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[CodeGen] Use SmallVector for FixedStackPSVs (#91760)

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Frame indices are dense and consecutive, so use a vector instead of a
std::map. Due to possibly negative frame indices, use zig-zag encoding.
IndexedMap was not usable, as it attempted to copy the null value, which
is not possible with a std::unique_ptr.

This is just a minor performance improvement, but a low-hanging fruit.
This commit is contained in:
aengelke 2024-05-14 13:13:24 +02:00 committed by GitHub
parent cbd72cb0de
commit e6d3a4212d
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2 changed files with 8 additions and 3 deletions
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4
llvm/include/llvm/CodeGen/PseudoSourceValueManager.h
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@ -13,10 +13,10 @@
#ifndef LLVM_CODEGEN_PSEUDOSOURCEVALUEMANAGER_H
#define LLVM_CODEGEN_PSEUDOSOURCEVALUEMANAGER_H
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/CodeGen/PseudoSourceValue.h"
#include "llvm/IR/ValueMap.h"
#include <map>
namespace llvm {
@ -27,7 +27,7 @@ class TargetMachine;
class PseudoSourceValueManager {
const TargetMachine &TM;
const PseudoSourceValue StackPSV, GOTPSV, JumpTablePSV, ConstantPoolPSV;
std::map<int, std::unique_ptr<FixedStackPseudoSourceValue>> FSValues;
SmallVector<std::unique_ptr<FixedStackPseudoSourceValue>> FSValues;
StringMap<std::unique_ptr<const ExternalSymbolPseudoSourceValue>>
ExternalCallEntries;
ValueMap<const GlobalValue *,

7
llvm/lib/CodeGen/PseudoSourceValue.cpp
View File

@ -122,7 +122,12 @@ const PseudoSourceValue *PseudoSourceValueManager::getJumpTable() {
const PseudoSourceValue *
PseudoSourceValueManager::getFixedStack(int FI) {
std::unique_ptr<FixedStackPseudoSourceValue> &V = FSValues[FI];
// Frame index is often continuously positive, but can be negative. Use
// zig-zag encoding for dense index into FSValues vector.
unsigned Idx = (2 * unsigned(FI)) ^ (FI >> (sizeof(FI) * 8 - 1));
if (FSValues.size() <= Idx)
FSValues.resize(Idx + 1);
std::unique_ptr<FixedStackPseudoSourceValue> &V = FSValues[Idx];
if (!V)
V = std::make_unique<FixedStackPseudoSourceValue>(FI, TM);
return V.get();