From b44d2c977ce2e5dbf9f227bd6ade5d85ae69a463 Mon Sep 17 00:00:00 2001
From: Craig Topper <craig.topper@sifive.com>
Date: Mon, 6 Apr 2026 09:58:04 -0700
Subject: [PATCH] [RISCV] Use a vector MemVT when converting store+extractelt
 into a vector store. (#190107)

This is needed so that `allowsMemoryAccessForAlignment` checks for
unaligned vector memory
support instead of unaligned scalar memory support when called from
`RISCVTargetLowering::expandUnalignedVPStore`

While there remove incorrect setting of the truncating store flag
on the vector instruction. And restrict the transform to simple stores
since we don't have tests for volatile or atomic.

Fixes #189037
---
 llvm/lib/Target/RISCV/RISCVISelLowering.cpp | 10 ++++++----
 llvm/test/CodeGen/RISCV/rvv/pr189037.ll     | 14 ++++++++++++++
 2 files changed, 20 insertions(+), 4 deletions(-)
 create mode 100644 llvm/test/CodeGen/RISCV/rvv/pr189037.ll

diff --git a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
index d00b734f6450..51d8c1ef2460 100644
--- a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
+++ b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
@@ -22378,16 +22378,18 @@ SDValue RISCVTargetLowering::PerformDAGCombine(SDNode *N,
       SDValue Src = Val.getOperand(0);
       MVT VecVT = Src.getSimpleValueType();
       // VecVT should be scalable and memory VT should match the element type.
-      if (!Store->isIndexed() && VecVT.isScalableVector() &&
-          MemVT == VecVT.getVectorElementType()) {
+      if (!Store->isIndexed() && Store->isSimple() &&
+          VecVT.isScalableVector() && MemVT == VecVT.getVectorElementType()) {
         SDLoc DL(N);
         MVT MaskVT = getMaskTypeFor(VecVT);
+        // Create a vector memory VT so allowsMisalignedMemoryAccesses will
+        // work correctly.
+        MemVT = EVT::getVectorVT(*DAG.getContext(), MemVT, 1);
         return DAG.getStoreVP(
             Store->getChain(), DL, Src, Store->getBasePtr(), Store->getOffset(),
             DAG.getConstant(1, DL, MaskVT),
             DAG.getConstant(1, DL, Subtarget.getXLenVT()), MemVT,
-            Store->getMemOperand(), Store->getAddressingMode(),
-            Store->isTruncatingStore(), /*IsCompress*/ false);
+            Store->getMemOperand(), Store->getAddressingMode());
       }
     }
 
diff --git a/llvm/test/CodeGen/RISCV/rvv/pr189037.ll b/llvm/test/CodeGen/RISCV/rvv/pr189037.ll
new file mode 100644
index 000000000000..b0165d2073f1
--- /dev/null
+++ b/llvm/test/CodeGen/RISCV/rvv/pr189037.ll
@@ -0,0 +1,14 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 6
+; RUN: llc < %s -mtriple=riscv64 -mattr=+v,+unaligned-scalar-mem | FileCheck %s
+
+; We should produce a vse8 due to the align 1
+define void @test(ptr %out, <1 x i16> %v) {
+; CHECK-LABEL: test:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    vsetivli zero, 2, e8, mf4, ta, ma
+; CHECK-NEXT:    vse8.v v8, (a0)
+; CHECK-NEXT:    ret
+  %coerce.val.ii.i = extractelement <1 x i16> %v, i64 0
+  store i16 %coerce.val.ii.i, ptr %out, align 1
+  ret void
+}