5e71839f77
In preparation for passing the MCSubtargetInfo (STI) through to writeNops so that it can use the STI in operation at the time, we need to record the STI in operation when a MCAlignFragment may write nops as padding. The STI is currently unused, a further patch will pass it through to writeNops. There are many places that can create an MCAlignFragment, in most cases we can find out the STI in operation at the time. In a few places this isn't possible as we are in initialisation or finalisation, or are emitting constant pools. When possible I've tried to find the most appropriate existing fragment to obtain the STI from, when none is available use the per module STI. For constant pools we don't actually need to use EmitCodeAlign as the constant pools are data anyway so falling through into it via an executable NOP is no better than falling through into data padding. This is a prerequisite for D45962 which uses the STI to emit the appropriate NOP for the STI. Which can differ per fragment. Note that involves an interface change to InitSections. It is now called initSections and requires a SubtargetInfo as a parameter. Differential Revision: https://reviews.llvm.org/D45961
116 lines
3.7 KiB
C++
116 lines
3.7 KiB
C++
//===- ConstantPools.cpp - ConstantPool class -----------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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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/MC/ConstantPools.h"
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#include "llvm/MC/MCContext.h"
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#include "llvm/MC/MCDirectives.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/Support/Casting.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.emitDataRegion(MCDR_DataRegion);
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for (const ConstantPoolEntry &Entry : Entries) {
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Streamer.emitValueToAlignment(Entry.Size); // align naturally
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Streamer.emitLabel(Entry.Label);
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Streamer.emitValue(Entry.Value, Entry.Size, Entry.Loc);
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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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unsigned Size, SMLoc Loc) {
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const MCConstantExpr *C = dyn_cast<MCConstantExpr>(Value);
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// Check if there is existing entry for the same constant. If so, reuse it.
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auto Itr = C ? CachedEntries.find(C->getValue()) : CachedEntries.end();
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if (Itr != CachedEntries.end())
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return Itr->second;
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MCSymbol *CPEntryLabel = Context.createTempSymbol();
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Entries.push_back(ConstantPoolEntry(CPEntryLabel, Value, Size, Loc));
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const auto SymRef = MCSymbolRefExpr::create(CPEntryLabel, Context);
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if (C)
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CachedEntries[C->getValue()] = SymRef;
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return SymRef;
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}
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bool ConstantPool::empty() { return Entries.empty(); }
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void ConstantPool::clearCache() {
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CachedEntries.clear();
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}
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//
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// AssemblerConstantPools implementation
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//
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ConstantPool *AssemblerConstantPools::getConstantPool(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(MCSection *Section) {
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return ConstantPools[Section];
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}
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static void emitConstantPool(MCStreamer &Streamer, 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 (auto &CPI : ConstantPools) {
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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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MCSection *Section = Streamer.getCurrentSectionOnly();
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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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void AssemblerConstantPools::clearCacheForCurrentSection(MCStreamer &Streamer) {
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MCSection *Section = Streamer.getCurrentSectionOnly();
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if (ConstantPool *CP = getConstantPool(Section))
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CP->clearCache();
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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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unsigned Size, SMLoc Loc) {
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MCSection *Section = Streamer.getCurrentSectionOnly();
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return getOrCreateConstantPool(Section).addEntry(Expr, Streamer.getContext(),
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Size, Loc);
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}
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