[llvm] r329791 - Eliminate a bitwise 'not' op of 'not' min/max by inverting the min/max.
Artur Gainullin via llvm-commits
llvm-commits at lists.llvm.org
Wed Apr 11 03:29:38 PDT 2018
Author: arturgainullin
Date: Wed Apr 11 03:29:37 2018
New Revision: 329791
URL: http://llvm.org/viewvc/llvm-project?rev=329791&view=rev
Log:
Eliminate a bitwise 'not' op of 'not' min/max by inverting the min/max.
Bitwise 'not' of the min/max could be eliminated in the pattern:
%notx = xor i32 %x, -1
%cmp1 = icmp sgt[slt/ugt/ult] i32 %notx, %y
%smax = select i1 %cmp1, i32 %notx, i32 %y
%res = xor i32 %smax, -1
https://rise4fun.com/Alive/lCN
Reviewers: spatel
Reviewed by: spatel
Subscribers: a.elovikov, llvm-commits
Differential Revision: https://reviews.llvm.org/D45317
Modified:
llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
llvm/trunk/test/Transforms/InstCombine/max-of-nots.ll
llvm/trunk/test/Transforms/InstCombine/xor.ll
Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp?rev=329791&r1=329790&r2=329791&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp Wed Apr 11 03:29:37 2018
@@ -2696,5 +2696,35 @@ Instruction *InstCombiner::visitXor(Bina
return SelectInst::Create(Cmp, Builder.CreateNeg(A), A);
}
+ // Eliminate a bitwise 'not' op of 'not' min/max by inverting the min/max:
+ //
+ // %notx = xor i32 %x, -1
+ // %cmp1 = icmp sgt i32 %notx, %y
+ // %smax = select i1 %cmp1, i32 %notx, i32 %y
+ // %res = xor i32 %smax, -1
+ // =>
+ // %noty = xor i32 %y, -1
+ // %cmp2 = icmp slt %x, %noty
+ // %res = select i1 %cmp2, i32 %x, i32 %noty
+ //
+ // Same is applicable for smin/umax/umin.
+ {
+ Value *LHS, *RHS;
+ SelectPatternFlavor SPF = matchSelectPattern(Op0, LHS, RHS).Flavor;
+ if (Op0->hasOneUse() && SelectPatternResult::isMinOrMax(SPF) &&
+ match(Op1, m_AllOnes())) {
+
+ Value *X;
+ if (match(RHS, m_Not(m_Value(X))))
+ std::swap(RHS, LHS);
+
+ if (match(LHS, m_Not(m_Value(X)))) {
+ Value *NotY = Builder.CreateNot(RHS);
+ return SelectInst::Create(
+ Builder.CreateICmp(getInverseMinMaxPred(SPF), X, NotY), X, NotY);
+ }
+ }
+ }
+
return Changed ? &I : nullptr;
}
Modified: llvm/trunk/test/Transforms/InstCombine/max-of-nots.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/max-of-nots.ll?rev=329791&r1=329790&r2=329791&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/max-of-nots.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/max-of-nots.ll Wed Apr 11 03:29:37 2018
@@ -238,10 +238,9 @@ define i32 @compute_min_pessimization(i3
; CHECK-LABEL: @compute_min_pessimization(
; CHECK-NEXT: [[NOT_VALUE:%.*]] = sub i32 3, [[X:%.*]]
; CHECK-NEXT: call void @fake_use(i32 [[NOT_VALUE]])
-; CHECK-NEXT: [[NOT_Y:%.*]] = xor i32 [[Y:%.*]], -1
-; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i32 [[NOT_VALUE]], [[NOT_Y]]
-; CHECK-NEXT: [[NOT_MIN:%.*]] = select i1 [[CMP]], i32 [[NOT_VALUE]], i32 [[NOT_Y]]
-; CHECK-NEXT: [[MIN:%.*]] = xor i32 [[NOT_MIN]], -1
+; CHECK-NEXT: [[TMP1:%.*]] = add i32 [[X]], -4
+; CHECK-NEXT: [[TMP2:%.*]] = icmp sgt i32 [[TMP1]], [[Y:%.*]]
+; CHECK-NEXT: [[MIN:%.*]] = select i1 [[TMP2]], i32 [[Y]], i32 [[TMP1]]
; CHECK-NEXT: ret i32 [[MIN]]
;
%not_value = sub i32 3, %x
Modified: llvm/trunk/test/Transforms/InstCombine/xor.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/xor.ll?rev=329791&r1=329790&r2=329791&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/xor.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/xor.ll Wed Apr 11 03:29:37 2018
@@ -575,3 +575,147 @@ define i32 @test38(i32 %A, i32 %B) {
%xor = xor i32 %and, %B
ret i32 %xor
}
+
+; The tests 39-47 are related to the canonicalization:
+; %notx = xor i32 %x, -1
+; %cmp = icmp sgt i32 %notx, %y
+; %smax = select i1 %cmp, i32 %notx, i32 %y
+; %res = xor i32 %smax, -1
+; =>
+; %noty = xor i32 %y, -1
+; %cmp2 = icmp slt %x, %noty
+; %res = select i1 %cmp2, i32 %x, i32 %noty
+;
+; Same transformations is valid for smin/umax/umin.
+
+define i32 @test39(i32 %x) {
+; CHECK-LABEL: @test39(
+; CHECK-NEXT: [[TMP1:%.*]] = icmp slt i32 [[X:%.*]], 255
+; CHECK-NEXT: [[RES:%.*]] = select i1 [[TMP1]], i32 [[X]], i32 255
+; CHECK-NEXT: ret i32 [[RES]]
+;
+ %1 = xor i32 %x, -1
+ %2 = icmp sgt i32 %1, -256
+ %3 = select i1 %2, i32 %1, i32 -256
+ %res = xor i32 %3, -1
+ ret i32 %res
+}
+
+define i32 @test40(i32 %x, i32 %y) {
+; CHECK-LABEL: @test40(
+; CHECK-NEXT: [[TMP1:%.*]] = xor i32 [[Y:%.*]], -1
+; CHECK-NEXT: [[TMP2:%.*]] = icmp sgt i32 [[TMP1]], [[X:%.*]]
+; CHECK-NEXT: [[RES:%.*]] = select i1 [[TMP2]], i32 [[X]], i32 [[TMP1]]
+; CHECK-NEXT: ret i32 [[RES]]
+;
+ %notx = xor i32 %x, -1
+ %cmp1 = icmp sgt i32 %notx, %y
+ %smax = select i1 %cmp1, i32 %notx, i32 %y
+ %res = xor i32 %smax, -1
+ ret i32 %res
+}
+
+define i32 @test41(i32 %x, i32 %y) {
+; CHECK-LABEL: @test41(
+; CHECK-NEXT: [[TMP1:%.*]] = xor i32 [[Y:%.*]], -1
+; CHECK-NEXT: [[TMP2:%.*]] = icmp slt i32 [[TMP1]], [[X:%.*]]
+; CHECK-NEXT: [[RES:%.*]] = select i1 [[TMP2]], i32 [[X]], i32 [[TMP1]]
+; CHECK-NEXT: ret i32 [[RES]]
+;
+ %notx = xor i32 %x, -1
+ %cmp1 = icmp slt i32 %notx, %y
+ %smin = select i1 %cmp1, i32 %notx, i32 %y
+ %res = xor i32 %smin, -1
+ ret i32 %res
+}
+
+define i32 @test42(i32 %x, i32 %y) {
+; CHECK-LABEL: @test42(
+; CHECK-NEXT: [[TMP1:%.*]] = xor i32 [[Y:%.*]], -1
+; CHECK-NEXT: [[TMP2:%.*]] = icmp ugt i32 [[TMP1]], [[X:%.*]]
+; CHECK-NEXT: [[RES:%.*]] = select i1 [[TMP2]], i32 [[X]], i32 [[TMP1]]
+; CHECK-NEXT: ret i32 [[RES]]
+;
+ %notx = xor i32 %x, -1
+ %cmp1 = icmp ugt i32 %notx, %y
+ %umax = select i1 %cmp1, i32 %notx, i32 %y
+ %res = xor i32 %umax, -1
+ ret i32 %res
+}
+
+define i32 @test43(i32 %x, i32 %y) {
+; CHECK-LABEL: @test43(
+; CHECK-NEXT: [[TMP1:%.*]] = xor i32 [[Y:%.*]], -1
+; CHECK-NEXT: [[TMP2:%.*]] = icmp ult i32 [[TMP1]], [[X:%.*]]
+; CHECK-NEXT: [[RES:%.*]] = select i1 [[TMP2]], i32 [[X]], i32 [[TMP1]]
+; CHECK-NEXT: ret i32 [[RES]]
+;
+ %notx = xor i32 %x, -1
+ %cmp1 = icmp ult i32 %notx, %y
+ %umin = select i1 %cmp1, i32 %notx, i32 %y
+ %res = xor i32 %umin, -1
+ ret i32 %res
+}
+
+define i32 @test44(i32 %x, i32 %y) {
+; CHECK-LABEL: @test44(
+; CHECK-NEXT: [[TMP1:%.*]] = sub i32 -4, [[Y:%.*]]
+; CHECK-NEXT: [[TMP2:%.*]] = icmp ult i32 [[TMP1]], [[X:%.*]]
+; CHECK-NEXT: [[RES:%.*]] = select i1 [[TMP2]], i32 [[X]], i32 [[TMP1]]
+; CHECK-NEXT: ret i32 [[RES]]
+;
+ %z = add i32 %y, 3 ; thwart complexity-based canonicalization
+ %notx = xor i32 %x, -1
+ %cmp1 = icmp ult i32 %z, %notx
+ %umin = select i1 %cmp1, i32 %z, i32 %notx
+ %res = xor i32 %umin, -1
+ ret i32 %res
+}
+
+define i32 @test45(i32 %x, i32 %y) {
+; CHECK-LABEL: @test45(
+; CHECK-NEXT: [[TMP1:%.*]] = icmp ugt i32 [[Y:%.*]], [[X:%.*]]
+; CHECK-NEXT: [[TMP2:%.*]] = select i1 [[TMP1]], i32 [[Y]], i32 [[X]]
+; CHECK-NEXT: ret i32 [[TMP2]]
+;
+ %z = xor i32 %y, -1
+ %notx = xor i32 %x, -1
+ %cmp1 = icmp ult i32 %z, %notx
+ %umin = select i1 %cmp1, i32 %z, i32 %notx
+ %res = xor i32 %umin, -1
+ ret i32 %res
+}
+
+; Check that we work with splat vectors also.
+define <4 x i32> @test46(<4 x i32> %x) {
+; CHECK-LABEL: @test46(
+; CHECK-NEXT: [[TMP1:%.*]] = icmp slt <4 x i32> [[X:%.*]], <i32 255, i32 255, i32 255, i32 255>
+; CHECK-NEXT: [[TMP2:%.*]] = select <4 x i1> [[TMP1]], <4 x i32> [[X]], <4 x i32> <i32 255, i32 255, i32 255, i32 255>
+; CHECK-NEXT: ret <4 x i32> [[TMP2]]
+;
+ %1 = xor <4 x i32> %x, <i32 -1, i32 -1, i32 -1, i32 -1>
+ %2 = icmp sgt <4 x i32> %1, <i32 -256, i32 -256, i32 -256, i32 -256>
+ %3 = select <4 x i1> %2, <4 x i32> %1, <4 x i32> <i32 -256, i32 -256, i32 -256, i32 -256>
+ %4 = xor <4 x i32> %3, <i32 -1, i32 -1, i32 -1, i32 -1>
+ ret <4 x i32> %4
+}
+
+; Test case when select pattern has more than one use.
+define i32 @test47(i32 %x, i32 %y, i32 %z) {
+; CHECK-LABEL: @test47(
+; CHECK-NEXT: [[NOTX:%.*]] = xor i32 [[X:%.*]], -1
+; CHECK-NEXT: [[CMP1:%.*]] = icmp ugt i32 [[NOTX]], [[Y:%.*]]
+; CHECK-NEXT: [[UMAX:%.*]] = select i1 [[CMP1]], i32 [[NOTX]], i32 [[Y]]
+; CHECK-NEXT: [[UMIN:%.*]] = xor i32 [[UMAX]], -1
+; CHECK-NEXT: [[ADD:%.*]] = add i32 [[UMAX]], [[Z:%.*]]
+; CHECK-NEXT: [[RES:%.*]] = mul i32 [[ADD]], [[UMIN]]
+; CHECK-NEXT: ret i32 [[RES]]
+;
+ %notx = xor i32 %x, -1
+ %cmp1 = icmp ugt i32 %notx, %y
+ %umax = select i1 %cmp1, i32 %notx, i32 %y
+ %umin = xor i32 %umax, -1
+ %add = add i32 %umax, %z
+ %res = mul i32 %umin, %add
+ ret i32 %res
+}
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