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Jon Ross-PerkinsandChandler Carruth
d437e4bffe
Based on discussion around the region handling in generic_region_stack, create a generic structure for the stack-of-vectors support. I also want to add this to InstBlockStack, but that's a little more complex due to GlobalInit, so cutting a PR here to check with review. My work here is how I noticed #4099; I want to be sure that I'm correct about the issue, but it's the difference between being able to use PeekArray or not. Note in scope_stack.h, I believe we could remove next_compile_time_index and make it just based on elements_size(). However, I want to verify with you before I make further changes there. --------- Co-authored-by: Chandler Carruth <chandlerc@gmail.com>
69 lines
2.4 KiB
C++
69 lines
2.4 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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#ifndef CARBON_TOOLCHAIN_CHECK_GENERIC_REGION_STACK_H_
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#define CARBON_TOOLCHAIN_CHECK_GENERIC_REGION_STACK_H_
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#include "common/array_stack.h"
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#include "llvm/ADT/BitmaskEnum.h"
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#include "toolchain/sem_ir/ids.h"
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namespace Carbon::Check {
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LLVM_ENABLE_BITMASK_ENUMS_IN_NAMESPACE();
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// A stack of enclosing regions that might be declaring or defining a generic
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// entity. In such a region, we track the generic constructs that are used, such
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// as symbolic constants and types, and instructions that depend on a template
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// parameter.
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//
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// TODO: For now we're just tracking symbolic constants.
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//
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// We split a generic into two regions -- declaration and definition -- because
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// these are in general introduced separately, and substituted into separately.
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// For example, for `class C(T:! type, N:! T) { var x: T; }`, a use such as
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// `C(i32, 0)*` substitutes into just the declaration, whereas a use such as
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// `var x: C(i32, 0) = {.x = 0};` also substitutes into the definition.
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class GenericRegionStack {
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public:
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// Ways in which an instruction can depend on a generic parameter.
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enum class DependencyKind : int8_t {
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None = 0x0,
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// The type of the instruction depends on a checked generic parameter.
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SymbolicType = 0x1,
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// The constant value of the instruction depends on a checked generic
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// parameter.
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SymbolicConstant = 0x2,
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Template = 0x4,
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LLVM_MARK_AS_BITMASK_ENUM(/*LargestValue=*/Template)
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};
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// An instruction that depends on a generic parameter in some way.
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struct DependentInst {
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SemIR::InstId inst_id;
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DependencyKind kind;
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};
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// Pushes a region that might be declaring or defining a generic.
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auto Push() -> void;
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// Pops a generic region.
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auto Pop() -> void;
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// Adds an instruction to the list of instructions in the current region that
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// in some way depend on a generic parameter.
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auto AddDependentInst(DependentInst inst) -> void;
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// Returns the list of dependent instructions in the current generic region.
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auto PeekDependentInsts() -> llvm::ArrayRef<DependentInst>;
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private:
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// A stack of symbolic constants for enclosing generic regions.
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ArrayStack<DependentInst> dependent_insts_stack_;
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};
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} // namespace Carbon::Check
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#endif // CARBON_TOOLCHAIN_CHECK_GENERIC_REGION_STACK_H_
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