[llvm] [LV] Stengthen loop-invariance checks in isPredicatedInst (PR #140744)
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Tue May 20 08:02:29 PDT 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-llvm-analysis
Author: Ramkumar Ramachandra (artagnon)
<details>
<summary>Changes</summary>
Check loop-invariance against SCEV as well.
---
Full diff: https://github.com/llvm/llvm-project/pull/140744.diff
3 Files Affected:
- (modified) llvm/lib/Analysis/LoopAccessAnalysis.cpp (+2-2)
- (modified) llvm/lib/Transforms/Vectorize/LoopVectorize.cpp (+2-2)
- (modified) llvm/test/Transforms/LoopVectorize/RISCV/pr88802.ll (+2-112)
``````````diff
diff --git a/llvm/lib/Analysis/LoopAccessAnalysis.cpp b/llvm/lib/Analysis/LoopAccessAnalysis.cpp
index 2a322a69a0dbf..ef86a1d4ba36e 100644
--- a/llvm/lib/Analysis/LoopAccessAnalysis.cpp
+++ b/llvm/lib/Analysis/LoopAccessAnalysis.cpp
@@ -2806,8 +2806,8 @@ LoopAccessInfo::recordAnalysis(StringRef RemarkName, const Instruction *I) {
bool LoopAccessInfo::isInvariant(Value *V) const {
auto *SE = PSE->getSE();
- // TODO: Is this really what we want? Even without FP SCEV, we may want some
- // trivially loop-invariant FP values to be considered invariant.
+ if (TheLoop->isLoopInvariant(V))
+ return true;
if (!SE->isSCEVable(V->getType()))
return false;
const SCEV *S = SE->getSCEV(V);
diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index b2d7c44761f6d..1a042609115f5 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -3102,14 +3102,14 @@ bool LoopVectorizationCostModel::isPredicatedInst(Instruction *I) const {
// is correct. The easiest form of the later is to require that all values
// stored are the same.
return !(Legal->isInvariant(getLoadStorePointerOperand(I)) &&
- TheLoop->isLoopInvariant(cast<StoreInst>(I)->getValueOperand()));
+ Legal->isInvariant(cast<StoreInst>(I)->getValueOperand()));
}
case Instruction::UDiv:
case Instruction::SDiv:
case Instruction::SRem:
case Instruction::URem:
// If the divisor is loop-invariant no predication is needed.
- return !TheLoop->isLoopInvariant(I->getOperand(1));
+ return !Legal->isInvariant(I->getOperand(1));
}
}
diff --git a/llvm/test/Transforms/LoopVectorize/RISCV/pr88802.ll b/llvm/test/Transforms/LoopVectorize/RISCV/pr88802.ll
index 3dc17e615048e..84c22153f0bc5 100644
--- a/llvm/test/Transforms/LoopVectorize/RISCV/pr88802.ll
+++ b/llvm/test/Transforms/LoopVectorize/RISCV/pr88802.ll
@@ -17,126 +17,16 @@ define void @test(ptr %p, i64 %a, i8 %b) {
; CHECK-NEXT: [[TMP3:%.*]] = zext <16 x i8> [[BROADCAST_SPLAT]] to <16 x i32>
; CHECK-NEXT: br label [[FOR_COND:%.*]]
; CHECK: vector.body:
-; CHECK-NEXT: [[INDEX:%.*]] = phi i32 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[PRED_STORE_CONTINUE8:%.*]] ]
-; CHECK-NEXT: [[VEC_IND:%.*]] = phi <16 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>, [[VECTOR_PH]] ], [ [[VEC_IND_NEXT:%.*]], [[PRED_STORE_CONTINUE8]] ]
+; CHECK-NEXT: [[INDEX:%.*]] = phi i32 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[FOR_COND]] ]
+; CHECK-NEXT: [[VEC_IND:%.*]] = phi <16 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>, [[VECTOR_PH]] ], [ [[VEC_IND_NEXT:%.*]], [[FOR_COND]] ]
; CHECK-NEXT: [[ACTIVE_LANE_MASK:%.*]] = call <16 x i1> @llvm.get.active.lane.mask.v16i1.i32(i32 [[INDEX]], i32 9)
; CHECK-NEXT: [[TMP4:%.*]] = icmp sge <16 x i32> [[VEC_IND]], splat (i32 2)
; CHECK-NEXT: [[TMP5:%.*]] = select <16 x i1> [[ACTIVE_LANE_MASK]], <16 x i1> [[TMP4]], <16 x i1> zeroinitializer
; CHECK-NEXT: [[PREDPHI:%.*]] = select <16 x i1> [[TMP5]], <16 x i32> [[TMP2]], <16 x i32> [[TMP3]]
; CHECK-NEXT: [[TMP6:%.*]] = shl <16 x i32> [[PREDPHI]], splat (i32 8)
; CHECK-NEXT: [[TMP8:%.*]] = trunc <16 x i32> [[TMP6]] to <16 x i8>
-; CHECK-NEXT: [[TMP9:%.*]] = extractelement <16 x i1> [[ACTIVE_LANE_MASK]], i32 0
-; CHECK-NEXT: br i1 [[TMP9]], label [[PRED_STORE_IF:%.*]], label [[VECTOR_BODY:%.*]]
-; CHECK: pred.store.if:
-; CHECK-NEXT: [[TMP19:%.*]] = extractelement <16 x i8> [[TMP8]], i32 0
-; CHECK-NEXT: store i8 [[TMP19]], ptr [[P]], align 1
-; CHECK-NEXT: br label [[VECTOR_BODY]]
-; CHECK: pred.store.continue:
-; CHECK-NEXT: [[CMP_N:%.*]] = extractelement <16 x i1> [[ACTIVE_LANE_MASK]], i32 1
-; CHECK-NEXT: br i1 [[CMP_N]], label [[EXIT:%.*]], label [[SCALAR_PH:%.*]]
-; CHECK: pred.store.if3:
-; CHECK-NEXT: [[TMP12:%.*]] = extractelement <16 x i8> [[TMP8]], i32 1
-; CHECK-NEXT: store i8 [[TMP12]], ptr [[P]], align 1
-; CHECK-NEXT: br label [[SCALAR_PH]]
-; CHECK: pred.store.continue4:
-; CHECK-NEXT: [[TMP13:%.*]] = extractelement <16 x i1> [[ACTIVE_LANE_MASK]], i32 2
-; CHECK-NEXT: br i1 [[TMP13]], label [[PRED_STORE_IF5:%.*]], label [[PRED_STORE_CONTINUE6:%.*]]
-; CHECK: pred.store.if5:
-; CHECK-NEXT: [[TMP14:%.*]] = extractelement <16 x i8> [[TMP8]], i32 2
-; CHECK-NEXT: store i8 [[TMP14]], ptr [[P]], align 1
-; CHECK-NEXT: br label [[PRED_STORE_CONTINUE6]]
-; CHECK: pred.store.continue6:
-; CHECK-NEXT: [[TMP15:%.*]] = extractelement <16 x i1> [[ACTIVE_LANE_MASK]], i32 3
-; CHECK-NEXT: br i1 [[TMP15]], label [[PRED_STORE_IF7:%.*]], label [[PRED_STORE_CONTINUE9:%.*]]
-; CHECK: pred.store.if7:
-; CHECK-NEXT: [[TMP16:%.*]] = extractelement <16 x i8> [[TMP8]], i32 3
-; CHECK-NEXT: store i8 [[TMP16]], ptr [[P]], align 1
-; CHECK-NEXT: br label [[PRED_STORE_CONTINUE9]]
-; CHECK: pred.store.continue8:
-; CHECK-NEXT: [[TMP17:%.*]] = extractelement <16 x i1> [[ACTIVE_LANE_MASK]], i32 4
-; CHECK-NEXT: br i1 [[TMP17]], label [[PRED_STORE_IF9:%.*]], label [[PRED_STORE_CONTINUE10:%.*]]
-; CHECK: pred.store.if9:
-; CHECK-NEXT: [[TMP18:%.*]] = extractelement <16 x i8> [[TMP8]], i32 4
-; CHECK-NEXT: store i8 [[TMP18]], ptr [[P]], align 1
-; CHECK-NEXT: br label [[PRED_STORE_CONTINUE10]]
-; CHECK: pred.store.continue10:
-; CHECK-NEXT: [[TMP41:%.*]] = extractelement <16 x i1> [[ACTIVE_LANE_MASK]], i32 5
-; CHECK-NEXT: br i1 [[TMP41]], label [[PRED_STORE_IF11:%.*]], label [[PRED_STORE_CONTINUE12:%.*]]
-; CHECK: pred.store.if11:
-; CHECK-NEXT: [[TMP20:%.*]] = extractelement <16 x i8> [[TMP8]], i32 5
-; CHECK-NEXT: store i8 [[TMP20]], ptr [[P]], align 1
-; CHECK-NEXT: br label [[PRED_STORE_CONTINUE12]]
-; CHECK: pred.store.continue12:
-; CHECK-NEXT: [[TMP21:%.*]] = extractelement <16 x i1> [[ACTIVE_LANE_MASK]], i32 6
-; CHECK-NEXT: br i1 [[TMP21]], label [[PRED_STORE_IF13:%.*]], label [[PRED_STORE_CONTINUE14:%.*]]
-; CHECK: pred.store.if13:
-; CHECK-NEXT: [[TMP22:%.*]] = extractelement <16 x i8> [[TMP8]], i32 6
-; CHECK-NEXT: store i8 [[TMP22]], ptr [[P]], align 1
-; CHECK-NEXT: br label [[PRED_STORE_CONTINUE14]]
-; CHECK: pred.store.continue14:
-; CHECK-NEXT: [[TMP23:%.*]] = extractelement <16 x i1> [[ACTIVE_LANE_MASK]], i32 7
-; CHECK-NEXT: br i1 [[TMP23]], label [[PRED_STORE_IF15:%.*]], label [[PRED_STORE_CONTINUE16:%.*]]
-; CHECK: pred.store.if15:
-; CHECK-NEXT: [[TMP24:%.*]] = extractelement <16 x i8> [[TMP8]], i32 7
-; CHECK-NEXT: store i8 [[TMP24]], ptr [[P]], align 1
-; CHECK-NEXT: br label [[PRED_STORE_CONTINUE16]]
-; CHECK: pred.store.continue16:
-; CHECK-NEXT: [[TMP25:%.*]] = extractelement <16 x i1> [[ACTIVE_LANE_MASK]], i32 8
-; CHECK-NEXT: br i1 [[TMP25]], label [[PRED_STORE_IF17:%.*]], label [[PRED_STORE_CONTINUE18:%.*]]
-; CHECK: pred.store.if17:
-; CHECK-NEXT: [[TMP26:%.*]] = extractelement <16 x i8> [[TMP8]], i32 8
-; CHECK-NEXT: store i8 [[TMP26]], ptr [[P]], align 1
-; CHECK-NEXT: br label [[PRED_STORE_CONTINUE18]]
-; CHECK: pred.store.continue18:
-; CHECK-NEXT: [[TMP27:%.*]] = extractelement <16 x i1> [[ACTIVE_LANE_MASK]], i32 9
-; CHECK-NEXT: br i1 [[TMP27]], label [[PRED_STORE_IF19:%.*]], label [[PRED_STORE_CONTINUE20:%.*]]
-; CHECK: pred.store.if19:
-; CHECK-NEXT: [[TMP28:%.*]] = extractelement <16 x i8> [[TMP8]], i32 9
-; CHECK-NEXT: store i8 [[TMP28]], ptr [[P]], align 1
-; CHECK-NEXT: br label [[PRED_STORE_CONTINUE20]]
-; CHECK: pred.store.continue20:
-; CHECK-NEXT: [[TMP29:%.*]] = extractelement <16 x i1> [[ACTIVE_LANE_MASK]], i32 10
-; CHECK-NEXT: br i1 [[TMP29]], label [[PRED_STORE_IF21:%.*]], label [[PRED_STORE_CONTINUE22:%.*]]
-; CHECK: pred.store.if21:
-; CHECK-NEXT: [[TMP30:%.*]] = extractelement <16 x i8> [[TMP8]], i32 10
-; CHECK-NEXT: store i8 [[TMP30]], ptr [[P]], align 1
-; CHECK-NEXT: br label [[PRED_STORE_CONTINUE22]]
-; CHECK: pred.store.continue22:
-; CHECK-NEXT: [[TMP31:%.*]] = extractelement <16 x i1> [[ACTIVE_LANE_MASK]], i32 11
-; CHECK-NEXT: br i1 [[TMP31]], label [[PRED_STORE_IF23:%.*]], label [[PRED_STORE_CONTINUE24:%.*]]
-; CHECK: pred.store.if23:
-; CHECK-NEXT: [[TMP32:%.*]] = extractelement <16 x i8> [[TMP8]], i32 11
-; CHECK-NEXT: store i8 [[TMP32]], ptr [[P]], align 1
-; CHECK-NEXT: br label [[PRED_STORE_CONTINUE24]]
-; CHECK: pred.store.continue24:
-; CHECK-NEXT: [[TMP33:%.*]] = extractelement <16 x i1> [[ACTIVE_LANE_MASK]], i32 12
-; CHECK-NEXT: br i1 [[TMP33]], label [[PRED_STORE_IF25:%.*]], label [[PRED_STORE_CONTINUE26:%.*]]
-; CHECK: pred.store.if25:
-; CHECK-NEXT: [[TMP34:%.*]] = extractelement <16 x i8> [[TMP8]], i32 12
-; CHECK-NEXT: store i8 [[TMP34]], ptr [[P]], align 1
-; CHECK-NEXT: br label [[PRED_STORE_CONTINUE26]]
-; CHECK: pred.store.continue26:
-; CHECK-NEXT: [[TMP35:%.*]] = extractelement <16 x i1> [[ACTIVE_LANE_MASK]], i32 13
-; CHECK-NEXT: br i1 [[TMP35]], label [[PRED_STORE_IF27:%.*]], label [[PRED_STORE_CONTINUE28:%.*]]
-; CHECK: pred.store.if27:
-; CHECK-NEXT: [[TMP36:%.*]] = extractelement <16 x i8> [[TMP8]], i32 13
-; CHECK-NEXT: store i8 [[TMP36]], ptr [[P]], align 1
-; CHECK-NEXT: br label [[PRED_STORE_CONTINUE28]]
-; CHECK: pred.store.continue28:
-; CHECK-NEXT: [[TMP37:%.*]] = extractelement <16 x i1> [[ACTIVE_LANE_MASK]], i32 14
-; CHECK-NEXT: br i1 [[TMP37]], label [[PRED_STORE_IF29:%.*]], label [[PRED_STORE_CONTINUE30:%.*]]
-; CHECK: pred.store.if29:
-; CHECK-NEXT: [[TMP38:%.*]] = extractelement <16 x i8> [[TMP8]], i32 14
-; CHECK-NEXT: store i8 [[TMP38]], ptr [[P]], align 1
-; CHECK-NEXT: br label [[PRED_STORE_CONTINUE30]]
-; CHECK: pred.store.continue30:
-; CHECK-NEXT: [[TMP39:%.*]] = extractelement <16 x i1> [[ACTIVE_LANE_MASK]], i32 15
-; CHECK-NEXT: br i1 [[TMP39]], label [[PRED_STORE_IF31:%.*]], label [[PRED_STORE_CONTINUE8]]
-; CHECK: pred.store.if31:
; CHECK-NEXT: [[TMP40:%.*]] = extractelement <16 x i8> [[TMP8]], i32 15
; CHECK-NEXT: store i8 [[TMP40]], ptr [[P]], align 1
-; CHECK-NEXT: br label [[PRED_STORE_CONTINUE8]]
-; CHECK: pred.store.continue32:
; CHECK-NEXT: [[VEC_IND_NEXT]] = add <16 x i32> [[VEC_IND]], splat (i32 16)
; CHECK-NEXT: [[INDEX_NEXT]] = add nuw i32 [[INDEX]], 16
; CHECK-NEXT: br i1 true, label [[MIDDLE_BLOCK:%.*]], label [[FOR_COND]], !llvm.loop [[LOOP0:![0-9]+]]
``````````
</details>
https://github.com/llvm/llvm-project/pull/140744
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