[llvm] [InstSimplify] Add basic simplifications for vp.reverse (PR #144112)
Philip Reames via llvm-commits
llvm-commits at lists.llvm.org
Fri Jun 13 09:23:31 PDT 2025
https://github.com/preames created https://github.com/llvm/llvm-project/pull/144112
Directly modeled after what we do for vector.reverse, but with restrictions on EVL and mask added.
>From a9e687335de321447b002b38b617a610ca33c86e Mon Sep 17 00:00:00 2001
From: Philip Reames <preames at rivosinc.com>
Date: Fri, 13 Jun 2025 09:14:58 -0700
Subject: [PATCH] [InstSimplify] Add basic simplifications for vp.reverse
Directly modeled after what we do for vector.reverse, but with
restrictions on EVL and mask added.
---
llvm/lib/Analysis/InstructionSimplify.cpp | 17 +++++++++++++++++
.../Transforms/InstSimplify/vp-reverse.ll | 19 ++++++-------------
2 files changed, 23 insertions(+), 13 deletions(-)
diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index e397a228afee0..d1ac8d9fbdfd1 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -6969,6 +6969,23 @@ static Value *simplifyIntrinsic(CallBase *Call, Value *Callee,
}
return nullptr;
}
+ case Intrinsic::experimental_vp_reverse: {
+ Value *Vec = Call->getArgOperand(0);
+ Value *Mask = Call->getArgOperand(1);
+ Value *EVL = Call->getArgOperand(2);
+
+ Value *X;
+ // vp.reverse(vp.reverse(X)) == X (with all ones mask and matching EVL)
+ if (match(Mask, m_AllOnes()) &&
+ match(Vec, m_Intrinsic<Intrinsic::experimental_vp_reverse>(
+ m_Value(X), m_AllOnes(), m_Specific(EVL))))
+ return X;
+
+ // vp.reverse(splat(X)) -> splat(X) (regardless of mask and EVL)
+ if (isSplatValue(Vec))
+ return Vec;
+ return nullptr;
+ }
default:
return nullptr;
}
diff --git a/llvm/test/Transforms/InstSimplify/vp-reverse.ll b/llvm/test/Transforms/InstSimplify/vp-reverse.ll
index 3c3bb871dc610..f19a2ac8ca9e1 100644
--- a/llvm/test/Transforms/InstSimplify/vp-reverse.ll
+++ b/llvm/test/Transforms/InstSimplify/vp-reverse.ll
@@ -3,9 +3,7 @@
define <vscale x 4 x i32> @rev_of_rev(<vscale x 4 x i32> %a, i32 %evl) {
; CHECK-LABEL: @rev_of_rev(
-; CHECK-NEXT: [[A_REV:%.*]] = tail call <vscale x 4 x i32> @llvm.experimental.vp.reverse.nxv4i32(<vscale x 4 x i32> [[A:%.*]], <vscale x 4 x i1> splat (i1 true), i32 [[EVL:%.*]])
-; CHECK-NEXT: [[RES:%.*]] = tail call <vscale x 4 x i32> @llvm.experimental.vp.reverse.nxv4i32(<vscale x 4 x i32> [[A_REV]], <vscale x 4 x i1> splat (i1 true), i32 [[EVL]])
-; CHECK-NEXT: ret <vscale x 4 x i32> [[RES]]
+; CHECK-NEXT: ret <vscale x 4 x i32> [[A:%.*]]
;
%a.rev = tail call <vscale x 4 x i32> @llvm.experimental.vp.reverse(<vscale x 4 x i32> %a, <vscale x 4 x i1> splat (i1 true), i32 %evl)
%res = tail call <vscale x 4 x i32> @llvm.experimental.vp.reverse(<vscale x 4 x i32> %a.rev, <vscale x 4 x i1> splat (i1 true), i32 %evl)
@@ -25,8 +23,7 @@ define <vscale x 4 x i32> @rev_of_rev_diffevl(<vscale x 4 x i32> %a, i32 %evl) {
define <vscale x 4 x i32> @rev_of_poison(i32 %evl) {
; CHECK-LABEL: @rev_of_poison(
-; CHECK-NEXT: [[REV:%.*]] = tail call <vscale x 4 x i32> @llvm.experimental.vp.reverse.nxv4i32(<vscale x 4 x i32> poison, <vscale x 4 x i1> splat (i1 true), i32 [[EVL:%.*]])
-; CHECK-NEXT: ret <vscale x 4 x i32> [[REV]]
+; CHECK-NEXT: ret <vscale x 4 x i32> poison
;
%rev = tail call <vscale x 4 x i32> @llvm.experimental.vp.reverse(<vscale x 4 x i32> poison, <vscale x 4 x i1> splat (i1 true), i32 %evl)
ret <vscale x 4 x i32> %rev
@@ -34,8 +31,7 @@ define <vscale x 4 x i32> @rev_of_poison(i32 %evl) {
define <vscale x 4 x i32> @rev_of_undef(i32 %evl) {
; CHECK-LABEL: @rev_of_undef(
-; CHECK-NEXT: [[REV:%.*]] = tail call <vscale x 4 x i32> @llvm.experimental.vp.reverse.nxv4i32(<vscale x 4 x i32> undef, <vscale x 4 x i1> splat (i1 true), i32 [[EVL:%.*]])
-; CHECK-NEXT: ret <vscale x 4 x i32> [[REV]]
+; CHECK-NEXT: ret <vscale x 4 x i32> undef
;
%rev = tail call <vscale x 4 x i32> @llvm.experimental.vp.reverse(<vscale x 4 x i32> undef, <vscale x 4 x i1> splat (i1 true), i32 %evl)
ret <vscale x 4 x i32> %rev
@@ -43,8 +39,7 @@ define <vscale x 4 x i32> @rev_of_undef(i32 %evl) {
define <vscale x 4 x i32> @rev_of_zero(i32 %evl) {
; CHECK-LABEL: @rev_of_zero(
-; CHECK-NEXT: [[REV:%.*]] = tail call <vscale x 4 x i32> @llvm.experimental.vp.reverse.nxv4i32(<vscale x 4 x i32> zeroinitializer, <vscale x 4 x i1> splat (i1 true), i32 [[EVL:%.*]])
-; CHECK-NEXT: ret <vscale x 4 x i32> [[REV]]
+; CHECK-NEXT: ret <vscale x 4 x i32> zeroinitializer
;
%rev = tail call <vscale x 4 x i32> @llvm.experimental.vp.reverse(<vscale x 4 x i32> zeroinitializer, <vscale x 4 x i1> splat (i1 true), i32 %evl)
ret <vscale x 4 x i32> %rev
@@ -54,8 +49,7 @@ define <vscale x 4 x i32> @rev_of_splat(i32 %a, i32 %evl) {
; CHECK-LABEL: @rev_of_splat(
; CHECK-NEXT: [[A_INS:%.*]] = insertelement <vscale x 4 x i32> poison, i32 [[A:%.*]], i32 0
; CHECK-NEXT: [[A_VEC:%.*]] = shufflevector <vscale x 4 x i32> [[A_INS]], <vscale x 4 x i32> poison, <vscale x 4 x i32> zeroinitializer
-; CHECK-NEXT: [[REV:%.*]] = tail call <vscale x 4 x i32> @llvm.experimental.vp.reverse.nxv4i32(<vscale x 4 x i32> [[A_VEC]], <vscale x 4 x i1> splat (i1 true), i32 [[EVL:%.*]])
-; CHECK-NEXT: ret <vscale x 4 x i32> [[REV]]
+; CHECK-NEXT: ret <vscale x 4 x i32> [[A_VEC]]
;
%a.ins = insertelement <vscale x 4 x i32> poison, i32 %a, i32 0
%a.vec = shufflevector <vscale x 4 x i32> %a.ins, <vscale x 4 x i32> poison, <vscale x 4 x i32> zeroinitializer
@@ -67,8 +61,7 @@ define <vscale x 4 x i32> @rev_of_splat2(i32 %a, <vscale x 4 x i1> %m, i32 %evl)
; CHECK-LABEL: @rev_of_splat2(
; CHECK-NEXT: [[A_INS:%.*]] = insertelement <vscale x 4 x i32> poison, i32 [[A:%.*]], i32 0
; CHECK-NEXT: [[A_VEC:%.*]] = shufflevector <vscale x 4 x i32> [[A_INS]], <vscale x 4 x i32> poison, <vscale x 4 x i32> zeroinitializer
-; CHECK-NEXT: [[REV:%.*]] = tail call <vscale x 4 x i32> @llvm.experimental.vp.reverse.nxv4i32(<vscale x 4 x i32> [[A_VEC]], <vscale x 4 x i1> [[M:%.*]], i32 [[EVL:%.*]])
-; CHECK-NEXT: ret <vscale x 4 x i32> [[REV]]
+; CHECK-NEXT: ret <vscale x 4 x i32> [[A_VEC]]
;
%a.ins = insertelement <vscale x 4 x i32> poison, i32 %a, i32 0
%a.vec = shufflevector <vscale x 4 x i32> %a.ins, <vscale x 4 x i32> poison, <vscale x 4 x i32> zeroinitializer
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