[llvm-branch-commits] [llvm] release/20.x: [RISCV] Use getSignedConstant for negative values. (#125903) (PR #125953)

[via llvm-branch-commits]

https://github.com/llvmbot created https://github.com/llvm/llvm-project/pull/125953

Backport 0d7ee520d3a9b8997adf8eaaa22b33db9659d94e

Requested by: @topperc

>From faa55e48821c02017d0e9c71602c46467de9fd6e Mon Sep 17 00:00:00 2001
From: Craig Topper <craig.topper at sifive.com>
Date: Wed, 5 Feb 2025 14:49:01 -0800
Subject: [PATCH] [RISCV] Use getSignedConstant for negative values. (#125903)

The APInt constructor asserts if bits are set past the size of the APInt
unless it is signed. This currently fails on RV32 because more than XLen
bits are set.

(cherry picked from commit 0d7ee520d3a9b8997adf8eaaa22b33db9659d94e)
---
 llvm/lib/Target/RISCV/RISCVISelLowering.cpp             | 4 ++--
 llvm/test/CodeGen/RISCV/rvv/vp-combine-reverse-load.ll  | 1 +
 llvm/test/CodeGen/RISCV/rvv/vp-combine-store-reverse.ll | 1 +
 3 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
index 8d09e534b1858bc..8b5ee3e67ce637c 100644
--- a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
+++ b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
@@ -16297,7 +16297,7 @@ static SDValue performVP_REVERSECombine(SDNode *N, SelectionDAG &DAG,
   SDValue Temp2 = DAG.getNode(ISD::MUL, DL, XLenVT, Temp1,
                               DAG.getConstant(ElemWidthByte, DL, XLenVT));
   SDValue Base = DAG.getNode(ISD::ADD, DL, XLenVT, VPLoad->getBasePtr(), Temp2);
-  SDValue Stride = DAG.getConstant(-ElemWidthByte, DL, XLenVT);
+  SDValue Stride = DAG.getSignedConstant(-ElemWidthByte, DL, XLenVT);
 
   MachineFunction &MF = DAG.getMachineFunction();
   MachinePointerInfo PtrInfo(VPLoad->getAddressSpace());
@@ -16358,7 +16358,7 @@ static SDValue performVP_STORECombine(SDNode *N, SelectionDAG &DAG,
                               DAG.getConstant(ElemWidthByte, DL, XLenVT));
   SDValue Base =
       DAG.getNode(ISD::ADD, DL, XLenVT, VPStore->getBasePtr(), Temp2);
-  SDValue Stride = DAG.getConstant(-ElemWidthByte, DL, XLenVT);
+  SDValue Stride = DAG.getSignedConstant(-ElemWidthByte, DL, XLenVT);
 
   MachineFunction &MF = DAG.getMachineFunction();
   MachinePointerInfo PtrInfo(VPStore->getAddressSpace());
diff --git a/llvm/test/CodeGen/RISCV/rvv/vp-combine-reverse-load.ll b/llvm/test/CodeGen/RISCV/rvv/vp-combine-reverse-load.ll
index 50e26bd14107002..24d8e56fa17febc 100644
--- a/llvm/test/CodeGen/RISCV/rvv/vp-combine-reverse-load.ll
+++ b/llvm/test/CodeGen/RISCV/rvv/vp-combine-reverse-load.ll
@@ -1,4 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc -mtriple=riscv32 -mattr=+f,+v -verify-machineinstrs < %s | FileCheck %s
 ; RUN: llc -mtriple=riscv64 -mattr=+f,+v -verify-machineinstrs < %s | FileCheck %s
 
 define <vscale x 2 x float> @test_reverse_load_combiner(<vscale x 2 x float>* %ptr, i32 zeroext %evl) {
diff --git a/llvm/test/CodeGen/RISCV/rvv/vp-combine-store-reverse.ll b/llvm/test/CodeGen/RISCV/rvv/vp-combine-store-reverse.ll
index 4896a1367935ac3..a2466c48b0ab7d9 100644
--- a/llvm/test/CodeGen/RISCV/rvv/vp-combine-store-reverse.ll
+++ b/llvm/test/CodeGen/RISCV/rvv/vp-combine-store-reverse.ll
@@ -1,4 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc -mtriple=riscv32 -mattr=+f,+v -verify-machineinstrs < %s | FileCheck %s
 ; RUN: llc -mtriple=riscv64 -mattr=+f,+v -verify-machineinstrs < %s | FileCheck %s
 
 define void @test_store_reverse_combiner(<vscale x 2 x float> %val, <vscale x 2 x float>* %ptr, i32 zeroext %evl) {