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LAA: strip unit-stride check in getPtrStride #122879

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LAA: strip unit-stride check in getPtrStride #122879

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9 changes: 4 additions & 5 deletions llvm/lib/Analysis/LoopAccessAnalysis.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1520,12 +1520,11 @@ llvm::getPtrStride(PredicatedScalarEvolution &PSE, Type *AccessTy, Value *Ptr,
GEP && GEP->hasNoUnsignedSignedWrap())
return Stride;

// If the null pointer is undefined, then a access sequence which would
// otherwise access it can be assumed not to unsigned wrap. Note that this
// assumes the object in memory is aligned to the natural alignment.
// If the null pointer dereference is undefined, then a access sequence which
// would otherwise access it can be assumed not to unsigned wrap. Note that
// this assumes the object in memory is aligned to the natural alignment.
unsigned AddrSpace = Ty->getPointerAddressSpace();
if (!NullPointerIsDefined(Lp->getHeader()->getParent(), AddrSpace) &&
(Stride == 1 || Stride == -1))
if (!NullPointerIsDefined(Lp->getHeader()->getParent(), AddrSpace))
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I am not sure we can apply the same reasoning as for a353e25 here.

If the stride is != 1,-1, we could wrap but never reach null I think

return Stride;

if (Assume) {
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3 changes: 0 additions & 3 deletions llvm/test/Analysis/LoopAccessAnalysis/nusw-predicates.ll
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Expand Up @@ -19,7 +19,6 @@ define void @int_and_pointer_predicate(ptr %v, i32 %N) {
; CHECK-NEXT: Non vectorizable stores to invariant address were not found in loop.
; CHECK-NEXT: SCEV assumptions:
; CHECK-NEXT: {0,+,1}<%loop> Added Flags: <nusw>
; CHECK-NEXT: {%v,+,4}<%loop> Added Flags: <nusw>
; CHECK-EMPTY:
; CHECK-NEXT: Expressions re-written:
;
Expand Down Expand Up @@ -93,8 +92,6 @@ define void @int_and_multiple_pointer_predicates(ptr %v, ptr %w, i32 %N) {
; CHECK-NEXT: Non vectorizable stores to invariant address were not found in loop.
; CHECK-NEXT: SCEV assumptions:
; CHECK-NEXT: {0,+,1}<%loop> Added Flags: <nusw>
; CHECK-NEXT: {%v,+,4}<%loop> Added Flags: <nusw>
; CHECK-NEXT: {%w,+,4}<%loop> Added Flags: <nusw>
; CHECK-EMPTY:
; CHECK-NEXT: Expressions re-written:
;
Expand Down
4 changes: 0 additions & 4 deletions llvm/test/Analysis/LoopAccessAnalysis/wrapping-pointer-versioning.ll
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Expand Up @@ -39,7 +39,6 @@ define void @f1(ptr noalias %a, ptr noalias %b, i64 %N) {
; CHECK-NEXT: Non vectorizable stores to invariant address were not found in loop.
; CHECK-NEXT: SCEV assumptions:
; CHECK-NEXT: {0,+,2}<%for.body> Added Flags: <nusw>
; CHECK-NEXT: {%a,+,4}<%for.body> Added Flags: <nusw>
; CHECK-EMPTY:
; CHECK-NEXT: Expressions re-written:
; CHECK-NEXT: [PSE] %arrayidxA = getelementptr i16, ptr %a, i64 %mul_ext:
Expand Down Expand Up @@ -115,7 +114,6 @@ define void @f2(ptr noalias %a, ptr noalias %b, i64 %N) {
; CHECK-NEXT: Non vectorizable stores to invariant address were not found in loop.
; CHECK-NEXT: SCEV assumptions:
; CHECK-NEXT: {(2 * (trunc i64 %N to i32)),+,-2}<%for.body> Added Flags: <nusw>
; CHECK-NEXT: {((4 * (zext i31 (trunc i64 %N to i31) to i64))<nuw><nsw> + %a),+,-4}<%for.body> Added Flags: <nusw>
; CHECK-EMPTY:
; CHECK-NEXT: Expressions re-written:
; CHECK-NEXT: [PSE] %arrayidxA = getelementptr i16, ptr %a, i64 %mul_ext:
Expand Down Expand Up @@ -176,7 +174,6 @@ define void @f3(ptr noalias %a, ptr noalias %b, i64 %N) {
; CHECK-NEXT: Non vectorizable stores to invariant address were not found in loop.
; CHECK-NEXT: SCEV assumptions:
; CHECK-NEXT: {0,+,2}<%for.body> Added Flags: <nssw>
; CHECK-NEXT: {%a,+,4}<%for.body> Added Flags: <nusw>
; CHECK-EMPTY:
; CHECK-NEXT: Expressions re-written:
; CHECK-NEXT: [PSE] %arrayidxA = getelementptr i16, ptr %a, i64 %mul_ext:
Expand Down Expand Up @@ -233,7 +230,6 @@ define void @f4(ptr noalias %a, ptr noalias %b, i64 %N) {
; CHECK-NEXT: Non vectorizable stores to invariant address were not found in loop.
; CHECK-NEXT: SCEV assumptions:
; CHECK-NEXT: {(2 * (trunc i64 %N to i32)),+,-2}<%for.body> Added Flags: <nssw>
; CHECK-NEXT: {((2 * (sext i32 (2 * (trunc i64 %N to i32)) to i64))<nsw> + %a),+,-4}<%for.body> Added Flags: <nusw>
; CHECK-EMPTY:
; CHECK-NEXT: Expressions re-written:
; CHECK-NEXT: [PSE] %arrayidxA = getelementptr i16, ptr %a, i64 %mul_ext:
Expand Down
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