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[InstCombine] icmp eq/ne (gep inbounds P, Idx..), null -> icmp eq/ne P, null for vectors 

Extend the transform introduced in https://reviews.llvm.org/D66608 to work for vector geps as well.

Differential Revision: https://reviews.llvm.org/D66671

llvm-svn: 369949
This commit is contained in:
Philip Reames 2019-08-26 19:11:49 +00:00
parent 7e3d043459
commit b92c971099
2 changed files with 11 additions and 8 deletions
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7
llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
View File

@ -895,7 +895,6 @@ Instruction *InstCombiner::foldGEPICmp(GEPOperator *GEPLHS, Value *RHS,
return new ICmpInst(ICmpInst::getSignedPredicate(Cond), Offset,
Constant::getNullValue(Offset->getType()));
} else if (GEPLHS->isInBounds() && ICmpInst::isEquality(Cond) &&
GEPLHS->getType()->isPointerTy() && // TODO: extend to vector geps
isa<Constant>(RHS) && cast<Constant>(RHS)->isNullValue() &&
!NullPointerIsDefined(I.getFunction(),
RHS->getType()->getPointerAddressSpace())) {
@ -914,7 +913,13 @@ Instruction *InstCombiner::foldGEPICmp(GEPOperator *GEPLHS, Value *RHS,
// In general, we're allowed to make values less poison (i.e. remove
// sources of full UB), so in this case, we just select between the two
// non-poison cases (1 and 4 above).
//
// For vectors, we apply the same reasoning on a per-lane basis.
auto *Base = GEPLHS->getPointerOperand();
if (GEPLHS->getType()->isVectorTy() && Base->getType()->isPointerTy()) {
int NumElts = GEPLHS->getType()->getVectorNumElements();
Base = Builder.CreateVectorSplat(NumElts, Base);
}
return new ICmpInst(Cond, Base,
ConstantExpr::getBitCast(cast<Constant>(RHS),
Base->getType()));

12
llvm/test/Transforms/InstCombine/gep-inbounds-null.ll
View File

@ -75,12 +75,10 @@ entry:
ret i1 %cnd
}
;; TODO: vectors not yet handled
define <2 x i1> @test_vector_base(<2 x i8*> %base, i64 %idx) {
; CHECK-LABEL: @test_vector_base(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[GEP:%.*]] = getelementptr inbounds i8, <2 x i8*> [[BASE:%.*]], i64 [[IDX:%.*]]
; CHECK-NEXT: [[CND:%.*]] = icmp eq <2 x i8*> [[GEP]], zeroinitializer
; CHECK-NEXT: [[CND:%.*]] = icmp eq <2 x i8*> [[BASE:%.*]], zeroinitializer
; CHECK-NEXT: ret <2 x i1> [[CND]]
;
entry:
@ -92,8 +90,9 @@ entry:
define <2 x i1> @test_vector_index(i8* %base, <2 x i64> %idx) {
; CHECK-LABEL: @test_vector_index(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[GEP:%.*]] = getelementptr inbounds i8, i8* [[BASE:%.*]], <2 x i64> [[IDX:%.*]]
; CHECK-NEXT: [[CND:%.*]] = icmp eq <2 x i8*> [[GEP]], zeroinitializer
; CHECK-NEXT: [[DOTSPLATINSERT:%.*]] = insertelement <2 x i8*> undef, i8* [[BASE:%.*]], i32 0
; CHECK-NEXT: [[DOTSPLAT:%.*]] = shufflevector <2 x i8*> [[DOTSPLATINSERT]], <2 x i8*> undef, <2 x i32> zeroinitializer
; CHECK-NEXT: [[CND:%.*]] = icmp eq <2 x i8*> [[DOTSPLAT]], zeroinitializer
; CHECK-NEXT: ret <2 x i1> [[CND]]
;
entry:
@ -105,8 +104,7 @@ entry:
define <2 x i1> @test_vector_both(<2 x i8*> %base, <2 x i64> %idx) {
; CHECK-LABEL: @test_vector_both(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[GEP:%.*]] = getelementptr inbounds i8, <2 x i8*> [[BASE:%.*]], <2 x i64> [[IDX:%.*]]
; CHECK-NEXT: [[CND:%.*]] = icmp eq <2 x i8*> [[GEP]], zeroinitializer
; CHECK-NEXT: [[CND:%.*]] = icmp eq <2 x i8*> [[BASE:%.*]], zeroinitializer
; CHECK-NEXT: ret <2 x i1> [[CND]]
;
entry: