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[LV] Fallback strategies if tail-folding fails 

This implements 2 different vectorisation fallback strategies if tail-folding
fails: 1) don't vectorise at all, or 2) vectorise using a scalar epilogue. This
can be controlled with option -prefer-predicate-over-epilogue, that has been
changed to take a numeric value corresponding to the tail-folding preference
and preferred fallback.

Patch by: Pierre van Houtryve, Sjoerd Meijer.

Differential Revision: https://reviews.llvm.org/D79783
This commit is contained in:
Sjoerd Meijer 2020-08-26 16:55:25 +01:00
parent 60db26a66d
commit bda8fbe2d2
15 changed files with 323 additions and 37 deletions
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9
llvm/include/llvm/Transforms/Vectorize/LoopVectorizationLegality.h
View File

@ -230,6 +230,7 @@ public:
/// Return true if we can vectorize this loop while folding its tail by
/// masking, and mark all respective loads/stores for masking.
/// This object's state is only modified iff this function returns true.
bool prepareToFoldTailByMasking();
/// Returns the primary induction variable.
@ -370,8 +371,14 @@ private:
/// its original trip-count, under a proper guard, which should be preserved.
/// \p SafePtrs is a list of addresses that are known to be legal and we know
/// that we can read from them without segfault.
/// \p MaskedOp is a list of instructions that have to be transformed into
/// calls to the appropriate masked intrinsic when the loop is vectorized.
/// \p ConditionalAssumes is a list of assume instructions in predicated
/// blocks that must be dropped if the CFG gets flattened.
bool blockCanBePredicated(BasicBlock *BB, SmallPtrSetImpl<Value *> &SafePtrs,
bool PreserveGuards = false);
SmallPtrSetImpl<const Instruction *> &MaskedOp,
SmallPtrSetImpl<Instruction *> &ConditionalAssumes,
bool PreserveGuards = false) const;
/// Updates the vectorization state by adding \p Phi to the inductions list.
/// This can set \p Phi as the main induction of the loop if \p Phi is a

34
llvm/lib/Transforms/Vectorize/LoopVectorizationLegality.cpp
View File

@ -919,7 +919,10 @@ bool LoopVectorizationLegality::blockNeedsPredication(BasicBlock *BB) {
}
bool LoopVectorizationLegality::blockCanBePredicated(
BasicBlock *BB, SmallPtrSetImpl<Value *> &SafePtrs, bool PreserveGuards) {
BasicBlock *BB, SmallPtrSetImpl<Value *> &SafePtrs,
SmallPtrSetImpl<const Instruction *> &MaskedOp,
SmallPtrSetImpl<Instruction *> &ConditionalAssumes,
bool PreserveGuards) const {
const bool IsAnnotatedParallel = TheLoop->isAnnotatedParallel();
for (Instruction &I : *BB) {
@ -1026,7 +1029,8 @@ bool LoopVectorizationLegality::canVectorizeWithIfConvert() {
// We must be able to predicate all blocks that need to be predicated.
if (blockNeedsPredication(BB)) {
if (!blockCanBePredicated(BB, SafePointers)) {
if (!blockCanBePredicated(BB, SafePointers, MaskedOp,
ConditionalAssumes)) {
reportVectorizationFailure(
"Control flow cannot be substituted for a select",
"control flow cannot be substituted for a select",
@ -1253,10 +1257,10 @@ bool LoopVectorizationLegality::prepareToFoldTailByMasking() {
Instruction *UI = cast<Instruction>(U);
if (TheLoop->contains(UI))
continue;
reportVectorizationFailure(
"Cannot fold tail by masking, loop has an outside user for",
"Cannot fold tail by masking in the presence of live outs.",
"LiveOutFoldingTailByMasking", ORE, TheLoop, UI);
LLVM_DEBUG(
dbgs()
<< "LV: Cannot fold tail by masking, loop has an outside user for "
<< *UI << "\n");
return false;
}
}
@ -1264,20 +1268,26 @@ bool LoopVectorizationLegality::prepareToFoldTailByMasking() {
// The list of pointers that we can safely read and write to remains empty.
SmallPtrSet<Value *, 8> SafePointers;
SmallPtrSet<const Instruction *, 8> TmpMaskedOp;
SmallPtrSet<Instruction *, 8> TmpConditionalAssumes;
// Check and mark all blocks for predication, including those that ordinarily
// do not need predication such as the header block.
for (BasicBlock *BB : TheLoop->blocks()) {
if (!blockCanBePredicated(BB, SafePointers, /* MaskAllLoads= */ true)) {
reportVectorizationFailure(
"Cannot fold tail by masking as required",
"control flow cannot be substituted for a select",
"NoCFGForSelect", ORE, TheLoop,
BB->getTerminator());
if (!blockCanBePredicated(BB, SafePointers, TmpMaskedOp,
TmpConditionalAssumes,
/* MaskAllLoads= */ true)) {
LLVM_DEBUG(dbgs() << "LV: Cannot fold tail by masking as requested.\n");
return false;
}
}
LLVM_DEBUG(dbgs() << "LV: can fold tail by masking.\n");
MaskedOp.insert(TmpMaskedOp.begin(), TmpMaskedOp.end());
ConditionalAssumes.insert(TmpConditionalAssumes.begin(),
TmpConditionalAssumes.end());
return true;
}

60
llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
View File

@ -178,13 +178,36 @@ static cl::opt<unsigned> TinyTripCountVectorThreshold(
"value are vectorized only if no scalar iteration overheads "
"are incurred."));
// Indicates that an epilogue is undesired, predication is preferred.
// This means that the vectorizer will try to fold the loop-tail (epilogue)
// into the loop and predicate the loop body accordingly.
static cl::opt<bool> PreferPredicateOverEpilog(
"prefer-predicate-over-epilog", cl::init(false), cl::Hidden,
cl::desc("Indicate that an epilogue is undesired, predication should be "
"used instead."));
// Option prefer-predicate-over-epilogue indicates that an epilogue is undesired,
// that predication is preferred, and this lists all options. I.e., the
// vectorizer will try to fold the tail-loop (epilogue) into the vector body
// and predicate the instructions accordingly. If tail-folding fails, there are
// different fallback strategies depending on these values:
namespace PreferPredicateTy {
enum Option {
ScalarEpilogue = 0,
PredicateElseScalarEpilogue,
PredicateOrDontVectorize
};
}
static cl::opt<PreferPredicateTy::Option> PreferPredicateOverEpilogue(
"prefer-predicate-over-epilogue",
cl::init(PreferPredicateTy::ScalarEpilogue),
cl::Hidden,
cl::desc("Tail-folding and predication preferences over creating a scalar "
"epilogue loop."),
cl::values(clEnumValN(PreferPredicateTy::ScalarEpilogue,
"scalar-epilogue",
"Don't tail-predicate loops, create scalar epilogue"),
clEnumValN(PreferPredicateTy::PredicateElseScalarEpilogue,
"predicate-else-scalar-epilogue",
"prefer tail-folding, create scalar epilogue if tail "
"folding fails."),
clEnumValN(PreferPredicateTy::PredicateOrDontVectorize,
"predicate-dont-vectorize",
"prefers tail-folding, don't attempt vectorization if "
"tail-folding fails.")));
static cl::opt<bool> MaximizeBandwidth(
"vectorizer-maximize-bandwidth", cl::init(false), cl::Hidden,
@ -196,7 +219,7 @@ static cl::opt<bool> EnableInterleavedMemAccesses(
cl::desc("Enable vectorization on interleaved memory accesses in a loop"));
/// An interleave-group may need masking if it resides in a block that needs
/// predication, or in order to mask away gaps.
/// predication, or in order to mask away gaps.
static cl::opt<bool> EnableMaskedInterleavedMemAccesses(
"enable-masked-interleaved-mem-accesses", cl::init(false), cl::Hidden,
cl::desc("Enable vectorization on masked interleaved memory accesses in a loop"));
@ -5241,6 +5264,19 @@ Optional<unsigned> LoopVectorizationCostModel::computeMaxVF(unsigned UserVF,
return MaxVF;
}
// If there was a tail-folding hint/switch, but we can't fold the tail by
// masking, fallback to a vectorization with a scalar epilogue.
if (ScalarEpilogueStatus == CM_ScalarEpilogueNotNeededUsePredicate) {
if (PreferPredicateOverEpilogue == PreferPredicateTy::PredicateOrDontVectorize) {
LLVM_DEBUG(dbgs() << "LV: Can't fold tail by masking: don't vectorize\n");
return None;
}
LLVM_DEBUG(dbgs() << "LV: Cannot fold tail by masking: vectorize with a "
"scalar epilogue instead.\n");
ScalarEpilogueStatus = CM_ScalarEpilogueAllowed;
return MaxVF;
}
if (TC == 0) {
reportVectorizationFailure(
"Unable to calculate the loop count due to complex control flow",
@ -8055,8 +8091,8 @@ static ScalarEpilogueLowering getScalarEpilogueLowering(
Hints.getForce() != LoopVectorizeHints::FK_Enabled))
return CM_ScalarEpilogueNotAllowedOptSize;
bool PredicateOptDisabled = PreferPredicateOverEpilog.getNumOccurrences() &&
!PreferPredicateOverEpilog;
bool PredicateOptDisabled = PreferPredicateOverEpilogue.getNumOccurrences() &&
!PreferPredicateOverEpilogue;
// 2) Next, if disabling predication is requested on the command line, honour
// this and request a scalar epilogue.
@ -8065,8 +8101,8 @@ static ScalarEpilogueLowering getScalarEpilogueLowering(
// 3) and 4) look if enabling predication is requested on the command line,
// with a loop hint, or if the TTI hook indicates this is profitable, request
// predication .
if (PreferPredicateOverEpilog ||
// predication.
if (PreferPredicateOverEpilogue ||
Hints.getPredicate() == LoopVectorizeHints::FK_Enabled ||
(TTI->preferPredicateOverEpilogue(L, LI, *SE, *AC, TLI, DT,
LVL.getLAI()) &&

4
llvm/test/Transforms/LoopVectorize/ARM/prefer-tail-loop-folding.ll
View File

@ -31,13 +31,13 @@
; RUN: FileCheck %s -check-prefixes=CHECK,PREFER-FOLDING
; RUN: opt -mtriple=thumbv8.1m.main-arm-eabihf -mattr=+mve.fp \
; RUN: -prefer-predicate-over-epilog=false \
; RUN: -prefer-predicate-over-epilogue=scalar-epilogue \
; RUN: -tail-predication=enabled -loop-vectorize \
; RUN: -enable-arm-maskedldst=true -S < %s | \
; RUN: FileCheck %s -check-prefixes=CHECK,NO-FOLDING
; RUN: opt -mtriple=thumbv8.1m.main-arm-eabihf -mattr=+mve.fp \
; RUN: -prefer-predicate-over-epilog=true \
; RUN: -prefer-predicate-over-epilogue=predicate-dont-vectorize \
; RUN: -tail-predication=enabled -loop-vectorize \
; RUN: -enable-arm-maskedldst=true -S < %s | \
; RUN: FileCheck %s -check-prefixes=CHECK,FOLDING-OPT

3
llvm/test/Transforms/LoopVectorize/ARM/tail-folding-counting-down.ll
View File

@ -1,5 +1,6 @@
; RUN: opt < %s -loop-vectorize -S | FileCheck %s --check-prefixes=COMMON,DEFAULT
; RUN: opt < %s -loop-vectorize -tail-predication=enabled -prefer-predicate-over-epilog -S | FileCheck %s --check-prefixes=COMMON,CHECK-TF,CHECK-PREFER
; RUN: opt < %s -loop-vectorize -tail-predication=enabled -prefer-predicate-over-epilogue=predicate-dont-vectorize -S | FileCheck %s --check-prefixes=COMMON,CHECK-TF,CHECK-PREFER
; RUN: opt < %s -loop-vectorize -tail-predication=enabled -prefer-predicate-over-epilogue=predicate-else-scalar-epilogue -S | FileCheck %s --check-prefixes=COMMON,CHECK-TF,CHECK-PREFER
; RUN: opt < %s -loop-vectorize -tail-predication=enabled -S | FileCheck %s --check-prefixes=COMMON,CHECK-TF,CHECK-ENABLE-TP
target datalayout = "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"

5
llvm/test/Transforms/LoopVectorize/ARM/tail-folding-prefer-flag.ll
View File

@ -1,8 +1,9 @@
; RUN: opt -mtriple=thumbv8.1m.main-arm-eabihf -mattr=+mve.fp -loop-vectorize -tail-predication=enabled -S < %s | \
; RUN: FileCheck %s -check-prefix=CHECK
; RUN: opt -mtriple=thumbv8.1m.main-arm-eabihf -mattr=+mve.fp -loop-vectorize -tail-predication=enabled -prefer-predicate-over-epilog -S < %s | \
; RUN: FileCheck -check-prefix=PREDFLAG %s
; RUN: opt -mtriple=thumbv8.1m.main-arm-eabihf -mattr=+mve.fp -loop-vectorize -tail-predication=enabled \
; RUN: -prefer-predicate-over-epilogue=predicate-dont-vectorize -S < %s | \
; RUN: FileCheck -check-prefix=PREDFLAG %s
; This test has a loop hint "predicate.predicate" set to false, so shouldn't
; get tail-folded, except with -prefer-predicate-over-epilog which then

2
llvm/test/Transforms/LoopVectorize/ARM/tail-folding-reduces-vf.ll
View File

@ -1,5 +1,5 @@
; RUN: opt < %s -mattr=+mve,+mve.fp -loop-vectorize -S | FileCheck %s --check-prefixes=DEFAULT
; RUN: opt < %s -mattr=+mve,+mve.fp -loop-vectorize -prefer-predicate-over-epilog -S | FileCheck %s --check-prefixes=TAILPRED
; RUN: opt < %s -mattr=+mve,+mve.fp -loop-vectorize -prefer-predicate-over-epilogue=predicate-else-scalar-epilogue -S | FileCheck %s --check-prefixes=TAILPRED
target datalayout = "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"
target triple = "thumbv8.1m.main-arm-none-eabi"

78
llvm/test/Transforms/LoopVectorize/ARM/tail-folding-scalar-epilogue-fallback.ll Normal file
View File

@ -0,0 +1,78 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -S -loop-vectorize -mattr=+armv8.1-m.main,+mve.fp -tail-predication=disabled< %s | FileCheck %s
; RUN: opt -S -loop-vectorize -mattr=+armv8.1-m.main,+mve.fp -tail-predication=enabled < %s | FileCheck %s
; This test should produce the same result (vectorized loop + scalar epilogue) with
; default options and when MVE Tail Predication is enabled, as this loop's tail cannot be folded
; by masking due to an outside user of %incdec.ptr in %end.
target datalayout = "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"
target triple = "thumbv8.1m.main-arm-unknown-eabihf"
define void @outside_user_blocks_tail_folding(i8* nocapture readonly %ptr, i32 %size, i8** %pos) {
; CHECK-LABEL: @outside_user_blocks_tail_folding(
; CHECK-NEXT: header:
; CHECK-NEXT: [[PTR0:%.*]] = load i8*, i8** [[POS:%.*]], align 4
; CHECK-NEXT: [[MIN_ITERS_CHECK:%.*]] = icmp ult i32 [[SIZE:%.*]], 16
; CHECK-NEXT: br i1 [[MIN_ITERS_CHECK]], label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]]
; CHECK: vector.ph:
; CHECK-NEXT: [[N_MOD_VF:%.*]] = urem i32 [[SIZE]], 16
; CHECK-NEXT: [[N_VEC:%.*]] = sub i32 [[SIZE]], [[N_MOD_VF]]
; CHECK-NEXT: [[IND_END:%.*]] = sub i32 [[SIZE]], [[N_VEC]]
; CHECK-NEXT: [[IND_END2:%.*]] = getelementptr i8, i8* [[PTR:%.*]], i32 [[N_VEC]]
; 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:%.*]] = sub i32 [[SIZE]], [[INDEX]]
; CHECK-NEXT: [[TMP0:%.*]] = add i32 [[OFFSET_IDX]], 0
; CHECK-NEXT: [[TMP1:%.*]] = add i32 [[INDEX]], 0
; CHECK-NEXT: [[NEXT_GEP:%.*]] = getelementptr i8, i8* [[PTR]], i32 [[TMP1]]
; CHECK-NEXT: [[TMP2:%.*]] = getelementptr inbounds i8, i8* [[NEXT_GEP]], i32 1
; CHECK-NEXT: [[TMP3:%.*]] = getelementptr inbounds i8, i8* [[TMP2]], i32 0
; CHECK-NEXT: [[TMP4:%.*]] = bitcast i8* [[TMP3]] to <16 x i8>*
; CHECK-NEXT: [[WIDE_LOAD:%.*]] = load <16 x i8>, <16 x i8>* [[TMP4]], align 1
; CHECK-NEXT: [[TMP5:%.*]] = getelementptr i8, i8* [[NEXT_GEP]], i32 0
; CHECK-NEXT: [[TMP6:%.*]] = bitcast i8* [[TMP5]] to <16 x i8>*
; CHECK-NEXT: store <16 x i8> [[WIDE_LOAD]], <16 x i8>* [[TMP6]], align 1
; CHECK-NEXT: [[INDEX_NEXT]] = add i32 [[INDEX]], 16
; CHECK-NEXT: [[TMP7:%.*]] = icmp eq i32 [[INDEX_NEXT]], [[N_VEC]]
; CHECK-NEXT: br i1 [[TMP7]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop !0
; CHECK: middle.block:
; CHECK-NEXT: [[CMP_N:%.*]] = icmp eq i32 [[SIZE]], [[N_VEC]]
; CHECK-NEXT: br i1 [[CMP_N]], label [[END:%.*]], label [[SCALAR_PH]]
; CHECK: scalar.ph:
; CHECK-NEXT: [[BC_RESUME_VAL:%.*]] = phi i32 [ [[IND_END]], [[MIDDLE_BLOCK]] ], [ [[SIZE]], [[HEADER:%.*]] ]
; CHECK-NEXT: [[BC_RESUME_VAL1:%.*]] = phi i8* [ [[IND_END2]], [[MIDDLE_BLOCK]] ], [ [[PTR]], [[HEADER]] ]
; CHECK-NEXT: br label [[BODY:%.*]]
; CHECK: body:
; CHECK-NEXT: [[DEC66:%.*]] = phi i32 [ [[DEC:%.*]], [[BODY]] ], [ [[BC_RESUME_VAL]], [[SCALAR_PH]] ]
; CHECK-NEXT: [[BUFF:%.*]] = phi i8* [ [[INCDEC_PTR:%.*]], [[BODY]] ], [ [[BC_RESUME_VAL1]], [[SCALAR_PH]] ]
; CHECK-NEXT: [[INCDEC_PTR]] = getelementptr inbounds i8, i8* [[BUFF]], i32 1
; CHECK-NEXT: [[DEC]] = add nsw i32 [[DEC66]], -1
; CHECK-NEXT: [[TMP8:%.*]] = load i8, i8* [[INCDEC_PTR]], align 1
; CHECK-NEXT: store i8 [[TMP8]], i8* [[BUFF]], align 1
; CHECK-NEXT: [[TOBOOL11:%.*]] = icmp eq i32 [[DEC]], 0
; CHECK-NEXT: br i1 [[TOBOOL11]], label [[END]], label [[BODY]], !llvm.loop !2
; CHECK: end:
; CHECK-NEXT: [[INCDEC_PTR_LCSSA:%.*]] = phi i8* [ [[INCDEC_PTR]], [[BODY]] ], [ [[IND_END2]], [[MIDDLE_BLOCK]] ]
; CHECK-NEXT: store i8* [[INCDEC_PTR_LCSSA]], i8** [[POS]], align 4
; CHECK-NEXT: ret void
;
header:
%ptr0 = load i8*, i8** %pos, align 4
br label %body
body:
%dec66 = phi i32 [ %dec, %body ], [ %size, %header ]
%buff = phi i8* [ %incdec.ptr, %body ], [ %ptr, %header ]
%incdec.ptr = getelementptr inbounds i8, i8* %buff, i32 1
%dec = add nsw i32 %dec66, -1
%0 = load i8, i8* %incdec.ptr, align 1
store i8 %0, i8* %buff, align 1
%tobool11 = icmp eq i32 %dec, 0
br i1 %tobool11, label %end, label %body
end:
store i8* %incdec.ptr, i8** %pos, align 4
ret void
}

2
llvm/test/Transforms/LoopVectorize/Hexagon/invalidate-cm-after-invalidating-interleavegroups.ll
View File

@ -1,4 +1,4 @@
; RUN: opt -loop-vectorize -hexagon-autohvx=1 -force-vector-width=64 -prefer-predicate-over-epilog -S %s | FileCheck %s
; RUN: opt -loop-vectorize -hexagon-autohvx=1 -force-vector-width=64 -prefer-predicate-over-epilogue=predicate-dont-vectorize -S %s | FileCheck %s
target datalayout = "e-m:e-p:32:32:32-a:0-n16:32-i64:64:64-i32:32:32-i16:16:16-i1:8:8-f32:32:32-f64:64:64-v32:32:32-v64:64:64-v512:512:512-v1024:1024:1024-v2048:2048:2048"
target triple = "hexagon"

2
llvm/test/Transforms/LoopVectorize/X86/tail_loop_folding.ll
View File

@ -1,6 +1,6 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt < %s -loop-vectorize -S | FileCheck %s
; RUN: opt < %s -loop-vectorize -prefer-predicate-over-epilog -S | FileCheck %s
; RUN: opt < %s -loop-vectorize -prefer-predicate-over-epilogue=predicate-dont-vectorize -S | FileCheck %s
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"

2
llvm/test/Transforms/LoopVectorize/memdep-fold-tail.ll
View File

@ -1,5 +1,5 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt < %s -loop-vectorize -vectorize-num-stores-pred=2 -prefer-predicate-over-epilog -S | FileCheck %s
; RUN: opt < %s -loop-vectorize -vectorize-num-stores-pred=2 -prefer-predicate-over-epilogue=predicate-dont-vectorize -S | FileCheck %s
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"

2
llvm/test/Transforms/LoopVectorize/pr46525-expander-insertpoint.ll
View File

@ -1,5 +1,5 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -loop-vectorize -force-vector-width=2 -S -prefer-predicate-over-epilog %s | FileCheck %s
; RUN: opt -loop-vectorize -force-vector-width=2 -S -prefer-predicate-over-epilogue=predicate-dont-vectorize %s | FileCheck %s
; Test case for PR46525. There are two candidates to pick for

2
llvm/test/Transforms/LoopVectorize/reduction-predselect.ll
View File

@ -1,5 +1,5 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt < %s -loop-vectorize -force-vector-width=4 -force-vector-interleave=1 -prefer-predicate-over-epilog -prefer-predicated-reduction-select -force-reduction-intrinsics -dce -instcombine -S | FileCheck %s
; RUN: opt < %s -loop-vectorize -force-vector-width=4 -force-vector-interleave=1 -prefer-predicate-over-epilogue=predicate-else-scalar-epilogue -prefer-predicated-reduction-select -force-reduction-intrinsics -dce -instcombine -S | FileCheck %s
target datalayout = "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"

2
llvm/test/Transforms/LoopVectorize/tail-folding-counting-down.ll
View File

@ -1,4 +1,4 @@
; RUN: opt < %s -loop-vectorize -prefer-predicate-over-epilog -force-vector-width=4 -S | FileCheck %s
; RUN: opt < %s -loop-vectorize -prefer-predicate-over-epilogue=predicate-dont-vectorize -force-vector-width=4 -S | FileCheck %s
; Check that a counting-down loop which has no primary induction variable
; is vectorized with preferred predication.

153
llvm/test/Transforms/LoopVectorize/use-scalar-epilogue-if-tp-fails.ll Normal file
View File

@ -0,0 +1,153 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -S -loop-vectorize -prefer-predicate-over-epilogue=predicate-else-scalar-epilogue < %s | FileCheck %s
; RUN: opt -S -loop-vectorize < %s | FileCheck %s
; This tests should produce the same result as with default options, and when tail folding
; is preferred, because the vectorizer can't fold the tail by masking (due to an
; outside user of %incdec.ptr in %end) and should fallback to a scalar epilogue.
;
; The first test (@basic_loop) simply relies on the command-line switches.
; The second test (@metadata) specificies its tail-folding preference via metadata.
; Both tests should always generate a scalar epilogue.
target datalayout = "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"
define void @basic_loop(i8* nocapture readonly %ptr, i32 %size, i8** %pos) {
; CHECK-LABEL: @basic_loop(
; CHECK-NEXT: header:
; CHECK-NEXT: [[PTR0:%.*]] = load i8*, i8** [[POS:%.*]], align 4
; CHECK-NEXT: [[MIN_ITERS_CHECK:%.*]] = icmp ult i32 [[SIZE:%.*]], 4
; CHECK-NEXT: br i1 [[MIN_ITERS_CHECK]], label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]]
; CHECK: vector.ph:
; CHECK-NEXT: [[N_MOD_VF:%.*]] = urem i32 [[SIZE]], 4
; CHECK-NEXT: [[N_VEC:%.*]] = sub i32 [[SIZE]], [[N_MOD_VF]]
; CHECK-NEXT: [[IND_END:%.*]] = sub i32 [[SIZE]], [[N_VEC]]
; CHECK-NEXT: [[IND_END2:%.*]] = getelementptr i8, i8* [[PTR:%.*]], i32 [[N_VEC]]
; 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:%.*]] = sub i32 [[SIZE]], [[INDEX]]
; CHECK-NEXT: [[TMP0:%.*]] = add i32 [[OFFSET_IDX]], 0
; CHECK-NEXT: [[TMP1:%.*]] = add i32 [[INDEX]], 0
; CHECK-NEXT: [[NEXT_GEP:%.*]] = getelementptr i8, i8* [[PTR]], i32 [[TMP1]]
; CHECK-NEXT: [[TMP2:%.*]] = getelementptr inbounds i8, i8* [[NEXT_GEP]], i32 1
; CHECK-NEXT: [[TMP3:%.*]] = getelementptr inbounds i8, i8* [[TMP2]], i32 0
; CHECK-NEXT: [[TMP4:%.*]] = bitcast i8* [[TMP3]] to <4 x i8>*
; CHECK-NEXT: [[WIDE_LOAD:%.*]] = load <4 x i8>, <4 x i8>* [[TMP4]], align 1
; CHECK-NEXT: [[TMP5:%.*]] = getelementptr i8, i8* [[NEXT_GEP]], i32 0
; CHECK-NEXT: [[TMP6:%.*]] = bitcast i8* [[TMP5]] to <4 x i8>*
; CHECK-NEXT: store <4 x i8> [[WIDE_LOAD]], <4 x i8>* [[TMP6]], align 1
; CHECK-NEXT: [[INDEX_NEXT]] = add i32 [[INDEX]], 4
; CHECK-NEXT: [[TMP7:%.*]] = icmp eq i32 [[INDEX_NEXT]], [[N_VEC]]
; CHECK-NEXT: br i1 [[TMP7]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop !0
; CHECK: middle.block:
; CHECK-NEXT: [[CMP_N:%.*]] = icmp eq i32 [[SIZE]], [[N_VEC]]
; CHECK-NEXT: br i1 [[CMP_N]], label [[END:%.*]], label [[SCALAR_PH]]
; CHECK: scalar.ph:
; CHECK-NEXT: [[BC_RESUME_VAL:%.*]] = phi i32 [ [[IND_END]], [[MIDDLE_BLOCK]] ], [ [[SIZE]], [[HEADER:%.*]] ]
; CHECK-NEXT: [[BC_RESUME_VAL1:%.*]] = phi i8* [ [[IND_END2]], [[MIDDLE_BLOCK]] ], [ [[PTR]], [[HEADER]] ]
; CHECK-NEXT: br label [[BODY:%.*]]
; CHECK: body:
; CHECK-NEXT: [[DEC66:%.*]] = phi i32 [ [[DEC:%.*]], [[BODY]] ], [ [[BC_RESUME_VAL]], [[SCALAR_PH]] ]
; CHECK-NEXT: [[BUFF:%.*]] = phi i8* [ [[INCDEC_PTR:%.*]], [[BODY]] ], [ [[BC_RESUME_VAL1]], [[SCALAR_PH]] ]
; CHECK-NEXT: [[INCDEC_PTR]] = getelementptr inbounds i8, i8* [[BUFF]], i32 1
; CHECK-NEXT: [[DEC]] = add nsw i32 [[DEC66]], -1
; CHECK-NEXT: [[TMP8:%.*]] = load i8, i8* [[INCDEC_PTR]], align 1
; CHECK-NEXT: store i8 [[TMP8]], i8* [[BUFF]], align 1
; CHECK-NEXT: [[TOBOOL11:%.*]] = icmp eq i32 [[DEC]], 0
; CHECK-NEXT: br i1 [[TOBOOL11]], label [[END]], label [[BODY]], !llvm.loop !2
; CHECK: end:
; CHECK-NEXT: [[INCDEC_PTR_LCSSA:%.*]] = phi i8* [ [[INCDEC_PTR]], [[BODY]] ], [ [[IND_END2]], [[MIDDLE_BLOCK]] ]
; CHECK-NEXT: store i8* [[INCDEC_PTR_LCSSA]], i8** [[POS]], align 4
; CHECK-NEXT: ret void
;
header:
%ptr0 = load i8*, i8** %pos, align 4
br label %body
body:
%dec66 = phi i32 [ %dec, %body ], [ %size, %header ]
%buff = phi i8* [ %incdec.ptr, %body ], [ %ptr, %header ]
%incdec.ptr = getelementptr inbounds i8, i8* %buff, i32 1
%dec = add nsw i32 %dec66, -1
%0 = load i8, i8* %incdec.ptr, align 1
store i8 %0, i8* %buff, align 1
%tobool11 = icmp eq i32 %dec, 0
br i1 %tobool11, label %end, label %body
end:
store i8* %incdec.ptr, i8** %pos, align 4
ret void
}
define void @metadata(i8* nocapture readonly %ptr, i32 %size, i8** %pos) {
; CHECK-LABEL: @metadata(
; CHECK-NEXT: header:
; CHECK-NEXT: [[PTR0:%.*]] = load i8*, i8** [[POS:%.*]], align 4
; CHECK-NEXT: [[MIN_ITERS_CHECK:%.*]] = icmp ult i32 [[SIZE:%.*]], 4
; CHECK-NEXT: br i1 [[MIN_ITERS_CHECK]], label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]]
; CHECK: vector.ph:
; CHECK-NEXT: [[N_MOD_VF:%.*]] = urem i32 [[SIZE]], 4
; CHECK-NEXT: [[N_VEC:%.*]] = sub i32 [[SIZE]], [[N_MOD_VF]]
; CHECK-NEXT: [[IND_END:%.*]] = sub i32 [[SIZE]], [[N_VEC]]
; CHECK-NEXT: [[IND_END2:%.*]] = getelementptr i8, i8* [[PTR:%.*]], i32 [[N_VEC]]
; 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:%.*]] = sub i32 [[SIZE]], [[INDEX]]
; CHECK-NEXT: [[TMP0:%.*]] = add i32 [[OFFSET_IDX]], 0
; CHECK-NEXT: [[TMP1:%.*]] = add i32 [[INDEX]], 0
; CHECK-NEXT: [[NEXT_GEP:%.*]] = getelementptr i8, i8* [[PTR]], i32 [[TMP1]]
; CHECK-NEXT: [[TMP2:%.*]] = getelementptr inbounds i8, i8* [[NEXT_GEP]], i32 1
; CHECK-NEXT: [[TMP3:%.*]] = getelementptr inbounds i8, i8* [[TMP2]], i32 0
; CHECK-NEXT: [[TMP4:%.*]] = bitcast i8* [[TMP3]] to <4 x i8>*
; CHECK-NEXT: [[WIDE_LOAD:%.*]] = load <4 x i8>, <4 x i8>* [[TMP4]], align 1
; CHECK-NEXT: [[TMP5:%.*]] = getelementptr i8, i8* [[NEXT_GEP]], i32 0
; CHECK-NEXT: [[TMP6:%.*]] = bitcast i8* [[TMP5]] to <4 x i8>*
; CHECK-NEXT: store <4 x i8> [[WIDE_LOAD]], <4 x i8>* [[TMP6]], align 1
; CHECK-NEXT: [[INDEX_NEXT]] = add i32 [[INDEX]], 4
; CHECK-NEXT: [[TMP7:%.*]] = icmp eq i32 [[INDEX_NEXT]], [[N_VEC]]
; CHECK-NEXT: br i1 [[TMP7]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop !4
; CHECK: middle.block:
; CHECK-NEXT: [[CMP_N:%.*]] = icmp eq i32 [[SIZE]], [[N_VEC]]
; CHECK-NEXT: br i1 [[CMP_N]], label [[END:%.*]], label [[SCALAR_PH]]
; CHECK: scalar.ph:
; CHECK-NEXT: [[BC_RESUME_VAL:%.*]] = phi i32 [ [[IND_END]], [[MIDDLE_BLOCK]] ], [ [[SIZE]], [[HEADER:%.*]] ]
; CHECK-NEXT: [[BC_RESUME_VAL1:%.*]] = phi i8* [ [[IND_END2]], [[MIDDLE_BLOCK]] ], [ [[PTR]], [[HEADER]] ]
; CHECK-NEXT: br label [[BODY:%.*]]
; CHECK: body:
; CHECK-NEXT: [[DEC66:%.*]] = phi i32 [ [[DEC:%.*]], [[BODY]] ], [ [[BC_RESUME_VAL]], [[SCALAR_PH]] ]
; CHECK-NEXT: [[BUFF:%.*]] = phi i8* [ [[INCDEC_PTR:%.*]], [[BODY]] ], [ [[BC_RESUME_VAL1]], [[SCALAR_PH]] ]
; CHECK-NEXT: [[INCDEC_PTR]] = getelementptr inbounds i8, i8* [[BUFF]], i32 1
; CHECK-NEXT: [[DEC]] = add nsw i32 [[DEC66]], -1
; CHECK-NEXT: [[TMP8:%.*]] = load i8, i8* [[INCDEC_PTR]], align 1
; CHECK-NEXT: store i8 [[TMP8]], i8* [[BUFF]], align 1
; CHECK-NEXT: [[TOBOOL11:%.*]] = icmp eq i32 [[DEC]], 0
; CHECK-NEXT: br i1 [[TOBOOL11]], label [[END]], label [[BODY]], !llvm.loop !5
; CHECK: end:
; CHECK-NEXT: [[INCDEC_PTR_LCSSA:%.*]] = phi i8* [ [[INCDEC_PTR]], [[BODY]] ], [ [[IND_END2]], [[MIDDLE_BLOCK]] ]
; CHECK-NEXT: store i8* [[INCDEC_PTR_LCSSA]], i8** [[POS]], align 4
; CHECK-NEXT: ret void
;
header:
%ptr0 = load i8*, i8** %pos, align 4
br label %body
body:
%dec66 = phi i32 [ %dec, %body ], [ %size, %header ]
%buff = phi i8* [ %incdec.ptr, %body ], [ %ptr, %header ]
%incdec.ptr = getelementptr inbounds i8, i8* %buff, i32 1
%dec = add nsw i32 %dec66, -1
%0 = load i8, i8* %incdec.ptr, align 1
store i8 %0, i8* %buff, align 1
%tobool11 = icmp eq i32 %dec, 0
br i1 %tobool11, label %end, label %body, !llvm.loop !1
end:
store i8* %incdec.ptr, i8** %pos, align 4
ret void
}
!1 = distinct !{!1, !2, !3}
!2 = !{!"llvm.loop.vectorize.predicate.enable", i1 true}
!3 = !{!"llvm.loop.vectorize.enable", i1 true}