[Utils] Salvage debug info from all no-op casts

We already try to salvage debug values from no-op bitcasts and inttoptr
instructions: we should handle ptrtoint instructions as well.

This saves an additional 24,444 debug values in a stage2 build of clang,
and (according to llvm-dwarfdump --statistics) provides an additional
289 unique source variables.

llvm-svn: 324982

1 files changed, 7 insertions, 4 deletions

diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index 45962ca9615..e170b22b740 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -1518,11 +1518,14 @@ void llvm::salvageDebugInfo(Instruction &I) {
     doSalvage(DII, Ops);
   };
 
-  if (isa<BitCastInst>(&I) || isa<IntToPtrInst>(&I)) {
-    // Bitcasts are entirely irrelevant for debug info. Rewrite dbg.value,
-    // dbg.addr, and dbg.declare to use the cast's source.
+  if (auto *CI = dyn_cast<CastInst>(&I)) {
+    if (!CI->isNoopCast(M.getDataLayout()))
+      return;
+
+    // No-op casts are irrelevant for debug info.
+    MetadataAsValue *CastSrc = wrapMD(I.getOperand(0));
     for (auto *DII : DbgUsers) {
-      DII->setOperand(0, wrapMD(I.getOperand(0)));
+      DII->setOperand(0, CastSrc);
       DEBUG(dbgs() << "SALVAGE: " << *DII << '\n');
     }
   } else if (auto *GEP = dyn_cast<GetElementPtrInst>(&I)) {