0e86e5214c
If ADR instruction references the same function, we can skip relaxation even if the function is split but ADR is in the main fragment.
126 lines
4.2 KiB
C++
126 lines
4.2 KiB
C++
//===- bolt/Passes/ADRRelaxationPass.cpp ----------------------------------===//
|
|
//
|
|
// 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 implements the ADRRelaxationPass class.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "bolt/Passes/ADRRelaxationPass.h"
|
|
#include "bolt/Core/ParallelUtilities.h"
|
|
#include "bolt/Utils/CommandLineOpts.h"
|
|
#include <iterator>
|
|
|
|
using namespace llvm;
|
|
|
|
namespace opts {
|
|
extern cl::OptionCategory BoltCategory;
|
|
|
|
static cl::opt<bool>
|
|
AdrPassOpt("adr-relaxation",
|
|
cl::desc("Replace ARM non-local ADR instructions with ADRP"),
|
|
cl::init(true), cl::cat(BoltCategory), cl::ReallyHidden);
|
|
} // namespace opts
|
|
|
|
namespace llvm {
|
|
namespace bolt {
|
|
|
|
// We don't exit directly from runOnFunction since it would call ThreadPool
|
|
// destructor which might result in internal assert if we're not finished
|
|
// creating async jobs on the moment of exit. So we're finishing all parallel
|
|
// jobs and checking the exit flag after it.
|
|
static bool PassFailed = false;
|
|
|
|
void ADRRelaxationPass::runOnFunction(BinaryFunction &BF) {
|
|
if (PassFailed)
|
|
return;
|
|
|
|
BinaryContext &BC = BF.getBinaryContext();
|
|
for (BinaryBasicBlock &BB : BF) {
|
|
for (auto It = BB.begin(); It != BB.end(); ++It) {
|
|
MCInst &Inst = *It;
|
|
if (!BC.MIB->isADR(Inst))
|
|
continue;
|
|
|
|
const MCSymbol *Symbol = BC.MIB->getTargetSymbol(Inst);
|
|
if (!Symbol)
|
|
continue;
|
|
|
|
if (BF.hasIslandsInfo()) {
|
|
BinaryFunction::IslandInfo &Islands = BF.getIslandInfo();
|
|
if (Islands.Symbols.count(Symbol) || Islands.ProxySymbols.count(Symbol))
|
|
continue;
|
|
}
|
|
|
|
// Don't relax ADR if it points to the same function and is in the main
|
|
// fragment and BF initial size is < 1MB.
|
|
const unsigned OneMB = 0x100000;
|
|
if (BF.getSize() < OneMB) {
|
|
BinaryFunction *TargetBF = BC.getFunctionForSymbol(Symbol);
|
|
if (TargetBF == &BF && !BB.isSplit())
|
|
continue;
|
|
|
|
// No relaxation needed if ADR references a basic block in the same
|
|
// fragment.
|
|
if (BinaryBasicBlock *TargetBB = BF.getBasicBlockForLabel(Symbol))
|
|
if (BB.getFragmentNum() == TargetBB->getFragmentNum())
|
|
continue;
|
|
}
|
|
|
|
MCPhysReg Reg;
|
|
BC.MIB->getADRReg(Inst, Reg);
|
|
int64_t Addend = BC.MIB->getTargetAddend(Inst);
|
|
InstructionListType Addr;
|
|
|
|
{
|
|
auto L = BC.scopeLock();
|
|
Addr = BC.MIB->materializeAddress(Symbol, BC.Ctx.get(), Reg, Addend);
|
|
}
|
|
|
|
if (It != BB.begin() && BC.MIB->isNoop(*std::prev(It))) {
|
|
It = BB.eraseInstruction(std::prev(It));
|
|
} else if (std::next(It) != BB.end() && BC.MIB->isNoop(*std::next(It))) {
|
|
BB.eraseInstruction(std::next(It));
|
|
} else if (!opts::StrictMode && !BF.isSimple()) {
|
|
// If the function is not simple, it may contain a jump table undetected
|
|
// by us. This jump table may use an offset from the branch instruction
|
|
// to land in the desired place. If we add new instructions, we
|
|
// invalidate this offset, so we have to rely on linker-inserted NOP to
|
|
// replace it with ADRP, and abort if it is not present.
|
|
auto L = BC.scopeLock();
|
|
BC.errs() << formatv(
|
|
"BOLT-ERROR: Cannot relax adr in non-simple function "
|
|
"{0}. Use --strict option to override\n",
|
|
BF.getOneName());
|
|
PassFailed = true;
|
|
return;
|
|
}
|
|
It = BB.replaceInstruction(It, Addr);
|
|
}
|
|
}
|
|
}
|
|
|
|
Error ADRRelaxationPass::runOnFunctions(BinaryContext &BC) {
|
|
if (!opts::AdrPassOpt || !BC.HasRelocations)
|
|
return Error::success();
|
|
|
|
ParallelUtilities::WorkFuncTy WorkFun = [&](BinaryFunction &BF) {
|
|
runOnFunction(BF);
|
|
};
|
|
|
|
ParallelUtilities::runOnEachFunction(
|
|
BC, ParallelUtilities::SchedulingPolicy::SP_TRIVIAL, WorkFun, nullptr,
|
|
"ADRRelaxationPass");
|
|
|
|
if (PassFailed)
|
|
return createFatalBOLTError("");
|
|
return Error::success();
|
|
}
|
|
|
|
} // end namespace bolt
|
|
} // end namespace llvm
|