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//===- Debugify.cpp - Attach synthetic debug info to everything -----------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
///
/// \file This pass attaches synthetic debug info to everything. It can be used
/// to create targeted tests for debug info preservation.
///
//===----------------------------------------------------------------------===//
#include "llvm/ADT/BitVector.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DIBuilder.h"
#include "llvm/IR/DebugInfo.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/GlobalVariable.h"
#include "llvm/IR/InstIterator.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Type.h"
#include "llvm/Pass.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/IPO.h"
using namespace llvm;
namespace {
bool applyDebugifyMetadata(Module &M) {
// Skip modules with debug info.
if (M.getNamedMetadata("llvm.dbg.cu")) {
errs() << "Debugify: Skipping module with debug info\n";
return false;
}
DIBuilder DIB(M);
LLVMContext &Ctx = M.getContext();
// Get a DIType which corresponds to Ty.
DenseMap<uint64_t, DIType *> TypeCache;
auto getCachedDIType = [&](Type *Ty) -> DIType * {
uint64_t Size = M.getDataLayout().getTypeAllocSizeInBits(Ty);
DIType *&DTy = TypeCache[Size];
if (!DTy) {
std::string Name = "ty" + utostr(Size);
DTy = DIB.createBasicType(Name, Size, dwarf::DW_ATE_unsigned);
}
return DTy;
};
unsigned NextLine = 1;
unsigned NextVar = 1;
auto File = DIB.createFile(M.getName(), "/");
auto CU =
DIB.createCompileUnit(dwarf::DW_LANG_C, DIB.createFile(M.getName(), "/"),
"debugify", /*isOptimized=*/true, "", 0);
// Visit each instruction.
for (Function &F : M) {
if (F.isDeclaration())
continue;
auto SPType = DIB.createSubroutineType(DIB.getOrCreateTypeArray(None));
bool IsLocalToUnit = F.hasPrivateLinkage() || F.hasInternalLinkage();
auto SP =
DIB.createFunction(CU, F.getName(), F.getName(), File, NextLine, SPType,
IsLocalToUnit, F.hasExactDefinition(), NextLine,
DINode::FlagZero, /*isOptimized=*/true);
F.setSubprogram(SP);
for (BasicBlock &BB : F) {
// Attach debug locations.
for (Instruction &I : BB)
I.setDebugLoc(DILocation::get(Ctx, NextLine++, 1, SP));
// Attach debug values.
for (Instruction &I : BB) {
// Skip void-valued instructions.
if (I.getType()->isVoidTy())
continue;
// Skip the terminator instruction and any just-inserted intrinsics.
if (isa<TerminatorInst>(&I) || isa<DbgValueInst>(&I))
break;
std::string Name = utostr(NextVar++);
const DILocation *Loc = I.getDebugLoc().get();
auto LocalVar = DIB.createAutoVariable(SP, Name, File, Loc->getLine(),
getCachedDIType(I.getType()),
/*AlwaysPreserve=*/true);
DIB.insertDbgValueIntrinsic(&I, LocalVar, DIB.createExpression(), Loc,
BB.getTerminator());
}
}
DIB.finalizeSubprogram(SP);
}
DIB.finalize();
// Track the number of distinct lines and variables.
NamedMDNode *NMD = M.getOrInsertNamedMetadata("llvm.debugify");
auto *IntTy = Type::getInt32Ty(Ctx);
auto addDebugifyOperand = [&](unsigned N) {
NMD->addOperand(MDNode::get(
Ctx, ValueAsMetadata::getConstant(ConstantInt::get(IntTy, N))));
};
addDebugifyOperand(NextLine - 1); // Original number of lines.
addDebugifyOperand(NextVar - 1); // Original number of variables.
return true;
}
void checkDebugifyMetadata(Module &M) {
// Skip modules without debugify metadata.
NamedMDNode *NMD = M.getNamedMetadata("llvm.debugify");
if (!NMD)
return;
auto getDebugifyOperand = [&](unsigned Idx) -> unsigned {
return mdconst::extract<ConstantInt>(NMD->getOperand(Idx)->getOperand(0))
->getZExtValue();
};
unsigned OriginalNumLines = getDebugifyOperand(0);
unsigned OriginalNumVars = getDebugifyOperand(1);
bool HasErrors = false;
// Find missing lines.
BitVector MissingLines{OriginalNumLines, true};
for (Function &F : M) {
for (Instruction &I : instructions(F)) {
if (isa<DbgValueInst>(&I))
continue;
auto DL = I.getDebugLoc();
if (DL) {
MissingLines.reset(DL.getLine() - 1);
continue;
}
outs() << "ERROR: Instruction with empty DebugLoc -- ";
I.print(outs());
outs() << "\n";
HasErrors = true;
}
}
for (unsigned Idx : MissingLines.set_bits())
outs() << "WARNING: Missing line " << Idx + 1 << "\n";
// Find missing variables.
BitVector MissingVars{OriginalNumVars, true};
for (Function &F : M) {
for (Instruction &I : instructions(F)) {
auto *DVI = dyn_cast<DbgValueInst>(&I);
if (!DVI)
continue;
unsigned Var = ~0U;
(void)to_integer(DVI->getVariable()->getName(), Var, 10);
assert(Var <= OriginalNumVars && "Unexpected name for DILocalVariable");
MissingVars.reset(Var - 1);
}
}
for (unsigned Idx : MissingVars.set_bits())
outs() << "ERROR: Missing variable " << Idx + 1 << "\n";
HasErrors |= MissingVars.count() > 0;
outs() << "CheckDebugify: " << (HasErrors ? "FAIL" : "PASS") << "\n";
}
/// Attach synthetic debug info to everything.
struct DebugifyPass : public ModulePass {
bool runOnModule(Module &M) override { return applyDebugifyMetadata(M); }
DebugifyPass() : ModulePass(ID) {}
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.setPreservesAll();
}
static char ID; // Pass identification.
};
/// Check debug info inserted by -debugify for completeness.
struct CheckDebugifyPass : public ModulePass {
bool runOnModule(Module &M) override {
checkDebugifyMetadata(M);
return false;
}
CheckDebugifyPass() : ModulePass(ID) {}
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.setPreservesAll();
}
static char ID; // Pass identification.
};
} // end anonymous namespace
char DebugifyPass::ID = 0;
static RegisterPass<DebugifyPass> X("debugify",
"Attach debug info to everything");
char CheckDebugifyPass::ID = 0;
static RegisterPass<CheckDebugifyPass> Y("check-debugify",
"Check debug info from -debugify");
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