From 88305251fe809ba384ea4ff4893bf671757504fb Mon Sep 17 00:00:00 2001
From: Craig Topper <craig.topper@sifive.com>
Date: Wed, 19 Nov 2025 15:50:36 -0800
Subject: [ConstantFolding] Add constant folding for scalable vector interleave
 intrinsics. (#168668)

We can constant fold interleave of identical splat vectors to a larger
splat vector.
---
 .../InstSimplify/ConstProp/vector-calls.ll         | 122 +++++++++++++++++++++
 1 file changed, 122 insertions(+)

(limited to 'llvm/test/Transforms')

diff --git a/llvm/test/Transforms/InstSimplify/ConstProp/vector-calls.ll b/llvm/test/Transforms/InstSimplify/ConstProp/vector-calls.ll
index 5d9ed867c5e6..3f3cf341357d 100644
--- a/llvm/test/Transforms/InstSimplify/ConstProp/vector-calls.ll
+++ b/llvm/test/Transforms/InstSimplify/ConstProp/vector-calls.ll
@@ -51,6 +51,32 @@ 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
+}
+
+; Negative test.
+define <vscale x 8 x i32> @fold_scalable_vector_interleave2_mismatch_splat() {
+; CHECK-LABEL: define <vscale x 8 x i32> @fold_scalable_vector_interleave2_mismatch_splat() {
+; CHECK-NEXT:    [[TMP1:%.*]] = 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 2))
+; CHECK-NEXT:    ret <vscale x 8 x i32> [[TMP1]]
+;
+  %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 2))
+  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 +85,22 @@ 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 +109,22 @@ 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 +133,22 @@ 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 +157,22 @@ 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 +181,22 @@ 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 +205,22 @@ 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> }
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