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/*========================== begin_copyright_notice ============================
Copyright (C) 2022-2023 Intel Corporation
SPDX-License-Identifier: MIT
============================= end_copyright_notice ===========================*/
//
/// GenXDebugLegalization
/// -----------------
///
/// Modifies incoming metadata to generate valid debug info later on.
///
/// Operation of the pass
/// ^^^^^^^^^^^^^^^^^^^^^
///
/// Remove DW_OP_constu 4/DW_OP_swap/DW_OP_xderef constructs. These are
/// generated by the FE compiler to annotate address space, which is not
/// used (directly) by the debugger.
///
//===----------------------------------------------------------------------===//
#include "GenX.h"
#include "GenXUtil.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/CFG.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/DIBuilder.h"
#include "llvm/InitializePasses.h"
#include "llvm/Pass.h"
#include "llvm/Support/Debug.h"
#define DEBUG_TYPE "GENX_DEBUGLEGALIZATION"
using namespace llvm;
using namespace genx;
namespace {
// GenXDebugLegalization : reduce integer size
class GenXDebugLegalization : public FunctionPass {
public:
static char ID;
explicit GenXDebugLegalization() : FunctionPass(ID) { }
StringRef getPassName() const override { return "GenX debug legalization"; }
void getAnalysisUsage(AnalysisUsage &AU) const override;
bool runOnFunction(Function &F) override;
private:
bool extractAddressClass(Function &F);
bool removeDIArgList(Function &F);
};
} // end anonymous namespace
char GenXDebugLegalization::ID = 0;
namespace llvm { void initializeGenXDebugLegalizationPass(PassRegistry &); }
INITIALIZE_PASS_BEGIN(GenXDebugLegalization, "GenXDebugLegalization", "GenXDebugLegalization", false, false)
INITIALIZE_PASS_END(GenXDebugLegalization, "GenXDebugLegalization", "GenXDebugLegalization", false, false)
FunctionPass *llvm::createGenXDebugLegalizationPass() {
initializeGenXDebugLegalizationPass(*PassRegistry::getPassRegistry());
return new GenXDebugLegalization;
}
void GenXDebugLegalization::getAnalysisUsage(AnalysisUsage &AU) const
{
AU.setPreservesCFG();
}
// Detect instructions with an address class pattern. Then remove all opcodes of this pattern from
// this instruction's last operand (metadata of DIExpression).
// Pattern: !DIExpression(DW_OP_constu, 4, DW_OP_swap, DW_OP_xderef)
bool GenXDebugLegalization::extractAddressClass(Function &F) {
bool Modified = false;
DIBuilder di(*F.getParent());
for (auto& bb : F) {
for (auto& pInst : bb) {
if (auto* DI = dyn_cast<DbgVariableIntrinsic>(&pInst)) {
const DIExpression* DIExpr = DI->getExpression();
llvm::SmallVector<uint64_t, 5> newElements;
for (auto I = DIExpr->expr_op_begin(), E = DIExpr->expr_op_end(); I != E; ++I) {
if (I->getOp() == dwarf::DW_OP_constu) {
auto patternI = I;
if (++patternI != E && patternI->getOp() == dwarf::DW_OP_swap &&
++patternI != E && patternI->getOp() == dwarf::DW_OP_xderef) {
I = patternI;
continue;
}
}
I->appendToVector(newElements);
}
if (newElements.size() < DIExpr->getNumElements()) {
DIExpression* newDIExpr = di.createExpression(newElements);
DI->setExpression(newDIExpr);
Modified = true;
}
}
}
}
return Modified;
}
// LLVM 12+ may generate DIArgList construct which is not (yet) supported.
// In order to prevent crashes, remove such metadata.
bool GenXDebugLegalization::removeDIArgList(Function &F) {
bool Modified = false;
for (auto &BB : F) {
for (auto &I : BB) {
if (auto *dbgInst = dyn_cast<DbgVariableIntrinsic>(&I)) {
if (dbgInst->getNumVariableLocationOps() > 1) {
dbgInst->setUndef();
Modified = true;
}
}
}
}
return Modified;
}
/***********************************************************************
* GenXDebugLegalization::runOnFunction : process one function to
* reduce integer size where possible
*/
bool GenXDebugLegalization::runOnFunction(Function &F)
{
bool Modified = false;
Modified |= extractAddressClass(F);
Modified |= removeDIArgList(F);
return Modified;
}
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