[llvm] [SCEV] Don't add predicates already implied by UnionPredicate. (PR #93397)
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llvm-commits at lists.llvm.org
Sat May 25 21:39:00 PDT 2024
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-llvm-transforms
Author: Florian Hahn (fhahn)
<details>
<summary>Changes</summary>
Update SCEVUnionPredicate::add to only add predicates from another union
predicate, if they aren't alread implied by the union predicate we add
them to.
Note that there exists logic elsewhere to avoid adding predicates if
they are already implied, but this logic misses cases when only some
predicates of a union predicate are implied by the current set of
predicates.
---
Full diff: https://github.com/llvm/llvm-project/pull/93397.diff
2 Files Affected:
- (modified) llvm/lib/Analysis/ScalarEvolution.cpp (+5-1)
- (modified) llvm/test/Transforms/LoopVectorize/scev-predicate-reasoning.ll (+102)
``````````diff
diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index b83e2b435f5d7..206dfac0379ea 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -14746,8 +14746,12 @@ void SCEVUnionPredicate::print(raw_ostream &OS, unsigned Depth) const {
void SCEVUnionPredicate::add(const SCEVPredicate *N) {
if (const auto *Set = dyn_cast<SCEVUnionPredicate>(N)) {
- for (const auto *Pred : Set->Preds)
+ for (const auto *Pred : Set->Preds) {
+ // Skip predicates already implied by this union predicate.
+ if (implies(Pred))
+ continue;
add(Pred);
+ }
return;
}
diff --git a/llvm/test/Transforms/LoopVectorize/scev-predicate-reasoning.ll b/llvm/test/Transforms/LoopVectorize/scev-predicate-reasoning.ll
index 6ae6645378b32..f44087ff632b4 100644
--- a/llvm/test/Transforms/LoopVectorize/scev-predicate-reasoning.ll
+++ b/llvm/test/Transforms/LoopVectorize/scev-predicate-reasoning.ll
@@ -149,3 +149,105 @@ for.cond: ; preds = %for.body, %entry
for.end: ; preds = %for.cond
ret void
}
+
+ at h = global i64 0
+
+; TODO: Currently we generate SCEV check code for the same predicate twice.
+define void @implied_wrap_predicate(ptr %A, ptr %B, ptr %C) {
+; CHECK-LABEL: define void @implied_wrap_predicate
+; CHECK-SAME: (ptr [[A:%.*]], ptr [[B:%.*]], ptr [[C:%.*]]) {
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[A3:%.*]] = ptrtoint ptr [[A]] to i64
+; CHECK-NEXT: [[C2:%.*]] = ptrtoint ptr [[C]] to i64
+; CHECK-NEXT: [[A1:%.*]] = ptrtoint ptr [[A]] to i64
+; CHECK-NEXT: [[TMP0:%.*]] = add i64 [[A3]], 16
+; CHECK-NEXT: [[UMAX4:%.*]] = call i64 @llvm.umax.i64(i64 [[TMP0]], i64 add (i64 ptrtoint (ptr @h to i64), i64 1))
+; CHECK-NEXT: [[TMP1:%.*]] = add i64 [[UMAX4]], -9
+; CHECK-NEXT: [[TMP2:%.*]] = sub i64 [[TMP1]], [[A3]]
+; CHECK-NEXT: [[TMP3:%.*]] = lshr i64 [[TMP2]], 3
+; CHECK-NEXT: [[TMP4:%.*]] = add nuw nsw i64 [[TMP3]], 1
+; CHECK-NEXT: [[MIN_ITERS_CHECK:%.*]] = icmp ult i64 [[TMP4]], 4
+; CHECK-NEXT: br i1 [[MIN_ITERS_CHECK]], label [[SCALAR_PH:%.*]], label [[VECTOR_SCEVCHECK:%.*]]
+; CHECK: vector.scevcheck:
+; CHECK-NEXT: [[TMP5:%.*]] = add i64 [[A1]], 16
+; CHECK-NEXT: [[UMAX:%.*]] = call i64 @llvm.umax.i64(i64 [[TMP5]], i64 add (i64 ptrtoint (ptr @h to i64), i64 1))
+; CHECK-NEXT: [[TMP6:%.*]] = add i64 [[UMAX]], -9
+; CHECK-NEXT: [[TMP7:%.*]] = sub i64 [[TMP6]], [[A1]]
+; CHECK-NEXT: [[TMP8:%.*]] = lshr i64 [[TMP7]], 3
+; CHECK-NEXT: [[TMP9:%.*]] = trunc i64 [[TMP8]] to i16
+; CHECK-NEXT: [[TMP10:%.*]] = add i16 1, [[TMP9]]
+; CHECK-NEXT: [[TMP11:%.*]] = icmp ult i16 [[TMP10]], 1
+; CHECK-NEXT: [[TMP12:%.*]] = icmp ugt i64 [[TMP8]], 65535
+; CHECK-NEXT: [[TMP13:%.*]] = or i1 [[TMP11]], [[TMP12]]
+; CHECK-NEXT: [[TMP14:%.*]] = trunc i64 [[TMP8]] to i16
+; CHECK-NEXT: [[TMP15:%.*]] = add i16 2, [[TMP14]]
+; CHECK-NEXT: [[TMP16:%.*]] = icmp ult i16 [[TMP15]], 2
+; CHECK-NEXT: [[TMP17:%.*]] = icmp ugt i64 [[TMP8]], 65535
+; CHECK-NEXT: [[TMP18:%.*]] = or i1 [[TMP16]], [[TMP17]]
+; CHECK-NEXT: [[TMP19:%.*]] = or i1 [[TMP13]], [[TMP18]]
+; CHECK-NEXT: br i1 [[TMP19]], label [[SCALAR_PH]], label [[VECTOR_MEMCHECK:%.*]]
+; CHECK: vector.memcheck:
+; CHECK-NEXT: [[TMP20:%.*]] = sub i64 [[C2]], [[A3]]
+; CHECK-NEXT: [[DIFF_CHECK:%.*]] = icmp ult i64 [[TMP20]], 32
+; CHECK-NEXT: br i1 [[DIFF_CHECK]], label [[SCALAR_PH]], label [[VECTOR_PH:%.*]]
+; CHECK: vector.ph:
+; CHECK-NEXT: [[N_MOD_VF:%.*]] = urem i64 [[TMP4]], 4
+; CHECK-NEXT: [[N_VEC:%.*]] = sub i64 [[TMP4]], [[N_MOD_VF]]
+; CHECK-NEXT: [[DOTCAST:%.*]] = trunc i64 [[N_VEC]] to i16
+; CHECK-NEXT: [[IND_END:%.*]] = add i16 1, [[DOTCAST]]
+; CHECK-NEXT: [[IND_END5:%.*]] = add i64 1, [[N_VEC]]
+; CHECK-NEXT: br label [[VECTOR_BODY:%.*]]
+; CHECK: vector.body:
+; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
+; CHECK-NEXT: [[OFFSET_IDX:%.*]] = add i64 1, [[INDEX]]
+; CHECK-NEXT: [[TMP21:%.*]] = add i64 [[OFFSET_IDX]], 0
+; CHECK-NEXT: [[TMP22:%.*]] = getelementptr i64, ptr [[A]], i64 [[TMP21]]
+; CHECK-NEXT: [[TMP23:%.*]] = getelementptr i64, ptr [[TMP22]], i32 0
+; CHECK-NEXT: store <4 x i64> zeroinitializer, ptr [[TMP23]], align 4
+; CHECK-NEXT: [[TMP24:%.*]] = getelementptr i64, ptr [[C]], i64 [[TMP21]]
+; CHECK-NEXT: [[TMP25:%.*]] = getelementptr i64, ptr [[TMP24]], i32 0
+; CHECK-NEXT: store <4 x i64> zeroinitializer, ptr [[TMP25]], align 4
+; CHECK-NEXT: [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 4
+; CHECK-NEXT: [[TMP26:%.*]] = icmp eq i64 [[INDEX_NEXT]], [[N_VEC]]
+; CHECK-NEXT: br i1 [[TMP26]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP6:![0-9]+]]
+; CHECK: middle.block:
+; CHECK-NEXT: [[CMP_N:%.*]] = icmp eq i64 [[TMP4]], [[N_VEC]]
+; CHECK-NEXT: br i1 [[CMP_N]], label [[EXIT:%.*]], label [[SCALAR_PH]]
+; CHECK: scalar.ph:
+; CHECK-NEXT: [[BC_RESUME_VAL:%.*]] = phi i16 [ [[IND_END]], [[MIDDLE_BLOCK]] ], [ 1, [[ENTRY:%.*]] ], [ 1, [[VECTOR_SCEVCHECK]] ], [ 1, [[VECTOR_MEMCHECK]] ]
+; CHECK-NEXT: [[BC_RESUME_VAL6:%.*]] = phi i64 [ [[IND_END5]], [[MIDDLE_BLOCK]] ], [ 1, [[ENTRY]] ], [ 1, [[VECTOR_SCEVCHECK]] ], [ 1, [[VECTOR_MEMCHECK]] ]
+; CHECK-NEXT: br label [[LOOP:%.*]]
+; CHECK: loop:
+; CHECK-NEXT: [[IV:%.*]] = phi i16 [ [[BC_RESUME_VAL]], [[SCALAR_PH]] ], [ [[IV_NEXT:%.*]], [[LOOP]] ]
+; CHECK-NEXT: [[IV_EXT:%.*]] = phi i64 [ [[BC_RESUME_VAL6]], [[SCALAR_PH]] ], [ [[IV_EXT_NEXT:%.*]], [[LOOP]] ]
+; CHECK-NEXT: [[GEP_A:%.*]] = getelementptr i64, ptr [[A]], i64 [[IV_EXT]]
+; CHECK-NEXT: store i64 0, ptr [[GEP_A]], align 4
+; CHECK-NEXT: [[GEP_C:%.*]] = getelementptr i64, ptr [[C]], i64 [[IV_EXT]]
+; CHECK-NEXT: store i64 0, ptr [[GEP_C]], align 4
+; CHECK-NEXT: [[IV_NEXT]] = add i16 [[IV]], 1
+; CHECK-NEXT: [[IV_EXT_NEXT]] = zext i16 [[IV_NEXT]] to i64
+; CHECK-NEXT: [[GEP:%.*]] = getelementptr i64, ptr [[A]], i64 [[IV_EXT_NEXT]]
+; CHECK-NEXT: [[CMP:%.*]] = icmp ugt ptr [[GEP]], @h
+; CHECK-NEXT: br i1 [[CMP]], label [[EXIT]], label [[LOOP]], !llvm.loop [[LOOP7:![0-9]+]]
+; CHECK: exit:
+; CHECK-NEXT: ret void
+;
+entry:
+ br label %loop
+
+loop:
+ %iv = phi i16 [ 1, %entry ], [ %iv.next, %loop ]
+ %iv.ext = phi i64 [ 1, %entry ], [ %iv.ext.next, %loop ]
+ %gep.A = getelementptr i64, ptr %A, i64 %iv.ext
+ store i64 0, ptr %gep.A
+ %gep.C = getelementptr i64, ptr %C, i64 %iv.ext
+ store i64 0, ptr %gep.C
+ %iv.next = add i16 %iv, 1
+ %iv.ext.next = zext i16 %iv.next to i64
+ %gep = getelementptr i64, ptr %A, i64 %iv.ext.next
+ %cmp = icmp ugt ptr %gep, @h
+ br i1 %cmp, label %exit, label %loop
+
+exit:
+ ret void
+}
``````````
</details>
https://github.com/llvm/llvm-project/pull/93397
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