// Rewrite all `DICompileUnit` pointers to the `DICompileUnit` specified. See
// the comment in `back/lto.rs` for why this exists.
extern "C" void
LLVMRustThinLTOPatchDICompileUnit(LLVMModuleRef Mod, DICompileUnit *Unit) {
Module *M = unwrap(Mod);
// If the original source module didn't have a `DICompileUnit` then try to
// merge all the existing compile units. If there aren't actually any though
// then there's not much for us to do so return.
if (Unit == nullptr) {
for (DICompileUnit *CU : M->debug_compile_units()) {
Unit = CU;
break;
}
if (Unit == nullptr)
return;
}
// Use LLVM's built-in `DebugInfoFinder` to find a bunch of debuginfo and
// process it recursively. Note that we specifically iterate over instructions
// to ensure we feed everything into it.
DebugInfoFinder Finder;
Finder.processModule(*M);
for (Function &F : M->functions()) {
for (auto &FI : F) {
for (Instruction &BI : FI) {
if (auto Loc = BI.getDebugLoc())
Finder.processLocation(*M, Loc);
if (auto DVI = dyn_cast<DbgValueInst>(&BI))
Finder.processValue(*M, DVI);
if (auto DDI = dyn_cast<DbgDeclareInst>(&BI))
Finder.processDeclare(*M, DDI);
}
}
}
// After we've found all our debuginfo, rewrite all subprograms to point to
// the same `DICompileUnit`.
for (auto &F : Finder.subprograms()) {
F->replaceUnit(Unit);
}
// Erase any other references to other `DICompileUnit` instances, the verifier
// will later ensure that we don't actually have any other stale references to
// worry about.
auto *MD = M->getNamedMetadata("llvm.dbg.cu");
MD->clearOperands();
MD->addOperand(Unit);
}
