35efe1d806
The gold linker veneers are written between functions without symbols, so we to handle it specially in BOLT. Vladislav Khmelevsky, Advanced Software Technology Lab, Huawei Differential Revision: https://reviews.llvm.org/D129260
96 lines
3.1 KiB
C++
96 lines
3.1 KiB
C++
//===- bolt/Passes/VeneerElimination.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 class implements a pass that removes linker-inserted veneers from the
|
|
// code and redirects veneer callers to call to veneers destinations
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "bolt/Passes/VeneerElimination.h"
|
|
#define DEBUG_TYPE "veneer-elim"
|
|
|
|
using namespace llvm;
|
|
|
|
namespace opts {
|
|
|
|
extern cl::OptionCategory BoltOptCategory;
|
|
|
|
static llvm::cl::opt<bool>
|
|
EliminateVeneers("elim-link-veneers",
|
|
cl::desc("run veneer elimination pass"), cl::init(true),
|
|
cl::Hidden, cl::cat(BoltOptCategory));
|
|
} // namespace opts
|
|
|
|
namespace llvm {
|
|
namespace bolt {
|
|
|
|
void VeneerElimination::runOnFunctions(BinaryContext &BC) {
|
|
if (!opts::EliminateVeneers || !BC.isAArch64())
|
|
return;
|
|
|
|
std::map<uint64_t, BinaryFunction> &BFs = BC.getBinaryFunctions();
|
|
std::unordered_map<const MCSymbol *, const MCSymbol *> VeneerDestinations;
|
|
uint64_t VeneersCount = 0;
|
|
for (auto &It : BFs) {
|
|
BinaryFunction &VeneerFunction = It.second;
|
|
if (!VeneerFunction.isAArch64Veneer())
|
|
continue;
|
|
|
|
VeneersCount++;
|
|
VeneerFunction.setPseudo(true);
|
|
MCInst &FirstInstruction = *(VeneerFunction.begin()->begin());
|
|
const MCSymbol *VeneerTargetSymbol =
|
|
BC.MIB->getTargetSymbol(FirstInstruction, 1);
|
|
assert(VeneerTargetSymbol && "Expecting target symbol for instruction");
|
|
for (const MCSymbol *Symbol : VeneerFunction.getSymbols())
|
|
VeneerDestinations[Symbol] = VeneerTargetSymbol;
|
|
}
|
|
|
|
outs() << "BOLT-INFO: number of removed linker-inserted veneers: "
|
|
<< VeneersCount << "\n";
|
|
|
|
// Handle veneers to veneers in case they occur
|
|
for (auto &Entry : VeneerDestinations) {
|
|
const MCSymbol *Src = Entry.first;
|
|
const MCSymbol *Dest = Entry.second;
|
|
while (VeneerDestinations.find(Dest) != VeneerDestinations.end())
|
|
Dest = VeneerDestinations[Dest];
|
|
|
|
VeneerDestinations[Src] = Dest;
|
|
}
|
|
|
|
uint64_t VeneerCallers = 0;
|
|
for (auto &It : BFs) {
|
|
BinaryFunction &Function = It.second;
|
|
for (BinaryBasicBlock &BB : Function) {
|
|
for (MCInst &Instr : BB) {
|
|
if (!BC.MIB->isCall(Instr) || BC.MIB->isIndirectCall(Instr))
|
|
continue;
|
|
|
|
const MCSymbol *TargetSymbol = BC.MIB->getTargetSymbol(Instr, 0);
|
|
if (VeneerDestinations.find(TargetSymbol) == VeneerDestinations.end())
|
|
continue;
|
|
|
|
VeneerCallers++;
|
|
if (!BC.MIB->replaceBranchTarget(
|
|
Instr, VeneerDestinations[TargetSymbol], BC.Ctx.get())) {
|
|
errs() << "BOLT-ERROR: updating veneer call destination failed\n";
|
|
exit(1);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
LLVM_DEBUG(
|
|
dbgs() << "BOLT-INFO: number of linker-inserted veneers call sites: "
|
|
<< VeneerCallers << "\n");
|
|
}
|
|
|
|
} // namespace bolt
|
|
} // namespace llvm
|