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//===--- SIDebuggerInsertNops.cpp - Inserts nops for debugger usage -------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
/// \file
/// \brief Inserts one nop instruction for each high level source statement for
/// debugger usage.
///
/// Tools, such as a debugger, need to pause execution based on user input (i.e.
/// breakpoint). In order to do this, one nop instruction is inserted before the
/// first isa instruction of each high level source statement. Further, the
/// debugger may replace nop instructions with trap instructions based on user
/// input.
//
//===----------------------------------------------------------------------===//
#include "SIInstrInfo.h"
#include "AMDGPUSubtarget.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
using namespace llvm;
#define DEBUG_TYPE "si-debugger-insert-nops"
#define PASS_NAME "SI Debugger Insert Nops"
namespace {
class SIDebuggerInsertNops : public MachineFunctionPass {
public:
static char ID;
SIDebuggerInsertNops() : MachineFunctionPass(ID) { }
const char *getPassName() const override { return PASS_NAME; }
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.setPreservesCFG();
MachineFunctionPass::getAnalysisUsage(AU);
}
bool runOnMachineFunction(MachineFunction &MF) override;
};
} // anonymous namespace
INITIALIZE_PASS(SIDebuggerInsertNops, DEBUG_TYPE, PASS_NAME, false, false)
char SIDebuggerInsertNops::ID = 0;
char &llvm::SIDebuggerInsertNopsID = SIDebuggerInsertNops::ID;
FunctionPass *llvm::createSIDebuggerInsertNopsPass() {
return new SIDebuggerInsertNops();
}
bool SIDebuggerInsertNops::runOnMachineFunction(MachineFunction &MF) {
// Skip this pass if "amdgpu-debugger-insert-nops" attribute was not
// specified.
const SISubtarget &ST = MF.getSubtarget<SISubtarget>();
if (!ST.debuggerInsertNops())
return false;
// Skip machine functions without debug info.
if (!MF.getMMI().hasDebugInfo())
return false;
// Target instruction info.
const SIInstrInfo *TII = ST.getInstrInfo();
// Set containing line numbers that have nop inserted.
DenseSet<unsigned> NopInserted;
for (auto &MBB : MF) {
for (auto MI = MBB.begin(); MI != MBB.end(); ++MI) {
// Skip DBG_VALUE instructions and instructions without location.
if (MI->isDebugValue() || !MI->getDebugLoc())
continue;
// Insert nop instruction if line number does not have nop inserted.
auto DL = MI->getDebugLoc();
if (NopInserted.find(DL.getLine()) == NopInserted.end()) {
BuildMI(MBB, *MI, DL, TII->get(AMDGPU::S_NOP))
.addImm(0);
NopInserted.insert(DL.getLine());
}
}
}
return true;
}