[llvm] [IR] Fix vector.splice verifier scaling by vscale for fixed length vectors (PR #170807)

[Luke Lau via llvm-commits]

https://github.com/lukel97 created https://github.com/llvm/llvm-project/pull/170807

Currently we multiply the known minimum number of elements by vscale even if the vector in question is fixed, so sometimes we miss some fixed vectors with out of bounds indices.


>From d82c8f51857074da263a5607becca48fe139c72f Mon Sep 17 00:00:00 2001
From: Luke Lau <luke at igalia.com>
Date: Fri, 5 Dec 2025 15:37:46 +0800
Subject: [PATCH] [IR] Fix vector.splice verifier scaling by vscale for fixed
 length vectors

Currently we multiply the known minimum number of elements by vscale even if the vector in question is fixed, so sometimes we miss some fixed vectors with out of bounds indices.
---
 llvm/lib/IR/Verifier.cpp             | 3 ++-
 llvm/test/Verifier/invalid-splice.ll | 2 +-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/llvm/lib/IR/Verifier.cpp b/llvm/lib/IR/Verifier.cpp
index 439b3859fd3ac..10e6c452680b0 100644
--- a/llvm/lib/IR/Verifier.cpp
+++ b/llvm/lib/IR/Verifier.cpp
@@ -6570,7 +6570,8 @@ void Verifier::visitIntrinsicCall(Intrinsic::ID ID, CallBase &Call) {
     VectorType *VecTy = cast<VectorType>(Call.getType());
     int64_t Idx = cast<ConstantInt>(Call.getArgOperand(2))->getSExtValue();
     int64_t KnownMinNumElements = VecTy->getElementCount().getKnownMinValue();
-    if (Call.getParent() && Call.getParent()->getParent()) {
+    if (VecTy->isScalableTy() && Call.getParent() &&
+        Call.getParent()->getParent()) {
       AttributeList Attrs = Call.getParent()->getParent()->getAttributes();
       if (Attrs.hasFnAttr(Attribute::VScaleRange))
         KnownMinNumElements *= Attrs.getFnAttrs().getVScaleRangeMin();
diff --git a/llvm/test/Verifier/invalid-splice.ll b/llvm/test/Verifier/invalid-splice.ll
index 2239386df562f..c34f4d0898aa0 100644
--- a/llvm/test/Verifier/invalid-splice.ll
+++ b/llvm/test/Verifier/invalid-splice.ll
@@ -26,7 +26,7 @@ define <2 x double> @splice_v2f64_idx2(<2 x double> %a, <2 x double> %b) #0 {
 
 ; CHECK: The splice index exceeds the range [-VL, VL-1] where VL is the known minimum number of elements in the vector
 define <2 x double> @splice_v2f64_idx3(<2 x double> %a, <2 x double> %b) #1 {
-  %res = call <2 x double> @llvm.vector.splice.v2f64(<2 x double> %a, <2 x double> %b, i32 4)
+  %res = call <2 x double> @llvm.vector.splice.v2f64(<2 x double> %a, <2 x double> %b, i32 3)
   ret <2 x double> %res
 }