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https://github.com/carbon-language/carbon-lang.git
synced 2026-09-24 22:02:23 +01:00
Richard Smith
a556cf41fc
Previously we created allocas for temporaries at whatever point in the output LLVM function we'd reached. This would result in these being dynamic allocas (performing a dynamic stack allocation), which is inefficent and can lead to a stack overflow if it happens in a loop. Switch to putting the allocas in the entry block instead, and instead generate a lifetime start marker when we reach the point where the temporary is introduced. We already did this for local variables; this is just factoring out and reusing that code.
74 lines
3.0 KiB
C++
74 lines
3.0 KiB
C++
// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
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// Exceptions. See /LICENSE for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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#include "toolchain/lower/function_context.h"
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#include "toolchain/sem_ir/expr_info.h"
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#include "toolchain/sem_ir/file.h"
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namespace Carbon::Lower {
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auto HandleInst(FunctionContext& context, SemIR::InstId inst_id,
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SemIR::BindValue inst) -> void {
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auto inst_type = context.GetTypeIdOfInst(inst_id);
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switch (context.GetValueRepr(inst_type).repr.kind) {
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case SemIR::ValueRepr::Unknown:
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CARBON_FATAL(
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"Value binding for type with incomplete value representation");
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case SemIR::ValueRepr::None:
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// Nothing should use this value, but StubRef needs a value to
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// propagate.
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// TODO: Remove this now the StubRefs are gone.
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context.SetLocal(inst_id,
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llvm::PoisonValue::get(context.GetType(inst_type)));
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break;
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case SemIR::ValueRepr::Copy: {
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auto* type = context.GetType(inst_type);
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context.SetLocal(inst_id, context.builder().CreateLoad(
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type, context.GetValue(inst.value_id)));
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} break;
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case SemIR::ValueRepr::Pointer:
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context.SetLocal(inst_id, context.GetValue(inst.value_id));
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break;
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case SemIR::ValueRepr::Custom:
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CARBON_FATAL("TODO: Add support for BindValue with custom value rep");
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}
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}
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auto HandleInst(FunctionContext& context, SemIR::InstId inst_id,
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SemIR::Temporary inst) -> void {
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context.FinishInit(context.GetTypeIdOfInst(inst_id), inst.storage_id,
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inst.init_id);
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context.SetLocal(inst_id, context.GetValue(inst.storage_id));
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}
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auto HandleInst(FunctionContext& context, SemIR::InstId inst_id,
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SemIR::TemporaryStorage /*inst*/) -> void {
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context.SetLocal(
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inst_id, context.CreateAlloca(context.GetTypeOfInst(inst_id), "temp"));
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}
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auto HandleInst(FunctionContext& context, SemIR::InstId inst_id,
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SemIR::ValueAsRef inst) -> void {
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CARBON_CHECK(SemIR::GetExprCategory(context.sem_ir(), inst.value_id) ==
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SemIR::ExprCategory::Value);
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auto inst_type = context.GetTypeIdOfInst(inst_id);
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auto value_repr = context.GetValueRepr(inst_type);
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CARBON_CHECK(value_repr.repr.kind == SemIR::ValueRepr::Pointer);
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context.SetLocal(inst_id, context.GetValue(inst.value_id));
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}
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auto HandleInst(FunctionContext& context, SemIR::InstId inst_id,
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SemIR::ValueOfInitializer inst) -> void {
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CARBON_CHECK(SemIR::GetExprCategory(context.sem_ir(), inst.init_id) ==
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SemIR::ExprCategory::Initializing);
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auto inst_type = context.GetTypeIdOfInst(inst_id);
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auto value_repr = context.GetValueRepr(inst_type);
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auto init_repr = context.GetInitRepr(inst_type);
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CARBON_CHECK(value_repr.repr.kind == SemIR::ValueRepr::Copy);
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CARBON_CHECK(init_repr.kind == SemIR::InitRepr::ByCopy);
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context.SetLocal(inst_id, context.GetValue(inst.init_id));
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}
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} // namespace Carbon::Lower
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