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copy elision: if-err with scalar types
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```zig
export fn entry() void {
    var x: error!i32 = 1234;
    var y = if (x) |a| a else |e| 5678;
}
```

```llvm
define void @entry() #2 !dbg !41 {
Entry:
  %x = alloca { i16, i32 }, align 4
  %y = alloca i32, align 4
  %0 = bitcast { i16, i32 }* %x to i8*, !dbg !56
  call void @llvm.memcpy.p0i8.p0i8.i64(i8* align 4 %0, i8* align 4 bitcast ({ i16, i32 }* @0 to i8*), i64 8, i1 false), !dbg !56
  call void @llvm.dbg.declare(metadata { i16, i32 }* %x, metadata !45, metadata !DIExpression()), !dbg !57
  %1 = getelementptr inbounds { i16, i32 }, { i16, i32 }* %x, i32 0, i32 0, !dbg !58
  %2 = load i16, i16* %1, align 2, !dbg !58
  %3 = icmp ne i16 %2, 0, !dbg !58
  br i1 %3, label %IfErrElse, label %IfErrThen, !dbg !58

IfErrThen:                                        ; preds = %Entry
  %4 = getelementptr inbounds { i16, i32 }, { i16, i32 }* %x, i32 0, i32 1, !dbg !58
  call void @llvm.dbg.declare(metadata i32* %4, metadata !52, metadata !DIExpression()), !dbg !58
  %5 = load i32, i32* %4, align 4, !dbg !59
  store i32 %5, i32* %y, align 4, !dbg !59
  br label %IfErrEnd, !dbg !58

IfErrElse:                                        ; preds = %Entry
  %6 = load i16, i16* %1, align 2, !dbg !58
  call void @llvm.dbg.declare(metadata i16* %1, metadata !54, metadata !DIExpression()), !dbg !58
  store i32 5678, i32* %y, align 4, !dbg !61
  br label %IfErrEnd, !dbg !58

IfErrEnd:                                         ; preds = %IfErrElse, %IfErrThen
  call void @llvm.dbg.declare(metadata i32* %y, metadata !55, metadata !DIExpression()), !dbg !63
  ret void, !dbg !64
}
```
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@andrewrk
andrewrk committed Oct 30, 2018
1 parent 7d6c967 commit 58a3d99
Showing 1 changed file with 18 additions and 35 deletions.
53 changes: 18 additions & 35 deletions src/ir.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -10984,19 +10984,7 @@ static IrInstruction *ir_analyze_cast(IrAnalyze *ira, IrInstruction *source_inst
if (actual_type->id == ZigTypeIdComptimeFloat ||
actual_type->id == ZigTypeIdComptimeInt)
{
if ((err = ensure_complete_type(ira->codegen, wanted_type)))
return ira->codegen->invalid_instruction;
if (wanted_type->id == ZigTypeIdEnum) {
IrInstruction *cast1 = ir_analyze_cast(ira, source_instr, wanted_type->data.enumeration.tag_int_type, value);
if (type_is_invalid(cast1->value.type))
return ira->codegen->invalid_instruction;

IrInstruction *cast2 = ir_analyze_cast(ira, source_instr, wanted_type, cast1);
if (type_is_invalid(cast2->value.type))
return ira->codegen->invalid_instruction;

return cast2;
} else if (ir_num_lit_fits_in_other_type(ira, value, wanted_type, true)) {
if (ir_num_lit_fits_in_other_type(ira, value, wanted_type, true)) {
CastOp op;
if ((actual_type->id == ZigTypeIdComptimeFloat &&
wanted_type->id == ZigTypeIdFloat) ||
Expand Down Expand Up @@ -11211,7 +11199,7 @@ static ZigType *adjust_ptr_len(CodeGen *g, ZigType *ptr_type, PtrLen ptr_len) {
}

static IrInstruction *ir_implicit_cast_result(IrAnalyze *ira, IrInstruction *result_loc,
ZigType *needed_child_type)
ZigType *needed_child_type, bool allow_failure)
{
Error err;
if (type_is_invalid(result_loc->value.type) || type_is_invalid(needed_child_type))
Expand Down Expand Up @@ -11278,14 +11266,18 @@ static IrInstruction *ir_implicit_cast_result(IrAnalyze *ira, IrInstruction *res
needed_child_type->id == ZigTypeIdComptimeFloat)
{
IrInstruction *cast1 = ir_implicit_cast_result(ira, result_loc,
have_child_type->data.error_union.payload_type);
have_child_type->data.error_union.payload_type, allow_failure);
if (type_is_invalid(cast1->value.type))
return ira->codegen->invalid_instruction;

return ir_implicit_cast_result(ira, cast1, needed_child_type);
return ir_implicit_cast_result(ira, cast1, needed_child_type, allow_failure);
}
}

if (allow_failure) {
return result_loc;
}

ErrorMsg *parent_msg = ir_add_error_node(ira, source_node,
buf_sprintf("expected type '%s', found '%s'",
buf_ptr(&have_child_type->name),
Expand Down Expand Up @@ -13377,7 +13369,7 @@ static IrInstruction *ir_get_var_ptr(IrAnalyze *ira, IrInstruction *instruction,
}

static IrInstruction *ir_analyze_store_ptr(IrAnalyze *ira, IrInstruction *source_instr,
IrInstruction *uncasted_ptr, IrInstruction *value)
IrInstruction *uncasted_ptr, IrInstruction *uncasted_value)
{
if (uncasted_ptr->value.type->id != ZigTypeIdPointer) {
ir_add_error(ira, uncasted_ptr,
Expand All @@ -13394,10 +13386,15 @@ static IrInstruction *ir_analyze_store_ptr(IrAnalyze *ira, IrInstruction *source
return ira->codegen->invalid_instruction;
}

IrInstruction *ptr = ir_implicit_cast_result(ira, uncasted_ptr, value->value.type);
IrInstruction *ptr = ir_implicit_cast_result(ira, uncasted_ptr, uncasted_value->value.type, true);
if (type_is_invalid(ptr->value.type))
return ira->codegen->invalid_instruction;

ZigType *child_type = ptr->value.type->data.pointer.child_type;
IrInstruction *value = ir_implicit_cast(ira, uncasted_value, child_type);
if (type_is_invalid(value->value.type))
return ira->codegen->invalid_instruction;

if (instr_is_comptime(ptr) && ptr->value.data.x_ptr.special != ConstPtrSpecialHardCodedAddr) {
if (ptr->value.data.x_ptr.mut == ConstPtrMutComptimeConst) {
ir_add_error(ira, source_instr, buf_sprintf("cannot assign to constant"));
Expand Down Expand Up @@ -13977,7 +13974,7 @@ static IrInstruction *ir_analyze_fn_call(IrAnalyze *ira, IrInstructionCall *call
IrInstruction *result_loc = nullptr;

if (call_instruction->result_loc != nullptr) {
result_loc = ir_implicit_cast_result(ira, call_instruction->result_loc->child, return_type);
result_loc = ir_implicit_cast_result(ira, call_instruction->result_loc->child, return_type, false);
if (type_is_invalid(result_loc->value.type))
return ira->codegen->invalid_instruction;
}
Expand Down Expand Up @@ -15434,21 +15431,7 @@ static IrInstruction *ir_analyze_instruction_store_ptr(IrAnalyze *ira, IrInstruc
static IrInstruction *ir_analyze_store_result(IrAnalyze *ira, IrInstruction *source_instr, IrInstruction *value,
IrInstruction *uncasted_result_loc)
{
if (instr_is_comptime(value)) {
// No need for the ir_implicit_cast_result for comptime values.
return ir_analyze_store_ptr(ira, source_instr, uncasted_result_loc, value);
}

if (value->id == IrInstructionIdCall && handle_is_ptr(value->value.type)) {
// Elide this copy because it was the sret pointer in the function call.
return ir_const_void(ira, source_instr);
}

IrInstruction *result_loc = ir_implicit_cast_result(ira, uncasted_result_loc, value->value.type);
if (type_is_invalid(result_loc->value.type))
return ira->codegen->invalid_instruction;

return ir_analyze_store_ptr(ira, source_instr, result_loc, value);
zig_panic("TODO delete this instruction");
}

static IrInstruction *ir_analyze_instruction_store_result(IrAnalyze *ira, IrInstructionStoreResult *instruction) {
Expand Down Expand Up @@ -21388,7 +21371,7 @@ static IrInstruction *ir_analyze_instruction_first_arg_result_loc(IrAnalyze *ira
return ira->codegen->invalid_instruction;

IrInstruction *new_result_loc = ir_implicit_cast_result(ira, instruction->prev_result_loc->child,
dest_type);
dest_type, false);
if (type_is_invalid(new_result_loc->value.type))
return ira->codegen->invalid_instruction;
return new_result_loc;
Expand Down

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