llvm/lib/MC/ConstantPools.cpp
Weiming Zhao 7e3119cb1a Fix 24560: assembler does not share constant pool for same constants
Summary: This patch returns the same label if the CP entry with the same value has been created.

Reviewers: eli.friedman, rengolin, jmolloy

Subscribers: majnemer, jmolloy, llvm-commits

Differential Revision: https://reviews.llvm.org/D25804

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@286006 91177308-0d34-0410-b5e6-96231b3b80d8
2016-11-04 19:17:32 +00:00

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3.4 KiB
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//===- ConstantPools.cpp - ConstantPool class --*- C++ -*---------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the ConstantPool and AssemblerConstantPools classes.
//
//===----------------------------------------------------------------------===//
#include "llvm/ADT/MapVector.h"
#include "llvm/MC/ConstantPools.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCStreamer.h"
using namespace llvm;
//
// ConstantPool implementation
//
// Emit the contents of the constant pool using the provided streamer.
void ConstantPool::emitEntries(MCStreamer &Streamer) {
if (Entries.empty())
return;
Streamer.EmitDataRegion(MCDR_DataRegion);
for (const ConstantPoolEntry &Entry : Entries) {
Streamer.EmitCodeAlignment(Entry.Size); // align naturally
Streamer.EmitLabel(Entry.Label);
Streamer.EmitValue(Entry.Value, Entry.Size, Entry.Loc);
}
Streamer.EmitDataRegion(MCDR_DataRegionEnd);
Entries.clear();
}
const MCExpr *ConstantPool::addEntry(const MCExpr *Value, MCContext &Context,
unsigned Size, SMLoc Loc) {
const MCConstantExpr *C = dyn_cast<MCConstantExpr>(Value);
// Check if there is existing entry for the same constant. If so, reuse it.
auto Itr = C ? CachedEntries.find(C->getValue()) : CachedEntries.end();
if (Itr != CachedEntries.end())
return Itr->second;
MCSymbol *CPEntryLabel = Context.createTempSymbol();
Entries.push_back(ConstantPoolEntry(CPEntryLabel, Value, Size, Loc));
const auto SymRef = MCSymbolRefExpr::create(CPEntryLabel, Context);
if (C)
CachedEntries[C->getValue()] = SymRef;
return SymRef;
}
bool ConstantPool::empty() { return Entries.empty(); }
//
// AssemblerConstantPools implementation
//
ConstantPool *AssemblerConstantPools::getConstantPool(MCSection *Section) {
ConstantPoolMapTy::iterator CP = ConstantPools.find(Section);
if (CP == ConstantPools.end())
return nullptr;
return &CP->second;
}
ConstantPool &
AssemblerConstantPools::getOrCreateConstantPool(MCSection *Section) {
return ConstantPools[Section];
}
static void emitConstantPool(MCStreamer &Streamer, MCSection *Section,
ConstantPool &CP) {
if (!CP.empty()) {
Streamer.SwitchSection(Section);
CP.emitEntries(Streamer);
}
}
void AssemblerConstantPools::emitAll(MCStreamer &Streamer) {
// Dump contents of assembler constant pools.
for (auto &CPI : ConstantPools) {
MCSection *Section = CPI.first;
ConstantPool &CP = CPI.second;
emitConstantPool(Streamer, Section, CP);
}
}
void AssemblerConstantPools::emitForCurrentSection(MCStreamer &Streamer) {
MCSection *Section = Streamer.getCurrentSectionOnly();
if (ConstantPool *CP = getConstantPool(Section)) {
emitConstantPool(Streamer, Section, *CP);
}
}
const MCExpr *AssemblerConstantPools::addEntry(MCStreamer &Streamer,
const MCExpr *Expr,
unsigned Size, SMLoc Loc) {
MCSection *Section = Streamer.getCurrentSectionOnly();
return getOrCreateConstantPool(Section).addEntry(Expr, Streamer.getContext(),
Size, Loc);
}