[llvm] 7a6d6f0 - [InstCombine] improve folds for icmp with multiply operands (PR47432)
Sanjay Patel via llvm-commits
llvm-commits at lists.llvm.org
Mon Sep 7 09:43:00 PDT 2020
Author: Sanjay Patel
Date: 2020-09-07T12:40:37-04:00
New Revision: 7a6d6f0f7046f6ebcbf06eaf8f996d991a90e440
URL: https://github.com/llvm/llvm-project/commit/7a6d6f0f7046f6ebcbf06eaf8f996d991a90e440
DIFF: https://github.com/llvm/llvm-project/commit/7a6d6f0f7046f6ebcbf06eaf8f996d991a90e440.diff
LOG: [InstCombine] improve folds for icmp with multiply operands (PR47432)
Check for no overflow along with an odd constant before
we lose information by converting to bitwise logic.
https://rise4fun.com/Alive/2Xl
Pre: C1 != 0
%mx = mul nsw i8 %x, C1
%my = mul nsw i8 %y, C1
%r = icmp eq i8 %mx, %my
=>
%r = icmp eq i8 %x, %y
Name: nuw ne
Pre: C1 != 0
%mx = mul nuw i8 %x, C1
%my = mul nuw i8 %y, C1
%r = icmp ne i8 %mx, %my
=>
%r = icmp ne i8 %x, %y
Name: odd ne
Pre: C1 % 2 != 0
%mx = mul i8 %x, C1
%my = mul i8 %y, C1
%r = icmp ne i8 %mx, %my
=>
%r = icmp ne i8 %x, %y
Added:
Modified:
llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
llvm/test/Transforms/InstCombine/icmp-mul.ll
Removed:
################################################################################
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index 350d00095c6f..608017b6dca2 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -3983,6 +3983,19 @@ Instruction *InstCombinerImpl::foldICmpBinOp(ICmpInst &I,
ConstantExpr::getNeg(RHSC));
}
+ {
+ // Try to remove shared constant multiplier from equality comparison:
+ // X * C == Y * C (with no overflowing/aliasing) --> X == Y
+ Value *X, *Y;
+ const APInt *C;
+ if (match(Op0, m_Mul(m_Value(X), m_APInt(C))) && *C != 0 &&
+ match(Op1, m_Mul(m_Value(Y), m_SpecificInt(*C))) && I.isEquality())
+ if (!C->countTrailingZeros() ||
+ (BO0->hasNoSignedWrap() && BO1->hasNoSignedWrap()) ||
+ (BO0->hasNoUnsignedWrap() && BO1->hasNoUnsignedWrap()))
+ return new ICmpInst(Pred, X, Y);
+ }
+
BinaryOperator *SRem = nullptr;
// icmp (srem X, Y), Y
if (BO0 && BO0->getOpcode() == Instruction::SRem && Op1 == BO0->getOperand(1))
@@ -4059,10 +4072,6 @@ Instruction *InstCombinerImpl::foldICmpBinOp(ICmpInst &I,
Value *And2 = Builder.CreateAnd(BO1->getOperand(0), Mask);
return new ICmpInst(Pred, And1, And2);
}
- // If there are no trailing zeros in the multiplier, just eliminate
- // the multiplies (no masking is needed):
- // icmp eq/ne (X * C), (Y * C) --> icmp eq/ne X, Y
- return new ICmpInst(Pred, BO0->getOperand(0), BO1->getOperand(0));
}
break;
}
diff --git a/llvm/test/Transforms/InstCombine/icmp-mul.ll b/llvm/test/Transforms/InstCombine/icmp-mul.ll
index 719150054015..e2aff1c304ad 100644
--- a/llvm/test/Transforms/InstCombine/icmp-mul.ll
+++ b/llvm/test/Transforms/InstCombine/icmp-mul.ll
@@ -392,8 +392,7 @@ define i1 @mul_constant_ne_extra_use1(i8 %x, i8 %y) {
; CHECK-LABEL: @mul_constant_ne_extra_use1(
; CHECK-NEXT: [[A:%.*]] = mul i8 [[X:%.*]], 5
; CHECK-NEXT: call void @use(i8 [[A]])
-; CHECK-NEXT: [[B:%.*]] = mul i8 [[Y:%.*]], 5
-; CHECK-NEXT: [[C:%.*]] = icmp ne i8 [[A]], [[B]]
+; CHECK-NEXT: [[C:%.*]] = icmp ne i8 [[X]], [[Y:%.*]]
; CHECK-NEXT: ret i1 [[C]]
;
%A = mul i8 %x, 5
@@ -405,10 +404,9 @@ define i1 @mul_constant_ne_extra_use1(i8 %x, i8 %y) {
define i1 @mul_constant_eq_extra_use2(i8 %x, i8 %y) {
; CHECK-LABEL: @mul_constant_eq_extra_use2(
-; CHECK-NEXT: [[A:%.*]] = mul i8 [[X:%.*]], 5
; CHECK-NEXT: [[B:%.*]] = mul i8 [[Y:%.*]], 5
; CHECK-NEXT: call void @use(i8 [[B]])
-; CHECK-NEXT: [[C:%.*]] = icmp eq i8 [[A]], [[B]]
+; CHECK-NEXT: [[C:%.*]] = icmp eq i8 [[X:%.*]], [[Y]]
; CHECK-NEXT: ret i1 [[C]]
;
%A = mul i8 %x, 5
@@ -424,7 +422,7 @@ define i1 @mul_constant_ne_extra_use3(i8 %x, i8 %y) {
; CHECK-NEXT: call void @use(i8 [[A]])
; CHECK-NEXT: [[B:%.*]] = mul i8 [[Y:%.*]], 5
; CHECK-NEXT: call void @use(i8 [[B]])
-; CHECK-NEXT: [[C:%.*]] = icmp ne i8 [[A]], [[B]]
+; CHECK-NEXT: [[C:%.*]] = icmp ne i8 [[X]], [[Y]]
; CHECK-NEXT: ret i1 [[C]]
;
%A = mul i8 %x, 5
@@ -437,9 +435,7 @@ define i1 @mul_constant_ne_extra_use3(i8 %x, i8 %y) {
define i1 @mul_constant_eq_nsw(i32 %x, i32 %y) {
; CHECK-LABEL: @mul_constant_eq_nsw(
-; CHECK-NEXT: [[TMP1:%.*]] = xor i32 [[X:%.*]], [[Y:%.*]]
-; CHECK-NEXT: [[TMP2:%.*]] = and i32 [[TMP1]], 2147483647
-; CHECK-NEXT: [[C:%.*]] = icmp eq i32 [[TMP2]], 0
+; CHECK-NEXT: [[C:%.*]] = icmp eq i32 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: ret i1 [[C]]
;
%A = mul nsw i32 %x, 6
@@ -450,9 +446,7 @@ define i1 @mul_constant_eq_nsw(i32 %x, i32 %y) {
define <2 x i1> @mul_constant_ne_nsw_splat(<2 x i32> %x, <2 x i32> %y) {
; CHECK-LABEL: @mul_constant_ne_nsw_splat(
-; CHECK-NEXT: [[TMP1:%.*]] = xor <2 x i32> [[X:%.*]], [[Y:%.*]]
-; CHECK-NEXT: [[TMP2:%.*]] = and <2 x i32> [[TMP1]], <i32 1073741823, i32 1073741823>
-; CHECK-NEXT: [[C:%.*]] = icmp ne <2 x i32> [[TMP2]], zeroinitializer
+; CHECK-NEXT: [[C:%.*]] = icmp ne <2 x i32> [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: ret <2 x i1> [[C]]
;
%A = mul nsw <2 x i32> %x, <i32 12, i32 12>
@@ -465,8 +459,7 @@ define i1 @mul_constant_ne_nsw_extra_use1(i8 %x, i8 %y) {
; CHECK-LABEL: @mul_constant_ne_nsw_extra_use1(
; CHECK-NEXT: [[A:%.*]] = mul nsw i8 [[X:%.*]], 74
; CHECK-NEXT: call void @use(i8 [[A]])
-; CHECK-NEXT: [[B:%.*]] = mul nsw i8 [[Y:%.*]], 74
-; CHECK-NEXT: [[C:%.*]] = icmp ne i8 [[A]], [[B]]
+; CHECK-NEXT: [[C:%.*]] = icmp ne i8 [[X]], [[Y:%.*]]
; CHECK-NEXT: ret i1 [[C]]
;
%A = mul nsw i8 %x, 74
@@ -478,10 +471,9 @@ define i1 @mul_constant_ne_nsw_extra_use1(i8 %x, i8 %y) {
define i1 @mul_constant_eq_nsw_extra_use2(i8 %x, i8 %y) {
; CHECK-LABEL: @mul_constant_eq_nsw_extra_use2(
-; CHECK-NEXT: [[A:%.*]] = mul nsw i8 [[X:%.*]], 20
; CHECK-NEXT: [[B:%.*]] = mul nsw i8 [[Y:%.*]], 20
; CHECK-NEXT: call void @use(i8 [[B]])
-; CHECK-NEXT: [[C:%.*]] = icmp eq i8 [[A]], [[B]]
+; CHECK-NEXT: [[C:%.*]] = icmp eq i8 [[X:%.*]], [[Y]]
; CHECK-NEXT: ret i1 [[C]]
;
%A = mul nsw i8 %x, 20
@@ -497,7 +489,7 @@ define i1 @mul_constant_ne_nsw_extra_use3(i8 %x, i8 %y) {
; CHECK-NEXT: call void @use(i8 [[A]])
; CHECK-NEXT: [[B:%.*]] = mul nsw i8 [[Y:%.*]], 24
; CHECK-NEXT: call void @use(i8 [[B]])
-; CHECK-NEXT: [[C:%.*]] = icmp ne i8 [[A]], [[B]]
+; CHECK-NEXT: [[C:%.*]] = icmp ne i8 [[X]], [[Y]]
; CHECK-NEXT: ret i1 [[C]]
;
%A = mul nsw i8 %x, 24
@@ -510,9 +502,7 @@ define i1 @mul_constant_ne_nsw_extra_use3(i8 %x, i8 %y) {
define i1 @mul_constant_nuw_eq(i32 %x, i32 %y) {
; CHECK-LABEL: @mul_constant_nuw_eq(
-; CHECK-NEXT: [[TMP1:%.*]] = xor i32 [[X:%.*]], [[Y:%.*]]
-; CHECK-NEXT: [[TMP2:%.*]] = and i32 [[TMP1]], 2147483647
-; CHECK-NEXT: [[C:%.*]] = icmp eq i32 [[TMP2]], 0
+; CHECK-NEXT: [[C:%.*]] = icmp eq i32 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: ret i1 [[C]]
;
%A = mul nuw i32 %x, 22
@@ -523,9 +513,7 @@ define i1 @mul_constant_nuw_eq(i32 %x, i32 %y) {
define <2 x i1> @mul_constant_ne_nuw_splat(<2 x i32> %x, <2 x i32> %y) {
; CHECK-LABEL: @mul_constant_ne_nuw_splat(
-; CHECK-NEXT: [[TMP1:%.*]] = xor <2 x i32> [[X:%.*]], [[Y:%.*]]
-; CHECK-NEXT: [[TMP2:%.*]] = and <2 x i32> [[TMP1]], <i32 2147483647, i32 2147483647>
-; CHECK-NEXT: [[C:%.*]] = icmp ne <2 x i32> [[TMP2]], zeroinitializer
+; CHECK-NEXT: [[C:%.*]] = icmp ne <2 x i32> [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: ret <2 x i1> [[C]]
;
%A = mul nuw <2 x i32> %x, <i32 10, i32 10>
@@ -538,8 +526,7 @@ define i1 @mul_constant_ne_nuw_extra_use1(i8 %x, i8 %y) {
; CHECK-LABEL: @mul_constant_ne_nuw_extra_use1(
; CHECK-NEXT: [[A:%.*]] = mul nuw i8 [[X:%.*]], 6
; CHECK-NEXT: call void @use(i8 [[A]])
-; CHECK-NEXT: [[B:%.*]] = mul nuw i8 [[Y:%.*]], 6
-; CHECK-NEXT: [[C:%.*]] = icmp ne i8 [[A]], [[B]]
+; CHECK-NEXT: [[C:%.*]] = icmp ne i8 [[X]], [[Y:%.*]]
; CHECK-NEXT: ret i1 [[C]]
;
%A = mul nuw i8 %x, 6
@@ -551,10 +538,9 @@ define i1 @mul_constant_ne_nuw_extra_use1(i8 %x, i8 %y) {
define i1 @mul_constant_eq_nuw_extra_use2(i8 %x, i8 %y) {
; CHECK-LABEL: @mul_constant_eq_nuw_extra_use2(
-; CHECK-NEXT: [[A:%.*]] = mul nuw i8 [[X:%.*]], 36
; CHECK-NEXT: [[B:%.*]] = mul nuw i8 [[Y:%.*]], 36
; CHECK-NEXT: call void @use(i8 [[B]])
-; CHECK-NEXT: [[C:%.*]] = icmp eq i8 [[A]], [[B]]
+; CHECK-NEXT: [[C:%.*]] = icmp eq i8 [[X:%.*]], [[Y]]
; CHECK-NEXT: ret i1 [[C]]
;
%A = mul nuw i8 %x, 36
@@ -570,7 +556,7 @@ define i1 @mul_constant_ne_nuw_extra_use3(i8 %x, i8 %y) {
; CHECK-NEXT: call void @use(i8 [[A]])
; CHECK-NEXT: [[B:%.*]] = mul nuw i8 [[Y:%.*]], 38
; CHECK-NEXT: call void @use(i8 [[B]])
-; CHECK-NEXT: [[C:%.*]] = icmp ne i8 [[A]], [[B]]
+; CHECK-NEXT: [[C:%.*]] = icmp ne i8 [[X]], [[Y]]
; CHECK-NEXT: ret i1 [[C]]
;
%A = mul nuw i8 %x, 38
@@ -581,6 +567,8 @@ define i1 @mul_constant_ne_nuw_extra_use3(i8 %x, i8 %y) {
ret i1 %C
}
+; Negative test - wrong pred
+
define i1 @mul_constant_ult(i32 %x, i32 %y) {
; CHECK-LABEL: @mul_constant_ult(
; CHECK-NEXT: [[A:%.*]] = mul i32 [[X:%.*]], 47
@@ -594,6 +582,8 @@ define i1 @mul_constant_ult(i32 %x, i32 %y) {
ret i1 %C
}
+; Negative test - wrong pred
+
define i1 @mul_constant_nuw_sgt(i32 %x, i32 %y) {
; CHECK-LABEL: @mul_constant_nuw_sgt(
; CHECK-NEXT: [[A:%.*]] = mul nuw i32 [[X:%.*]], 46
@@ -607,6 +597,8 @@ define i1 @mul_constant_nuw_sgt(i32 %x, i32 %y) {
ret i1 %C
}
+; Negative test - wrong constants
+
define i1 @mul_mismatch_constant_nuw_eq(i32 %x, i32 %y) {
; CHECK-LABEL: @mul_mismatch_constant_nuw_eq(
; CHECK-NEXT: [[A:%.*]] = mul nuw i32 [[X:%.*]], 46
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