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Revert "[LV] Extend trunc optimization to all IVs with constant integer steps"

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This reverts commit r294967. This patch caused execution time slowdowns in a
few LLVM test-suite tests, as reported by the clang-cmake-aarch64-quick bot.
I'm reverting to investigate.

llvm-svn: 294973
This commit is contained in:
Matthew Simpson 2017-02-13 18:02:35 +00:00
parent 58a221a4e2
commit 659f92e2aa
3 changed files with 14 additions and 54 deletions
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32
llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
View File

@ -4879,15 +4879,12 @@ void InnerLoopVectorizer::vectorizeBlockInLoop(BasicBlock *BB, PhiVector *PV) {
// induction variable. Notice that we can only optimize the 'trunc' case
// because (a) FP conversions lose precision, (b) sext/zext may wrap, and
// (c) other casts depend on pointer size.
if (auto *Trunc = dyn_cast<TruncInst>(CI))
if (auto *Phi = dyn_cast<PHINode>(Trunc->getOperand(0))) {
auto II = Legal->getInductionVars()->find(Phi);
if (II != Legal->getInductionVars()->end())
if (II->second.getConstIntStepValue()) {
widenIntInduction(Phi, Trunc);
break;
}
}
auto ID = Legal->getInductionVars()->lookup(OldInduction);
if (isa<TruncInst>(CI) && CI->getOperand(0) == OldInduction &&
ID.getConstIntStepValue()) {
widenIntInduction(OldInduction, cast<TruncInst>(CI));
break;
}
/// Vectorize casts.
Type *DestTy =
@ -7227,17 +7224,12 @@ unsigned LoopVectorizationCostModel::getInstructionCost(Instruction *I,
case Instruction::Trunc:
case Instruction::FPTrunc:
case Instruction::BitCast: {
// We optimize the truncation of induction variables having constant
// integer steps. The cost of these truncations is the same as the scalar
// operation.
if (auto *Trunc = dyn_cast<TruncInst>(I))
if (auto *Phi = dyn_cast<PHINode>(Trunc->getOperand(0))) {
auto II = Legal->getInductionVars()->find(Phi);
if (II != Legal->getInductionVars()->end())
if (II->second.getConstIntStepValue())
return TTI.getCastInstrCost(Instruction::Trunc, Trunc->getDestTy(),
Trunc->getSrcTy());
}
// We optimize the truncation of induction variable.
// The cost of these is the same as the scalar operation.
if (I->getOpcode() == Instruction::Trunc &&
Legal->isInductionVariable(I->getOperand(0)))
return TTI.getCastInstrCost(I->getOpcode(), I->getType(),
I->getOperand(0)->getType());
Type *SrcScalarTy = I->getOperand(0)->getType();
Type *SrcVecTy = ToVectorTy(SrcScalarTy, VF);

31
llvm/test/Transforms/LoopVectorize/induction.ll
View File

@ -773,34 +773,3 @@ for.body:
exit:
ret void
}
; CHECK-LABEL: @non_primary_iv_trunc(
; CHECK: vector.body:
; CHECK-NEXT: %index = phi i64 [ 0, %vector.ph ], [ %index.next, %vector.body ]
; CHECK: [[VEC_IND:%.*]] = phi <2 x i32> [ <i32 0, i32 2>, %vector.ph ], [ [[VEC_IND_NEXT:%.*]], %vector.body ]
; CHECK: [[TMP3:%.*]] = add i64 %index, 0
; CHECK-NEXT: [[TMP4:%.*]] = getelementptr inbounds i32, i32* %a, i64 [[TMP3]]
; CHECK-NEXT: [[TMP5:%.*]] = getelementptr i32, i32* [[TMP4]], i32 0
; CHECK-NEXT: [[TMP6:%.*]] = bitcast i32* [[TMP5]] to <2 x i32>*
; CHECK-NEXT: store <2 x i32> [[VEC_IND]], <2 x i32>* [[TMP6]], align 4
; CHECK-NEXT: %index.next = add i64 %index, 2
; CHECK: [[VEC_IND_NEXT]] = add <2 x i32> [[VEC_IND]], <i32 4, i32 4>
; CHECK: br i1 {{.*}}, label %middle.block, label %vector.body
define void @non_primary_iv_trunc(i32* %a, i64 %n) {
entry:
br label %for.body
for.body:
%i = phi i64 [ %i.next, %for.body ], [ 0, %entry ]
%j = phi i64 [ %j.next, %for.body ], [ 0, %entry ]
%tmp0 = getelementptr inbounds i32, i32* %a, i64 %i
%tmp1 = trunc i64 %j to i32
store i32 %tmp1, i32* %tmp0, align 4
%i.next = add nuw nsw i64 %i, 1
%j.next = add nuw nsw i64 %j, 2
%cond = icmp slt i64 %i.next, %n
br i1 %cond, label %for.body, label %for.end
for.end:
ret void
}

5
llvm/test/Transforms/LoopVectorize/reverse_iter.ll
View File

@ -2,8 +2,7 @@
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"
; PR15882: This test ensures that we do not produce wrapping arithmetic when
; creating constant reverse step vectors.
; Make sure that the reverse iterators are calculated using 64bit arithmetic, not 32.
;
; int foo(int n, int *A) {
; int sum;
@ -14,7 +13,7 @@ target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f3
;
;CHECK-LABEL: @foo(
;CHECK: <i32 0, i32 -1, i32 -2, i32 -3>
;CHECK: <i64 0, i64 -1, i64 -2, i64 -3>
;CHECK: ret
define i32 @foo(i32 %n, i32* nocapture %A) {
%1 = icmp sgt i32 %n, 0