[Utils] Salvage debug info of DCE'ed mul/sdiv/srem instructions

Here are the number of additional debug values salvaged in a stage2
build of clang:

  63 SALVAGE: MUL
  1250 SALVAGE: SDIV

(No values were salvaged from `srem` instructions in this experiment,
but it's a simple case to handle so we might as well.)

llvm-svn: 324976

1 files changed, 9 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index 1340e12c5c6..45962ca9615 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -1549,6 +1549,15 @@ void llvm::salvageDebugInfo(Instruction &I) {
       case Instruction::Sub:
         applyOffset(DII, -int64_t(Val));
         break;
+      case Instruction::Mul:
+        applyOps(DII, {dwarf::DW_OP_constu, Val, dwarf::DW_OP_mul});
+        break;
+      case Instruction::SDiv:
+        applyOps(DII, {dwarf::DW_OP_constu, Val, dwarf::DW_OP_div});
+        break;
+      case Instruction::SRem:
+        applyOps(DII, {dwarf::DW_OP_constu, Val, dwarf::DW_OP_mod});
+        break;
       case Instruction::Or:
         applyOps(DII, {dwarf::DW_OP_constu, Val, dwarf::DW_OP_or});
         break;