llvm-6502/lib/ExecutionEngine/TargetSelect.cpp
Peter Collingbourne fbb662f840 Introduce llvm::sys::getProcessTriple() function.
In r143502, we renamed getHostTriple() to getDefaultTargetTriple()
as part of work to allow the user to supply a different default
target triple at configure time.  This change also affected the JIT.
However, it is inappropriate to use the default target triple in the
JIT in most circumstances because this will not necessarily match
the current architecture used by the process, leading to illegal
instruction and other such errors at run time.

Introduce the getProcessTriple() function for use in the JIT and
its clients, and cause the JIT to use it.  On architectures with a
single bitness, the host and process triples are identical.  On other
architectures, the host triple represents the architecture of the
host CPU, while the process triple represents the architecture used
by the host CPU to interpret machine code within the current process.
For example, when executing 32-bit code on a 64-bit Linux machine,
the host triple may be 'x86_64-unknown-linux-gnu', while the process
triple may be 'i386-unknown-linux-gnu'.

This fixes JIT for the 32-on-64-bit (and vice versa) build on non-Apple
platforms.

Differential Revision: http://llvm-reviews.chandlerc.com/D254

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@172627 91177308-0d34-0410-b5e6-96231b3b80d8
2013-01-16 17:27:22 +00:00

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3.5 KiB
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//===-- TargetSelect.cpp - Target Chooser Code ----------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This just asks the TargetRegistry for the appropriate target to use, and
// allows the user to specify a specific one on the commandline with -march=x,
// -mcpu=y, and -mattr=a,-b,+c. Clients should initialize targets prior to
// calling selectTarget().
//
//===----------------------------------------------------------------------===//
#include "llvm/ExecutionEngine/ExecutionEngine.h"
#include "llvm/ADT/Triple.h"
#include "llvm/IR/Module.h"
#include "llvm/MC/SubtargetFeature.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Host.h"
#include "llvm/Support/TargetRegistry.h"
#include "llvm/Target/TargetMachine.h"
using namespace llvm;
TargetMachine *EngineBuilder::selectTarget() {
Triple TT;
// MCJIT can generate code for remote targets, but the old JIT and Interpreter
// must use the host architecture.
if (UseMCJIT && WhichEngine != EngineKind::Interpreter && M)
TT.setTriple(M->getTargetTriple());
return selectTarget(TT, MArch, MCPU, MAttrs);
}
/// selectTarget - Pick a target either via -march or by guessing the native
/// arch. Add any CPU features specified via -mcpu or -mattr.
TargetMachine *EngineBuilder::selectTarget(const Triple &TargetTriple,
StringRef MArch,
StringRef MCPU,
const SmallVectorImpl<std::string>& MAttrs) {
Triple TheTriple(TargetTriple);
if (TheTriple.getTriple().empty())
TheTriple.setTriple(sys::getProcessTriple());
// Adjust the triple to match what the user requested.
const Target *TheTarget = 0;
if (!MArch.empty()) {
for (TargetRegistry::iterator it = TargetRegistry::begin(),
ie = TargetRegistry::end(); it != ie; ++it) {
if (MArch == it->getName()) {
TheTarget = &*it;
break;
}
}
if (!TheTarget) {
if (ErrorStr)
*ErrorStr = "No available targets are compatible with this -march, "
"see -version for the available targets.\n";
return 0;
}
// Adjust the triple to match (if known), otherwise stick with the
// requested/host triple.
Triple::ArchType Type = Triple::getArchTypeForLLVMName(MArch);
if (Type != Triple::UnknownArch)
TheTriple.setArch(Type);
} else {
std::string Error;
TheTarget = TargetRegistry::lookupTarget(TheTriple.getTriple(), Error);
if (TheTarget == 0) {
if (ErrorStr)
*ErrorStr = Error;
return 0;
}
}
// Package up features to be passed to target/subtarget
std::string FeaturesStr;
if (!MAttrs.empty()) {
SubtargetFeatures Features;
for (unsigned i = 0; i != MAttrs.size(); ++i)
Features.AddFeature(MAttrs[i]);
FeaturesStr = Features.getString();
}
// Allocate a target...
TargetMachine *Target = TheTarget->createTargetMachine(TheTriple.getTriple(),
MCPU, FeaturesStr,
Options,
RelocModel, CMModel,
OptLevel);
assert(Target && "Could not allocate target machine!");
return Target;
}