[llvm] bc19b7c - [LV] Remove collectTriviallyDeadInstructions, already handled by VP DCE.
Florian Hahn via llvm-commits
llvm-commits at lists.llvm.org
Thu Jul 7 08:40:44 PDT 2022
Author: Florian Hahn
Date: 2022-07-07T08:40:27-07:00
New Revision: bc19b7c3cc169151ef30883c9b313114d7d5a9db
URL: https://github.com/llvm/llvm-project/commit/bc19b7c3cc169151ef30883c9b313114d7d5a9db
DIFF: https://github.com/llvm/llvm-project/commit/bc19b7c3cc169151ef30883c9b313114d7d5a9db.diff
LOG: [LV] Remove collectTriviallyDeadInstructions, already handled by VP DCE.
Now that removeDeadRecipes can remove most dead recipes across a whole
VPlan, there is no need to first collect some dead instructions.
Instead removeDeadRecipes can simply clean them up.
Depends D127580.
Reviewed By: Ayal
Differential Revision: https://reviews.llvm.org/D128408
Added:
Modified:
llvm/lib/Transforms/Vectorize/LoopVectorizationPlanner.h
llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
llvm/test/Transforms/LoopVectorize/X86/consecutive-ptr-uniforms.ll
llvm/test/Transforms/LoopVectorize/pointer-induction.ll
Removed:
################################################################################
diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorizationPlanner.h b/llvm/lib/Transforms/Vectorize/LoopVectorizationPlanner.h
index 933ea9e023021..0845ec5c682c7 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorizationPlanner.h
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorizationPlanner.h
@@ -332,11 +332,6 @@ class LoopVectorizationPlanner {
bool requiresTooManyRuntimeChecks() const;
protected:
- /// Collect the instructions from the original loop that would be trivially
- /// dead in the vectorized loop if generated.
- void collectTriviallyDeadInstructions(
- SmallPtrSetImpl<Instruction *> &DeadInstructions);
-
/// Build VPlans for power-of-2 VF's between \p MinVF and \p MaxVF inclusive,
/// according to the information gathered by Legal when it checked if it is
/// legal to vectorize the loop.
diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index 6926da58b7810..83c3122a8d0be 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -7645,51 +7645,6 @@ void LoopVectorizationPlanner::printPlans(raw_ostream &O) {
}
#endif
-void LoopVectorizationPlanner::collectTriviallyDeadInstructions(
- SmallPtrSetImpl<Instruction *> &DeadInstructions) {
-
- // We create new control-flow for the vectorized loop, so the original exit
- // conditions will be dead after vectorization if it's only used by the
- // terminator
- SmallVector<BasicBlock*> ExitingBlocks;
- OrigLoop->getExitingBlocks(ExitingBlocks);
- for (auto *BB : ExitingBlocks) {
- auto *Cmp = dyn_cast<Instruction>(BB->getTerminator()->getOperand(0));
- if (!Cmp || !Cmp->hasOneUse())
- continue;
-
- // TODO: we should introduce a getUniqueExitingBlocks on Loop
- if (!DeadInstructions.insert(Cmp).second)
- continue;
-
- // The operands of the icmp is often a dead trunc, used by IndUpdate.
- // TODO: can recurse through operands in general
- for (Value *Op : Cmp->operands()) {
- if (isa<TruncInst>(Op) && Op->hasOneUse())
- DeadInstructions.insert(cast<Instruction>(Op));
- }
- }
-
- // We create new "steps" for induction variable updates to which the original
- // induction variables map. An original update instruction will be dead if
- // all its users except the induction variable are dead.
- auto *Latch = OrigLoop->getLoopLatch();
- for (auto &Induction : Legal->getInductionVars()) {
- PHINode *Ind = Induction.first;
- auto *IndUpdate = cast<Instruction>(Ind->getIncomingValueForBlock(Latch));
-
- // If the tail is to be folded by masking, the primary induction variable,
- // if exists, isn't dead: it will be used for masking. Don't kill it.
- if (CM.foldTailByMasking() && IndUpdate == Legal->getPrimaryInduction())
- continue;
-
- if (llvm::all_of(IndUpdate->users(), [&](User *U) -> bool {
- return U == Ind || DeadInstructions.count(cast<Instruction>(U));
- }))
- DeadInstructions.insert(IndUpdate);
- }
-}
-
Value *InnerLoopUnroller::getBroadcastInstrs(Value *V) { return V; }
//===--------------------------------------------------------------------===//
@@ -8577,19 +8532,11 @@ void LoopVectorizationPlanner::buildVPlansWithVPRecipes(ElementCount MinVF,
ElementCount MaxVF) {
assert(OrigLoop->isInnermost() && "Inner loop expected.");
- // Collect instructions from the original loop that will become trivially dead
- // in the vectorized loop. We don't need to vectorize these instructions. For
- // example, original induction update instructions can become dead because we
- // separately emit induction "steps" when generating code for the new loop.
- // Similarly, we create a new latch condition when setting up the structure
- // of the new loop, so the old one can become dead.
- SmallPtrSet<Instruction *, 4> DeadInstructions;
- collectTriviallyDeadInstructions(DeadInstructions);
-
// Add assume instructions we need to drop to DeadInstructions, to prevent
// them from being added to the VPlan.
// TODO: We only need to drop assumes in blocks that get flattend. If the
// control flow is preserved, we should keep them.
+ SmallPtrSet<Instruction *, 4> DeadInstructions;
auto &ConditionalAssumes = Legal->getConditionalAssumes();
DeadInstructions.insert(ConditionalAssumes.begin(), ConditionalAssumes.end());
diff --git a/llvm/test/Transforms/LoopVectorize/X86/consecutive-ptr-uniforms.ll b/llvm/test/Transforms/LoopVectorize/X86/consecutive-ptr-uniforms.ll
index 53a95d9a5ed93..6088fbe6a3c43 100644
--- a/llvm/test/Transforms/LoopVectorize/X86/consecutive-ptr-uniforms.ll
+++ b/llvm/test/Transforms/LoopVectorize/X86/consecutive-ptr-uniforms.ll
@@ -98,10 +98,9 @@ attributes #0 = { "target-cpu"="knl" }
; FORCE-NEXT: store i32 [[TMP0]], i32* @b, align 1
; FORCE-NEXT: [[TMP6:%.*]] = getelementptr inbounds [3 x i32], [3 x i32]* @a, i32 0, i32 [[TMP0]]
; FORCE-NEXT: [[TMP7:%.*]] = load i32, i32* [[TMP6]], align 1
-; FORCE-NEXT: [[TMP8:%.*]] = insertelement <2 x i32> poison, i32 [[TMP7]], i32 0
; FORCE-NEXT: br label [[PRED_LOAD_CONTINUE]]
; FORCE: pred.load.continue:
-; FORCE-NEXT: [[TMP9:%.*]] = phi <2 x i32> [ poison, [[VECTOR_BODY]] ], [ [[TMP8]], [[PRED_LOAD_IF]] ]
+; FORCE-NEXT: [[TMP9:%.*]] = phi i32 [ poison, [[VECTOR_BODY]] ], [ [[TMP7]], [[PRED_LOAD_IF]] ]
; FORCE-NEXT: [[TMP10:%.*]] = extractelement <2 x i1> [[TMP2]], i32 1
; FORCE-NEXT: br i1 [[TMP10]], label [[PRED_LOAD_IF3:%.*]], label [[PRED_LOAD_CONTINUE4]]
; FORCE: pred.load.if1:
@@ -109,10 +108,9 @@ attributes #0 = { "target-cpu"="knl" }
; FORCE-NEXT: store i32 [[TMP1]], i32* @b, align 1
; FORCE-NEXT: [[TMP11:%.*]] = getelementptr inbounds [3 x i32], [3 x i32]* @a, i32 0, i32 [[TMP1]]
; FORCE-NEXT: [[TMP12:%.*]] = load i32, i32* [[TMP11]], align 1
-; FORCE-NEXT: [[TMP13:%.*]] = insertelement <2 x i32> [[TMP9]], i32 [[TMP12]], i32 1
; FORCE-NEXT: br label [[PRED_LOAD_CONTINUE4]]
; FORCE: pred.load.continue2:
-; FORCE-NEXT: [[TMP14:%.*]] = phi <2 x i32> [ [[TMP9]], [[PRED_LOAD_CONTINUE]] ], [ [[TMP13]], [[PRED_LOAD_IF3]] ]
+; FORCE-NEXT: [[TMP13:%.*]] = phi i32 [ poison, %pred.load.continue ], [ [[TMP12]], %pred.load.if1 ]
; FORCE-NEXT: [[INDEX_NEXT]] = add i32 [[INDEX]], 2
; FORCE-NEXT: [[VEC_IND_NEXT]] = add <2 x i32> [[VEC_IND]], <i32 2, i32 2>
; FORCE-NEXT: [[TMP15:%.*]] = icmp eq i32 [[INDEX_NEXT]], 4
diff --git a/llvm/test/Transforms/LoopVectorize/pointer-induction.ll b/llvm/test/Transforms/LoopVectorize/pointer-induction.ll
index f10ac3f28da80..78596882891a6 100644
--- a/llvm/test/Transforms/LoopVectorize/pointer-induction.ll
+++ b/llvm/test/Transforms/LoopVectorize/pointer-induction.ll
@@ -36,8 +36,7 @@ define void @a(i8* readnone %b) {
; CHECK-NEXT: [[TMP10:%.*]] = extractelement <4 x i1> [[TMP9]], i32 0
; CHECK-NEXT: br i1 [[TMP10]], label [[PRED_STORE_IF:%.*]], label [[PRED_STORE_CONTINUE:%.*]]
; CHECK: pred.store.if:
-; CHECK-NEXT: [[TMP11:%.*]] = getelementptr inbounds i8, i8* [[NEXT_GEP]], i64 -1
-; CHECK-NEXT: store i8 95, i8* [[TMP11]], align 1
+; CHECK-NEXT: store i8 95, i8* [[TMP4]], align 1
; CHECK-NEXT: br label [[PRED_STORE_CONTINUE]]
; CHECK: pred.store.continue:
; CHECK-NEXT: [[TMP12:%.*]] = extractelement <4 x i1> [[TMP9]], i32 1
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