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clang-p2996/llvm/test/Transforms/LoopVectorize/induction-step.ll
Florian Hahn 23c2f2e6b2 [LV] Mark increment of main vector loop induction variable as NUW. 
This patch marks the induction increment of the main induction variable
of the vector loop as NUW when not folding the tail.

If the tail is not folded, we know that End - Start >= Step (either
statically or through the minimum iteration checks). We also know that both
Start % Step == 0 and End % Step == 0. We exit the vector loop if %IV +
%Step == %End. Hence we must exit the loop before %IV + %Step unsigned
overflows and we can mark the induction increment as NUW.

This should make SCEV return more precise bounds for the created vector
loops, used by later optimizations, like late unrolling.

At the moment quite a few tests still need to be updated, but before
doing so I'd like to get initial feedback to make sure I am not missing
anything.

Note that this could probably be further improved by using information
from the original IV.

Attempt of modeling of the assumption in Alive2:
https://alive2.llvm.org/ce/z/H_DL_g

Part of a set of fixes required for PR50412.

Reviewed By: mkazantsev

Differential Revision: https://reviews.llvm.org/D103255
2021-06-07 10:47:52 +01:00

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9.7 KiB
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; RUN: opt < %s -loop-vectorize -force-vector-interleave=1 -force-vector-width=8 -S | FileCheck %s
; int int_inc;
;
;int induction_with_global(int init, int *restrict A, int N) {
; int x = init;
; for (int i=0;i<N;i++){
; A[i] = x;
; x += int_inc;
; }
; return x;
;}
; CHECK-LABEL: @induction_with_global(
; CHECK: for.body.lr.ph:
; CHECK-NEXT: [[TMP0:%.*]] = load i32, i32* @int_inc, align 4
; CHECK: vector.ph:
; CHECK: [[DOTSPLATINSERT:%.*]] = insertelement <8 x i32> poison, i32 %init, i32 0
; CHECK-NEXT: [[DOTSPLAT:%.*]] = shufflevector <8 x i32> [[DOTSPLATINSERT]], <8 x i32> poison, <8 x i32> zeroinitializer
; CHECK-NEXT: [[DOTSPLATINSERT2:%.*]] = insertelement <8 x i32> poison, i32 [[TMP0]], i32 0
; CHECK-NEXT: [[DOTSPLAT3:%.*]] = shufflevector <8 x i32> [[DOTSPLATINSERT2]], <8 x i32> poison, <8 x i32> zeroinitializer
; CHECK-NEXT: [[TMP6:%.*]] = mul <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7>, [[DOTSPLAT3]]
; CHECK-NEXT: [[INDUCTION4:%.*]] = add <8 x i32> [[DOTSPLAT]], [[TMP6]]
; CHECK-NEXT: [[TMP7:%.*]] = mul i32 [[TMP0]], 8
; CHECK-NEXT: [[DOTSPLATINSERT5:%.*]] = insertelement <8 x i32> poison, i32 [[TMP7]], i32 0
; CHECK-NEXT: [[DOTSPLAT6:%.*]] = shufflevector <8 x i32> [[DOTSPLATINSERT5]], <8 x i32> poison, <8 x i32> zeroinitializer
; CHECK-NEXT: br label %vector.body
; CHECK: vector.body:
; CHECK-NEXT: %index = phi i64 [ 0, %vector.ph ], [ %index.next, %vector.body ]
; CHECK-NEXT: %vec.ind = phi <8 x i32> [ [[INDUCTION4]], %vector.ph ], [ %vec.ind.next, %vector.body ]
; CHECK: [[TMP8:%.*]] = add i64 %index, 0
; CHECK-NEXT: [[TMP9:%.*]] = getelementptr inbounds i32, i32* [[A:%.*]], i64 [[TMP8]]
; CHECK-NEXT: [[TMP10:%.*]] = getelementptr inbounds i32, i32* [[TMP9]], i32 0
; CHECK-NEXT: [[TMP11:%.*]] = bitcast i32* [[TMP10]] to <8 x i32>*
; CHECK-NEXT: store <8 x i32> %vec.ind, <8 x i32>* [[TMP11]], align 4
; CHECK: %index.next = add nuw i64 %index, 8
; CHECK-NEXT: %vec.ind.next = add <8 x i32> %vec.ind, [[DOTSPLAT6]]
; CHECK: br i1 {{.*}}, label %middle.block, label %vector.body
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
@int_inc = common global i32 0, align 4
define i32 @induction_with_global(i32 %init, i32* noalias nocapture %A, i32 %N) {
entry:
%cmp4 = icmp sgt i32 %N, 0
br i1 %cmp4, label %for.body.lr.ph, label %for.end
for.body.lr.ph: ; preds = %entry
%0 = load i32, i32* @int_inc, align 4
%1 = mul i32 %0, %N
br label %for.body
for.body: ; preds = %for.body, %for.body.lr.ph
%indvars.iv = phi i64 [ 0, %for.body.lr.ph ], [ %indvars.iv.next, %for.body ]
%x.05 = phi i32 [ %init, %for.body.lr.ph ], [ %add, %for.body ]
%arrayidx = getelementptr inbounds i32, i32* %A, i64 %indvars.iv
store i32 %x.05, i32* %arrayidx, align 4
%add = add nsw i32 %0, %x.05
%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, %N
br i1 %exitcond, label %for.end.loopexit, label %for.body
for.end.loopexit: ; preds = %for.body
%2 = add i32 %1, %init
br label %for.end
for.end: ; preds = %for.end.loopexit, %entry
%x.0.lcssa = phi i32 [ %init, %entry ], [ %2, %for.end.loopexit ]
ret i32 %x.0.lcssa
}
;int induction_with_loop_inv(int init, int *restrict A, int N, int M) {
; int x = init;
; for (int j = 0; j < M; j++) {
; for (int i=0; i<N; i++){
; A[i] = x;
; x += j; // induction step is a loop invariant variable
; }
; }
; return x;
;}
; CHECK-LABEL: @induction_with_loop_inv(
; CHECK: vector.ph:
; CHECK: [[DOTSPLATINSERT:%.*]] = insertelement <8 x i32> poison, i32 %x.011, i32 0
; CHECK-NEXT: [[DOTSPLAT:%.*]] = shufflevector <8 x i32> [[DOTSPLATINSERT]], <8 x i32> poison, <8 x i32> zeroinitializer
; CHECK-NEXT: [[DOTSPLATINSERT2:%.*]] = insertelement <8 x i32> poison, i32 %j.012, i32 0
; CHECK-NEXT: [[DOTSPLAT3:%.*]] = shufflevector <8 x i32> [[DOTSPLATINSERT2]], <8 x i32> poison, <8 x i32> zeroinitializer
; CHECK-NEXT: [[TMP4:%.*]] = mul <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7>, [[DOTSPLAT3]]
; CHECK-NEXT: [[INDUCTION4:%.*]] = add <8 x i32> [[DOTSPLAT]], [[TMP4]]
; CHECK-NEXT: [[TMP5:%.*]] = mul i32 %j.012, 8
; CHECK-NEXT: [[DOTSPLATINSERT5:%.*]] = insertelement <8 x i32> poison, i32 [[TMP5]], i32 0
; CHECK-NEXT: [[DOTSPLAT6:%.*]] = shufflevector <8 x i32> [[DOTSPLATINSERT5]], <8 x i32> poison, <8 x i32> zeroinitializer
; CHECK-NEXT: br label %vector.body
; CHECK: vector.body:
; CHECK-NEXT: %index = phi i64 [ 0, %vector.ph ], [ %index.next, %vector.body ]
; CHECK-NEXT: %vec.ind = phi <8 x i32> [ [[INDUCTION4]], %vector.ph ], [ %vec.ind.next, %vector.body ]
; CHECK: [[TMP6:%.*]] = add i64 %index, 0
; CHECK-NEXT: [[TMP7:%.*]] = getelementptr inbounds i32, i32* [[A:%.*]], i64 [[TMP6]]
; CHECK-NEXT: [[TMP8:%.*]] = getelementptr inbounds i32, i32* [[TMP7]], i32 0
; CHECK-NEXT: [[TMP9:%.*]] = bitcast i32* [[TMP8]] to <8 x i32>*
; CHECK-NEXT: store <8 x i32> %vec.ind, <8 x i32>* [[TMP9]], align 4
; CHECK: %index.next = add nuw i64 %index, 8
; CHECK-NEXT: %vec.ind.next = add <8 x i32> %vec.ind, [[DOTSPLAT6]]
; CHECK: br i1 {{.*}}, label %middle.block, label %vector.body
define i32 @induction_with_loop_inv(i32 %init, i32* noalias nocapture %A, i32 %N, i32 %M) {
entry:
%cmp10 = icmp sgt i32 %M, 0
br i1 %cmp10, label %for.cond1.preheader.lr.ph, label %for.end6
for.cond1.preheader.lr.ph: ; preds = %entry
%cmp27 = icmp sgt i32 %N, 0
br label %for.cond1.preheader
for.cond1.preheader: ; preds = %for.inc4, %for.cond1.preheader.lr.ph
%indvars.iv15 = phi i32 [ 0, %for.cond1.preheader.lr.ph ], [ %indvars.iv.next16, %for.inc4 ]
%j.012 = phi i32 [ 0, %for.cond1.preheader.lr.ph ], [ %inc5, %for.inc4 ]
%x.011 = phi i32 [ %init, %for.cond1.preheader.lr.ph ], [ %x.1.lcssa, %for.inc4 ]
br i1 %cmp27, label %for.body3.preheader, label %for.inc4
for.body3.preheader: ; preds = %for.cond1.preheader
br label %for.body3
for.body3: ; preds = %for.body3.preheader, %for.body3
%indvars.iv = phi i64 [ %indvars.iv.next, %for.body3 ], [ 0, %for.body3.preheader ]
%x.18 = phi i32 [ %add, %for.body3 ], [ %x.011, %for.body3.preheader ]
%arrayidx = getelementptr inbounds i32, i32* %A, i64 %indvars.iv
store i32 %x.18, i32* %arrayidx, align 4
%add = add nsw i32 %x.18, %j.012
%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, %N
br i1 %exitcond, label %for.inc4.loopexit, label %for.body3
for.inc4.loopexit: ; preds = %for.body3
%0 = add i32 %x.011, %indvars.iv15
br label %for.inc4
for.inc4: ; preds = %for.inc4.loopexit, %for.cond1.preheader
%x.1.lcssa = phi i32 [ %x.011, %for.cond1.preheader ], [ %0, %for.inc4.loopexit ]
%inc5 = add nuw nsw i32 %j.012, 1
%indvars.iv.next16 = add i32 %indvars.iv15, %N
%exitcond17 = icmp eq i32 %inc5, %M
br i1 %exitcond17, label %for.end6.loopexit, label %for.cond1.preheader
for.end6.loopexit: ; preds = %for.inc4
%x.1.lcssa.lcssa = phi i32 [ %x.1.lcssa, %for.inc4 ]
br label %for.end6
for.end6: ; preds = %for.end6.loopexit, %entry
%x.0.lcssa = phi i32 [ %init, %entry ], [ %x.1.lcssa.lcssa, %for.end6.loopexit ]
ret i32 %x.0.lcssa
}
; CHECK-LABEL: @non_primary_iv_loop_inv_trunc(
; CHECK: vector.ph:
; CHECK: [[TMP3:%.*]] = trunc i64 %step to i32
; CHECK-NEXT: [[DOTSPLATINSERT5:%.*]] = insertelement <8 x i32> poison, i32 [[TMP3]], i32 0
; CHECK-NEXT: [[DOTSPLAT6:%.*]] = shufflevector <8 x i32> [[DOTSPLATINSERT5]], <8 x i32> poison, <8 x i32> zeroinitializer
; CHECK-NEXT: [[TMP4:%.*]] = mul <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7>, [[DOTSPLAT6]]
; CHECK-NEXT: [[INDUCTION7:%.*]] = add <8 x i32> zeroinitializer, [[TMP4]]
; CHECK-NEXT: [[TMP5:%.*]] = mul i32 [[TMP3]], 8
; CHECK-NEXT: [[DOTSPLATINSERT8:%.*]] = insertelement <8 x i32> poison, i32 [[TMP5]], i32 0
; CHECK-NEXT: [[DOTSPLAT9:%.*]] = shufflevector <8 x i32> [[DOTSPLATINSERT8]], <8 x i32> poison, <8 x i32> zeroinitializer
; CHECK-NEXT: br label %vector.body
; CHECK: vector.body:
; CHECK-NEXT: %index = phi i64 [ 0, %vector.ph ], [ %index.next, %vector.body ]
; CHECK: [[VEC_IND10:%.*]] = phi <8 x i32> [ [[INDUCTION7]], %vector.ph ], [ [[VEC_IND_NEXT11:%.*]], %vector.body ]
; CHECK: [[TMP6:%.*]] = add i64 %index, 0
; CHECK-NEXT: [[TMP7:%.*]] = getelementptr inbounds i32, i32* [[A:%.*]], i64 [[TMP6]]
; CHECK-NEXT: [[TMP8:%.*]] = getelementptr inbounds i32, i32* [[TMP7]], i32 0
; CHECK-NEXT: [[TMP9:%.*]] = bitcast i32* [[TMP8]] to <8 x i32>*
; CHECK-NEXT: store <8 x i32> [[VEC_IND10]], <8 x i32>* [[TMP9]], align 4
; CHECK-NEXT: %index.next = add nuw i64 %index, 8
; CHECK: [[VEC_IND_NEXT11]] = add <8 x i32> [[VEC_IND10]], [[DOTSPLAT9]]
; CHECK: br i1 {{.*}}, label %middle.block, label %vector.body
define void @non_primary_iv_loop_inv_trunc(i32* %a, i64 %n, i64 %step) {
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, %step
%cond = icmp slt i64 %i.next, %n
br i1 %cond, label %for.body, label %for.end
for.end:
ret void
}
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