[DebugInfo] Disallow fragmenting DIExpressions with shift operators

DIExpressions with shift operators should not be fragmented for the same
reason as arithmetic operators: carry over cannot be expressed from one
fragment to the other, so an invalid result would be produced.

Differential Revision: https://reviews.llvm.org/D70601

1 files changed, 6 insertions, 2 deletions

diff --git a/llvm/lib/IR/DebugInfoMetadata.cpp b/llvm/lib/IR/DebugInfoMetadata.cpp
index e4036ee1eb0..b0102275b36 100644
--- a/llvm/lib/IR/DebugInfoMetadata.cpp
+++ b/llvm/lib/IR/DebugInfoMetadata.cpp
@@ -1148,10 +1148,14 @@ Optional<DIExpression *> DIExpression::createFragmentExpression(
     for (auto Op : Expr->expr_ops()) {
       switch (Op.getOp()) {
       default: break;
+      case dwarf::DW_OP_shr:
+      case dwarf::DW_OP_shra:
+      case dwarf::DW_OP_shl:
       case dwarf::DW_OP_plus:
+      case dwarf::DW_OP_plus_uconst:
       case dwarf::DW_OP_minus:
-        // We can't safely split arithmetic into multiple fragments because we
-        // can't express carry-over between fragments.
+        // We can't safely split arithmetic or shift operations into multiple
+        // fragments because we can't express carry-over between fragments.
         //
         // FIXME: We *could* preserve the lowest fragment of a constant offset
         // operation if the offset fits into SizeInBits.