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llvm-6502/lib/Transforms/Instrumentation/DebugIR.cpp

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//===--- DebugIR.cpp - Transform debug metadata to allow debugging IR -----===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// A Module transform pass that emits a succinct version of the IR and replaces
// the source file metadata to allow debuggers to step through the IR.
//
// The location where the IR file is emitted is the same as the directory
// operand of the !llvm.dbg.cu metadata node present in the input module. The
// file name is constructed from the original file name by stripping the
// extension and replacing it with "-debug-ll" or the Postfix string specified
// at construction.
//
// FIXME: instead of replacing debug metadata, additional metadata should be
// used to point capable debuggers to the IR file without destroying the
// mapping to the original source file.
//
// FIXME: this pass should not depend on the existance of debug metadata in
// the module as it does now. Instead, it should use DIBuilder to create the
// required metadata.
//
//===----------------------------------------------------------------------===//
#include <string>
#include "llvm/ADT/OwningPtr.h"
#include "llvm/ADT/ValueMap.h"
#include "llvm/Assembly/AssemblyAnnotationWriter.h"
#include "llvm/DebugInfo.h"
#include "llvm/DIBuilder.h"
#include "llvm/InstVisitor.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Module.h"
#include "llvm/Pass.h"
#include "llvm/Transforms/Instrumentation.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ToolOutputFile.h"
#include "llvm/Support/FormattedStream.h"
using namespace llvm;
namespace {
/// Builds a map of Value* to line numbers on which the Value appears in a
/// textual representation of the IR by plugging into the AssemblyWriter by
/// masquerading as an AssemblyAnnotationWriter.
class ValueToLineMap : public AssemblyAnnotationWriter {
ValueMap<const Value *, unsigned int> Lines;
typedef ValueMap<const Value *, unsigned int>::const_iterator LineIter;
public:
/// Prints Module to a null buffer in order to build the map of Value pointers
/// to line numbers.
ValueToLineMap(Module *M) {
raw_null_ostream ThrowAway;
M->print(ThrowAway, this);
}
// This function is called after an Instruction, GlobalValue, or GlobalAlias
// is printed.
void printInfoComment(const Value &V, formatted_raw_ostream &Out) {
Out.flush();
Lines.insert(std::make_pair(&V, Out.getLine() + 1));
}
/// If V appears on a line in the textual IR representation, sets Line to the
/// line number and returns true, otherwise returns false.
bool getLine(const Value *V, unsigned int &Line) const {
LineIter i = Lines.find(V);
if (i != Lines.end()) {
Line = i->second;
return true;
}
return false;
}
};
/// Removes debug intrisncs like llvm.dbg.declare and llvm.dbg.value.
class DebugIntrinsicsRemover : public InstVisitor<DebugIntrinsicsRemover> {
void remove(Instruction &I) { I.eraseFromParent(); }
public:
void visitDbgDeclareInst(DbgDeclareInst &I) { remove(I); }
void visitDbgValueInst(DbgValueInst &I) { remove(I); }
void visitDbgInfoIntrinsic(DbgInfoIntrinsic &I) { remove(I); }
};
/// Removes debug metadata (!dbg) nodes from all instructions as well as
/// metadata named "llvm.dbg.cu" in the Module.
class DebugMetadataRemover : public InstVisitor<DebugMetadataRemover> {
public:
void visitInstruction(Instruction &I) {
if (I.getMetadata(LLVMContext::MD_dbg))
I.setMetadata(LLVMContext::MD_dbg, 0);
}
void run(Module *M) {
// Remove debug metadata attached to instructions
visit(M);
// Remove CU named metadata (and all children nodes)
NamedMDNode *Node = M->getNamedMetadata("llvm.dbg.cu");
M->eraseNamedMetadata(Node);
}
};
/// Replaces line number metadata attached to Instruction nodes with new line
/// numbers provided by the ValueToLineMap.
class LineNumberReplacer : public InstVisitor<LineNumberReplacer> {
/// Table of line numbers
const ValueToLineMap &LineTable;
/// Table of cloned values
const ValueToValueMapTy &VMap;
/// Directory of debug metadata
const DebugInfoFinder &Finder;
public:
LineNumberReplacer(const ValueToLineMap &VLM, const DebugInfoFinder &Finder,
const ValueToValueMapTy &VMap)
: LineTable(VLM), VMap(VMap), Finder(Finder) {}
void visitInstruction(Instruction &I) {
DebugLoc Loc(I.getDebugLoc());
unsigned Col = 0; // FIXME: support columns
unsigned Line;
if (!LineTable.getLine(VMap.lookup(&I), Line))
// Instruction has no line, it may have been removed (in the module that
// will be passed to the debugger) so there is nothing to do here.
return;
DebugLoc NewLoc;
if (!Loc.isUnknown())
// I had a previous debug location: re-use the DebugLoc
NewLoc = DebugLoc::get(Line, Col, Loc.getScope(I.getContext()),
Loc.getInlinedAt(I.getContext()));
else if (MDNode *scope = findFunctionMD(I.getParent()->getParent()))
// I had no previous debug location, but M has some debug information
NewLoc =
DebugLoc::get(Line, Col, scope, /*FIXME: inlined instructions*/ 0);
else
// Neither I nor M has any debug information -- nothing to do here.
// FIXME: support debugging of undecorated IR (generated by clang without
// the -g option)
return;
addDebugLocation(const_cast<Instruction &>(I), NewLoc);
}
private:
/// Returns the MDNode that corresponds with F
MDNode *findFunctionMD(const Function *F) {
for (DebugInfoFinder::iterator i = Finder.subprogram_begin(),
e = Finder.subprogram_end();
i != e; ++i) {
DISubprogram S(*i);
if (S.getFunction() == F)
return *i;
}
// cannot find F -- likely means there is no debug information
return 0;
}
void addDebugLocation(Instruction &I, DebugLoc Loc) {
MDNode *MD = Loc.getAsMDNode(I.getContext());
I.setMetadata(LLVMContext::MD_dbg, MD);
}
};
class DebugIR : public ModulePass {
std::string Postfix;
std::string Filename;
/// Flags to control the verbosity of the generated IR file
bool hideDebugIntrinsics;
bool hideDebugMetadata;
public:
static char ID;
const char *getPassName() const { return "DebugIR"; }
// FIXME: figure out if we are compiling something that already exists on disk
// in text IR form, in which case we can omit outputting a new IR file, or if
// we're building something from memory where we actually need to emit a new
// IR file for the debugger.
/// Output a file with the same base name as the original, but with the
/// postfix "-debug-ll" appended.
DebugIR()
: ModulePass(ID), Postfix("-debug-ll"), hideDebugIntrinsics(true),
hideDebugMetadata(true) {}
/// Customize the postfix string used to replace the extension of the
/// original filename that appears in the !llvm.dbg.cu metadata node.
DebugIR(StringRef postfix, bool hideDebugIntrinsics, bool hideDebugMetadata)
: ModulePass(ID), Postfix(postfix),
hideDebugIntrinsics(hideDebugIntrinsics),
hideDebugMetadata(hideDebugMetadata) {}
private:
// Modify the filename embedded in the Compilation-Unit debug information of M
bool replaceFilename(Module &M, const DebugInfoFinder &Finder) {
bool changed = false;
// Sanity check -- if llvm.dbg.cu node exists, the DebugInfoFinder
// better have found at least one CU!
if (M.getNamedMetadata("llvm.dbg.cu"))
assert(Finder.compile_unit_count() > 0 &&
"Found no compile units but llvm.dbg.cu node exists");
for (DebugInfoFinder::iterator i = Finder.compile_unit_begin(),
e = Finder.compile_unit_end();
i != e; ++i) {
DICompileUnit CU(*i);
Filename = CU.getFilename();
// Replace extension with postfix
size_t dot = Filename.find_last_of(".");
if (dot != std::string::npos)
Filename.erase(dot);
Filename += Postfix;
CU.setFilename(Filename, M.getContext());
changed = true;
}
return changed;
}
/// Replace existing line number metadata with line numbers that correspond
/// with the IR file that is seen by the debugger.
void addLineNumberMetadata(Module *M, const ValueToLineMap &VLM,
const ValueToValueMapTy &VMap,
const DebugInfoFinder &Finder) {
LineNumberReplacer Replacer(VLM, Finder, VMap);
Replacer.visit(M);
}
void writeDebugBitcode(Module *M) {
std::string error;
tool_output_file OutFile(Filename.c_str(), error);
OutFile.keep();
formatted_raw_ostream OS;
OS.setStream(OutFile.os());
M->print(OS, 0);
}
void removeDebugIntrinsics(Module *M) {
DebugIntrinsicsRemover Remover;
Remover.visit(M);
}
void removeDebugMetadata(Module *M) {
DebugMetadataRemover Remover;
Remover.run(M);
}
void updateAndWriteDebugIRFile(Module *M, const DebugInfoFinder &Finder) {
// The module we output in text form for a debugger to open is stripped of
// 'extras' like debug intrinsics that end up in DWARF anyways and just
// clutter the debug experience.
ValueToValueMapTy VMap;
Module *DebuggerM = CloneModule(M, VMap);
if (hideDebugIntrinsics)
removeDebugIntrinsics(DebuggerM);
if (hideDebugMetadata)
removeDebugMetadata(DebuggerM);
// FIXME: remove all debug metadata from M once we support generating DWARF
// subprogram attributes.
ValueToLineMap LineTable(DebuggerM);
addLineNumberMetadata(M, LineTable, VMap, Finder);
writeDebugBitcode(DebuggerM);
}
bool runOnModule(Module &M) {
// Stores existing debug info needed when creating new line number entries.
DebugInfoFinder Finder;
Finder.processModule(M);
bool changed = replaceFilename(M, Finder);
if (changed)
updateAndWriteDebugIRFile(&M, Finder);
return changed;
}
};
} // anonymous namespace
char DebugIR::ID = 0;
INITIALIZE_PASS(DebugIR, "debug-ir", "Enable debugging IR", false, false)
ModulePass *llvm::createDebugIRPass(StringRef FilenamePostfix,
bool hideDebugIntrinsics,
bool hideDebugMetadata) {
return new DebugIR(FilenamePostfix, hideDebugIntrinsics, hideDebugMetadata);
}