[DebugInfo] Describe size of spilled values in call site params

A call site parameter description of a memory operand needs to
unambiguously convey the size of the operand to prevent incorrect entry
value evaluation.

Thanks for David Stenberg for pointing this issue out!

1 files changed, 5 insertions, 1 deletions

diff --git a/llvm/lib/CodeGen/TargetInstrInfo.cpp b/llvm/lib/CodeGen/TargetInstrInfo.cpp
index 2b987dabd24..d7a02eb61a2 100644
--- a/llvm/lib/CodeGen/TargetInstrInfo.cpp
+++ b/llvm/lib/CodeGen/TargetInstrInfo.cpp
@@ -1150,7 +1150,11 @@ TargetInstrInfo::describeLoadedValue(const MachineInstr &MI) const {
     if (!TII->getMemOperandWithOffset(MI, BaseOp, Offset, TRI))
       return None;
 
-    Expr = DIExpression::prepend(Expr, DIExpression::DerefAfter, Offset);
+    SmallVector<uint64_t, 8> Ops;
+    DIExpression::appendOffset(Ops, Offset);
+    Ops.push_back(dwarf::DW_OP_deref_size);
+    Ops.push_back(MMO->getSize());
+    Expr = DIExpression::prependOpcodes(Expr, Ops);
     return ParamLoadedValue(*BaseOp, Expr);
   }