t actual_len_index = actual_type->data.structure.fields[slice_len_index].gen_index;
+    size_t wanted_ptr_index = wanted_type->data.structure.fields[slice_ptr_index].gen_index;
+    size_t wanted_len_index = wanted_type->data.structure.fields[slice_len_index].gen_index;
+
+    LLVMValueRef src_ptr_ptr = LLVMBuildStructGEP(g->builder, expr_val, (unsigned)actual_ptr_index, "");
+    LLVMValueRef src_ptr = gen_load_untyped(g, src_ptr_ptr, 0, false, "");
+    LLVMValueRef src_ptr_casted = LLVMBuildBitCast(g->builder, src_ptr,
+            wanted_type->data.structure.fields[0].type_entry->type_ref, "");
+    LLVMValueRef dest_ptr_ptr = LLVMBuildStructGEP(g->builder, instruction->tmp_ptr,
+            (unsigned)wanted_ptr_index, "");
+    gen_store_untyped(g, src_ptr_casted, dest_ptr_ptr, 0, false);
+
+    LLVMValueRef src_len_ptr = LLVMBuildStructGEP(g->builder, expr_val, (unsigned)actual_len_index, "");
+    LLVMValueRef src_len = gen_load_untyped(g, src_len_ptr, 0, false, "");
+    uint64_t src_size = type_size(g, actual_child_type);
+    uint64_t dest_size = type_size(g, wanted_child_type);
+
+    LLVMValueRef new_len;
+    if (dest_size == 1) {
+        LLVMValueRef src_size_val = LLVMConstInt(g->builtin_types.entry_usize->type_ref, src_size, false);
+        new_len = LLVMBuildMul(g->builder, src_len, src_size_val, "");
+    } else if (src_size == 1) {
+        LLVMValueRef dest_size_val = LLVMConstInt(g->builtin_types.entry_usize->type_ref, dest_size, false);
+        if (ir_want_runtime_safety(g, &instruction->base)) {
+            LLVMValueRef remainder_val = LLVMBuildURem(g->builder, src_len, dest_size_val, "");
+            LLVMValueRef zero = LLVMConstNull(g->builtin_types.entry_usize->type_ref);
+            LLVMValueRef ok_bit = LLVMBuildICmp(g->builder, LLVMIntEQ, remainder_val, zero, "");
+            LLVMBasicBlockRef ok_block = LLVMAppendBasicBlock(g->cur_fn_val, "SliceWidenOk");
+            LLVMBasicBlockRef fail_block = LLVMAppendBasicBlock(g->cur_fn_val, "SliceWidenFail");
+            LLVMBuildCondBr(g->builder, ok_bit, ok_block, fail_block);
+
+            LLVMPositionBuilderAtEnd(g->builder, fail_block);
+            gen_safety_crash(g, PanicMsgIdSliceWidenRemainder);
+
+            LLVMPositionBuilderAtEnd(g->builder, ok_block);
+        }
+        new_len = LLVMBuildExactUDiv(g->builder, src_len, dest_size_val, "");
+    } else {
+        zig_unreachable();
+    }
+
+    LLVMValueRef dest_len_ptr = LLVMBuildStructGEP(g->builder, instruction->tmp_ptr,
+            (unsigned)wanted_len_index, "");
+    gen_store_untyped(g, new_len, dest_len_ptr, 0, false);
+
+
+    return instruction->tmp_ptr;
+}
+
 static LLVMValueRef ir_render_cast(CodeGen *g, IrExecutable *executable,
         IrInstructionCast *cast_instruction)
 {
@@ -2896,69 +2966,6 @@ static LLVMValueRef ir_render_cast(CodeGen *g, IrExecutable *executable,
             zig_unreachable();
         case CastOpNoop:
             return expr_val;
-        case CastOpResizeSlice:
-            {
-                assert(cast_instruction->tmp_ptr);
-                assert(wanted_type->id == ZigTypeIdStruct);
-                assert(wanted_type->data.structure.is_slice);
-                assert(actual_type->id == ZigTypeIdStruct);
-                assert(actual_type->data.structure.is_slice);
-
-                ZigType *actual_pointer_type = actual_type->data.structure.fields[0].type_entry;
-                ZigType *actual_child_type = actual_pointer_type->data.pointer.child_type;
-                ZigType *wanted_pointer_type = wanted_type->data.structure.fields[0].type_entry;
-                ZigType *wanted_child_type = wanted_pointer_type->data.pointer.child_type;
-
-
-                size_t actual_ptr_index = actual_type->data.structure.fields[slice_ptr_index].gen_index;
-                size_t actual_len_index = actual_type->data.structure.fields[slice_len_index].gen_index;
-                size_t wanted_ptr_index = wanted_type->data.structure.fields[slice_ptr_index].gen_index;
-                size_t wanted_len_index = wanted_type->data.structure.fields[slice_len_index].gen_index;
-
-                LLVMValueRef src_ptr_ptr = LLVMBuildStructGEP(g->builder, expr_val, (unsigned)actual_ptr_index, "");
-                LLVMValueRef src_ptr = gen_load_untyped(g, src_ptr_ptr, 0, false, "");
-                LLVMValueRef src_ptr_casted = LLVMBuildBitCast(g->builder, src_ptr,
-                        wanted_type->data.structure.fields[0].type_entry->type_ref, "");
-                LLVMValueRef dest_ptr_ptr = LLVMBuildStructGEP(g->builder, cast_instruction->tmp_ptr,
-                        (unsigned)wanted_ptr_index, "");
-                gen_store_untyped(g, src_ptr_casted, dest_ptr_ptr, 0, false);
-
-                LLVMValueRef src_len_ptr = LLVMBuildStructGEP(g->builder, expr_val, (unsigned)actual_len_index, "");
-                LLVMValueRef src_len = gen_load_untyped(g, src_len_ptr, 0, false, "");
-                uint64_t src_size = type_size(g, actual_child_type);
-                uint64_t dest_size = type_size(g, wanted_child_type);
-
-                LLVMValueRef new_len;
-                if (dest_size == 1) {
-                    LLVMValueRef src_size_val = LLVMConstInt(g->builtin_types.entry_usize->type_ref, src_size, false);
-                    new_len = LLVMBuildMul(g->builder, src_len, src_size_val, "");
-                } else if (src_size == 1) {
-                    LLVMValueRef dest_size_val = LLVMConstInt(g->builtin_types.entry_usize->type_ref, dest_size, false);
-                    if (ir_want_runtime_safety(g, &cast_instruction->base)) {
-                        LLVMValueRef remainder_val = LLVMBuildURem(g->builder, src_len, dest_size_val, "");
-                        LLVMValueRef zero = LLVMConstNull(g->builtin_types.entry_usize->type_ref);
-                        LLVMValueRef ok_bit = LLVMBuildICmp(g->builder, LLVMIntEQ, remainder_val, zero, "");
-                        LLVMBasicBlockRef ok_block = LLVMAppendBasicBlock(g->cur_fn_val, "SliceWidenOk");
-                        LLVMBasicBlockRef fail_block = LLVMAppendBasicBlock(g->cur_fn_val, "SliceWidenFail");
-                        LLVMBuildCondBr(g->builder, ok_bit, ok_block, fail_block);
-
-                        LLVMPositionBuilderAtEnd(g->builder, fail_block);
-                        gen_safety_crash(g, PanicMsgIdSliceWidenRemainder);
-
-                        LLVMPositionBuilderAtEnd(g->builder, ok_block);
-                    }
-                    new_len = LLVMBuildExactUDiv(g->builder, src_len, dest_size_val, "");
-                } else {
-                    zig_unreachable();
-                }
-
-                LLVMValueRef dest_len_ptr = LLVMBuildStructGEP(g->builder, cast_instruction->tmp_ptr,
-                        (unsigned)wanted_len_index, "");
-                gen_store_untyped(g, new_len, dest_len_ptr, 0, false);
-
-
-                return cast_instruction->tmp_ptr;
-            }
         case CastOpIntToFloat:
             assert(actual_type->id == ZigTypeIdInt);
             if (actual_type->data.integral.is_signed) {
@@ -5625,6 +5632,8 @@ static LLVMValueRef ir_render_instruction(CodeGen *g, IrExecutable *executable,
             return ir_render_vector_to_array(g, executable, (IrInstructionVectorToArray *)instruction);
         case IrInstructionIdAssertZero:
             return ir_render_assert_zero(g, executable, (IrInstructionAssertZero *)instruction);
+        case IrInstructionIdResizeSlice:
+            return ir_render_resize_slice(g, executable, (IrInstructionResizeSlice *)instruction);
     }
     zig_unreachable();
 }
@@ -6716,6 +6725,9 @@ static void do_code_gen(CodeGen *g) {
             } else if (instruction->id == IrInstructionIdCmpxchgGen) {
                 IrInstructionCmpxchgGen *cmpxchg_instruction = (IrInstructionCmpxchgGen *)instruction;
                 slot = &cmpxchg_instruction->tmp_ptr;
+            } else if (instruction->id == IrInstructionIdResizeSlice) {
+                IrInstructionResizeSlice *resize_slice_instruction = (IrInstructionResizeSlice *)instruction;
+                slot = &resize_slice_instruction->tmp_ptr;
             } else if (instruction->id == IrInstructionIdVectorToArray) {
                 IrInstructionVectorToArray *vector_to_array_instruction = (IrInstructionVectorToArray *)instruction;
                 alignment_bytes = get_abi_alignment(g, vector_to_array_instruction->vector->value.type);
src/ir.cpp
@@ -456,6 +456,10 @@ static constexpr IrInstructionId ir_instruction_id(IrInstructionCast *) {
     return IrInstructionIdCast;
 }
 
+static constexpr IrInstructionId ir_instruction_id(IrInstructionResizeSlice *) {
+    return IrInstructionIdResizeSlice;
+}
+
 static constexpr IrInstructionId ir_instruction_id(IrInstructionContainerInitList *) {
     return IrInstructionIdContainerInitList;
 }
@@ -1475,6 +1479,19 @@ static IrInstruction *ir_build_var_decl_gen(IrAnalyze *ira, IrInstruction *sourc
     return &decl_var_instruction->base;
 }
 
+static IrInstruction *ir_build_resize_slice(IrAnalyze *ira, IrInstruction *source_instruction,
+        IrInstruction *operand, ZigType *ty)
+{
+    IrInstructionResizeSlice *instruction = ir_build_instruction<IrInstructionResizeSlice>(&ira->new_irb,
+            source_instruction->scope, source_instruction->source_node);
+    instruction->base.value.type = ty;
+    instruction->operand = operand;
+
+    ir_ref_instruction(operand, ira->new_irb.current_basic_block);
+
+    return &instruction->base;
+}
+
 static IrInstruction *ir_build_export(IrBuilder *irb, Scope *scope, AstNode *source_node,
         IrInstruction *name, IrInstruction *target, IrInstruction *linkage)
 {
@@ -9674,9 +9691,6 @@ static bool eval_const_expr_implicit_cast(IrAnalyze *ira, IrInstruction *source_
             }
             const_val->type = new_type;
             break;
-        case CastOpResizeSlice:
-            // can't do it
-            zig_unreachable();
         case CastOpIntToFloat:
             {
                 assert(new_type->id == ZigTypeIdFloat);
@@ -9740,9 +9754,7 @@ static IrInstruction *ir_const(IrAnalyze *ira, IrInstruction *old_instruction, Z
 static IrInstruction *ir_resolve_cast(IrAnalyze *ira, IrInstruction *source_instr, IrInstruction *value,
         ZigType *wanted_type, CastOp cast_op, bool need_alloca)
 {
-    if ((instr_is_comptime(value) || !type_has_bits(wanted_type)) &&
-        cast_op != CastOpResizeSlice)
-    {
+    if (instr_is_comptime(value) || !type_has_bits(wanted_type)) {
         IrInstruction *result = ir_const(ira, source_instr, wanted_type);
         if (!eval_const_expr_implicit_cast(ira, source_instr, cast_op, &value->value, value->value.type,
             &result->value, wanted_type))
@@ -19082,7 +19094,9 @@ static IrInstruction *ir_analyze_instruction_from_bytes(IrAnalyze *ira, IrInstru
         }
     }
 
-    return ir_resolve_cast(ira, &instruction->base, casted_value, dest_slice_type, CastOpResizeSlice, true);
+    IrInstruction *result = ir_build_resize_slice(ira, &instruction->base, casted_value, dest_slice_type);
+    ir_add_alloca(ira, result, dest_slice_type);
+    return result;
 }
 
 static IrInstruction *ir_analyze_instruction_to_bytes(IrAnalyze *ira, IrInstructionToBytes *instruction) {
@@ -19109,7 +19123,34 @@ static IrInstruction *ir_analyze_instruction_to_bytes(IrAnalyze *ira, IrInstruct
             alignment, 0, 0);
     ZigType *dest_slice_type = get_slice_type(ira->codegen, dest_ptr_type);
 
-    return ir_resolve_cast(ira, &instruction->base, target, dest_slice_type, CastOpResizeSlice, true);
+    if (instr_is_comptime(target)) {
+        ConstExprValue *target_val = ir_resolve_const(ira, target, UndefBad);
+        if (target_val == nullptr)
+            return ira->codegen->invalid_instruction;
+
+        IrInstruction *result = ir_const(ira, &instruction->base, dest_slice_type);
+        result->value.data.x_struct.fields = create_const_vals(2);
+
+        ConstExprValue *ptr_val = &result->value.data.x_struct.fields[slice_ptr_index];
+        ConstExprValue *target_ptr_val = &target_val->data.x_struct.fields[slice_ptr_index];
+        copy_const_val(ptr_val, target_ptr_val, false);
+        ptr_val->type = dest_ptr_type;
+
+        ConstExprValue *len_val = &result->value.data.x_struct.fields[slice_len_index];
+        len_val->special = ConstValSpecialStatic;
+        len_val->type = ira->codegen->builtin_types.entry_usize;
+        ConstExprValue *target_len_val = &target_val->data.x_struct.fields[slice_len_index];
+        ZigType *elem_type = src_ptr_type->data.pointer.child_type;
+        BigInt elem_size_bigint;
+        bigint_init_unsigned(&elem_size_bigint, type_size(ira->codegen, elem_type));
+        bigint_mul(&len_val->data.x_bigint, &target_len_val->data.x_bigint, &elem_size_bigint);
+
+        return result;
+    }
+
+    IrInstruction *result = ir_build_resize_slice(ira, &instruction->base, target, dest_slice_type);
+    ir_add_alloca(ira, result, dest_slice_type);
+    return result;
 }
 
 static Error resolve_ptr_align(IrAnalyze *ira, ZigType *ty, uint32_t *result_align) {
@@ -22274,6 +22315,7 @@ static IrInstruction *ir_analyze_instruction_nocast(IrAnalyze *ira, IrInstructio
         case IrInstructionIdArrayToVector:
         case IrInstructionIdVectorToArray:
         case IrInstructionIdAssertZero:
+        case IrInstructionIdResizeSlice:
             zig_unreachable();
 
         case IrInstructionIdReturn:
@@ -22673,6 +22715,7 @@ bool ir_has_side_effects(IrInstruction *instruction) {
         case IrInstructionIdCmpxchgGen:
         case IrInstructionIdCmpxchgSrc:
         case IrInstructionIdAssertZero:
+        case IrInstructionIdResizeSlice:
             return true;
 
         case IrInstructionIdPhi:
src/ir_print.cpp
@@ -990,6 +990,12 @@ static void ir_print_assert_zero(IrPrint *irp, IrInstructionAssertZero *instruct
     fprintf(irp->f, ")");
 }
 
+static void ir_print_resize_slice(IrPrint *irp, IrInstructionResizeSlice *instruction) {
+    fprintf(irp->f, "@resizeSlice(");
+    ir_print_other_instruction(irp, instruction->operand);
+    fprintf(irp->f, ")");
+}
+
 static void ir_print_int_to_err(IrPrint *irp, IrInstructionIntToErr *instruction) {
     fprintf(irp->f, "inttoerr ");
     ir_print_other_instruction(irp, instruction->target);
@@ -1852,6 +1858,9 @@ static void ir_print_instruction(IrPrint *irp, IrInstruction *instruction) {
         case IrInstructionIdAssertZero:
             ir_print_assert_zero(irp, (IrInstructionAssertZero *)instruction);
             break;
+        case IrInstructionIdResizeSlice:
+            ir_print_resize_slice(irp, (IrInstructionResizeSlice *)instruction);
+            break;
     }
     fprintf(irp->f, "\n");
 }
test/stage1/behavior/slicetobytes.zig
@@ -0,0 +1,29 @@
+const std = @import("std");
+const builtin = @import("builtin");
+const expect = std.testing.expect;
+
+test "@sliceToBytes packed struct at runtime and comptime" {
+    const Foo = packed struct {
+        a: u4,
+        b: u4,
+    };
+    const S = struct {
+        fn doTheTest() void {
+            var foo: Foo = undefined;
+            var slice = @sliceToBytes(((*[1]Foo)(&foo))[0..1]);
+            slice[0] = 0x13;
+            switch (builtin.endian) {
+                builtin.Endian.Big => {
+                    expect(foo.a == 0x1);
+                    expect(foo.b == 0x3);
+                },
+                builtin.Endian.Little => {
+                    expect(foo.a == 0x3);
+                    expect(foo.b == 0x1);
+                },
+            }
+        }
+    };
+    S.doTheTest();
+    comptime S.doTheTest();
+}
test/stage1/behavior.zig
@@ -61,6 +61,7 @@ comptime {
     _ = @import("behavior/reflection.zig");
     _ = @import("behavior/sizeof_and_typeof.zig");
     _ = @import("behavior/slice.zig");
+    _ = @import("behavior/slicetobytes.zig");
     _ = @import("behavior/struct.zig");
     _ = @import("behavior/struct_contains_null_ptr_itself.zig");
     _ = @import("behavior/struct_contains_slice_of_itself.zig");