| Issue |
209269
|
| Summary |
[InstCombine][InstCombineVectorOps] crash after 0aa9ec6a36 (fold zext into de-interleaving)
|
| Labels |
new issue
|
| Assignees |
mshockwave
|
| Reporter |
clin111
|
Just a small missed case in an optimization. This showed up while building gcc with our branch.
```
commit 0aa9ec6a361002f54deb2a8036410455ee527950
Author: Min-Yih Hsu <[email protected]>
Date: Thu May 28 10:34:22 2026 -0700
[InstCombine] Fold zext into de-interleaving (factor=2) instructions (#195330)
```
https://godbolt.org/z/haE4effrE
```
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
@global.1 = constant [27 x [2 x i32]] [[2 x i32] zeroinitializer, [2 x i32] [i32 1, i32 0], [2 x i32] [i32 2, i32 0], [2 x i32] [i32 4, i32 0], [2 x i32] [i32 8, i32 0], [2 x i32] [i32 16, i32 0], [2 x i32] [i32 32, i32 0], [2 x i32] [i32 3, i32 0], [2 x i32] [i32 7, i32 0], [2 x i32] [i32 15, i32 0], [2 x i32] [i32 1114352, i32 8160], [2 x i32] [i32 127, i32 8160], [2 x i32] [i32 1114367, i32 0], [2 x i32] [i32 1114367, i32 8160], [2 x i32] [i32 256, i32 0], [2 x i32] [i32 512, i32 0], [2 x i32] [i32 65280, i32 0], [2 x i32] [i32 2097152, i32 0], [2 x i32] [i32 534773760, i32 2088960], [2 x i32] [i32 -536870912, i32 31], [2 x i32] [i32 534774016, i32 2088960], [2 x i32] [i32 534774272, i32 2088960], [2 x i32] [i32 534839040, i32 4186112], [2 x i32] [i32 131071, i32 8160], [2 x i32] [i32 534839551, i32 2097120], [2 x i32] [i32 534904831, i32 2097120], [2 x i32] [i32 -1, i32 2097151]]
define void @wobble(ptr %global) {
bb:
br label %bb1
bb1: ; preds = %bb1, %bb
%phi1 = phi i64 [ 0, %bb ], [ %add, %bb1 ]
%getelementptr = getelementptr [27 x [2 x i32]], ptr @global.1, i64 0, i64 %phi1, i64 0
%load = load <32 x i32>, ptr %getelementptr, align 8
%shufflevector = shufflevector <32 x i32> %load, <32 x i32> zeroinitializer, <16 x i32> <i32 0, i32 2, i32 4, i32 6, i32 8, i32 10, i32 12, i32 14, i32 16, i32 18, i32 20, i32 22, i32 24, i32 26, i32 28, i32 30>
%shufflevector2 = shufflevector <32 x i32> %load, <32 x i32> zeroinitializer, <16 x i32> <i32 1, i32 3, i32 5, i32 7, i32 9, i32 11, i32 13, i32 15, i32 17, i32 19, i32 21, i32 23, i32 25, i32 27, i32 29, i32 31>
%and3 = and <16 x i32> %shufflevector2, splat (i32 32)
%icmp4 = icmp ne <16 x i32> %and3, zeroinitializer
%and = and <16 x i32> %shufflevector, splat (i32 -2147483648)
%icmp = icmp ne <16 x i32> %and, zeroinitializer
%select = select <16 x i1> %icmp, <16 x i64> splat (i64 1), <16 x i64> zeroinitializer
%or = or <16 x i64> %select, splat (i64 137438953472)
%and6 = and <16 x i32> %shufflevector2, splat (i32 64)
%icmp7 = icmp ne <16 x i32> %and6, zeroinitializer
%select5 = select <16 x i1> %icmp4, <16 x i64> %or, <16 x i64> zeroinitializer
%or8 = or <16 x i64> %select5, splat (i64 274877906944)
%select9 = select <16 x i1> %icmp7, <16 x i64> %or8, <16 x i64> %select5
%or12 = or <16 x i64> %select9, splat (i64 549755813888)
%or16 = or <16 x i64> %or12, splat (i64 1099511627776)
%or20 = or <16 x i64> %or16, splat (i64 2199023255552)
%or24 = or <16 x i64> %or20, splat (i64 4398046511104)
%or28 = or <16 x i64> %or24, splat (i64 8796093022208)
%or32 = or <16 x i64> %or28, splat (i64 17592186044416)
store <16 x i64> %or32, ptr %global, align 16
%add = or i64 %phi1, 0
br label %bb1
}
```
Suggested fix:
```
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp b/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
index 86f64363d418..6993401da830 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
@@ -3393,6 +3393,8 @@ InstCombinerImpl::foldExtractionOfVectorDeinterleave(ZExtInst &RootZExt) {
return nullptr;
}
+ if (isa<ConstantData>(DIV))
+ return nullptr;
auto *InputVecTy = dyn_cast<VectorType>(DIV->getType());
if (!InputVecTy)
return nullptr;
```
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