[llvm] r207512 - [OPENMP][LV][D3423] Respect Hints.Force meta-data for loops in LoopVectorizer
Kostya Serebryany
kcc at google.com
Tue Apr 29 02:40:15 PDT 2014
hope r207514 fixes it.
On Tue, Apr 29, 2014 at 1:33 PM, Kostya Serebryany <kcc at google.com> wrote:
> This causes build breakage in release mode:
> lib/Transforms/Vectorize/LoopVectorize.cpp:5099:15: error: unused variable
> 'ScalarCost' [-Werror,-Wunused-variable]
> const float ScalarCost = Cost;
>
> (The constant is used in DEBUG() statement which is void in Release mode)
>
>
>
> On Tue, Apr 29, 2014 at 12:55 PM, Zinovy Nis <zinovy.nis at gmail.com> wrote:
>
>> Author: zinovy.nis
>> Date: Tue Apr 29 03:55:11 2014
>> New Revision: 207512
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=207512&view=rev
>> Log:
>> [OPENMP][LV][D3423] Respect Hints.Force meta-data for loops in
>> LoopVectorizer
>>
>> Added:
>> llvm/trunk/test/Transforms/LoopVectorize/X86/vect.omp.force.ll
>>
>> llvm/trunk/test/Transforms/LoopVectorize/X86/vect.omp.force.small-tc.ll
>> Modified:
>> llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp
>>
>> Modified: llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp?rev=207512&r1=207511&r2=207512&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp (original)
>> +++ llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp Tue Apr 29
>> 03:55:11 2014
>> @@ -819,7 +819,8 @@ public:
>> /// then this vectorization factor will be selected if vectorization is
>> /// possible.
>> VectorizationFactor selectVectorizationFactor(bool OptForSize,
>> - unsigned UserVF);
>> + unsigned UserVF,
>> + bool ForceVectorization);
>>
>> /// \return The size (in bits) of the widest type in the code that
>> /// needs to be vectorized. We ignore values that remain scalar such as
>> @@ -891,13 +892,17 @@ struct LoopVectorizeHints {
>> unsigned Width;
>> /// Vectorization unroll factor.
>> unsigned Unroll;
>> - /// Vectorization forced (-1 not selected, 0 force disabled, 1 force
>> enabled)
>> - int Force;
>> + /// Vectorization forced
>> + enum ForceKind {
>> + FK_Undefined = -1, ///< Not selected.
>> + FK_Disabled = 0, ///< Forcing disabled.
>> + FK_Enabled = 1, ///< Forcing enabled.
>> + } Force;
>>
>> LoopVectorizeHints(const Loop *L, bool DisableUnrolling)
>> : Width(VectorizationFactor)
>> , Unroll(DisableUnrolling ? 1 : VectorizationUnroll)
>> - , Force(-1)
>> + , Force(FK_Undefined)
>> , LoopID(L->getLoopID()) {
>> getHints(L);
>> // The command line options override any loop metadata except for
>> when
>> @@ -1010,7 +1015,8 @@ private:
>> DEBUG(dbgs() << "LV: ignoring invalid unroll hint metadata\n");
>> } else if (Hint == "enable") {
>> if (C->getBitWidth() == 1)
>> - Force = Val;
>> + Force = Val == 1 ? LoopVectorizeHints::FK_Enabled
>> + : LoopVectorizeHints::FK_Disabled;
>> else
>> DEBUG(dbgs() << "LV: ignoring invalid enable hint metadata\n");
>> } else {
>> @@ -1106,18 +1112,20 @@ struct LoopVectorize : public FunctionPa
>> LoopVectorizeHints Hints(L, DisableUnrolling);
>>
>> DEBUG(dbgs() << "LV: Loop hints:"
>> - << " force=" << (Hints.Force == 0
>> - ? "disabled"
>> - : (Hints.Force == 1 ? "enabled" :
>> "?"))
>> - << " width=" << Hints.Width << " unroll=" <<
>> Hints.Unroll
>> - << "\n");
>> + << " force="
>> + << (Hints.Force == LoopVectorizeHints::FK_Disabled
>> + ? "disabled"
>> + : (Hints.Force == LoopVectorizeHints::FK_Enabled
>> + ? "enabled"
>> + : "?")) << " width=" << Hints.Width
>> + << " unroll=" << Hints.Unroll << "\n");
>>
>> - if (Hints.Force == 0) {
>> + if (Hints.Force == LoopVectorizeHints::FK_Disabled) {
>> DEBUG(dbgs() << "LV: Not vectorizing: #pragma vectorize
>> disable.\n");
>> return false;
>> }
>>
>> - if (!AlwaysVectorize && Hints.Force != 1) {
>> + if (!AlwaysVectorize && Hints.Force !=
>> LoopVectorizeHints::FK_Enabled) {
>> DEBUG(dbgs() << "LV: Not vectorizing: No #pragma vectorize
>> enable.\n");
>> return false;
>> }
>> @@ -1127,6 +1135,21 @@ struct LoopVectorize : public FunctionPa
>> return false;
>> }
>>
>> + // Check the loop for a trip count threshold:
>> + // do not vectorize loops with a tiny trip count.
>> + BasicBlock *Latch = L->getLoopLatch();
>> + const unsigned TC = SE->getSmallConstantTripCount(L, Latch);
>> + if (TC > 0u && TC < TinyTripCountVectorThreshold) {
>> + DEBUG(dbgs() << "LV: Found a loop with a very small trip count. "
>> + << "This loop is not worth vectorizing.");
>> + if (Hints.Force == LoopVectorizeHints::FK_Enabled)
>> + DEBUG(dbgs() << " But vectorizing was explicitly forced.\n");
>> + else {
>> + DEBUG(dbgs() << "\n");
>> + return false;
>> + }
>> + }
>> +
>> // Check if it is legal to vectorize the loop.
>> LoopVectorizationLegality LVL(L, SE, DL, DT, TLI);
>> if (!LVL.canVectorize()) {
>> @@ -1140,8 +1163,8 @@ struct LoopVectorize : public FunctionPa
>> // Check the function attributes to find out if this function should
>> be
>> // optimized for size.
>> Function *F = L->getHeader()->getParent();
>> - bool OptForSize =
>> - Hints.Force != 1 &&
>> F->hasFnAttribute(Attribute::OptimizeForSize);
>> + bool OptForSize = Hints.Force != LoopVectorizeHints::FK_Enabled &&
>> + F->hasFnAttribute(Attribute::OptimizeForSize);
>>
>> // Compute the weighted frequency of this loop being executed and
>> see if it
>> // is less than 20% of the function entry baseline frequency. Note
>> that we
>> @@ -1150,7 +1173,8 @@ struct LoopVectorize : public FunctionPa
>> // exactly what block frequency models.
>> if (LoopVectorizeWithBlockFrequency) {
>> BlockFrequency LoopEntryFreq =
>> BFI->getBlockFreq(L->getLoopPreheader());
>> - if (Hints.Force != 1 && LoopEntryFreq < ColdEntryFreq)
>> + if (Hints.Force != LoopVectorizeHints::FK_Enabled &&
>> + LoopEntryFreq < ColdEntryFreq)
>> OptForSize = true;
>> }
>>
>> @@ -1166,7 +1190,10 @@ struct LoopVectorize : public FunctionPa
>>
>> // Select the optimal vectorization factor.
>> const LoopVectorizationCostModel::VectorizationFactor VF =
>> - CM.selectVectorizationFactor(OptForSize,
>> Hints.Width);
>> + CM.selectVectorizationFactor(OptForSize, Hints.Width,
>> + Hints.Force ==
>> + LoopVectorizeHints::FK_Enabled);
>> +
>> // Select the unroll factor.
>> const unsigned UF = CM.selectUnrollFactor(OptForSize, Hints.Unroll,
>> VF.Width,
>> VF.Cost);
>> @@ -3300,15 +3327,6 @@ bool LoopVectorizationLegality::canVecto
>> return false;
>> }
>>
>> - // Do not loop-vectorize loops with a tiny trip count.
>> - BasicBlock *Latch = TheLoop->getLoopLatch();
>> - unsigned TC = SE->getSmallConstantTripCount(TheLoop, Latch);
>> - if (TC > 0u && TC < TinyTripCountVectorThreshold) {
>> - DEBUG(dbgs() << "LV: Found a loop with a very small trip count. " <<
>> - "This loop is not worth vectorizing.\n");
>> - return false;
>> - }
>> -
>> // Check if we can vectorize the instructions and CFG in this loop.
>> if (!canVectorizeInstrs()) {
>> DEBUG(dbgs() << "LV: Can't vectorize the instructions or CFG\n");
>> @@ -5007,7 +5025,8 @@ bool LoopVectorizationLegality::blockCan
>>
>> LoopVectorizationCostModel::VectorizationFactor
>> LoopVectorizationCostModel::selectVectorizationFactor(bool OptForSize,
>> - unsigned UserVF) {
>> + unsigned UserVF,
>> + bool
>> ForceVectorization) {
>> // Width 1 means no vectorize
>> VectorizationFactor Factor = { 1U, 0U };
>> if (OptForSize && Legal->getRuntimePointerCheck()->Need) {
>> @@ -5077,8 +5096,16 @@ LoopVectorizationCostModel::selectVector
>> }
>>
>> float Cost = expectedCost(1);
>> + const float ScalarCost = Cost;
>> unsigned Width = 1;
>> DEBUG(dbgs() << "LV: Scalar loop costs: " << (int)Cost << ".\n");
>> +
>> + // Ignore scalar width, because the user explicitly wants
>> vectorization.
>> + if (ForceVectorization && VF > 1) {
>> + Width = 2;
>> + Cost = expectedCost(Width) / (float)Width;
>> + }
>> +
>> for (unsigned i=2; i <= VF; i*=2) {
>> // Notice that the vector loop needs to be executed less times, so
>> // we need to divide the cost of the vector loops by the width of
>> @@ -5092,6 +5119,9 @@ LoopVectorizationCostModel::selectVector
>> }
>> }
>>
>> + DEBUG(if (ForceVectorization && Width > 1 && Cost >= ScalarCost) dbgs()
>> + << "LV: Vectorization seems to be not beneficial, "
>> + << "but was forced by a user.\n");
>> DEBUG(dbgs() << "LV: Selecting VF: "<< Width << ".\n");
>> Factor.Width = Width;
>> Factor.Cost = Width * Cost;
>>
>> Added: llvm/trunk/test/Transforms/LoopVectorize/X86/vect.omp.force.ll
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopVectorize/X86/vect.omp.force.ll?rev=207512&view=auto
>>
>> ==============================================================================
>> --- llvm/trunk/test/Transforms/LoopVectorize/X86/vect.omp.force.ll (added)
>> +++ llvm/trunk/test/Transforms/LoopVectorize/X86/vect.omp.force.ll Tue
>> Apr 29 03:55:11 2014
>> @@ -0,0 +1,93 @@
>> +; RUN: opt < %s -loop-vectorize -mtriple=x86_64-apple-macosx10.8.0
>> -mcpu=corei7-avx -debug-only=loop-vectorize -stats -S 2>&1 | FileCheck %s
>> +; REQUIRES: asserts
>> +
>> +; CHECK: LV: Loop hints: force=enabled
>> +; CHECK: LV: Loop hints: force=?
>> +; No more loops in the module
>> +; CHECK-NOT: LV: Loop hints: force=
>> +; CHECK: 2 loop-vectorize - Number of loops analyzed for
>> vectorization
>> +; CHECK: 1 loop-vectorize - Number of loops vectorized
>> +
>> +target datalayout =
>> "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
>> +target triple = "x86_64-apple-macosx10.8.0"
>> +
>> +;
>> +; The source code for the test:
>> +;
>> +; #include <math.h>
>> +; void foo(float* restrict A, float * restrict B, int size)
>> +; {
>> +; for (int i = 0; i < size; ++i) A[i] = sinf(B[i]);
>> +; }
>> +;
>> +
>> +;
>> +; This loop will be vectorized, although the scalar cost is lower than
>> any of vector costs, but vectorization is explicitly forced in metadata.
>> +;
>> +
>> +define void @vectorized(float* noalias nocapture %A, float* noalias
>> nocapture %B, i32 %size) {
>> +entry:
>> + %cmp6 = icmp sgt i32 %size, 0
>> + br i1 %cmp6, label %for.body.preheader, label %for.end
>> +
>> +for.body.preheader:
>> + br label %for.body
>> +
>> +for.body:
>> + %indvars.iv = phi i64 [ %indvars.iv.next, %for.body ], [ 0,
>> %for.body.preheader ]
>> + %arrayidx = getelementptr inbounds float* %B, i64 %indvars.iv
>> + %0 = load float* %arrayidx, align 4, !llvm.mem.parallel_loop_access !1
>> + %call = tail call float @llvm.sin.f32(float %0)
>> + %arrayidx2 = getelementptr inbounds float* %A, i64 %indvars.iv
>> + store float %call, float* %arrayidx2, align 4,
>> !llvm.mem.parallel_loop_access !1
>> + %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
>> + %lftr.wideiv = trunc i64 %indvars.iv.next to i32
>> + %exitcond = icmp eq i32 %lftr.wideiv, %size
>> + br i1 %exitcond, label %for.end.loopexit, label %for.body, !llvm.loop
>> !1
>> +
>> +for.end.loopexit:
>> + br label %for.end
>> +
>> +for.end:
>> + ret void
>> +}
>> +
>> +!1 = metadata !{metadata !1, metadata !2}
>> +!2 = metadata !{metadata !"llvm.vectorizer.enable", i1 true}
>> +
>> +;
>> +; This method will not be vectorized, as scalar cost is lower than any
>> of vector costs.
>> +;
>> +
>> +define void @not_vectorized(float* noalias nocapture %A, float* noalias
>> nocapture %B, i32 %size) {
>> +entry:
>> + %cmp6 = icmp sgt i32 %size, 0
>> + br i1 %cmp6, label %for.body.preheader, label %for.end
>> +
>> +for.body.preheader:
>> + br label %for.body
>> +
>> +for.body:
>> + %indvars.iv = phi i64 [ %indvars.iv.next, %for.body ], [ 0,
>> %for.body.preheader ]
>> + %arrayidx = getelementptr inbounds float* %B, i64 %indvars.iv
>> + %0 = load float* %arrayidx, align 4, !llvm.mem.parallel_loop_access !3
>> + %call = tail call float @llvm.sin.f32(float %0)
>> + %arrayidx2 = getelementptr inbounds float* %A, i64 %indvars.iv
>> + store float %call, float* %arrayidx2, align 4,
>> !llvm.mem.parallel_loop_access !3
>> + %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
>> + %lftr.wideiv = trunc i64 %indvars.iv.next to i32
>> + %exitcond = icmp eq i32 %lftr.wideiv, %size
>> + br i1 %exitcond, label %for.end.loopexit, label %for.body, !llvm.loop
>> !3
>> +
>> +for.end.loopexit:
>> + br label %for.end
>> +
>> +for.end:
>> + ret void
>> +}
>> +
>> +declare float @llvm.sin.f32(float) nounwind readnone
>> +
>> +; Dummy metadata
>> +!3 = metadata !{metadata !3}
>> +
>>
>> Added:
>> llvm/trunk/test/Transforms/LoopVectorize/X86/vect.omp.force.small-tc.ll
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopVectorize/X86/vect.omp.force.small-tc.ll?rev=207512&view=auto
>>
>> ==============================================================================
>> ---
>> llvm/trunk/test/Transforms/LoopVectorize/X86/vect.omp.force.small-tc.ll
>> (added)
>> +++
>> llvm/trunk/test/Transforms/LoopVectorize/X86/vect.omp.force.small-tc.ll Tue
>> Apr 29 03:55:11 2014
>> @@ -0,0 +1,73 @@
>> +; RUN: opt < %s -loop-vectorize -mtriple=x86_64-apple-macosx10.8.0
>> -mcpu=corei7-avx -debug-only=loop-vectorize -stats -S
>> -vectorizer-min-trip-count=21 2>&1 | FileCheck %s
>> +; REQUIRES: asserts
>> +
>> +; CHECK: LV: Loop hints: force=enabled
>> +; CHECK: LV: Loop hints: force=?
>> +; No more loops in the module
>> +; CHECK-NOT: LV: Loop hints: force=
>> +; CHECK: 2 loop-vectorize - Number of loops analyzed for
>> vectorization
>> +; CHECK: 1 loop-vectorize - Number of loops vectorized
>> +
>> +target datalayout =
>> "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
>> +target triple = "x86_64-apple-macosx10.8.0"
>> +
>> +;
>> +; The source code for the test:
>> +;
>> +; void foo(float* restrict A, float* restrict B)
>> +; {
>> +; for (int i = 0; i < 20; ++i) A[i] += B[i];
>> +; }
>> +;
>> +
>> +;
>> +; This loop will be vectorized, although the trip count is below the
>> threshold, but vectorization is explicitly forced in metadata.
>> +;
>> +define void @vectorized(float* noalias nocapture %A, float* noalias
>> nocapture readonly %B) {
>> +entry:
>> + br label %for.body
>> +
>> +for.body:
>> + %indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
>> + %arrayidx = getelementptr inbounds float* %B, i64 %indvars.iv
>> + %0 = load float* %arrayidx, align 4, !llvm.mem.parallel_loop_access !1
>> + %arrayidx2 = getelementptr inbounds float* %A, i64 %indvars.iv
>> + %1 = load float* %arrayidx2, align 4, !llvm.mem.parallel_loop_access !1
>> + %add = fadd fast float %0, %1
>> + store float %add, float* %arrayidx2, align 4,
>> !llvm.mem.parallel_loop_access !1
>> + %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
>> + %exitcond = icmp eq i64 %indvars.iv.next, 20
>> + br i1 %exitcond, label %for.end, label %for.body, !llvm.loop !1
>> +
>> +for.end:
>> + ret void
>> +}
>> +
>> +!1 = metadata !{metadata !1, metadata !2}
>> +!2 = metadata !{metadata !"llvm.vectorizer.enable", i1 true}
>> +
>> +;
>> +; This loop will not be vectorized as the trip count is below the
>> threshold.
>> +;
>> +define void @not_vectorized(float* noalias nocapture %A, float* noalias
>> nocapture readonly %B) {
>> +entry:
>> + br label %for.body
>> +
>> +for.body:
>> + %indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
>> + %arrayidx = getelementptr inbounds float* %B, i64 %indvars.iv
>> + %0 = load float* %arrayidx, align 4, !llvm.mem.parallel_loop_access !3
>> + %arrayidx2 = getelementptr inbounds float* %A, i64 %indvars.iv
>> + %1 = load float* %arrayidx2, align 4, !llvm.mem.parallel_loop_access !3
>> + %add = fadd fast float %0, %1
>> + store float %add, float* %arrayidx2, align 4,
>> !llvm.mem.parallel_loop_access !3
>> + %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
>> + %exitcond = icmp eq i64 %indvars.iv.next, 20
>> + br i1 %exitcond, label %for.end, label %for.body, !llvm.loop !3
>> +
>> +for.end:
>> + ret void
>> +}
>> +
>> +!3 = metadata !{metadata !3}
>> +
>>
>>
>> _______________________________________________
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>>
>
>
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