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author | Florian Hahn <flo@fhahn.com> | 2024-06-20 20:44:16 +0100 |
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committer | Florian Hahn <flo@fhahn.com> | 2024-06-20 20:44:17 +0100 |
commit | eea150c84053035163f307b46549a2997a343ce9 (patch) | |
tree | f8c5118164c7441b779bca14cc049b9751bd2c27 | |
parent | dfe55a11cb2cdd0180be2d00eebcbcfc9f52fbec (diff) | |
download | llvm-eea150c84053035163f307b46549a2997a343ce9.zip llvm-eea150c84053035163f307b46549a2997a343ce9.tar.gz llvm-eea150c84053035163f307b46549a2997a343ce9.tar.bz2 |
[VPlan] Include IV phi and backedge cost in VPlan cost computation.
In WebAssembly, costs != 0 are assigned to be backedge and induction
phis, so make sure we include those costs in the VPlan-based cost model.
This fixes a downstream crash with WebAssembly after 242cc200ccb
(https://github.com/llvm/llvm-project/pull/92555)
4 files changed, 99 insertions, 22 deletions
diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp index d4a2399..63e7c55 100644 --- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp +++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp @@ -7325,38 +7325,31 @@ InstructionCost LoopVectorizationPlanner::cost(VPlan &Plan, // cost model. Note that we do this as pre-processing; the VPlan may not have // any recipes associated with the original induction increment instruction // and may replace truncates with VPWidenIntOrFpInductionRecipe. We precompute - // the cost of both induction increment instructions that are represented by - // recipes and those that are not, to avoid distinguishing between them here, - // and skip all recipes that represent induction increments (the former case) - // later on, if they exist, to avoid counting them twice. Similarly we - // pre-compute the cost of any optimized truncates. + // the cost of induction phis and increments (both that are represented by + // recipes and those that are not), to avoid distinguishing between them here, + // and skip all recipes that represent induction phis and increments (the + // former case) later on, if they exist, to avoid counting them twice. + // Similarly we pre-compute the cost of any optimized truncates. // TODO: Switch to more accurate costing based on VPlan. for (const auto &[IV, IndDesc] : Legal->getInductionVars()) { Instruction *IVInc = cast<Instruction>( IV->getIncomingValueForBlock(OrigLoop->getLoopLatch())); - if (CostCtx.SkipCostComputation.insert(IVInc).second) { - InstructionCost InductionCost = CostCtx.getLegacyCost(IVInc, VF); - LLVM_DEBUG({ - dbgs() << "Cost of " << InductionCost << " for VF " << VF - << ":\n induction increment " << *IVInc << "\n"; - IVInc->dump(); - }); - Cost += InductionCost; - } + SmallVector<Instruction *> IVInsts = {IV, IVInc}; for (User *U : IV->users()) { auto *CI = cast<Instruction>(U); if (!CostCtx.CM.isOptimizableIVTruncate(CI, VF)) continue; - assert(!CostCtx.SkipCostComputation.contains(CI) && - "Same cast for multiple inductions?"); - CostCtx.SkipCostComputation.insert(CI); - InstructionCost CastCost = CostCtx.getLegacyCost(CI, VF); + IVInsts.push_back(CI); + } + for (Instruction *IVInst : IVInsts) { + if (!CostCtx.SkipCostComputation.insert(IVInst).second) + continue; + InstructionCost InductionCost = CostCtx.getLegacyCost(IVInst, VF); LLVM_DEBUG({ - dbgs() << "Cost of " << CastCost << " for VF " << VF - << ":\n induction cast " << *CI << "\n"; - CI->dump(); + dbgs() << "Cost of " << InductionCost << " for VF " << VF + << ": induction instruction " << *IVInst << "\n"; }); - Cost += CastCost; + Cost += InductionCost; } } diff --git a/llvm/lib/Transforms/Vectorize/VPlan.cpp b/llvm/lib/Transforms/Vectorize/VPlan.cpp index 3ad1ae3..fe6de48 100644 --- a/llvm/lib/Transforms/Vectorize/VPlan.cpp +++ b/llvm/lib/Transforms/Vectorize/VPlan.cpp @@ -764,6 +764,11 @@ InstructionCost VPRegionBlock::cost(ElementCount VF, VPCostContext &Ctx) { InstructionCost Cost = 0; for (VPBlockBase *Block : vp_depth_first_shallow(getEntry())) Cost += Block->cost(VF, Ctx); + InstructionCost BackedgeCost = + Ctx.TTI.getCFInstrCost(Instruction::Br, TTI::TCK_RecipThroughput); + LLVM_DEBUG(dbgs() << "Cost of " << BackedgeCost << " for VF " << VF + << ": vector loop backedge\n"); + Cost += BackedgeCost; return Cost; } diff --git a/llvm/test/Transforms/LoopVectorize/WebAssembly/induction-branch-cost.ll b/llvm/test/Transforms/LoopVectorize/WebAssembly/induction-branch-cost.ll new file mode 100644 index 0000000..785af155 --- /dev/null +++ b/llvm/test/Transforms/LoopVectorize/WebAssembly/induction-branch-cost.ll @@ -0,0 +1,77 @@ +; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5 +; RUN: opt -p loop-vectorize -S %s | FileCheck %s + +target datalayout = "e-m:e-p:32:32-p10:8:8-p20:8:8-i64:64-f128:64-n32:64-S128-ni:1:10:20" +target triple = "wasm32-unknown-emscripten" + +define void @induction_phi_and_branch_cost(ptr %end, ptr %start.1, ptr %start.2) #0 { +; CHECK-LABEL: define void @induction_phi_and_branch_cost( +; CHECK-SAME: ptr [[END:%.*]], ptr [[START_1:%.*]], ptr [[START_2:%.*]]) #[[ATTR0:[0-9]+]] { +; CHECK-NEXT: [[ENTRY:.*]]: +; CHECK-NEXT: [[END2:%.*]] = ptrtoint ptr [[END]] to i32 +; CHECK-NEXT: [[START_11:%.*]] = ptrtoint ptr [[START_1]] to i32 +; CHECK-NEXT: [[TMP0:%.*]] = sub i32 [[START_11]], [[END2]] +; CHECK-NEXT: [[TMP1:%.*]] = lshr i32 [[TMP0]], 2 +; CHECK-NEXT: [[TMP2:%.*]] = add nuw nsw i32 [[TMP1]], 1 +; CHECK-NEXT: [[MIN_ITERS_CHECK:%.*]] = icmp ult i32 [[TMP2]], 4 +; CHECK-NEXT: br i1 [[MIN_ITERS_CHECK]], label %[[SCALAR_PH:.*]], label %[[VECTOR_PH:.*]] +; CHECK: [[VECTOR_PH]]: +; CHECK-NEXT: [[N_MOD_VF:%.*]] = urem i32 [[TMP2]], 4 +; CHECK-NEXT: [[N_VEC:%.*]] = sub i32 [[TMP2]], [[N_MOD_VF]] +; CHECK-NEXT: [[TMP3:%.*]] = mul i32 [[N_VEC]], -4 +; CHECK-NEXT: [[IND_END:%.*]] = getelementptr i8, ptr [[START_1]], i32 [[TMP3]] +; CHECK-NEXT: [[TMP4:%.*]] = mul i32 [[N_VEC]], -4 +; CHECK-NEXT: [[IND_END3:%.*]] = getelementptr i8, ptr [[START_2]], i32 [[TMP4]] +; CHECK-NEXT: br label %[[VECTOR_BODY:.*]] +; CHECK: [[VECTOR_BODY]]: +; CHECK-NEXT: [[INDEX:%.*]] = phi i32 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[VECTOR_BODY]] ] +; CHECK-NEXT: [[OFFSET_IDX:%.*]] = mul i32 [[INDEX]], -4 +; CHECK-NEXT: [[TMP5:%.*]] = add i32 [[OFFSET_IDX]], 0 +; CHECK-NEXT: [[NEXT_GEP:%.*]] = getelementptr i8, ptr [[START_2]], i32 [[TMP5]] +; CHECK-NEXT: [[TMP6:%.*]] = getelementptr i32, ptr [[NEXT_GEP]], i32 0 +; CHECK-NEXT: [[TMP7:%.*]] = getelementptr i32, ptr [[TMP6]], i32 -3 +; CHECK-NEXT: store <4 x i32> zeroinitializer, ptr [[TMP7]], align 4 +; CHECK-NEXT: [[INDEX_NEXT]] = add nuw i32 [[INDEX]], 4 +; CHECK-NEXT: [[TMP8:%.*]] = icmp eq i32 [[INDEX_NEXT]], [[N_VEC]] +; CHECK-NEXT: br i1 [[TMP8]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]] +; CHECK: [[MIDDLE_BLOCK]]: +; CHECK-NEXT: [[CMP_N:%.*]] = icmp eq i32 [[TMP2]], [[N_VEC]] +; CHECK-NEXT: br i1 [[CMP_N]], label %[[EXIT:.*]], label %[[SCALAR_PH]] +; CHECK: [[SCALAR_PH]]: +; CHECK-NEXT: [[BC_RESUME_VAL:%.*]] = phi ptr [ [[IND_END]], %[[MIDDLE_BLOCK]] ], [ [[START_1]], %[[ENTRY]] ] +; CHECK-NEXT: [[BC_RESUME_VAL4:%.*]] = phi ptr [ [[IND_END3]], %[[MIDDLE_BLOCK]] ], [ [[START_2]], %[[ENTRY]] ] +; CHECK-NEXT: br label %[[LOOP:.*]] +; CHECK: [[LOOP]]: +; CHECK-NEXT: [[PTR_IV:%.*]] = phi ptr [ [[BC_RESUME_VAL]], %[[SCALAR_PH]] ], [ [[PTR_IV_NEXT:%.*]], %[[LOOP]] ] +; CHECK-NEXT: [[PTR_IV_2:%.*]] = phi ptr [ [[BC_RESUME_VAL4]], %[[SCALAR_PH]] ], [ [[PTR_IV_2_NEXT:%.*]], %[[LOOP]] ] +; CHECK-NEXT: [[PTR_IV_NEXT]] = getelementptr nusw i8, ptr [[PTR_IV]], i32 -4 +; CHECK-NEXT: [[PTR_IV_2_NEXT]] = getelementptr i8, ptr [[PTR_IV_2]], i32 -4 +; CHECK-NEXT: store i32 0, ptr [[PTR_IV_2]], align 4 +; CHECK-NEXT: [[EC:%.*]] = icmp eq ptr [[PTR_IV]], [[END]] +; CHECK-NEXT: br i1 [[EC]], label %[[EXIT]], label %[[LOOP]], !llvm.loop [[LOOP3:![0-9]+]] +; CHECK: [[EXIT]]: +; CHECK-NEXT: ret void +; +entry: + br label %loop + +loop: + %ptr.iv = phi ptr [ %start.1, %entry ], [ %ptr.iv.next, %loop ] + %ptr.iv.2 = phi ptr [ %start.2, %entry ], [ %ptr.iv.2.next, %loop ] + %ptr.iv.next = getelementptr nusw i8, ptr %ptr.iv, i32 -4 + %ptr.iv.2.next = getelementptr i8, ptr %ptr.iv.2, i32 -4 + store i32 0, ptr %ptr.iv.2, align 4 + %ec = icmp eq ptr %ptr.iv, %end + br i1 %ec, label %exit, label %loop + +exit: + ret void +} + +attributes #0 = { "target-features"="+simd128" } +;. +; CHECK: [[LOOP0]] = distinct !{[[LOOP0]], [[META1:![0-9]+]], [[META2:![0-9]+]]} +; CHECK: [[META1]] = !{!"llvm.loop.isvectorized", i32 1} +; CHECK: [[META2]] = !{!"llvm.loop.unroll.runtime.disable"} +; CHECK: [[LOOP3]] = distinct !{[[LOOP3]], [[META2]], [[META1]]} +;. diff --git a/llvm/test/Transforms/LoopVectorize/WebAssembly/lit.local.cfg b/llvm/test/Transforms/LoopVectorize/WebAssembly/lit.local.cfg new file mode 100644 index 0000000..d5f39ab --- /dev/null +++ b/llvm/test/Transforms/LoopVectorize/WebAssembly/lit.local.cfg @@ -0,0 +1,2 @@ +if not "WebAssembly" in config.root.targets: + config.unsupported = True |