[llvm] [LoopVectorize] Add the cost of VPInstruction::AnyOf to vplan (PR #125058)
David Sherwood via llvm-commits
llvm-commits at lists.llvm.org
Wed Feb 5 06:54:42 PST 2025
https://github.com/david-arm updated https://github.com/llvm/llvm-project/pull/125058
>From 57998f874af2d8c8cc51bc6fe563034733bcf5e9 Mon Sep 17 00:00:00 2001
From: David Sherwood <david.sherwood at arm.com>
Date: Thu, 30 Jan 2025 13:37:34 +0000
Subject: [PATCH 1/4] [LoopVectorize] Add the cost of VPInstruction::AnyOf to
vplan
This patch adds an initial implementation of
VPInstruction::computeCost with support for only one
instruction so far - VPInstruction::AnyOf. This is only
used when vectorising loops with uncountable early exits.
---
.../Transforms/Vectorize/LoopVectorize.cpp | 1 +
llvm/lib/Transforms/Vectorize/VPlan.h | 5 +-
.../lib/Transforms/Vectorize/VPlanRecipes.cpp | 14 ++++++
.../AArch64/simple_early_exit.ll | 48 ++++++++++++-------
4 files changed, 48 insertions(+), 20 deletions(-)
diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index 5208343de4deb77..093e51371ae8ad4 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -7553,6 +7553,7 @@ VectorizationFactor LoopVectorizationPlanner::computeBestVF() {
CM.CostKind);
precomputeCosts(BestPlan, BestFactor.Width, CostCtx);
assert((BestFactor.Width == LegacyVF.Width ||
+ Legal->hasUncountableEarlyExit() ||
planContainsAdditionalSimplifications(getPlanFor(BestFactor.Width),
CostCtx, OrigLoop) ||
planContainsAdditionalSimplifications(getPlanFor(LegacyVF.Width),
diff --git a/llvm/lib/Transforms/Vectorize/VPlan.h b/llvm/lib/Transforms/Vectorize/VPlan.h
index fac207287e0bcc7..5b9dcf68a62bec5 100644
--- a/llvm/lib/Transforms/Vectorize/VPlan.h
+++ b/llvm/lib/Transforms/Vectorize/VPlan.h
@@ -972,10 +972,7 @@ class VPInstruction : public VPRecipeWithIRFlags,
/// Return the cost of this VPInstruction.
InstructionCost computeCost(ElementCount VF,
- VPCostContext &Ctx) const override {
- // TODO: Compute accurate cost after retiring the legacy cost model.
- return 0;
- }
+ VPCostContext &Ctx) const override;
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
/// Print the VPInstruction to \p O.
diff --git a/llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp b/llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp
index c84a93d7398f73b..ed937c4c7732a11 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp
+++ b/llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp
@@ -711,6 +711,20 @@ Value *VPInstruction::generate(VPTransformState &State) {
}
}
+InstructionCost VPInstruction::computeCost(ElementCount VF,
+ VPCostContext &Ctx) const {
+ switch (getOpcode()) {
+ case VPInstruction::AnyOf: {
+ auto *VecI1Ty = VectorType::get(Type::getInt1Ty(Ctx.LLVMCtx), VF);
+ return Ctx.TTI.getArithmeticReductionCost(Instruction::Or, VecI1Ty,
+ std::nullopt, Ctx.CostKind);
+ }
+ default:
+ // TODO: Fill out other opcodes!
+ return 0;
+ }
+}
+
bool VPInstruction::isVectorToScalar() const {
return getOpcode() == VPInstruction::ExtractFromEnd ||
getOpcode() == VPInstruction::ExtractFirstActive ||
diff --git a/llvm/test/Transforms/LoopVectorize/AArch64/simple_early_exit.ll b/llvm/test/Transforms/LoopVectorize/AArch64/simple_early_exit.ll
index 9d21ea0ab6de39c..b439b64e829e5f1 100644
--- a/llvm/test/Transforms/LoopVectorize/AArch64/simple_early_exit.ll
+++ b/llvm/test/Transforms/LoopVectorize/AArch64/simple_early_exit.ll
@@ -272,36 +272,52 @@ define i64 @loop_contains_safe_div() #1 {
; CHECK-NEXT: [[P2:%.*]] = alloca [1024 x i8], align 4
; CHECK-NEXT: call void @init_mem(ptr [[P1]], i64 1024)
; CHECK-NEXT: call void @init_mem(ptr [[P2]], i64 1024)
+; CHECK-NEXT: [[TMP11:%.*]] = call i64 @llvm.vscale.i64()
+; CHECK-NEXT: [[TMP12:%.*]] = mul i64 [[TMP11]], 4
; CHECK-NEXT: br i1 false, label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]]
; CHECK: vector.ph:
+; CHECK-NEXT: [[TMP10:%.*]] = call i64 @llvm.vscale.i64()
+; CHECK-NEXT: [[TMP3:%.*]] = mul i64 [[TMP10]], 4
+; CHECK-NEXT: [[N_MOD_VF:%.*]] = urem i64 64, [[TMP3]]
+; CHECK-NEXT: [[INDEX1:%.*]] = sub i64 64, [[N_MOD_VF]]
+; CHECK-NEXT: [[TMP4:%.*]] = call i64 @llvm.vscale.i64()
+; CHECK-NEXT: [[TMP5:%.*]] = mul i64 [[TMP4]], 4
+; CHECK-NEXT: [[OFFSET_IDX:%.*]] = add i64 3, [[INDEX1]]
+; CHECK-NEXT: [[TMP16:%.*]] = call <vscale x 4 x i64> @llvm.stepvector.nxv4i64()
+; CHECK-NEXT: [[TMP17:%.*]] = mul <vscale x 4 x i64> [[TMP16]], splat (i64 1)
+; CHECK-NEXT: [[INDUCTION:%.*]] = add <vscale x 4 x i64> splat (i64 3), [[TMP17]]
+; CHECK-NEXT: [[TMP9:%.*]] = mul i64 1, [[TMP5]]
+; CHECK-NEXT: [[DOTSPLATINSERT:%.*]] = insertelement <vscale x 4 x i64> poison, i64 [[TMP9]], i64 0
+; CHECK-NEXT: [[DOTSPLAT:%.*]] = shufflevector <vscale x 4 x i64> [[DOTSPLATINSERT]], <vscale x 4 x i64> poison, <vscale x 4 x i32> zeroinitializer
; CHECK-NEXT: br label [[VECTOR_BODY:%.*]]
; CHECK: vector.body:
-; CHECK-NEXT: [[INDEX1:%.*]] = phi i64 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT2:%.*]], [[VECTOR_BODY]] ]
-; CHECK-NEXT: [[VEC_IND:%.*]] = phi <2 x i64> [ <i64 3, i64 4>, [[VECTOR_PH]] ], [ [[VEC_IND_NEXT:%.*]], [[VECTOR_BODY]] ]
-; CHECK-NEXT: [[OFFSET_IDX:%.*]] = add i64 3, [[INDEX1]]
-; CHECK-NEXT: [[TMP0:%.*]] = add i64 [[OFFSET_IDX]], 0
+; CHECK-NEXT: [[INDEX2:%.*]] = phi i64 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT2:%.*]], [[VECTOR_BODY]] ]
+; CHECK-NEXT: [[VEC_IND:%.*]] = phi <vscale x 4 x i64> [ [[INDUCTION]], [[VECTOR_PH]] ], [ [[VEC_IND_NEXT:%.*]], [[VECTOR_BODY]] ]
+; CHECK-NEXT: [[OFFSET_IDX1:%.*]] = add i64 3, [[INDEX2]]
+; CHECK-NEXT: [[TMP0:%.*]] = add i64 [[OFFSET_IDX1]], 0
; CHECK-NEXT: [[TMP1:%.*]] = getelementptr inbounds i32, ptr [[P1]], i64 [[TMP0]]
; CHECK-NEXT: [[TMP2:%.*]] = getelementptr inbounds i32, ptr [[TMP1]], i32 0
-; CHECK-NEXT: [[WIDE_LOAD:%.*]] = load <2 x i32>, ptr [[TMP2]], align 1
-; CHECK-NEXT: [[TMP3:%.*]] = udiv <2 x i32> [[WIDE_LOAD]], splat (i32 20000)
-; CHECK-NEXT: [[TMP4:%.*]] = icmp eq <2 x i32> [[TMP3]], splat (i32 1)
-; CHECK-NEXT: [[INDEX_NEXT2]] = add nuw i64 [[INDEX1]], 2
-; CHECK-NEXT: [[TMP5:%.*]] = xor <2 x i1> [[TMP4]], splat (i1 true)
-; CHECK-NEXT: [[TMP6:%.*]] = call i1 @llvm.vector.reduce.or.v2i1(<2 x i1> [[TMP5]])
-; CHECK-NEXT: [[TMP7:%.*]] = icmp eq i64 [[INDEX_NEXT2]], 64
-; CHECK-NEXT: [[VEC_IND_NEXT]] = add <2 x i64> [[VEC_IND]], splat (i64 2)
+; CHECK-NEXT: [[WIDE_LOAD:%.*]] = load <vscale x 4 x i32>, ptr [[TMP2]], align 1
+; CHECK-NEXT: [[TMP13:%.*]] = udiv <vscale x 4 x i32> [[WIDE_LOAD]], splat (i32 20000)
+; CHECK-NEXT: [[TMP14:%.*]] = icmp eq <vscale x 4 x i32> [[TMP13]], splat (i32 1)
+; CHECK-NEXT: [[INDEX_NEXT2]] = add nuw i64 [[INDEX2]], [[TMP5]]
+; CHECK-NEXT: [[TMP15:%.*]] = xor <vscale x 4 x i1> [[TMP14]], splat (i1 true)
+; CHECK-NEXT: [[TMP6:%.*]] = call i1 @llvm.vector.reduce.or.nxv4i1(<vscale x 4 x i1> [[TMP15]])
+; CHECK-NEXT: [[TMP7:%.*]] = icmp eq i64 [[INDEX_NEXT2]], [[INDEX1]]
+; CHECK-NEXT: [[VEC_IND_NEXT]] = add <vscale x 4 x i64> [[VEC_IND]], [[DOTSPLAT]]
; CHECK-NEXT: [[TMP8:%.*]] = or i1 [[TMP6]], [[TMP7]]
; CHECK-NEXT: br i1 [[TMP8]], label [[MIDDLE_SPLIT:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP8:![0-9]+]]
; CHECK: middle.split:
; CHECK-NEXT: br i1 [[TMP6]], label [[VECTOR_EARLY_EXIT:%.*]], label [[MIDDLE_BLOCK:%.*]]
; CHECK: vector.early.exit:
-; CHECK-NEXT: [[FIRST_ACTIVE_LANE:%.*]] = call i64 @llvm.experimental.cttz.elts.i64.v2i1(<2 x i1> [[TMP5]], i1 true)
-; CHECK-NEXT: [[EARLY_EXIT_VALUE:%.*]] = extractelement <2 x i64> [[VEC_IND]], i64 [[FIRST_ACTIVE_LANE]]
+; CHECK-NEXT: [[FIRST_ACTIVE_LANE:%.*]] = call i64 @llvm.experimental.cttz.elts.i64.nxv4i1(<vscale x 4 x i1> [[TMP15]], i1 true)
+; CHECK-NEXT: [[EARLY_EXIT_VALUE:%.*]] = extractelement <vscale x 4 x i64> [[VEC_IND]], i64 [[FIRST_ACTIVE_LANE]]
; CHECK-NEXT: br label [[LOOP_END:%.*]]
; CHECK: middle.block:
-; CHECK-NEXT: br i1 true, label [[LOOP_END]], label [[SCALAR_PH]]
+; CHECK-NEXT: [[CMP_N:%.*]] = icmp eq i64 64, [[INDEX1]]
+; CHECK-NEXT: br i1 [[CMP_N]], label [[LOOP_END]], label [[SCALAR_PH]]
; CHECK: scalar.ph:
-; CHECK-NEXT: [[BC_RESUME_VAL:%.*]] = phi i64 [ 67, [[MIDDLE_BLOCK]] ], [ 3, [[ENTRY:%.*]] ]
+; CHECK-NEXT: [[BC_RESUME_VAL:%.*]] = phi i64 [ [[OFFSET_IDX]], [[MIDDLE_BLOCK]] ], [ 3, [[ENTRY:%.*]] ]
; CHECK-NEXT: br label [[LOOP:%.*]]
; CHECK: loop:
; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ [[INDEX_NEXT:%.*]], [[LOOP_INC:%.*]] ], [ [[BC_RESUME_VAL]], [[SCALAR_PH]] ]
>From 7dae35dcd60886e0df4f88e54a003ff798fe0721 Mon Sep 17 00:00:00 2001
From: David Sherwood <david.sherwood at arm.com>
Date: Mon, 3 Feb 2025 13:06:08 +0000
Subject: [PATCH 2/4] Address review comments
---
llvm/lib/Transforms/Vectorize/LoopVectorize.cpp | 2 +-
llvm/lib/Transforms/Vectorize/VPlan.h | 9 +++++++++
llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp | 6 +++---
3 files changed, 13 insertions(+), 4 deletions(-)
diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index 093e51371ae8ad4..21c711af2bf1014 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -7553,7 +7553,7 @@ VectorizationFactor LoopVectorizationPlanner::computeBestVF() {
CM.CostKind);
precomputeCosts(BestPlan, BestFactor.Width, CostCtx);
assert((BestFactor.Width == LegacyVF.Width ||
- Legal->hasUncountableEarlyExit() ||
+ BestPlan.hasRegionWithEarlyExit() ||
planContainsAdditionalSimplifications(getPlanFor(BestFactor.Width),
CostCtx, OrigLoop) ||
planContainsAdditionalSimplifications(getPlanFor(LegacyVF.Width),
diff --git a/llvm/lib/Transforms/Vectorize/VPlan.h b/llvm/lib/Transforms/Vectorize/VPlan.h
index 5b9dcf68a62bec5..a608dcd32bcedd0 100644
--- a/llvm/lib/Transforms/Vectorize/VPlan.h
+++ b/llvm/lib/Transforms/Vectorize/VPlan.h
@@ -3623,6 +3623,15 @@ class VPlan {
/// of VPBlockShallowTraversalWrapper.
auto getExitBlocks();
+ /// Returns true if the plan has a region containing an early exit, i.e. the
+ /// loop exits due to a condition other than testing the canonical induction
+ /// variable against the trip count.
+ bool hasRegionWithEarlyExit() {
+ auto *VectorRegion = getVectorLoopRegion();
+ return VectorRegion &&
+ VectorRegion->getSingleSuccessor() != getMiddleBlock();
+ }
+
/// Returns true if \p VPBB is an exit block.
bool isExitBlock(VPBlockBase *VPBB);
diff --git a/llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp b/llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp
index ed937c4c7732a11..b734ddfce788e21 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp
+++ b/llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp
@@ -715,9 +715,9 @@ InstructionCost VPInstruction::computeCost(ElementCount VF,
VPCostContext &Ctx) const {
switch (getOpcode()) {
case VPInstruction::AnyOf: {
- auto *VecI1Ty = VectorType::get(Type::getInt1Ty(Ctx.LLVMCtx), VF);
- return Ctx.TTI.getArithmeticReductionCost(Instruction::Or, VecI1Ty,
- std::nullopt, Ctx.CostKind);
+ auto *VecTy = toVectorTy(Ctx.Types.inferScalarType(this), VF);
+ return Ctx.TTI.getArithmeticReductionCost(
+ Instruction::Or, cast<VectorType>(VecTy), std::nullopt, Ctx.CostKind);
}
default:
// TODO: Fill out other opcodes!
>From 686adb279448c081e70df8a4fea616d427214323 Mon Sep 17 00:00:00 2001
From: David Sherwood <david.sherwood at arm.com>
Date: Tue, 4 Feb 2025 17:01:42 +0000
Subject: [PATCH 3/4] Address review comment
---
llvm/lib/Transforms/Vectorize/LoopVectorize.cpp | 4 +++-
llvm/lib/Transforms/Vectorize/VPlan.h | 9 ---------
2 files changed, 3 insertions(+), 10 deletions(-)
diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index 21c711af2bf1014..e1eae88776af9c8 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -7553,7 +7553,9 @@ VectorizationFactor LoopVectorizationPlanner::computeBestVF() {
CM.CostKind);
precomputeCosts(BestPlan, BestFactor.Width, CostCtx);
assert((BestFactor.Width == LegacyVF.Width ||
- BestPlan.hasRegionWithEarlyExit() ||
+ (BestPlan.getVectorLoopRegion() &&
+ BestPlan.getVectorLoopRegion()->getSingleSuccessor() !=
+ BestPlan.getMiddleBlock()) ||
planContainsAdditionalSimplifications(getPlanFor(BestFactor.Width),
CostCtx, OrigLoop) ||
planContainsAdditionalSimplifications(getPlanFor(LegacyVF.Width),
diff --git a/llvm/lib/Transforms/Vectorize/VPlan.h b/llvm/lib/Transforms/Vectorize/VPlan.h
index a608dcd32bcedd0..5b9dcf68a62bec5 100644
--- a/llvm/lib/Transforms/Vectorize/VPlan.h
+++ b/llvm/lib/Transforms/Vectorize/VPlan.h
@@ -3623,15 +3623,6 @@ class VPlan {
/// of VPBlockShallowTraversalWrapper.
auto getExitBlocks();
- /// Returns true if the plan has a region containing an early exit, i.e. the
- /// loop exits due to a condition other than testing the canonical induction
- /// variable against the trip count.
- bool hasRegionWithEarlyExit() {
- auto *VectorRegion = getVectorLoopRegion();
- return VectorRegion &&
- VectorRegion->getSingleSuccessor() != getMiddleBlock();
- }
-
/// Returns true if \p VPBB is an exit block.
bool isExitBlock(VPBlockBase *VPBB);
>From 4944d54e1f82087891f287b06b05eec0a58cd69e Mon Sep 17 00:00:00 2001
From: David Sherwood <david.sherwood at arm.com>
Date: Wed, 5 Feb 2025 09:27:04 +0000
Subject: [PATCH 4/4] Address review comment
---
llvm/lib/Transforms/Vectorize/LoopVectorize.cpp | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index e1eae88776af9c8..02b79f2053d59d6 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -7552,10 +7552,14 @@ VectorizationFactor LoopVectorizationPlanner::computeBestVF() {
VPCostContext CostCtx(CM.TTI, *CM.TLI, Legal->getWidestInductionType(), CM,
CM.CostKind);
precomputeCosts(BestPlan, BestFactor.Width, CostCtx);
- assert((BestFactor.Width == LegacyVF.Width ||
- (BestPlan.getVectorLoopRegion() &&
- BestPlan.getVectorLoopRegion()->getSingleSuccessor() !=
- BestPlan.getMiddleBlock()) ||
+ // Set PlanForEarlyExitLoop to true if the BestPlan has been built from a
+ // loop with an uncountable early exit. The legacy cost model doesn't
+ // properly model costs for such loops.
+ bool PlanForEarlyExitLoop =
+ BestPlan.getVectorLoopRegion() &&
+ BestPlan.getVectorLoopRegion()->getSingleSuccessor() !=
+ BestPlan.getMiddleBlock();
+ assert((BestFactor.Width == LegacyVF.Width || PlanForEarlyExitLoop ||
planContainsAdditionalSimplifications(getPlanFor(BestFactor.Width),
CostCtx, OrigLoop) ||
planContainsAdditionalSimplifications(getPlanFor(LegacyVF.Width),
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