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[LV] Apply loop guards when checking recur during hoisting RT checks.

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Apply loop guards when checking if the recurrence is non-negative in
cases where runtime checks are hoisted out of an inner loop.
This commit is contained in:
Florian Hahn
2024-06-04 20:37:45 +01:00
parent fbaec0f46b
commit e775efcec4
2 changed files with 13 additions and 15 deletions
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3
llvm/lib/Transforms/Utils/LoopUtils.cpp
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@@ -1760,7 +1760,8 @@ static PointerBounds expandBounds(const RuntimeCheckingPtrGroup *CG,
Low = cast<SCEVAddRecExpr>(Low)->getStart();
// If there is a possibility that the stride is negative then we have
// to generate extra checks to ensure the stride is positive.
if (!SE.isKnownNonNegative(Recur)) {
if (!SE.isKnownNonNegative(
SE.applyLoopGuards(Recur, HighAR->getLoop()))) {
Stride = Recur;
LLVM_DEBUG(dbgs() << "LAA: ... but need to check stride is "
"positive: "

25
llvm/test/Transforms/LoopVectorize/runtime-checks-hoist.ll
View File

@@ -1509,7 +1509,8 @@ outer.exit:
ret void
}
; TODO: STRIDE_CHECK can be eliminated via loop guards.
; The stride for the access in the inner loop is known to be non-negative via
; loop guards.
define void @stride_check_known_via_loop_guard(ptr %C, ptr %A, i32 %Acols) {
; CHECK-LABEL: define void @stride_check_known_via_loop_guard
; CHECK-SAME: (ptr [[C:%.*]], ptr [[A:%.*]], i32 [[ACOLS:%.*]]) {
@@ -1518,8 +1519,6 @@ define void @stride_check_known_via_loop_guard(ptr %C, ptr %A, i32 %Acols) {
; CHECK-NEXT: br i1 [[PRE_C]], label [[EXIT:%.*]], label [[OUTER_HEADER_PREHEADER:%.*]]
; CHECK: outer.header.preheader:
; CHECK-NEXT: [[SCEVGEP:%.*]] = getelementptr i8, ptr [[A]], i64 8
; CHECK-NEXT: [[TMP0:%.*]] = sext i32 [[ACOLS]] to i64
; CHECK-NEXT: [[TMP1:%.*]] = shl nsw i64 [[TMP0]], 3
; CHECK-NEXT: [[SCEVGEP1:%.*]] = getelementptr i8, ptr [[C]], i64 34359738368
; CHECK-NEXT: br label [[OUTER_HEADER:%.*]]
; CHECK: outer.header:
@@ -1533,23 +1532,21 @@ define void @stride_check_known_via_loop_guard(ptr %C, ptr %A, i32 %Acols) {
; CHECK-NEXT: [[BOUND0:%.*]] = icmp ult ptr [[A]], [[SCEVGEP1]]
; CHECK-NEXT: [[BOUND1:%.*]] = icmp ult ptr [[C]], [[SCEVGEP]]
; CHECK-NEXT: [[FOUND_CONFLICT:%.*]] = and i1 [[BOUND0]], [[BOUND1]]
; CHECK-NEXT: [[STRIDE_CHECK:%.*]] = icmp slt i64 [[TMP1]], 0
; CHECK-NEXT: [[TMP2:%.*]] = or i1 [[FOUND_CONFLICT]], [[STRIDE_CHECK]]
; CHECK-NEXT: br i1 [[TMP2]], label [[SCALAR_PH]], label [[VECTOR_PH:%.*]]
; CHECK-NEXT: br i1 [[FOUND_CONFLICT]], label [[SCALAR_PH]], label [[VECTOR_PH:%.*]]
; CHECK: vector.ph:
; CHECK-NEXT: br label [[VECTOR_BODY:%.*]]
; CHECK: vector.body:
; CHECK-NEXT: [[INDEX:%.*]] = phi i32 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
; CHECK-NEXT: [[TMP3:%.*]] = add i32 [[INDEX]], 0
; CHECK-NEXT: [[TMP4:%.*]] = getelementptr inbounds double, ptr [[C]], i32 [[TMP3]]
; CHECK-NEXT: [[TMP5:%.*]] = load double, ptr [[ARRAYIDX_US]], align 8, !alias.scope [[META69:![0-9]+]], !noalias [[META72:![0-9]+]]
; CHECK-NEXT: [[BROADCAST_SPLATINSERT:%.*]] = insertelement <4 x double> poison, double [[TMP5]], i64 0
; CHECK-NEXT: [[TMP0:%.*]] = add i32 [[INDEX]], 0
; CHECK-NEXT: [[TMP1:%.*]] = getelementptr inbounds double, ptr [[C]], i32 [[TMP0]]
; CHECK-NEXT: [[TMP2:%.*]] = load double, ptr [[ARRAYIDX_US]], align 8, !alias.scope [[META69:![0-9]+]], !noalias [[META72:![0-9]+]]
; CHECK-NEXT: [[BROADCAST_SPLATINSERT:%.*]] = insertelement <4 x double> poison, double [[TMP2]], i64 0
; CHECK-NEXT: [[BROADCAST_SPLAT:%.*]] = shufflevector <4 x double> [[BROADCAST_SPLATINSERT]], <4 x double> poison, <4 x i32> zeroinitializer
; CHECK-NEXT: [[TMP6:%.*]] = getelementptr inbounds double, ptr [[TMP4]], i32 0
; CHECK-NEXT: store <4 x double> [[BROADCAST_SPLAT]], ptr [[TMP6]], align 8, !alias.scope [[META72]]
; CHECK-NEXT: [[TMP3:%.*]] = getelementptr inbounds double, ptr [[TMP1]], i32 0
; CHECK-NEXT: store <4 x double> [[BROADCAST_SPLAT]], ptr [[TMP3]], align 8, !alias.scope [[META72]]
; CHECK-NEXT: [[INDEX_NEXT]] = add nuw i32 [[INDEX]], 4
; CHECK-NEXT: [[TMP7:%.*]] = icmp eq i32 [[INDEX_NEXT]], 0
; CHECK-NEXT: br i1 [[TMP7]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP74:![0-9]+]]
; CHECK-NEXT: [[TMP4:%.*]] = icmp eq i32 [[INDEX_NEXT]], 0
; CHECK-NEXT: br i1 [[TMP4]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP74:![0-9]+]]
; CHECK: middle.block:
; CHECK-NEXT: br i1 true, label [[OUTER_LATCH]], label [[SCALAR_PH]]
; CHECK: scalar.ph: