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Commit de04c48

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Weiming Zhao
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[ARM] [MC] Refactor the constant pool classes
ARMTargetStreamer implements ConstantPool and AssmeblerConstantPools to keep track of assembler-generated constant pools that are used for ldr-pseudo. When implementing ldr-pseudo for AArch64, these two classes can be reused. So this patch factors them out from ARM target to the general MC lib. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211198 91177308-0d34-0410-b5e6-96231b3b80d8
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‎include/llvm/MC/ConstantPools.h

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//===- ConstantPool.h - Keep track of assembler-generated ------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file declares the ConstantPool and AssemblerConstantPools classes.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_MC_CONSTANTPOOL_H
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#define LLVM_MC_CONSTANTPOOL_H
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#include "llvm/ADT/SmallVector.h"
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namespace llvm {
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class MCContext;
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class MCExpr;
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class MCSection;
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class MCStreamer;
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class MCSymbol;
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// A class to keep track of assembler-generated constant pools that are use to
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// implement the ldr-pseudo.
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class ConstantPool {
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typedef SmallVector<std::pair<MCSymbol *, const MCExpr *>, 4> EntryVecTy;
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EntryVecTy Entries;
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public:
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// Initialize a new empty constant pool
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ConstantPool() {}
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// Add a new entry to the constant pool in the next slot.
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// \param Value is the new entry to put in the constant pool.
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//
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// \returns a MCExpr that references the newly inserted value
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const MCExpr *addEntry(const MCExpr *Value, MCContext &Context);
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// Emit the contents of the constant pool using the provided streamer.
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void emitEntries(MCStreamer &Streamer);
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// Return true if the constant pool is empty
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bool empty();
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};
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class AssemblerConstantPools {
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// Map type used to keep track of per-Section constant pools used by the
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// ldr-pseudo opcode. The map associates a section to its constant pool. The
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// constant pool is a vector of (label, value) pairs. When the ldr
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// pseudo is parsed we insert a new (label, value) pair into the constant pool
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// for the current section and add MCSymbolRefExpr to the new label as
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// an opcode to the ldr. After we have parsed all the user input we
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// output the (label, value) pairs in each constant pool at the end of the
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// section.
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//
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// We use the MapVector for the map type to ensure stable iteration of
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// the sections at the end of the parse. We need to iterate over the
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// sections in a stable order to ensure that we have print the
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// constant pools in a deterministic order when printing an assembly
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// file.
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typedef MapVector<const MCSection *, ConstantPool> ConstantPoolMapTy;
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ConstantPoolMapTy ConstantPools;
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public:
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AssemblerConstantPools() {}
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~AssemblerConstantPools() {}
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void emitAll(MCStreamer &Streamer);
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void emitForCurrentSection(MCStreamer &Streamer);
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const MCExpr *addEntry(MCStreamer &Streamer, const MCExpr *Expr);
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private:
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ConstantPool *getConstantPool(const MCSection *Section);
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ConstantPool &getOrCreateConstantPool(const MCSection *Section);
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};
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} // end namespace llvm
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#endif

‎lib/MC/CMakeLists.txt

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add_llvm_library(LLVMMC
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ConstantPools.cpp
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ELFObjectWriter.cpp
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MCAsmBackend.cpp
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MCAsmInfo.cpp

‎lib/MC/ConstantPools.cpp

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//===- ConstantPools.cpp - ConstantPool class --*- C++ -*---------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the ConstantPool and AssemblerConstantPools classes.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/ADT/MapVector.h"
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#include "llvm/MC/MCContext.h"
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#include "llvm/MC/MCExpr.h"
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#include "llvm/MC/MCStreamer.h"
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#include "llvm/MC/ConstantPools.h"
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using namespace llvm;
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//
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// ConstantPool implementation
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//
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// Emit the contents of the constant pool using the provided streamer.
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void ConstantPool::emitEntries(MCStreamer &Streamer) {
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if (Entries.empty())
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return;
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Streamer.EmitCodeAlignment(4); // align to 4-byte address
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Streamer.EmitDataRegion(MCDR_DataRegion);
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for (EntryVecTy::const_iterator I = Entries.begin(), E = Entries.end();
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I != E; ++I) {
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Streamer.EmitLabel(I->first);
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Streamer.EmitValue(I->second, 4);
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}
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Streamer.EmitDataRegion(MCDR_DataRegionEnd);
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Entries.clear();
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}
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const MCExpr *ConstantPool::addEntry(const MCExpr *Value, MCContext &Context) {
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MCSymbol *CPEntryLabel = Context.CreateTempSymbol();
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Entries.push_back(std::make_pair(CPEntryLabel, Value));
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return MCSymbolRefExpr::Create(CPEntryLabel, Context);
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}
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bool ConstantPool::empty() { return Entries.empty(); }
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//
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// AssemblerConstantPools implementation
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//
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ConstantPool *
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AssemblerConstantPools::getConstantPool(const MCSection *Section) {
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ConstantPoolMapTy::iterator CP = ConstantPools.find(Section);
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if (CP == ConstantPools.end())
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return nullptr;
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return &CP->second;
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}
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ConstantPool &
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AssemblerConstantPools::getOrCreateConstantPool(const MCSection *Section) {
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return ConstantPools[Section];
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}
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static void emitConstantPool(MCStreamer &Streamer, const MCSection *Section,
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ConstantPool &CP) {
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if (!CP.empty()) {
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Streamer.SwitchSection(Section);
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CP.emitEntries(Streamer);
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}
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}
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void AssemblerConstantPools::emitAll(MCStreamer &Streamer) {
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// Dump contents of assembler constant pools.
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for (ConstantPoolMapTy::iterator CPI = ConstantPools.begin(),
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CPE = ConstantPools.end();
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CPI != CPE; ++CPI) {
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const MCSection *Section = CPI->first;
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ConstantPool &CP = CPI->second;
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emitConstantPool(Streamer, Section, CP);
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}
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}
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void AssemblerConstantPools::emitForCurrentSection(MCStreamer &Streamer) {
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const MCSection *Section = Streamer.getCurrentSection().first;
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if (ConstantPool *CP = getConstantPool(Section)) {
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emitConstantPool(Streamer, Section, *CP);
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}
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}
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const MCExpr *AssemblerConstantPools::addEntry(MCStreamer &Streamer,
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const MCExpr *Expr) {
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const MCSection *Section = Streamer.getCurrentSection().first;
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return getOrCreateConstantPool(Section).addEntry(Expr, Streamer.getContext());
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}

‎lib/Target/ARM/MCTargetDesc/ARMTargetStreamer.cpp

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//
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//===----------------------------------------------------------------------===//
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#include "llvm/ADT/MapVector.h"
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#include "llvm/MC/ConstantPools.h"
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#include "llvm/MC/MCContext.h"
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#include "llvm/MC/MCExpr.h"
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#include "llvm/MC/MCStreamer.h"
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using namespace llvm;
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namespace {
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// A class to keep track of assembler-generated constant pools that are use to
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// implement the ldr-pseudo.
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class ConstantPool {
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typedef SmallVector<std::pair<MCSymbol *, const MCExpr *>, 4> EntryVecTy;
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EntryVecTy Entries;
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public:
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// Initialize a new empty constant pool
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ConstantPool() {}
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// Add a new entry to the constant pool in the next slot.
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// \param Value is the new entry to put in the constant pool.
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//
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// \returns a MCExpr that references the newly inserted value
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const MCExpr *addEntry(const MCExpr *Value, MCContext &Context);
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// Emit the contents of the constant pool using the provided streamer.
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void emitEntries(MCStreamer &Streamer);
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// Return true if the constant pool is empty
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bool empty();
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};
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}
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namespace llvm {
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class AssemblerConstantPools {
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// Map type used to keep track of per-Section constant pools used by the
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// ldr-pseudo opcode. The map associates a section to its constant pool. The
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// constant pool is a vector of (label, value) pairs. When the ldr
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// pseudo is parsed we insert a new (label, value) pair into the constant pool
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// for the current section and add MCSymbolRefExpr to the new label as
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// an opcode to the ldr. After we have parsed all the user input we
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// output the (label, value) pairs in each constant pool at the end of the
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// section.
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//
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// We use the MapVector for the map type to ensure stable iteration of
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// the sections at the end of the parse. We need to iterate over the
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// sections in a stable order to ensure that we have print the
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// constant pools in a deterministic order when printing an assembly
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// file.
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typedef MapVector<const MCSection *, ConstantPool> ConstantPoolMapTy;
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ConstantPoolMapTy ConstantPools;
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public:
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AssemblerConstantPools() {}
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~AssemblerConstantPools() {}
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void emitAll(MCStreamer &Streamer);
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void emitForCurrentSection(MCStreamer &Streamer);
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const MCExpr *addEntry(MCStreamer &Streamer, const MCExpr *Expr);
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private:
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ConstantPool *getConstantPool(const MCSection *Section);
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ConstantPool &getOrCreateConstantPool(const MCSection *Section);
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};
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}
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//
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// ConstantPool implementation
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//
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// Emit the contents of the constant pool using the provided streamer.
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void ConstantPool::emitEntries(MCStreamer &Streamer) {
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if (Entries.empty())
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return;
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Streamer.EmitCodeAlignment(4); // align to 4-byte address
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Streamer.EmitDataRegion(MCDR_DataRegion);
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for (EntryVecTy::const_iterator I = Entries.begin(), E = Entries.end();
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I != E; ++I) {
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Streamer.EmitLabel(I->first);
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Streamer.EmitValue(I->second, 4);
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}
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Streamer.EmitDataRegion(MCDR_DataRegionEnd);
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Entries.clear();
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}
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const MCExpr *ConstantPool::addEntry(const MCExpr *Value, MCContext &Context) {
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MCSymbol *CPEntryLabel = Context.CreateTempSymbol();
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Entries.push_back(std::make_pair(CPEntryLabel, Value));
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return MCSymbolRefExpr::Create(CPEntryLabel, Context);
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}
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bool ConstantPool::empty() { return Entries.empty(); }
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//
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// AssemblerConstantPools implementation
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//
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ConstantPool *
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AssemblerConstantPools::getConstantPool(const MCSection *Section) {
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ConstantPoolMapTy::iterator CP = ConstantPools.find(Section);
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if (CP == ConstantPools.end())
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return nullptr;
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return &CP->second;
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}
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ConstantPool &
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AssemblerConstantPools::getOrCreateConstantPool(const MCSection *Section) {
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return ConstantPools[Section];
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}
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static void emitConstantPool(MCStreamer &Streamer, const MCSection *Section,
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ConstantPool &CP) {
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if (!CP.empty()) {
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Streamer.SwitchSection(Section);
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CP.emitEntries(Streamer);
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}
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}
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void AssemblerConstantPools::emitAll(MCStreamer &Streamer) {
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// Dump contents of assembler constant pools.
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for (ConstantPoolMapTy::iterator CPI = ConstantPools.begin(),
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CPE = ConstantPools.end();
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CPI != CPE; ++CPI) {
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const MCSection *Section = CPI->first;
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ConstantPool &CP = CPI->second;
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emitConstantPool(Streamer, Section, CP);
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}
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}
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void AssemblerConstantPools::emitForCurrentSection(MCStreamer &Streamer) {
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const MCSection *Section = Streamer.getCurrentSection().first;
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if (ConstantPool *CP = getConstantPool(Section)) {
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emitConstantPool(Streamer, Section, *CP);
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}
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}
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const MCExpr *AssemblerConstantPools::addEntry(MCStreamer &Streamer,
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const MCExpr *Expr) {
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const MCSection *Section = Streamer.getCurrentSection().first;
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return getOrCreateConstantPool(Section).addEntry(Expr, Streamer.getContext());
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}
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//
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// ARMTargetStreamer Implemenation
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//

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