[llvm] [ConstantFolding] Add constant folding for scalable vector interleave intrinsics. (PR #168668)
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Tue Nov 18 21:57:29 PST 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-llvm-transforms
Author: Craig Topper (topperc)
<details>
<summary>Changes</summary>
We can constant fold interleave of identical splat vectors to a larger splat vector.
---
Full diff: https://github.com/llvm/llvm-project/pull/168668.diff
2 Files Affected:
- (modified) llvm/lib/Analysis/ConstantFolding.cpp (+16)
- (modified) llvm/test/Transforms/InstSimplify/ConstProp/vector-calls.ll (+112)
``````````diff
diff --git a/llvm/lib/Analysis/ConstantFolding.cpp b/llvm/lib/Analysis/ConstantFolding.cpp
old mode 100755
new mode 100644
index a13df6c5bf552..e1bbcec306edc
--- a/llvm/lib/Analysis/ConstantFolding.cpp
+++ b/llvm/lib/Analysis/ConstantFolding.cpp
@@ -4307,6 +4307,22 @@ static Constant *ConstantFoldScalableVectorCall(
return ConstantVector::getNullValue(SVTy);
break;
}
+ case Intrinsic::vector_interleave2:
+ case Intrinsic::vector_interleave3:
+ case Intrinsic::vector_interleave4:
+ case Intrinsic::vector_interleave5:
+ case Intrinsic::vector_interleave6:
+ case Intrinsic::vector_interleave7:
+ case Intrinsic::vector_interleave8: {
+ Constant *SplatVal = Operands[0]->getSplatValue();
+ if (!SplatVal)
+ return nullptr;
+
+ if (!llvm::all_equal(Operands))
+ return nullptr;
+
+ return ConstantVector::getSplat(SVTy->getElementCount(), SplatVal);
+ }
default:
break;
}
diff --git a/llvm/test/Transforms/InstSimplify/ConstProp/vector-calls.ll b/llvm/test/Transforms/InstSimplify/ConstProp/vector-calls.ll
index 848f0d17ff373..2d8a444141a2b 100644
--- a/llvm/test/Transforms/InstSimplify/ConstProp/vector-calls.ll
+++ b/llvm/test/Transforms/InstSimplify/ConstProp/vector-calls.ll
@@ -51,6 +51,22 @@ define <8 x i32> @fold_vector_interleave2() {
ret <8 x i32> %1
}
+define <vscale x 8 x i32> @fold_scalable_vector_interleave2() {
+; CHECK-LABEL: define <vscale x 8 x i32> @fold_scalable_vector_interleave2() {
+; CHECK-NEXT: ret <vscale x 8 x i32> zeroinitializer
+;
+ %1 = call <vscale x 8 x i32> @llvm.vector.interleave2.nxv8i32(<vscale x 4 x i32> zeroinitializer, <vscale x 4 x i32> zeroinitializer)
+ ret <vscale x 8 x i32> %1
+}
+
+define <vscale x 8 x i32> @fold_scalable_vector_interleave2_splat() {
+; CHECK-LABEL: define <vscale x 8 x i32> @fold_scalable_vector_interleave2_splat() {
+; CHECK-NEXT: ret <vscale x 8 x i32> splat (i32 1)
+;
+ %1 = call <vscale x 8 x i32> @llvm.vector.interleave2.nxv8i32(<vscale x 4 x i32> splat (i32 1), <vscale x 4 x i32> splat (i32 1))
+ ret <vscale x 8 x i32> %1
+}
+
define <12 x i32> @fold_vector_interleave3() {
; CHECK-LABEL: define <12 x i32> @fold_vector_interleave3() {
; CHECK-NEXT: ret <12 x i32> <i32 1, i32 5, i32 9, i32 2, i32 6, i32 10, i32 3, i32 7, i32 11, i32 4, i32 8, i32 12>
@@ -59,6 +75,22 @@ define <12 x i32> @fold_vector_interleave3() {
ret <12 x i32> %1
}
+define <vscale x 12 x i32> @fold_scalable_vector_interleave3() {
+; CHECK-LABEL: define <vscale x 12 x i32> @fold_scalable_vector_interleave3() {
+; CHECK-NEXT: ret <vscale x 12 x i32> zeroinitializer
+;
+ %1 = call <vscale x 12 x i32> @llvm.vector.interleave3.nxv8i32(<vscale x 4 x i32> zeroinitializer, <vscale x 4 x i32> zeroinitializer, <vscale x 4 x i32> zeroinitializer)
+ ret <vscale x 12 x i32> %1
+}
+
+define <vscale x 12 x i32> @fold_scalable_vector_interleave3_splat() {
+; CHECK-LABEL: define <vscale x 12 x i32> @fold_scalable_vector_interleave3_splat() {
+; CHECK-NEXT: ret <vscale x 12 x i32> splat (i32 1)
+;
+ %1 = call <vscale x 12 x i32> @llvm.vector.interleave3.nxv8i32(<vscale x 4 x i32> splat (i32 1), <vscale x 4 x i32> splat (i32 1), <vscale x 4 x i32> splat (i32 1))
+ ret <vscale x 12 x i32> %1
+}
+
define <16 x i32> @fold_vector_interleave4() {
; CHECK-LABEL: define <16 x i32> @fold_vector_interleave4() {
; CHECK-NEXT: ret <16 x i32> <i32 1, i32 5, i32 9, i32 13, i32 2, i32 6, i32 10, i32 14, i32 3, i32 7, i32 11, i32 15, i32 4, i32 8, i32 12, i32 16>
@@ -67,6 +99,22 @@ define <16 x i32> @fold_vector_interleave4() {
ret <16 x i32> %1
}
+define <vscale x 16 x i32> @fold_scalable_vector_interleave4() {
+; CHECK-LABEL: define <vscale x 16 x i32> @fold_scalable_vector_interleave4() {
+; CHECK-NEXT: ret <vscale x 16 x i32> zeroinitializer
+;
+ %1 = call <vscale x 16 x i32> @llvm.vector.interleave4.nxv16i32(<vscale x 4 x i32> zeroinitializer, <vscale x 4 x i32> zeroinitializer, <vscale x 4 x i32> zeroinitializer, <vscale x 4 x i32> zeroinitializer)
+ ret <vscale x 16 x i32> %1
+}
+
+define <vscale x 16 x i32> @fold_scalable_vector_interleave4_splat() {
+; CHECK-LABEL: define <vscale x 16 x i32> @fold_scalable_vector_interleave4_splat() {
+; CHECK-NEXT: ret <vscale x 16 x i32> splat (i32 1)
+;
+ %1 = call <vscale x 16 x i32> @llvm.vector.interleave4.nxv16i32(<vscale x 4 x i32> splat (i32 1), <vscale x 4 x i32> splat (i32 1), <vscale x 4 x i32> splat (i32 1), <vscale x 4 x i32> splat (i32 1))
+ ret <vscale x 16 x i32> %1
+}
+
define <20 x i32> @fold_vector_interleave5() {
; CHECK-LABEL: define <20 x i32> @fold_vector_interleave5() {
; CHECK-NEXT: ret <20 x i32> <i32 1, i32 5, i32 9, i32 13, i32 17, i32 2, i32 6, i32 10, i32 14, i32 18, i32 3, i32 7, i32 11, i32 15, i32 19, i32 4, i32 8, i32 12, i32 16, i32 20>
@@ -75,6 +123,22 @@ define <20 x i32> @fold_vector_interleave5() {
ret <20 x i32> %1
}
+define <vscale x 20 x i32> @fold_scalable_vector_interleave5() {
+; CHECK-LABEL: define <vscale x 20 x i32> @fold_scalable_vector_interleave5() {
+; CHECK-NEXT: ret <vscale x 20 x i32> zeroinitializer
+;
+ %1 = call <vscale x 20 x i32> @llvm.vector.interleave5.nxv20i32(<vscale x 4 x i32> zeroinitializer, <vscale x 4 x i32> zeroinitializer, <vscale x 4 x i32> zeroinitializer, <vscale x 4 x i32> zeroinitializer, <vscale x 4 x i32> zeroinitializer)
+ ret <vscale x 20 x i32> %1
+}
+
+define <vscale x 20 x i32> @fold_scalable_vector_interleave5_splat() {
+; CHECK-LABEL: define <vscale x 20 x i32> @fold_scalable_vector_interleave5_splat() {
+; CHECK-NEXT: ret <vscale x 20 x i32> splat (i32 1)
+;
+ %1 = call <vscale x 20 x i32> @llvm.vector.interleave5.nxv20i32(<vscale x 4 x i32> splat (i32 1), <vscale x 4 x i32> splat (i32 1), <vscale x 4 x i32> splat (i32 1), <vscale x 4 x i32> splat (i32 1), <vscale x 4 x i32> splat (i32 1))
+ ret <vscale x 20 x i32> %1
+}
+
define <24 x i32> @fold_vector_interleave6() {
; CHECK-LABEL: define <24 x i32> @fold_vector_interleave6() {
; CHECK-NEXT: ret <24 x i32> <i32 1, i32 5, i32 9, i32 13, i32 17, i32 21, i32 2, i32 6, i32 10, i32 14, i32 18, i32 22, i32 3, i32 7, i32 11, i32 15, i32 19, i32 23, i32 4, i32 8, i32 12, i32 16, i32 20, i32 24>
@@ -83,6 +147,22 @@ define <24 x i32> @fold_vector_interleave6() {
ret <24 x i32> %1
}
+define <vscale x 24 x i32> @fold_scalable_vector_interleave6() {
+; CHECK-LABEL: define <vscale x 24 x i32> @fold_scalable_vector_interleave6() {
+; CHECK-NEXT: ret <vscale x 24 x i32> zeroinitializer
+;
+ %1 = call <vscale x 24 x i32> @llvm.vector.interleave6.nxv24i32(<vscale x 4 x i32> zeroinitializer, <vscale x 4 x i32> zeroinitializer, <vscale x 4 x i32> zeroinitializer, <vscale x 4 x i32> zeroinitializer, <vscale x 4 x i32> zeroinitializer, <vscale x 4 x i32> zeroinitializer)
+ ret <vscale x 24 x i32> %1
+}
+
+define <vscale x 24 x i32> @fold_scalable_vector_interleave6_splat() {
+; CHECK-LABEL: define <vscale x 24 x i32> @fold_scalable_vector_interleave6_splat() {
+; CHECK-NEXT: ret <vscale x 24 x i32> splat (i32 1)
+;
+ %1 = call <vscale x 24 x i32> @llvm.vector.interleave6.nxv24i32(<vscale x 4 x i32> splat (i32 1), <vscale x 4 x i32> splat (i32 1), <vscale x 4 x i32> splat (i32 1), <vscale x 4 x i32> splat (i32 1), <vscale x 4 x i32> splat (i32 1), <vscale x 4 x i32> splat (i32 1))
+ ret <vscale x 24 x i32> %1
+}
+
define <28 x i32> @fold_vector_interleave7() {
; CHECK-LABEL: define <28 x i32> @fold_vector_interleave7() {
; CHECK-NEXT: ret <28 x i32> <i32 1, i32 5, i32 9, i32 13, i32 17, i32 21, i32 25, i32 2, i32 6, i32 10, i32 14, i32 18, i32 22, i32 26, i32 3, i32 7, i32 11, i32 15, i32 19, i32 23, i32 27, i32 4, i32 8, i32 12, i32 16, i32 20, i32 24, i32 28>
@@ -91,6 +171,22 @@ define <28 x i32> @fold_vector_interleave7() {
ret <28 x i32> %1
}
+define <vscale x 28 x i32> @fold_scalable_vector_interleave7() {
+; CHECK-LABEL: define <vscale x 28 x i32> @fold_scalable_vector_interleave7() {
+; CHECK-NEXT: ret <vscale x 28 x i32> zeroinitializer
+;
+ %1 = call <vscale x 28 x i32> @llvm.vector.interleave7.nxv28i32(<vscale x 4 x i32> zeroinitializer, <vscale x 4 x i32> zeroinitializer, <vscale x 4 x i32> zeroinitializer, <vscale x 4 x i32> zeroinitializer, <vscale x 4 x i32> zeroinitializer, <vscale x 4 x i32> zeroinitializer, <vscale x 4 x i32> zeroinitializer)
+ ret <vscale x 28 x i32> %1
+}
+
+define <vscale x 28 x i32> @fold_scalable_vector_interleave7_splat() {
+; CHECK-LABEL: define <vscale x 28 x i32> @fold_scalable_vector_interleave7_splat() {
+; CHECK-NEXT: ret <vscale x 28 x i32> splat (i32 1)
+;
+ %1 = call <vscale x 28 x i32> @llvm.vector.interleave7.nxv28i32(<vscale x 4 x i32> splat (i32 1), <vscale x 4 x i32> splat (i32 1), <vscale x 4 x i32> splat (i32 1), <vscale x 4 x i32> splat (i32 1), <vscale x 4 x i32> splat (i32 1), <vscale x 4 x i32> splat (i32 1), <vscale x 4 x i32> splat (i32 1))
+ ret <vscale x 28 x i32> %1
+}
+
define <32 x i32> @fold_vector_interleave8() {
; CHECK-LABEL: define <32 x i32> @fold_vector_interleave8() {
; CHECK-NEXT: ret <32 x i32> <i32 1, i32 5, i32 9, i32 13, i32 17, i32 21, i32 25, i32 29, i32 2, i32 6, i32 10, i32 14, i32 18, i32 22, i32 26, i32 30, i32 3, i32 7, i32 11, i32 15, i32 19, i32 23, i32 27, i32 31, i32 4, i32 8, i32 12, i32 16, i32 20, i32 24, i32 28, i32 32>
@@ -99,6 +195,22 @@ define <32 x i32> @fold_vector_interleave8() {
ret <32 x i32> %1
}
+define <vscale x 32 x i32> @fold_scalable_vector_interleave8() {
+; CHECK-LABEL: define <vscale x 32 x i32> @fold_scalable_vector_interleave8() {
+; CHECK-NEXT: ret <vscale x 32 x i32> zeroinitializer
+;
+ %1 = call <vscale x 32 x i32> @llvm.vector.interleave8.nxv32i32(<vscale x 4 x i32> zeroinitializer, <vscale x 4 x i32> zeroinitializer, <vscale x 4 x i32> zeroinitializer, <vscale x 4 x i32> zeroinitializer, <vscale x 4 x i32> zeroinitializer, <vscale x 4 x i32> zeroinitializer, <vscale x 4 x i32> zeroinitializer, <vscale x 4 x i32> zeroinitializer)
+ ret <vscale x 32 x i32> %1
+}
+
+define <vscale x 32 x i32> @fold_scalable_vector_interleave8_splat() {
+; CHECK-LABEL: define <vscale x 32 x i32> @fold_scalable_vector_interleave8_splat() {
+; CHECK-NEXT: ret <vscale x 32 x i32> splat (i32 1)
+;
+ %1 = call <vscale x 32 x i32> @llvm.vector.interleave8.nxv32i32(<vscale x 4 x i32> splat (i32 1), <vscale x 4 x i32> splat (i32 1), <vscale x 4 x i32> splat (i32 1), <vscale x 4 x i32> splat (i32 1), <vscale x 4 x i32> splat (i32 1), <vscale x 4 x i32> splat (i32 1), <vscale x 4 x i32> splat (i32 1), <vscale x 4 x i32> splat (i32 1))
+ ret <vscale x 32 x i32> %1
+}
+
define {<4 x i32>, <4 x i32>} @fold_vector_deinterleave2() {
; CHECK-LABEL: define { <4 x i32>, <4 x i32> } @fold_vector_deinterleave2() {
; CHECK-NEXT: ret { <4 x i32>, <4 x i32> } { <4 x i32> <i32 1, i32 2, i32 3, i32 4>, <4 x i32> <i32 5, i32 6, i32 7, i32 8> }
``````````
</details>
https://github.com/llvm/llvm-project/pull/168668
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