Skip to content

[SCEV] Don't add wrap predicates known to be false. #157351

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
wants to merge 1 commit into
base: main
Choose a base branch
from
Open

[SCEV] Don't add wrap predicates known to be false. #157351

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
26 changes: 26 additions & 0 deletions llvm/lib/Analysis/ScalarEvolution.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -15169,6 +15169,32 @@ void SCEVUnionPredicate::add(const SCEVPredicate *N, ScalarEvolution &SE) {
return;
}

if (auto *WrapPred = dyn_cast<SCEVWrapPredicate>(N)) {
const SCEVAddRecExpr *AddRecToCheck = WrapPred->getExpr();
const SCEV *ExitCount =
SE.getSymbolicMaxBackedgeTakenCount(AddRecToCheck->getLoop());
if (!isa<SCEVCouldNotCompute>(ExitCount) &&
WrapPred->getFlags() == SCEVWrapPredicate::IncrementNUSW) {
const SCEV *Step = AddRecToCheck->getStepRecurrence(SE);
unsigned SrcBits = SE.getTypeSizeInBits(ExitCount->getType());
unsigned DstBits = SE.getTypeSizeInBits(AddRecToCheck->getType());

// AddRecs starting at zero with positive steps won't wrap if (Step *
// trunc ExitCount) does not wrap.
if (AddRecToCheck->getStart()->isZero() && SE.isKnownPositive(Step) &&
DstBits < SrcBits &&
ExitCount ==
SE.getZeroExtendExpr(
SE.getTruncateExpr(ExitCount, AddRecToCheck->getType()),
ExitCount->getType()) &&
SE.willNotOverflow(
Instruction::Mul, /*Signed=*/false, Step,
SE.getTruncateExpr(ExitCount, AddRecToCheck->getType()))) {
return;
}
}
}

// Only add predicate if it is not already implied by this union predicate.
if (implies(N, SE))
return;
Expand Down
38 changes: 28 additions & 10 deletions llvm/test/Transforms/LoopVectorize/X86/optsize.ll
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -353,31 +353,49 @@ exit:
define void @can_prove_scev_predicate_is_always_true(ptr %dst) {
; CHECK-LABEL: define void @can_prove_scev_predicate_is_always_true(
; CHECK-SAME: ptr [[DST:%.*]]) #[[ATTR2]] {
; CHECK-NEXT: [[ENTRY:.*]]:
; CHECK-NEXT: [[ENTRY:.*:]]
; CHECK-NEXT: br i1 false, label %[[SCALAR_PH:.*]], label %[[VECTOR_PH:.*]]
; CHECK: [[VECTOR_PH]]:
; CHECK-NEXT: br label %[[VECTOR_BODY:.*]]
; CHECK: [[VECTOR_BODY]]:
; CHECK-NEXT: call void @llvm.masked.store.v64i32.p0(<64 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7, i32 8, i32 9, i32 10, i32 11, i32 12, i32 13, i32 14, i32 15, i32 16, i32 17, i32 18, i32 19, i32 20, i32 21, i32 22, i32 23, i32 24, i32 25, i32 26, i32 27, i32 28, i32 29, i32 30, i32 31, i32 32, i32 33, i32 34, i32 35, i32 36, i32 37, i32 38, i32 39, i32 40, i32 41, i32 42, i32 43, i32 44, i32 45, i32 46, i32 47, i32 48, i32 49, i32 50, i32 51, i32 52, i32 53, i32 54, i32 55, i32 56, i32 57, i32 58, i32 59, i32 60, i32 61, i32 62, i32 63>, ptr [[DST]], i32 4, <64 x i1> <i1 true, i1 true, i1 true, i1 true, i1 true, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false>)
; CHECK-NEXT: br label %[[MIDDLE_BLOCK:.*]]
; CHECK: [[MIDDLE_BLOCK]]:
; CHECK-NEXT: br label %[[EXIT:.*]]
; CHECK: [[SCALAR_PH]]:
; CHECK-NEXT: br label %[[LOOP:.*]]
; CHECK: [[LOOP]]:
; CHECK-NEXT: [[IV:%.*]] = phi i32 [ 0, %[[ENTRY]] ], [ [[ADD:%.*]], %[[LOOP]] ]
; CHECK-NEXT: [[IV:%.*]] = phi i32 [ 0, %[[SCALAR_PH]] ], [ [[ADD:%.*]], %[[LOOP]] ]
; CHECK-NEXT: [[GEP:%.*]] = getelementptr inbounds i32, ptr [[DST]], i32 [[IV]]
; CHECK-NEXT: store i32 [[IV]], ptr [[GEP]], align 4
; CHECK-NEXT: [[CONV:%.*]] = and i32 [[IV]], 65535
; CHECK-NEXT: [[CMP:%.*]] = icmp ult i32 [[CONV]], 4
; CHECK-NEXT: [[ADD]] = add nuw nsw i32 [[CONV]], 1
; CHECK-NEXT: br i1 [[CMP]], label %[[LOOP]], label %[[EXIT:.*]]
; CHECK-NEXT: br i1 [[CMP]], label %[[LOOP]], label %[[EXIT]], !llvm.loop [[LOOP8:![0-9]+]]
; CHECK: [[EXIT]]:
; CHECK-NEXT: ret void
;
; AUTOVF-LABEL: define void @can_prove_scev_predicate_is_always_true(
; AUTOVF-SAME: ptr [[DST:%.*]]) #[[ATTR2]] {
; AUTOVF-NEXT: [[ENTRY:.*]]:
; AUTOVF-NEXT: [[ENTRY:.*:]]
; AUTOVF-NEXT: br i1 false, label %[[SCALAR_PH:.*]], label %[[VECTOR_PH:.*]]
; AUTOVF: [[VECTOR_PH]]:
; AUTOVF-NEXT: br label %[[VECTOR_BODY:.*]]
; AUTOVF: [[VECTOR_BODY]]:
; AUTOVF-NEXT: call void @llvm.masked.store.v8i32.p0(<8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7>, ptr [[DST]], i32 4, <8 x i1> <i1 true, i1 true, i1 true, i1 true, i1 true, i1 false, i1 false, i1 false>)
; AUTOVF-NEXT: br label %[[MIDDLE_BLOCK:.*]]
; AUTOVF: [[MIDDLE_BLOCK]]:
; AUTOVF-NEXT: br label %[[EXIT:.*]]
; AUTOVF: [[SCALAR_PH]]:
; AUTOVF-NEXT: br label %[[LOOP:.*]]
; AUTOVF: [[LOOP]]:
; AUTOVF-NEXT: [[IV:%.*]] = phi i32 [ 0, %[[ENTRY]] ], [ [[ADD:%.*]], %[[LOOP]] ]
; AUTOVF-NEXT: [[IV:%.*]] = phi i32 [ 0, %[[SCALAR_PH]] ], [ [[ADD:%.*]], %[[LOOP]] ]
; AUTOVF-NEXT: [[GEP:%.*]] = getelementptr inbounds i32, ptr [[DST]], i32 [[IV]]
; AUTOVF-NEXT: store i32 [[IV]], ptr [[GEP]], align 4
; AUTOVF-NEXT: [[CONV:%.*]] = and i32 [[IV]], 65535
; AUTOVF-NEXT: [[CMP:%.*]] = icmp ult i32 [[CONV]], 4
; AUTOVF-NEXT: [[ADD]] = add nuw nsw i32 [[CONV]], 1
; AUTOVF-NEXT: br i1 [[CMP]], label %[[LOOP]], label %[[EXIT:.*]]
; AUTOVF-NEXT: br i1 [[CMP]], label %[[LOOP]], label %[[EXIT]], !llvm.loop [[LOOP8:![0-9]+]]
; AUTOVF: [[EXIT]]:
; AUTOVF-NEXT: ret void
;
Expand Down Expand Up @@ -428,7 +446,7 @@ define void @tail_folded_store_avx512(ptr %start, ptr %end) #3 {
; CHECK-NEXT: [[INDEX_NEXT]] = add nuw i32 [[INDEX]], 64
; CHECK-NEXT: [[PTR_IND]] = getelementptr i8, ptr [[POINTER_PHI]], i32 -4608
; CHECK-NEXT: [[TMP7:%.*]] = icmp eq i32 [[INDEX_NEXT]], [[N_VEC]]
; CHECK-NEXT: br i1 [[TMP7]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP8:![0-9]+]]
; CHECK-NEXT: br i1 [[TMP7]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP9:![0-9]+]]
; CHECK: [[MIDDLE_BLOCK]]:
; CHECK-NEXT: br label %[[EXIT:.*]]
; CHECK: [[SCALAR_PH]]:
Expand All @@ -438,7 +456,7 @@ define void @tail_folded_store_avx512(ptr %start, ptr %end) #3 {
; CHECK-NEXT: [[PTR_IV_NEXT]] = getelementptr nusw i8, ptr [[PTR_IV]], i64 -72
; CHECK-NEXT: store ptr null, ptr [[PTR_IV]], align 8
; CHECK-NEXT: [[EC:%.*]] = icmp eq ptr [[PTR_IV_NEXT]], [[END]]
; CHECK-NEXT: br i1 [[EC]], label %[[EXIT]], label %[[LOOP]], !llvm.loop [[LOOP9:![0-9]+]]
; CHECK-NEXT: br i1 [[EC]], label %[[EXIT]], label %[[LOOP]], !llvm.loop [[LOOP10:![0-9]+]]
; CHECK: [[EXIT]]:
; CHECK-NEXT: ret void
;
Expand Down Expand Up @@ -472,7 +490,7 @@ define void @tail_folded_store_avx512(ptr %start, ptr %end) #3 {
; AUTOVF-NEXT: [[INDEX_NEXT]] = add nuw i32 [[INDEX]], 8
; AUTOVF-NEXT: [[PTR_IND]] = getelementptr i8, ptr [[POINTER_PHI]], i32 -576
; AUTOVF-NEXT: [[TMP7:%.*]] = icmp eq i32 [[INDEX_NEXT]], [[N_VEC]]
; AUTOVF-NEXT: br i1 [[TMP7]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP8:![0-9]+]]
; AUTOVF-NEXT: br i1 [[TMP7]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP9:![0-9]+]]
; AUTOVF: [[MIDDLE_BLOCK]]:
; AUTOVF-NEXT: br label %[[EXIT:.*]]
; AUTOVF: [[SCALAR_PH]]:
Expand All @@ -482,7 +500,7 @@ define void @tail_folded_store_avx512(ptr %start, ptr %end) #3 {
; AUTOVF-NEXT: [[PTR_IV_NEXT]] = getelementptr nusw i8, ptr [[PTR_IV]], i64 -72
; AUTOVF-NEXT: store ptr null, ptr [[PTR_IV]], align 8
; AUTOVF-NEXT: [[EC:%.*]] = icmp eq ptr [[PTR_IV_NEXT]], [[END]]
; AUTOVF-NEXT: br i1 [[EC]], label %[[EXIT]], label %[[LOOP]], !llvm.loop [[LOOP9:![0-9]+]]
; AUTOVF-NEXT: br i1 [[EC]], label %[[EXIT]], label %[[LOOP]], !llvm.loop [[LOOP10:![0-9]+]]
; AUTOVF: [[EXIT]]:
; AUTOVF-NEXT: ret void
;
Expand Down