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.
134 lines
4.5 KiB
C++
134 lines
4.5 KiB
C++
//==-LTOInternalize.cpp - LLVM Link Time Optimizer Internalization Utility -==//
|
|
//
|
|
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
|
|
// See https://llvm.org/LICENSE.txt for license information.
|
|
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// This file defines a helper to run the internalization part of LTO.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "llvm/LTO/legacy/UpdateCompilerUsed.h"
|
|
#include "llvm/Analysis/TargetLibraryInfo.h"
|
|
#include "llvm/CodeGen/TargetLowering.h"
|
|
#include "llvm/CodeGen/TargetSubtargetInfo.h"
|
|
#include "llvm/IR/Mangler.h"
|
|
#include "llvm/IR/Module.h"
|
|
#include "llvm/Target/TargetMachine.h"
|
|
#include "llvm/Transforms/Utils/ModuleUtils.h"
|
|
|
|
using namespace llvm;
|
|
|
|
namespace {
|
|
|
|
// Helper class that collects AsmUsed and user supplied libcalls.
|
|
class PreserveLibCallsAndAsmUsed {
|
|
public:
|
|
PreserveLibCallsAndAsmUsed(const StringSet<> &AsmUndefinedRefs,
|
|
const TargetMachine &TM,
|
|
std::vector<GlobalValue *> &LLVMUsed)
|
|
: AsmUndefinedRefs(AsmUndefinedRefs), TM(TM), LLVMUsed(LLVMUsed) {}
|
|
|
|
void findInModule(Module &TheModule) {
|
|
initializeLibCalls(TheModule);
|
|
for (Function &F : TheModule)
|
|
findLibCallsAndAsm(F);
|
|
for (GlobalVariable &GV : TheModule.globals())
|
|
findLibCallsAndAsm(GV);
|
|
for (GlobalAlias &GA : TheModule.aliases())
|
|
findLibCallsAndAsm(GA);
|
|
}
|
|
|
|
private:
|
|
// Inputs
|
|
const StringSet<> &AsmUndefinedRefs;
|
|
const TargetMachine &TM;
|
|
|
|
// Temps
|
|
llvm::Mangler Mangler;
|
|
StringSet<> Libcalls;
|
|
|
|
// Output
|
|
std::vector<GlobalValue *> &LLVMUsed;
|
|
|
|
// Collect names of runtime library functions. User-defined functions with the
|
|
// same names are added to llvm.compiler.used to prevent them from being
|
|
// deleted by optimizations.
|
|
void initializeLibCalls(const Module &TheModule) {
|
|
TargetLibraryInfoImpl TLII(TM.getTargetTriple());
|
|
TargetLibraryInfo TLI(TLII);
|
|
|
|
// TargetLibraryInfo has info on C runtime library calls on the current
|
|
// target.
|
|
for (unsigned I = 0, E = static_cast<unsigned>(LibFunc::NumLibFuncs);
|
|
I != E; ++I) {
|
|
LibFunc F = static_cast<LibFunc>(I);
|
|
if (TLI.has(F))
|
|
Libcalls.insert(TLI.getName(F));
|
|
}
|
|
|
|
SmallPtrSet<const TargetLowering *, 1> TLSet;
|
|
|
|
for (const Function &F : TheModule) {
|
|
const TargetLowering *Lowering =
|
|
TM.getSubtargetImpl(F)->getTargetLowering();
|
|
|
|
if (Lowering && TLSet.insert(Lowering).second)
|
|
// TargetLowering has info on library calls that CodeGen expects to be
|
|
// available, both from the C runtime and compiler-rt.
|
|
for (unsigned I = 0, E = static_cast<unsigned>(RTLIB::UNKNOWN_LIBCALL);
|
|
I != E; ++I)
|
|
if (const char *Name =
|
|
Lowering->getLibcallName(static_cast<RTLIB::Libcall>(I)))
|
|
Libcalls.insert(Name);
|
|
}
|
|
}
|
|
|
|
void findLibCallsAndAsm(GlobalValue &GV) {
|
|
// There are no restrictions to apply to declarations.
|
|
if (GV.isDeclaration())
|
|
return;
|
|
|
|
// There is nothing more restrictive than private linkage.
|
|
if (GV.hasPrivateLinkage())
|
|
return;
|
|
|
|
// Conservatively append user-supplied runtime library functions (supplied
|
|
// either directly, or via a function alias) to llvm.compiler.used. These
|
|
// could be internalized and deleted by optimizations like -globalopt,
|
|
// causing problems when later optimizations add new library calls (e.g.,
|
|
// llvm.memset => memset and printf => puts).
|
|
// Leave it to the linker to remove any dead code (e.g. with -dead_strip).
|
|
GlobalValue *FuncAliasee = nullptr;
|
|
if (isa<GlobalAlias>(GV)) {
|
|
auto *A = cast<GlobalAlias>(&GV);
|
|
FuncAliasee = dyn_cast<Function>(A->getAliasee());
|
|
}
|
|
if ((isa<Function>(GV) || FuncAliasee) && Libcalls.count(GV.getName())) {
|
|
LLVMUsed.push_back(&GV);
|
|
return;
|
|
}
|
|
|
|
SmallString<64> Buffer;
|
|
TM.getNameWithPrefix(Buffer, &GV, Mangler);
|
|
if (AsmUndefinedRefs.count(Buffer))
|
|
LLVMUsed.push_back(&GV);
|
|
}
|
|
};
|
|
|
|
} // namespace anonymous
|
|
|
|
void llvm::updateCompilerUsed(Module &TheModule, const TargetMachine &TM,
|
|
const StringSet<> &AsmUndefinedRefs) {
|
|
std::vector<GlobalValue *> UsedValues;
|
|
PreserveLibCallsAndAsmUsed(AsmUndefinedRefs, TM, UsedValues)
|
|
.findInModule(TheModule);
|
|
|
|
if (UsedValues.empty())
|
|
return;
|
|
|
|
appendToCompilerUsed(TheModule, UsedValues);
|
|
}
|