[llvm-branch-commits] [llvm] release/21.x: [RISCV] Remove incorrect and untested FrameIndex support from SelectAddrRegImm9. (#148779) (PR #148913)

[via llvm-branch-commits]

https://github.com/llvmbot created https://github.com/llvm/llvm-project/pull/148913

Backport 63d099a

Requested by: @topperc

>From 9bd120ac74d712e411dc461fe959953326d48e23 Mon Sep 17 00:00:00 2001
From: Craig Topper <craig.topper at sifive.com>
Date: Tue, 15 Jul 2025 10:49:23 -0700
Subject: [PATCH] [RISCV] Remove incorrect and untested FrameIndex support from
 SelectAddrRegImm9. (#148779)

To fold a FrameIndex, we need to teach eliminateFrameIndex to respect
the uimm9 range.

(cherry picked from commit 63d099af146a19bc8fd5a791d6184125e6cc42e7)
---
 llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp b/llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp
index 666c76b21e631..880e6b0d48892 100644
--- a/llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp
+++ b/llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp
@@ -2936,8 +2936,8 @@ bool RISCVDAGToDAGISel::SelectAddrRegImm(SDValue Addr, SDValue &Base,
 /// Similar to SelectAddrRegImm, except that the offset is restricted to uimm9.
 bool RISCVDAGToDAGISel::SelectAddrRegImm9(SDValue Addr, SDValue &Base,
                                           SDValue &Offset) {
-  if (SelectAddrFrameIndex(Addr, Base, Offset))
-    return true;
+  // FIXME: Support FrameIndex. Need to teach eliminateFrameIndex that only
+  // a 9-bit immediate can be folded.
 
   SDLoc DL(Addr);
   MVT VT = Addr.getSimpleValueType();
@@ -2947,8 +2947,8 @@ bool RISCVDAGToDAGISel::SelectAddrRegImm9(SDValue Addr, SDValue &Base,
     if (isUInt<9>(CVal)) {
       Base = Addr.getOperand(0);
 
-      if (auto *FIN = dyn_cast<FrameIndexSDNode>(Base))
-        Base = CurDAG->getTargetFrameIndex(FIN->getIndex(), VT);
+      // FIXME: Support FrameIndex. Need to teach eliminateFrameIndex that only
+      // a 9-bit immediate can be folded.
       Offset = CurDAG->getSignedTargetConstant(CVal, DL, VT);
       return true;
     }