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Reland "[LV] Print remark when loop cannot be vectorized due to invalid costs."

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The original patch was:
  https://reviews.llvm.org/D105806

There were some issues with undeterministic behaviour of the sorting
function, which led to scalable-call.ll passing and/or failing. This
patch fixes the issue by numbering all instructions in the array first,
and using that number as the order, which should provide a consistent
ordering.

This reverts commit a607f64118240f70bf1b14ec121b65f49d63800d.
This commit is contained in:
Sander de Smalen 2021-07-15 15:32:31 +01:00
parent a6ca88e908
commit 239d01fa88
2 changed files with 144 additions and 11 deletions
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79
llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
View File

@ -1676,8 +1676,13 @@ private:
/// Returns the expected execution cost. The unit of the cost does
/// not matter because we use the 'cost' units to compare different
/// vector widths. The cost that is returned is *not* normalized by
/// the factor width.
VectorizationCostTy expectedCost(ElementCount VF);
/// the factor width. If \p Invalid is not nullptr, this function
/// will add a pair(Instruction*, ElementCount) to \p Invalid for
/// each instruction that has an Invalid cost for the given VF.
using InstructionVFPair = std::pair<Instruction *, ElementCount>;
VectorizationCostTy
expectedCost(ElementCount VF,
SmallVectorImpl<InstructionVFPair> *Invalid = nullptr);
/// Returns the execution time cost of an instruction for a given vector
/// width. Vector width of one means scalar.
@ -6075,12 +6080,13 @@ VectorizationFactor LoopVectorizationCostModel::selectVectorizationFactor(
ChosenFactor.Cost = InstructionCost::getMax();
}
SmallVector<InstructionVFPair> InvalidCosts;
for (const auto &i : VFCandidates) {
// The cost for scalar VF=1 is already calculated, so ignore it.
if (i.isScalar())
continue;
VectorizationCostTy C = expectedCost(i);
VectorizationCostTy C = expectedCost(i, &InvalidCosts);
VectorizationFactor Candidate(i, C.first);
LLVM_DEBUG(
dbgs() << "LV: Vector loop of width " << i << " costs: "
@ -6103,6 +6109,66 @@ VectorizationFactor LoopVectorizationCostModel::selectVectorizationFactor(
ChosenFactor = Candidate;
}
// Emit a report of VFs with invalid costs in the loop.
if (!InvalidCosts.empty()) {
// Group the remarks per instruction, keeping the instruction order from
// InvalidCosts.
std::map<Instruction *, unsigned> Numbering;
unsigned I = 0;
for (auto &Pair : InvalidCosts)
if (!Numbering.count(Pair.first))
Numbering[Pair.first] = I++;
// Sort the list, first on instruction(number) then on VF.
llvm::sort(InvalidCosts,
[&Numbering](InstructionVFPair &A, InstructionVFPair &B) {
if (Numbering[A.first] != Numbering[B.first])
return Numbering[A.first] < Numbering[B.first];
ElementCountComparator ECC;
return ECC(A.second, B.second);
});
// For a list of ordered instruction-vf pairs:
// [(load, vf1), (load, vf2), (store, vf1)]
// Group the instructions together to emit separate remarks for:
// load (vf1, vf2)
// store (vf1)
auto Tail = ArrayRef<InstructionVFPair>(InvalidCosts);
auto Subset = ArrayRef<InstructionVFPair>();
do {
if (Subset.empty())
Subset = Tail.take_front(1);
Instruction *I = Subset.front().first;
// If the next instruction is different, or if there are no other pairs,
// emit a remark for the collated subset. e.g.
// [(load, vf1), (load, vf2))]
// to emit:
// remark: invalid costs for 'load' at VF=(vf, vf2)
if (Subset == Tail || Tail[Subset.size()].first != I) {
std::string OutString;
raw_string_ostream OS(OutString);
assert(!Subset.empty() && "Unexpected empty range");
OS << "Instruction with invalid costs prevented vectorization at VF=(";
for (auto &Pair : Subset)
OS << (Pair.second == Subset.front().second ? "" : ", ")
<< Pair.second;
OS << "):";
if (auto *CI = dyn_cast<CallInst>(I))
OS << " call to " << CI->getCalledFunction()->getName();
else
OS << " " << I->getOpcodeName();
OS.flush();
reportVectorizationInfo(OutString, "InvalidCost", ORE, TheLoop, I);
Tail = Tail.drop_front(Subset.size());
Subset = {};
} else
// Grow the subset by one element
Subset = Tail.take_front(Subset.size() + 1);
} while (!Tail.empty());
}
if (!EnableCondStoresVectorization && NumPredStores) {
reportVectorizationFailure("There are conditional stores.",
"store that is conditionally executed prevents vectorization",
@ -6884,7 +6950,8 @@ int LoopVectorizationCostModel::computePredInstDiscount(
}
LoopVectorizationCostModel::VectorizationCostTy
LoopVectorizationCostModel::expectedCost(ElementCount VF) {
LoopVectorizationCostModel::expectedCost(
ElementCount VF, SmallVectorImpl<InstructionVFPair> *Invalid) {
VectorizationCostTy Cost;
// For each block.
@ -6904,6 +6971,10 @@ LoopVectorizationCostModel::expectedCost(ElementCount VF) {
if (ForceTargetInstructionCost.getNumOccurrences() > 0)
C.first = InstructionCost(ForceTargetInstructionCost);
// Keep a list of instructions with invalid costs.
if (Invalid && !C.first.isValid())
Invalid->emplace_back(&I, VF);
BlockCost.first += C.first;
BlockCost.second |= C.second;
LLVM_DEBUG(dbgs() << "LV: Found an estimated cost of " << C.first

76
llvm/test/Transforms/LoopVectorize/AArch64/scalable-call.ll
View File

@ -1,4 +1,6 @@
; RUN: opt -S -loop-vectorize -force-vector-interleave=1 -instcombine -mattr=+sve -mtriple aarch64-unknown-linux-gnu -scalable-vectorization=on < %s | FileCheck %s
; RUN: opt -S -loop-vectorize -force-vector-interleave=1 -instcombine -mattr=+sve -mtriple aarch64-unknown-linux-gnu -scalable-vectorization=on \
; RUN: -pass-remarks-missed=loop-vectorize < %s 2>%t | FileCheck %s
; RUN: cat %t | FileCheck %s --check-prefix=CHECK-REMARKS
define void @vec_load(i64 %N, double* nocapture %a, double* nocapture readonly %b) {
; CHECK-LABEL: @vec_load
@ -95,6 +97,10 @@ for.end:
ret void
}
; CHECK-REMARKS: UserVF ignored because of invalid costs.
; CHECK-REMARKS-NEXT: t.c:3:10: Instruction with invalid costs prevented vectorization at VF=(vscale x 1): load
; CHECK-REMARKS-NEXT: t.c:3:20: Instruction with invalid costs prevented vectorization at VF=(vscale x 1, vscale x 2): call to llvm.sin.f32
; CHECK-REMARKS-NEXT: t.c:3:30: Instruction with invalid costs prevented vectorization at VF=(vscale x 1): store
define void @vec_sin_no_mapping(float* noalias nocapture %dst, float* noalias nocapture readonly %src, i64 %n) {
; CHECK: @vec_sin_no_mapping
; CHECK: call fast <2 x float> @llvm.sin.v2f32
@ -105,10 +111,10 @@ entry:
for.body: ; preds = %entry, %for.body
%i.07 = phi i64 [ %inc, %for.body ], [ 0, %entry ]
%arrayidx = getelementptr inbounds float, float* %src, i64 %i.07
%0 = load float, float* %arrayidx, align 4
%1 = tail call fast float @llvm.sin.f32(float %0)
%0 = load float, float* %arrayidx, align 4, !dbg !11
%1 = tail call fast float @llvm.sin.f32(float %0), !dbg !12
%arrayidx1 = getelementptr inbounds float, float* %dst, i64 %i.07
store float %1, float* %arrayidx1, align 4
store float %1, float* %arrayidx1, align 4, !dbg !13
%inc = add nuw nsw i64 %i.07, 1
%exitcond.not = icmp eq i64 %inc, %n
br i1 %exitcond.not, label %for.cond.cleanup, label %for.body, !llvm.loop !1
@ -117,6 +123,46 @@ for.cond.cleanup: ; preds = %for.body
ret void
}
; CHECK-REMARKS: UserVF ignored because of invalid costs.
; CHECK-REMARKS-NEXT: t.c:3:10: Instruction with invalid costs prevented vectorization at VF=(vscale x 1): load
; CHECK-REMARKS-NEXT: t.c:3:30: Instruction with invalid costs prevented vectorization at VF=(vscale x 1, vscale x 2): call to llvm.sin.f32
; CHECK-REMARKS-NEXT: t.c:3:20: Instruction with invalid costs prevented vectorization at VF=(vscale x 1, vscale x 2): call to llvm.sin.f32
; CHECK-REMARKS-NEXT: t.c:3:40: Instruction with invalid costs prevented vectorization at VF=(vscale x 1): store
define void @vec_sin_no_mapping_ite(float* noalias nocapture %dst, float* noalias nocapture readonly %src, i64 %n) {
; CHECK: @vec_sin_no_mapping_ite
; CHECK-NOT: <vscale x
; CHECK: ret
entry:
br label %for.body
for.body: ; preds = %entry, %if.end
%i.07 = phi i64 [ %inc, %if.end ], [ 0, %entry ]
%arrayidx = getelementptr inbounds float, float* %src, i64 %i.07
%0 = load float, float* %arrayidx, align 4, !dbg !11
%cmp = fcmp ugt float %0, 0.0000
br i1 %cmp, label %if.then, label %if.else
if.then:
%1 = tail call fast float @llvm.sin.f32(float %0), !dbg !12
br label %if.end
if.else:
%2 = tail call fast float @llvm.sin.f32(float 0.0), !dbg !13
br label %if.end
if.end:
%3 = phi float [%1, %if.then], [%2, %if.else]
%arrayidx1 = getelementptr inbounds float, float* %dst, i64 %i.07
store float %3, float* %arrayidx1, align 4, !dbg !14
%inc = add nuw nsw i64 %i.07, 1
%exitcond.not = icmp eq i64 %inc, %n
br i1 %exitcond.not, label %for.cond.cleanup, label %for.body, !llvm.loop !1
for.cond.cleanup: ; preds = %for.body
ret void
}
; CHECK-REMARKS: UserVF ignored because of invalid costs.
; CHECK-REMARKS-NEXT: t.c:3:10: Instruction with invalid costs prevented vectorization at VF=(vscale x 1): load
; CHECK-REMARKS-NEXT: t.c:3:20: Instruction with invalid costs prevented vectorization at VF=(vscale x 1, vscale x 2): call to llvm.sin.f32
; CHECK-REMARKS-NEXT: t.c:3:30: Instruction with invalid costs prevented vectorization at VF=(vscale x 1): store
define void @vec_sin_fixed_mapping(float* noalias nocapture %dst, float* noalias nocapture readonly %src, i64 %n) {
; CHECK: @vec_sin_fixed_mapping
; CHECK: call fast <2 x float> @llvm.sin.v2f32
@ -127,10 +173,10 @@ entry:
for.body: ; preds = %entry, %for.body
%i.07 = phi i64 [ %inc, %for.body ], [ 0, %entry ]
%arrayidx = getelementptr inbounds float, float* %src, i64 %i.07
%0 = load float, float* %arrayidx, align 4
%1 = tail call fast float @llvm.sin.f32(float %0) #3
%0 = load float, float* %arrayidx, align 4, !dbg !11
%1 = tail call fast float @llvm.sin.f32(float %0) #3, !dbg !12
%arrayidx1 = getelementptr inbounds float, float* %dst, i64 %i.07
store float %1, float* %arrayidx1, align 4
store float %1, float* %arrayidx1, align 4, !dbg !13
%inc = add nuw nsw i64 %i.07, 1
%exitcond.not = icmp eq i64 %inc, %n
br i1 %exitcond.not, label %for.cond.cleanup, label %for.body, !llvm.loop !1
@ -183,3 +229,19 @@ attributes #3 = { "vector-function-abi-variant"="_ZGV_LLVM_N2v_llvm.sin.f64(sin_
!1 = distinct !{!1, !2, !3}
!2 = !{!"llvm.loop.vectorize.width", i32 2}
!3 = !{!"llvm.loop.vectorize.scalable.enable", i1 true}
!llvm.dbg.cu = !{!4}
!llvm.module.flags = !{!7}
!llvm.ident = !{!8}
!4 = distinct !DICompileUnit(language: DW_LANG_C99, file: !5, producer: "clang", isOptimized: true, runtimeVersion: 0, emissionKind: NoDebug, enums: !6, splitDebugInlining: false, nameTableKind: None)
!5 = !DIFile(filename: "t.c", directory: "somedir")
!6 = !{}
!7 = !{i32 2, !"Debug Info Version", i32 3}
!8 = !{!"clang"}
!9 = distinct !DISubprogram(name: "foo", scope: !5, file: !5, line: 2, type: !10, scopeLine: 2, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !4, retainedNodes: !6)
!10 = !DISubroutineType(types: !6)
!11 = !DILocation(line: 3, column: 10, scope: !9)
!12 = !DILocation(line: 3, column: 20, scope: !9)
!13 = !DILocation(line: 3, column: 30, scope: !9)
!14 = !DILocation(line: 3, column: 40, scope: !9)