[CodeGenPrepare] Replace deleted ext instr with the promoted value. (#71058)

This PR replaces the deleted ext with the promoted value in `AddrMode`.
Fixes #70938.

1 files changed, 11 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/CodeGenPrepare.cpp b/llvm/lib/CodeGen/CodeGenPrepare.cpp
index 47486a3..088062afa 100644
--- a/llvm/lib/CodeGen/CodeGenPrepare.cpp
+++ b/llvm/lib/CodeGen/CodeGenPrepare.cpp
@@ -3074,6 +3074,14 @@ struct ExtAddrMode : public TargetLowering::AddrMode {
   void print(raw_ostream &OS) const;
   void dump() const;
 
+  // Replace From in ExtAddrMode with To.
+  // E.g., SExt insts may be promoted and deleted. We should replace them with
+  // the promoted values.
+  void replaceWith(Value *From, Value *To) {
+    if (ScaledReg == From)
+      ScaledReg = To;
+  }
+
   FieldName compare(const ExtAddrMode &other) {
     // First check that the types are the same on each field, as differing types
     // is something we can't cope with later on.
@@ -5365,6 +5373,9 @@ bool AddressingModeMatcher::matchOperationAddr(User *AddrInst, unsigned Opcode,
       TPT.rollback(LastKnownGood);
       return false;
     }
+
+    // SExt has been deleted. Make sure it is not referenced by the AddrMode.
+    AddrMode.replaceWith(Ext, PromotedOperand);
     return true;
   }
   case Instruction::Call: