979c275097
The module currently stores the target triple as a string. This means that any code that wants to actually use the triple first has to instantiate a Triple, which is somewhat expensive. The change in #121652 caused a moderate compile-time regression due to this. While it would be easy enough to work around, I think that architecturally, it makes more sense to store the parsed Triple in the module, so that it can always be directly queried. For this change, I've opted not to add any magic conversions between std::string and Triple for backwards-compatibilty purses, and instead write out needed Triple()s or str()s explicitly. This is because I think a decent number of them should be changed to work on Triple as well, to avoid unnecessary conversions back and forth. The only interesting part in this patch is that the default triple is Triple("") instead of Triple() to preserve existing behavior. The former defaults to using the ELF object format instead of unknown object format. We should fix that as well.
96 lines
3.3 KiB
C++
96 lines
3.3 KiB
C++
//===-- TargetSelect.cpp - Target Chooser Code ----------------------------===//
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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 just asks the TargetRegistry for the appropriate target to use, and
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// allows the user to specify a specific one on the commandline with -march=x,
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// -mcpu=y, and -mattr=a,-b,+c. Clients should initialize targets prior to
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// calling selectTarget().
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/ExecutionEngine/ExecutionEngine.h"
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#include "llvm/IR/Module.h"
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#include "llvm/MC/TargetRegistry.h"
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#include "llvm/Target/TargetMachine.h"
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#include "llvm/TargetParser/Host.h"
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#include "llvm/TargetParser/SubtargetFeature.h"
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#include "llvm/TargetParser/Triple.h"
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using namespace llvm;
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TargetMachine *EngineBuilder::selectTarget() {
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Triple TT;
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// MCJIT can generate code for remote targets, but the old JIT and Interpreter
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// must use the host architecture.
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if (WhichEngine != EngineKind::Interpreter && M)
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TT = M->getTargetTriple();
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return selectTarget(TT, MArch, MCPU, MAttrs);
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}
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/// selectTarget - Pick a target either via -march or by guessing the native
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/// arch. Add any CPU features specified via -mcpu or -mattr.
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TargetMachine *EngineBuilder::selectTarget(const Triple &TargetTriple,
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StringRef MArch,
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StringRef MCPU,
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const SmallVectorImpl<std::string>& MAttrs) {
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Triple TheTriple(TargetTriple);
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if (TheTriple.getTriple().empty())
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TheTriple.setTriple(sys::getProcessTriple());
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// Adjust the triple to match what the user requested.
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const Target *TheTarget = nullptr;
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if (!MArch.empty()) {
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auto I = find_if(TargetRegistry::targets(),
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[&](const Target &T) { return MArch == T.getName(); });
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if (I == TargetRegistry::targets().end()) {
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if (ErrorStr)
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*ErrorStr = "No available targets are compatible with this -march, "
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"see -version for the available targets.\n";
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return nullptr;
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}
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TheTarget = &*I;
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// Adjust the triple to match (if known), otherwise stick with the
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// requested/host triple.
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Triple::ArchType Type = Triple::getArchTypeForLLVMName(MArch);
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if (Type != Triple::UnknownArch)
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TheTriple.setArch(Type);
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} else {
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std::string Error;
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TheTarget = TargetRegistry::lookupTarget(TheTriple, Error);
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if (!TheTarget) {
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if (ErrorStr)
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*ErrorStr = Error;
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return nullptr;
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}
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}
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// Package up features to be passed to target/subtarget
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std::string FeaturesStr;
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if (!MAttrs.empty()) {
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SubtargetFeatures Features;
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for (unsigned i = 0; i != MAttrs.size(); ++i)
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Features.AddFeature(MAttrs[i]);
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FeaturesStr = Features.getString();
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}
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// Allocate a target...
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TargetMachine *Target =
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TheTarget->createTargetMachine(TheTriple.getTriple(), MCPU, FeaturesStr,
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Options, RelocModel, CMModel, OptLevel,
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/*JIT*/ true);
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Target->Options.EmulatedTLS = EmulatedTLS;
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assert(Target && "Could not allocate target machine!");
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return Target;
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}
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