[llvm] r371921 - [InstSimplify] simplifyUnsignedRangeCheck(): handle few tautological cases (PR43251)
Roman Lebedev via llvm-commits
llvm-commits at lists.llvm.org
Sat Sep 14 06:47:27 PDT 2019
Author: lebedevri
Date: Sat Sep 14 06:47:27 2019
New Revision: 371921
URL: http://llvm.org/viewvc/llvm-project?rev=371921&view=rev
Log:
[InstSimplify] simplifyUnsignedRangeCheck(): handle few tautological cases (PR43251)
Summary:
This is split off from D67356, since these cases produce a constant,
no real need to keep them in instcombine.
Alive proofs:
https://rise4fun.com/Alive/u7Fk
https://rise4fun.com/Alive/4lV
https://bugs.llvm.org/show_bug.cgi?id=43251
Reviewers: spatel, nikic, xbolva00
Reviewed By: spatel
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D67498
Modified:
llvm/trunk/lib/Analysis/InstructionSimplify.cpp
llvm/trunk/test/Transforms/InstSimplify/result-of-usub-is-non-zero-and-no-overflow.ll
Modified: llvm/trunk/lib/Analysis/InstructionSimplify.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/InstructionSimplify.cpp?rev=371921&r1=371920&r2=371921&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/InstructionSimplify.cpp (original)
+++ llvm/trunk/lib/Analysis/InstructionSimplify.cpp Sat Sep 14 06:47:27 2019
@@ -1382,23 +1382,44 @@ static Value *simplifyUnsignedRangeCheck
ICmpInst::Predicate UnsignedPred;
- // Y = (A - B); Y >= A && Y != 0 --> Y >= A iff B != 0
- // Y = (A - B); Y < A || Y == 0 --> Y < A iff B != 0
Value *A, *B;
- if (match(Y, m_Sub(m_Value(A), m_Value(B))) &&
- match(UnsignedICmp,
- m_c_ICmp(UnsignedPred, m_Specific(Y), m_Specific(A)))) {
- if (UnsignedICmp->getOperand(0) != Y)
- UnsignedPred = ICmpInst::getSwappedPredicate(UnsignedPred);
-
- if (UnsignedPred == ICmpInst::ICMP_UGE && IsAnd &&
- EqPred == ICmpInst::ICMP_NE &&
- isKnownNonZero(B, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT))
- return UnsignedICmp;
- if (UnsignedPred == ICmpInst::ICMP_ULT && !IsAnd &&
- EqPred == ICmpInst::ICMP_EQ &&
- isKnownNonZero(B, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT))
- return UnsignedICmp;
+ // Y = (A - B);
+ if (match(Y, m_Sub(m_Value(A), m_Value(B)))) {
+ if (match(UnsignedICmp,
+ m_c_ICmp(UnsignedPred, m_Specific(A), m_Specific(B))) &&
+ ICmpInst::isUnsigned(UnsignedPred)) {
+ if (UnsignedICmp->getOperand(0) != A)
+ UnsignedPred = ICmpInst::getSwappedPredicate(UnsignedPred);
+
+ // A >=/<= B || (A - B) != 0 <--> true
+ if ((UnsignedPred == ICmpInst::ICMP_UGE ||
+ UnsignedPred == ICmpInst::ICMP_ULE) &&
+ EqPred == ICmpInst::ICMP_NE && !IsAnd)
+ return ConstantInt::getTrue(UnsignedICmp->getType());
+ // A </> B && (A - B) == 0 <--> false
+ if ((UnsignedPred == ICmpInst::ICMP_ULT ||
+ UnsignedPred == ICmpInst::ICMP_UGT) &&
+ EqPred == ICmpInst::ICMP_EQ && IsAnd)
+ return ConstantInt::getFalse(UnsignedICmp->getType());
+ }
+
+ // Given Y = (A - B)
+ // Y >= A && Y != 0 --> Y >= A iff B != 0
+ // Y < A || Y == 0 --> Y < A iff B != 0
+ if (match(UnsignedICmp,
+ m_c_ICmp(UnsignedPred, m_Specific(Y), m_Specific(A)))) {
+ if (UnsignedICmp->getOperand(0) != Y)
+ UnsignedPred = ICmpInst::getSwappedPredicate(UnsignedPred);
+
+ if (UnsignedPred == ICmpInst::ICMP_UGE && IsAnd &&
+ EqPred == ICmpInst::ICMP_NE &&
+ isKnownNonZero(B, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT))
+ return UnsignedICmp;
+ if (UnsignedPred == ICmpInst::ICMP_ULT && !IsAnd &&
+ EqPred == ICmpInst::ICMP_EQ &&
+ isKnownNonZero(B, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT))
+ return UnsignedICmp;
+ }
}
if (match(UnsignedICmp, m_ICmp(UnsignedPred, m_Value(X), m_Specific(Y))) &&
Modified: llvm/trunk/test/Transforms/InstSimplify/result-of-usub-is-non-zero-and-no-overflow.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstSimplify/result-of-usub-is-non-zero-and-no-overflow.ll?rev=371921&r1=371920&r2=371921&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstSimplify/result-of-usub-is-non-zero-and-no-overflow.ll (original)
+++ llvm/trunk/test/Transforms/InstSimplify/result-of-usub-is-non-zero-and-no-overflow.ll Sat Sep 14 06:47:27 2019
@@ -22,8 +22,7 @@ define i1 @t1(i8 %base, i8 %offset) {
; CHECK-NEXT: call void @use1(i1 [[NO_UNDERFLOW]])
; CHECK-NEXT: [[NOT_NULL:%.*]] = icmp ne i8 [[ADJUSTED]], 0
; CHECK-NEXT: call void @use1(i1 [[NOT_NULL]])
-; CHECK-NEXT: [[R:%.*]] = or i1 [[NOT_NULL]], [[NO_UNDERFLOW]]
-; CHECK-NEXT: ret i1 [[R]]
+; CHECK-NEXT: ret i1 true
;
%adjusted = sub i8 %base, %offset
call void @use8(i8 %adjusted)
@@ -62,8 +61,7 @@ define i1 @t1_commutativity(i8 %base, i8
; CHECK-NEXT: call void @use1(i1 [[NO_UNDERFLOW]])
; CHECK-NEXT: [[NOT_NULL:%.*]] = icmp ne i8 [[ADJUSTED]], 0
; CHECK-NEXT: call void @use1(i1 [[NOT_NULL]])
-; CHECK-NEXT: [[R:%.*]] = or i1 [[NOT_NULL]], [[NO_UNDERFLOW]]
-; CHECK-NEXT: ret i1 [[R]]
+; CHECK-NEXT: ret i1 true
;
%adjusted = sub i8 %base, %offset
call void @use8(i8 %adjusted)
@@ -86,8 +84,7 @@ define i1 @t2(i8 %base, i8 %offset) {
; CHECK-NEXT: call void @use1(i1 [[UNDERFLOW]])
; CHECK-NEXT: [[NULL:%.*]] = icmp eq i8 [[ADJUSTED]], 0
; CHECK-NEXT: call void @use1(i1 [[NULL]])
-; CHECK-NEXT: [[R:%.*]] = and i1 [[NULL]], [[UNDERFLOW]]
-; CHECK-NEXT: ret i1 [[R]]
+; CHECK-NEXT: ret i1 false
;
%adjusted = sub i8 %base, %offset
call void @use8(i8 %adjusted)
@@ -126,8 +123,7 @@ define i1 @t2_commutativity(i8 %base, i8
; CHECK-NEXT: call void @use1(i1 [[UNDERFLOW]])
; CHECK-NEXT: [[NULL:%.*]] = icmp eq i8 [[ADJUSTED]], 0
; CHECK-NEXT: call void @use1(i1 [[NULL]])
-; CHECK-NEXT: [[R:%.*]] = and i1 [[NULL]], [[UNDERFLOW]]
-; CHECK-NEXT: ret i1 [[R]]
+; CHECK-NEXT: ret i1 false
;
%adjusted = sub i8 %base, %offset
call void @use8(i8 %adjusted)
@@ -148,8 +144,7 @@ define i1 @t3(i8 %base, i8 %offset) {
; CHECK-NEXT: call void @use1(i1 [[NO_UNDERFLOW]])
; CHECK-NEXT: [[NOT_NULL:%.*]] = icmp ne i8 [[ADJUSTED]], 0
; CHECK-NEXT: call void @use1(i1 [[NOT_NULL]])
-; CHECK-NEXT: [[R:%.*]] = or i1 [[NOT_NULL]], [[NO_UNDERFLOW]]
-; CHECK-NEXT: ret i1 [[R]]
+; CHECK-NEXT: ret i1 true
;
%adjusted = sub i8 %base, %offset
call void @use8(i8 %adjusted)
@@ -170,8 +165,7 @@ define i1 @t4(i8 %base, i8 %offset) {
; CHECK-NEXT: call void @use1(i1 [[NO_UNDERFLOW]])
; CHECK-NEXT: [[NOT_NULL:%.*]] = icmp eq i8 [[ADJUSTED]], 0
; CHECK-NEXT: call void @use1(i1 [[NOT_NULL]])
-; CHECK-NEXT: [[R:%.*]] = and i1 [[NOT_NULL]], [[NO_UNDERFLOW]]
-; CHECK-NEXT: ret i1 [[R]]
+; CHECK-NEXT: ret i1 false
;
%adjusted = sub i8 %base, %offset
call void @use8(i8 %adjusted)
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