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//===- DebugTranslation.cpp - MLIR to LLVM Debug conversion ---------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
#include "DebugTranslation.h"
#include "mlir/Dialect/LLVMIR/LLVMDialect.h"
#include "llvm/IR/Metadata.h"
#include "llvm/IR/Module.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/Path.h"
using namespace mlir;
using namespace mlir::LLVM;
using namespace mlir::LLVM::detail;
/// A utility walker that interrupts if the operation has valid debug
/// information.
static WalkResult interruptIfValidLocation(Operation *op) {
return op->getLoc().isa<UnknownLoc>() ? WalkResult::advance()
: WalkResult::interrupt();
}
DebugTranslation::DebugTranslation(Operation *module, llvm::Module &llvmModule)
: builder(llvmModule), llvmCtx(llvmModule.getContext()),
compileUnit(nullptr) {
// If the module has no location information, there is nothing to do.
if (!module->walk(interruptIfValidLocation).wasInterrupted())
return;
// TODO: Several parts of this are incorrect. Different source
// languages may interpret different parts of the debug information
// differently. Frontends will also want to pipe in various information, like
// flags. This is fine for now as we only emit line-table information and not
// types or variables. This should disappear as the debug information story
// evolves; i.e. when we have proper attributes for LLVM debug metadata.
compileUnit = builder.createCompileUnit(
llvm::dwarf::DW_LANG_C,
builder.createFile(llvmModule.getModuleIdentifier(), "/"),
/*Producer=*/"mlir", /*isOptimized=*/true, /*Flags=*/"", /*RV=*/0);
// Mark this module as having debug information.
StringRef debugVersionKey = "Debug Info Version";
if (!llvmModule.getModuleFlag(debugVersionKey))
llvmModule.addModuleFlag(llvm::Module::Warning, debugVersionKey,
llvm::DEBUG_METADATA_VERSION);
if (auto targetTripleAttr =
module->getAttr(LLVM::LLVMDialect::getTargetTripleAttrName())) {
auto targetTriple =
llvm::Triple(targetTripleAttr.cast<StringAttr>().getValue());
if (targetTriple.isKnownWindowsMSVCEnvironment()) {
// Dwarf debugging files will be generated by default, unless "CodeView"
// is set explicitly. Windows/MSVC should use CodeView instead.
llvmModule.addModuleFlag(llvm::Module::Warning, "CodeView", 1);
}
}
}
/// Finalize the translation of debug information.
void DebugTranslation::finalize() { builder.finalize(); }
/// Attempt to extract a filename for the given loc.
static FileLineColLoc extractFileLoc(Location loc) {
if (auto fileLoc = loc.dyn_cast<FileLineColLoc>())
return fileLoc;
if (auto nameLoc = loc.dyn_cast<NameLoc>())
return extractFileLoc(nameLoc.getChildLoc());
if (auto opaqueLoc = loc.dyn_cast<OpaqueLoc>())
return extractFileLoc(opaqueLoc.getFallbackLocation());
return FileLineColLoc();
}
/// Translate the debug information for the given function.
void DebugTranslation::translate(LLVMFuncOp func, llvm::Function &llvmFunc) {
// If the function doesn't have location information, there is nothing to
// translate.
if (!compileUnit || !func.walk(interruptIfValidLocation).wasInterrupted())
return;
// If we are to create debug info for the function, we need to ensure that all
// inlinable calls in it are with debug info, otherwise the LLVM verifier will
// complain. For now, be more restricted and treat all calls as inlinable.
const bool hasCallWithoutDebugInfo =
func.walk([](LLVM::CallOp call) {
return call.getLoc().isa<UnknownLoc>() ? WalkResult::interrupt()
: WalkResult::advance();
})
.wasInterrupted();
if (hasCallWithoutDebugInfo)
return;
FileLineColLoc fileLoc = extractFileLoc(func.getLoc());
auto *file = translateFile(fileLoc ? fileLoc.getFilename() : "<unknown>");
unsigned line = fileLoc ? fileLoc.getLine() : 0;
// TODO: This is the bare essentials for now. We will likely end
// up with wrapper metadata around LLVMs metadata in the future, so this
// doesn't need to be smart until then.
llvm::DISubroutineType *type =
builder.createSubroutineType(builder.getOrCreateTypeArray(llvm::None));
llvm::DISubprogram::DISPFlags spFlags = llvm::DISubprogram::SPFlagDefinition |
llvm::DISubprogram::SPFlagOptimized;
llvm::DISubprogram *program =
builder.createFunction(compileUnit, func.getName(), func.getName(), file,
line, type, line, llvm::DINode::FlagZero, spFlags);
llvmFunc.setSubprogram(program);
builder.finalizeSubprogram(program);
}
//===----------------------------------------------------------------------===//
// Locations
//===----------------------------------------------------------------------===//
/// Translate the given location to an llvm debug location.
const llvm::DILocation *
DebugTranslation::translateLoc(Location loc, llvm::DILocalScope *scope) {
if (!compileUnit)
return nullptr;
return translateLoc(loc, scope, /*inlinedAt=*/nullptr);
}
/// Translate the given location to an llvm DebugLoc.
const llvm::DILocation *
DebugTranslation::translateLoc(Location loc, llvm::DILocalScope *scope,
const llvm::DILocation *inlinedAt) {
// LLVM doesn't have a representation for unknown.
if (!scope || loc.isa<UnknownLoc>())
return nullptr;
// Check for a cached instance.
auto existingIt = locationToLoc.find(std::make_pair(loc, scope));
if (existingIt != locationToLoc.end())
return existingIt->second;
const llvm::DILocation *llvmLoc = nullptr;
if (auto callLoc = loc.dyn_cast<CallSiteLoc>()) {
// For callsites, the caller is fed as the inlinedAt for the callee.
const auto *callerLoc = translateLoc(callLoc.getCaller(), scope, inlinedAt);
llvmLoc = translateLoc(callLoc.getCallee(), scope, callerLoc);
} else if (auto fileLoc = loc.dyn_cast<FileLineColLoc>()) {
auto *file = translateFile(fileLoc.getFilename());
auto *fileScope = builder.createLexicalBlockFile(scope, file);
llvmLoc = llvm::DILocation::get(llvmCtx, fileLoc.getLine(),
fileLoc.getColumn(), fileScope,
const_cast<llvm::DILocation *>(inlinedAt));
} else if (auto fusedLoc = loc.dyn_cast<FusedLoc>()) {
ArrayRef<Location> locations = fusedLoc.getLocations();
// For fused locations, merge each of the nodes.
llvmLoc = translateLoc(locations.front(), scope, inlinedAt);
for (Location locIt : locations.drop_front()) {
llvmLoc = llvm::DILocation::getMergedLocation(
llvmLoc, translateLoc(locIt, scope, inlinedAt));
}
} else if (auto nameLoc = loc.dyn_cast<NameLoc>()) {
llvmLoc = translateLoc(loc.cast<NameLoc>().getChildLoc(), scope, inlinedAt);
} else if (auto opaqueLoc = loc.dyn_cast<OpaqueLoc>()) {
llvmLoc = translateLoc(loc.cast<OpaqueLoc>().getFallbackLocation(), scope,
inlinedAt);
} else {
llvm_unreachable("unknown location kind");
}
locationToLoc.try_emplace(std::make_pair(loc, scope), llvmLoc);
return llvmLoc;
}
/// Create an llvm debug file for the given file path.
llvm::DIFile *DebugTranslation::translateFile(StringRef fileName) {
auto *&file = fileMap[fileName];
if (file)
return file;
// Make sure the current working directory is up-to-date.
if (currentWorkingDir.empty())
llvm::sys::fs::current_path(currentWorkingDir);
StringRef directory = currentWorkingDir;
SmallString<128> dirBuf;
SmallString<128> fileBuf;
if (llvm::sys::path::is_absolute(fileName)) {
// Strip the common prefix (if it is more than just "/") from current
// directory and FileName for a more space-efficient encoding.
auto fileIt = llvm::sys::path::begin(fileName);
auto fileE = llvm::sys::path::end(fileName);
auto curDirIt = llvm::sys::path::begin(directory);
auto curDirE = llvm::sys::path::end(directory);
for (; curDirIt != curDirE && *curDirIt == *fileIt; ++curDirIt, ++fileIt)
llvm::sys::path::append(dirBuf, *curDirIt);
if (std::distance(llvm::sys::path::begin(directory), curDirIt) == 1) {
// Don't strip the common prefix if it is only the root "/" since that
// would make LLVM diagnostic locations confusing.
directory = StringRef();
} else {
for (; fileIt != fileE; ++fileIt)
llvm::sys::path::append(fileBuf, *fileIt);
directory = dirBuf;
fileName = fileBuf;
}
}
return (file = builder.createFile(fileName, directory));
}