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[InstCombine] use m_APInt to allow icmp eq (op X, Y), C folds for splat constant vectors

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I'm removing a misplaced pair of more specific folds from InstCombine in this patch as well,
so we know where those folds are happening in InstSimplify.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@277738 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Sanjay Patel 2016-08-04 17:48:04 +00:00
parent dbed1dc732
commit 47b6d6791b
3 changed files with 9 additions and 24 deletions
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13
lib/Analysis/InstructionSimplify.cpp
View File

@ -3121,17 +3121,16 @@ static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
// If a bit is known to be zero for A and known to be one for B,
// then A and B cannot be equal.
if (ICmpInst::isEquality(Pred)) {
if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
uint32_t BitWidth = CI->getBitWidth();
const APInt *RHSVal;
if (match(RHS, m_APInt(RHSVal))) {
unsigned BitWidth = RHSVal->getBitWidth();
APInt LHSKnownZero(BitWidth, 0);
APInt LHSKnownOne(BitWidth, 0);
computeKnownBits(LHS, LHSKnownZero, LHSKnownOne, Q.DL, /*Depth=*/0, Q.AC,
Q.CxtI, Q.DT);
const APInt &RHSVal = CI->getValue();
if (((LHSKnownZero & RHSVal) != 0) || ((LHSKnownOne & ~RHSVal) != 0))
return Pred == ICmpInst::ICMP_EQ
? ConstantInt::getFalse(CI->getContext())
: ConstantInt::getTrue(CI->getContext());
if (((LHSKnownZero & *RHSVal) != 0) || ((LHSKnownOne & ~(*RHSVal)) != 0))
return Pred == ICmpInst::ICMP_EQ ? ConstantInt::getFalse(ITy)
: ConstantInt::getTrue(ITy);
}
}

11
lib/Transforms/InstCombine/InstCombineCompares.cpp
View File

@ -2277,14 +2277,8 @@ Instruction *InstCombiner::foldICmpEqualityWithConstant(ICmpInst &ICI) {
}
break;
case Instruction::Or:
// If bits are being or'd in that are not present in the constant we
// are comparing against, then the comparison could never succeed!
// FIXME: Vectors are excluded by ConstantInt.
if (ConstantInt *BOC = dyn_cast<ConstantInt>(BOp1)) {
Constant *NotCI = ConstantExpr::getNot(RHS);
if (!ConstantExpr::getAnd(BOC, NotCI)->isNullValue())
return replaceInstUsesWith(ICI, Builder->getInt1(isICMP_NE));
// Comparing if all bits outside of a constant mask are set?
// Replace (X | C) == -1 with (X & ~C) == ~C.
// This removes the -1 constant.
@ -2299,11 +2293,6 @@ Instruction *InstCombiner::foldICmpEqualityWithConstant(ICmpInst &ICI) {
case Instruction::And:
// FIXME: Vectors are excluded by ConstantInt.
if (ConstantInt *BOC = dyn_cast<ConstantInt>(BOp1)) {
// If bits are being compared against that are and'd out, then the
// comparison can never succeed!
if ((*RHSV & ~BOC->getValue()) != 0)
return replaceInstUsesWith(ICI, Builder->getInt1(isICMP_NE));
// If we have ((X & C) == C), turn it into ((X & C) != 0).
if (RHS == BOC && RHSV->isPowerOf2())
return new ICmpInst(isICMP_NE ? ICmpInst::ICMP_EQ : ICmpInst::ICMP_NE,

9
test/Transforms/InstSimplify/compare.ll
View File

@ -1,3 +1,4 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt < %s -instsimplify -S | FileCheck %s
target datalayout = "p:32:32"
@ -1017,9 +1018,7 @@ define i1 @icmp_eq_const(i32 %a) {
; FIXME: Vectors should fold the same way.
define <2 x i1> @icmp_eq_const_vec(<2 x i32> %a) {
; CHECK-LABEL: @icmp_eq_const_vec(
; CHECK-NEXT: [[B:%.*]] = mul nsw <2 x i32> %a, <i32 -2, i32 -2>
; CHECK-NEXT: [[C:%.*]] = icmp eq <2 x i32> [[B]], <i32 1, i32 1>
; CHECK-NEXT: ret <2 x i1> [[C]]
; CHECK-NEXT: ret <2 x i1> zeroinitializer
;
%b = mul nsw <2 x i32> %a, <i32 -2, i32 -2>
%c = icmp eq <2 x i32> %b, <i32 1, i32 1>
@ -1038,9 +1037,7 @@ define i1 @icmp_ne_const(i32 %a) {
; FIXME: Vectors should fold the same way.
define <2 x i1> @icmp_ne_const_vec(<2 x i32> %a) {
; CHECK-LABEL: @icmp_ne_const_vec(
; CHECK-NEXT: [[B:%.*]] = mul nsw <2 x i32> %a, <i32 -2, i32 -2>
; CHECK-NEXT: [[C:%.*]] = icmp ne <2 x i32> [[B]], <i32 1, i32 1>
; CHECK-NEXT: ret <2 x i1> [[C]]
; CHECK-NEXT: ret <2 x i1> <i1 true, i1 true>
;
%b = mul nsw <2 x i32> %a, <i32 -2, i32 -2>
%c = icmp ne <2 x i32> %b, <i32 1, i32 1>