[llvm] 2df6309 - [InstCombine] Transform (icmp eq/ne rotate(X,AX),rotate(Y,AY)) -> (icmp eq/ne rotate(Y,AX-AY))
Noah Goldstein via llvm-commits
llvm-commits at lists.llvm.org
Sat Jun 10 12:39:05 PDT 2023
Author: Noah Goldstein
Date: 2023-06-10T14:38:46-05:00
New Revision: 2df6309555963fb9411ed8023a8e585f7981b3bf
URL: https://github.com/llvm/llvm-project/commit/2df6309555963fb9411ed8023a8e585f7981b3bf
DIFF: https://github.com/llvm/llvm-project/commit/2df6309555963fb9411ed8023a8e585f7981b3bf.diff
LOG: [InstCombine] Transform (icmp eq/ne rotate(X,AX),rotate(Y,AY)) -> (icmp eq/ne rotate(Y,AX-AY))
Only do so if we don't create more instructions, so either both
rotates have one use or one of the rotates has one use and both `AX`
and `AY` are constant.
Proof: https://alive2.llvm.org/ce/z/rVmJgz
Differential Revision: https://reviews.llvm.org/D152348
Added:
Modified:
llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
llvm/test/Transforms/InstCombine/icmp-equality-rotate.ll
llvm/test/Transforms/InstCombine/icmp-rotate.ll
Removed:
################################################################################
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index 0865de3d39893..23c161f80a41f 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -3443,7 +3443,9 @@ Instruction *InstCombinerImpl::foldICmpEqIntrinsicWithConstant(
}
/// Fold an icmp with LLVM intrinsics
-static Instruction *foldICmpIntrinsicWithIntrinsic(ICmpInst &Cmp) {
+static Instruction *
+foldICmpIntrinsicWithIntrinsic(ICmpInst &Cmp,
+ InstCombiner::BuilderTy &Builder) {
assert(Cmp.isEquality());
ICmpInst::Predicate Pred = Cmp.getPredicate();
@@ -3461,16 +3463,32 @@ static Instruction *foldICmpIntrinsicWithIntrinsic(ICmpInst &Cmp) {
// original values.
return new ICmpInst(Pred, IIOp0->getOperand(0), IIOp1->getOperand(0));
case Intrinsic::fshl:
- case Intrinsic::fshr:
+ case Intrinsic::fshr: {
// If both operands are rotated by same amount, just compare the
// original values.
if (IIOp0->getOperand(0) != IIOp0->getOperand(1))
break;
if (IIOp1->getOperand(0) != IIOp1->getOperand(1))
break;
- if (IIOp0->getOperand(2) != IIOp1->getOperand(2))
- break;
- return new ICmpInst(Pred, IIOp0->getOperand(0), IIOp1->getOperand(0));
+ if (IIOp0->getOperand(2) == IIOp1->getOperand(2))
+ return new ICmpInst(Pred, IIOp0->getOperand(0), IIOp1->getOperand(0));
+
+ // rotate(X, AmtX) == rotate(Y, AmtY)
+ // -> rotate(X, AmtX - AmtY) == Y
+ // Do this if either both rotates have one use or if only one has one use
+ // and AmtX/AmtY are constants.
+ unsigned OneUses = IIOp0->hasOneUse() + IIOp1->hasOneUse();
+ if (OneUses == 2 ||
+ (OneUses == 1 && match(IIOp0->getOperand(2), m_ImmConstant()) &&
+ match(IIOp1->getOperand(2), m_ImmConstant()))) {
+ Value *SubAmt =
+ Builder.CreateSub(IIOp0->getOperand(2), IIOp1->getOperand(2));
+ Value *CombinedRotate = Builder.CreateIntrinsic(
+ Op0->getType(), IIOp0->getIntrinsicID(),
+ {IIOp0->getOperand(0), IIOp0->getOperand(0), SubAmt});
+ return new ICmpInst(Pred, IIOp1->getOperand(0), CombinedRotate);
+ }
+ } break;
default:
break;
}
@@ -4970,7 +4988,7 @@ Instruction *InstCombinerImpl::foldICmpEquality(ICmpInst &I) {
}
}
- if (Instruction *ICmp = foldICmpIntrinsicWithIntrinsic(I))
+ if (Instruction *ICmp = foldICmpIntrinsicWithIntrinsic(I, Builder))
return ICmp;
// Canonicalize checking for a power-of-2-or-zero value:
diff --git a/llvm/test/Transforms/InstCombine/icmp-equality-rotate.ll b/llvm/test/Transforms/InstCombine/icmp-equality-rotate.ll
index 8decf28333953..f87f786e004f8 100644
--- a/llvm/test/Transforms/InstCombine/icmp-equality-rotate.ll
+++ b/llvm/test/Transforms/InstCombine/icmp-equality-rotate.ll
@@ -63,9 +63,9 @@ define i1 @cmpeq_rorr_to_rorl_multiuse_fail(i8 %x, i8 %C) {
define i1 @cmpne_rorr_rorr(i8 %x, i8 %C0, i8 %C1) {
; CHECK-LABEL: @cmpne_rorr_rorr(
-; CHECK-NEXT: [[X_RORR0:%.*]] = call i8 @llvm.fshr.i8(i8 [[X:%.*]], i8 [[X]], i8 [[C0:%.*]])
-; CHECK-NEXT: [[X_RORR1:%.*]] = call i8 @llvm.fshr.i8(i8 [[X]], i8 [[X]], i8 [[C1:%.*]])
-; CHECK-NEXT: [[R:%.*]] = icmp ne i8 [[X_RORR0]], [[X_RORR1]]
+; CHECK-NEXT: [[TMP1:%.*]] = sub i8 [[C0:%.*]], [[C1:%.*]]
+; CHECK-NEXT: [[TMP2:%.*]] = call i8 @llvm.fshr.i8(i8 [[X:%.*]], i8 [[X]], i8 [[TMP1]])
+; CHECK-NEXT: [[R:%.*]] = icmp ne i8 [[TMP2]], [[X]]
; CHECK-NEXT: ret i1 [[R]]
;
%x_rorr0 = call i8 @llvm.fshr.i8(i8 %x, i8 %x, i8 %C0)
@@ -76,9 +76,9 @@ define i1 @cmpne_rorr_rorr(i8 %x, i8 %C0, i8 %C1) {
define i1 @cmpne_rorrX_rorrY(i8 %x, i8 %y, i8 %C0, i8 %C1) {
; CHECK-LABEL: @cmpne_rorrX_rorrY(
-; CHECK-NEXT: [[X_RORR0:%.*]] = call i8 @llvm.fshr.i8(i8 [[X:%.*]], i8 [[X]], i8 [[C0:%.*]])
-; CHECK-NEXT: [[Y_RORR1:%.*]] = call i8 @llvm.fshr.i8(i8 [[Y:%.*]], i8 [[Y]], i8 [[C1:%.*]])
-; CHECK-NEXT: [[R:%.*]] = icmp ne i8 [[X_RORR0]], [[Y_RORR1]]
+; CHECK-NEXT: [[TMP1:%.*]] = sub i8 [[C0:%.*]], [[C1:%.*]]
+; CHECK-NEXT: [[TMP2:%.*]] = call i8 @llvm.fshr.i8(i8 [[X:%.*]], i8 [[X]], i8 [[TMP1]])
+; CHECK-NEXT: [[R:%.*]] = icmp ne i8 [[TMP2]], [[Y:%.*]]
; CHECK-NEXT: ret i1 [[R]]
;
%x_rorr0 = call i8 @llvm.fshr.i8(i8 %x, i8 %x, i8 %C0)
@@ -132,10 +132,10 @@ define i1 @cmpne_rorl_rorl_multiuse1_fail(i8 %x, i8 %C0) {
define i1 @cmpeq_rorlXC_rorlYC_multiuse1(i8 %x, i8 %y) {
; CHECK-LABEL: @cmpeq_rorlXC_rorlYC_multiuse1(
-; CHECK-NEXT: [[X_RORL0:%.*]] = call i8 @llvm.fshl.i8(i8 [[X:%.*]], i8 [[X]], i8 6)
; CHECK-NEXT: [[Y_RORL1:%.*]] = call i8 @llvm.fshl.i8(i8 [[Y:%.*]], i8 [[Y]], i8 3)
; CHECK-NEXT: call void @use.i8(i8 [[Y_RORL1]])
-; CHECK-NEXT: [[R:%.*]] = icmp eq i8 [[X_RORL0]], [[Y_RORL1]]
+; CHECK-NEXT: [[TMP1:%.*]] = call i8 @llvm.fshl.i8(i8 [[X:%.*]], i8 [[X]], i8 3)
+; CHECK-NEXT: [[R:%.*]] = icmp eq i8 [[TMP1]], [[Y]]
; CHECK-NEXT: ret i1 [[R]]
;
%x_rorl0 = call i8 @llvm.fshl.i8(i8 %x, i8 %x, i8 6)
diff --git a/llvm/test/Transforms/InstCombine/icmp-rotate.ll b/llvm/test/Transforms/InstCombine/icmp-rotate.ll
index abd7caf621a51..2580bb6a865c7 100644
--- a/llvm/test/Transforms/InstCombine/icmp-rotate.ll
+++ b/llvm/test/Transforms/InstCombine/icmp-rotate.ll
@@ -211,9 +211,9 @@ define i1 @wrong_pred(i8 %x, i8 %y, i8 %z) {
; negative test - rotate amounts mismatch
define i1 @amounts_mismatch(i8 %x, i8 %y, i8 %z, i8 %w) {
; CHECK-LABEL: @amounts_mismatch(
-; CHECK-NEXT: [[F:%.*]] = tail call i8 @llvm.fshl.i8(i8 [[X:%.*]], i8 [[X]], i8 [[Z:%.*]])
-; CHECK-NEXT: [[F2:%.*]] = tail call i8 @llvm.fshl.i8(i8 [[Y:%.*]], i8 [[Y]], i8 [[W:%.*]])
-; CHECK-NEXT: [[R:%.*]] = icmp eq i8 [[F]], [[F2]]
+; CHECK-NEXT: [[TMP1:%.*]] = sub i8 [[Z:%.*]], [[W:%.*]]
+; CHECK-NEXT: [[TMP2:%.*]] = call i8 @llvm.fshl.i8(i8 [[X:%.*]], i8 [[X]], i8 [[TMP1]])
+; CHECK-NEXT: [[R:%.*]] = icmp eq i8 [[TMP2]], [[Y:%.*]]
; CHECK-NEXT: ret i1 [[R]]
;
%f = tail call i8 @llvm.fshl.i8(i8 %x, i8 %x, i8 %z)
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