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clang-p2996/llvm/test/Transforms/LoopVectorize/first-order-recurrence.ll
Anna Thomas dcdb325fee [LV] Fix the vector code generation for first order recurrence 
Summary:
In first order recurrences where phi's are used outside the loop,
we should generate an additional vector.extract of the second last element from
the vectorized phi update.
This is because we require the phi itself (which is the value at the second last
iteration of the vector loop) and not the phi's update within the loop.
Also fix the code gen when we just unroll, but don't vectorize.
Fixes PR32396.

Reviewers: mssimpso, mkuper, anemet

Subscribers: llvm-commits, mzolotukhin

Differential Revision: https://reviews.llvm.org/D31979

llvm-svn: 300238
2017-04-13 18:59:25 +00:00

399 lines
17 KiB
LLVM
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; RUN: opt < %s -loop-vectorize -force-vector-width=4 -force-vector-interleave=1 -dce -instcombine -S | FileCheck %s
; RUN: opt < %s -loop-vectorize -force-vector-width=4 -force-vector-interleave=2 -dce -instcombine -S | FileCheck %s --check-prefix=UNROLL
; RUN: opt < %s -loop-vectorize -force-vector-width=4 -force-vector-interleave=2 -S | FileCheck %s --check-prefix=UNROLL-NO-IC
; RUN: opt < %s -loop-vectorize -force-vector-width=1 -force-vector-interleave=2 -S | FileCheck %s --check-prefix=UNROLL-NO-VF
target datalayout = "e-m:e-i64:64-i128:128-n32:64-S128"
; void recurrence_1(int *a, int *b, int n) {
; for(int i = 0; i < n; i++)
; b[i] = a[i] + a[i - 1]
; }
;
; CHECK-LABEL: @recurrence_1(
; CHECK: vector.ph:
; CHECK: %vector.recur.init = insertelement <4 x i32> undef, i32 %pre_load, i32 3
; CHECK: vector.body:
; CHECK: %vector.recur = phi <4 x i32> [ %vector.recur.init, %vector.ph ], [ [[L1:%[a-zA-Z0-9.]+]], %vector.body ]
; CHECK: [[L1]] = load <4 x i32>
; CHECK: {{.*}} = shufflevector <4 x i32> %vector.recur, <4 x i32> [[L1]], <4 x i32> <i32 3, i32 4, i32 5, i32 6>
; CHECK: middle.block:
; CHECK: %vector.recur.extract = extractelement <4 x i32> [[L1]], i32 3
; CHECK: scalar.ph:
; CHECK: %scalar.recur.init = phi i32 [ %vector.recur.extract, %middle.block ], [ %pre_load, %vector.memcheck ], [ %pre_load, %min.iters.checked ], [ %pre_load, %for.preheader ]
; CHECK: scalar.body:
; CHECK: %scalar.recur = phi i32 [ %scalar.recur.init, %scalar.ph ], [ {{.*}}, %scalar.body ]
;
; UNROLL-LABEL: @recurrence_1(
; UNROLL: vector.body:
; UNROLL: %vector.recur = phi <4 x i32> [ %vector.recur.init, %vector.ph ], [ [[L2:%[a-zA-Z0-9.]+]], %vector.body ]
; UNROLL: [[L1:%[a-zA-Z0-9.]+]] = load <4 x i32>
; UNROLL: [[L2]] = load <4 x i32>
; UNROLL: {{.*}} = shufflevector <4 x i32> %vector.recur, <4 x i32> [[L1]], <4 x i32> <i32 3, i32 4, i32 5, i32 6>
; UNROLL: {{.*}} = shufflevector <4 x i32> [[L1]], <4 x i32> [[L2]], <4 x i32> <i32 3, i32 4, i32 5, i32 6>
; UNROLL: middle.block:
; UNROLL: %vector.recur.extract = extractelement <4 x i32> [[L2]], i32 3
;
define void @recurrence_1(i32* nocapture readonly %a, i32* nocapture %b, i32 %n) {
entry:
br label %for.preheader
for.preheader:
%arrayidx.phi.trans.insert = getelementptr inbounds i32, i32* %a, i64 0
%pre_load = load i32, i32* %arrayidx.phi.trans.insert
br label %scalar.body
scalar.body:
%0 = phi i32 [ %pre_load, %for.preheader ], [ %1, %scalar.body ]
%indvars.iv = phi i64 [ 0, %for.preheader ], [ %indvars.iv.next, %scalar.body ]
%indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
%arrayidx32 = getelementptr inbounds i32, i32* %a, i64 %indvars.iv.next
%1 = load i32, i32* %arrayidx32
%arrayidx34 = getelementptr inbounds i32, i32* %b, i64 %indvars.iv
%add35 = add i32 %1, %0
store i32 %add35, i32* %arrayidx34
%lftr.wideiv = trunc i64 %indvars.iv.next to i32
%exitcond = icmp eq i32 %lftr.wideiv, %n
br i1 %exitcond, label %for.exit, label %scalar.body
for.exit:
ret void
}
; int recurrence_2(int *a, int n) {
; int minmax;
; for (int i = 0; i < n; ++i)
; minmax = min(minmax, max(a[i] - a[i-1], 0));
; return minmax;
; }
;
; CHECK-LABEL: @recurrence_2(
; CHECK: vector.ph:
; CHECK: %vector.recur.init = insertelement <4 x i32> undef, i32 %.pre, i32 3
; CHECK: vector.body:
; CHECK: %vector.recur = phi <4 x i32> [ %vector.recur.init, %vector.ph ], [ [[L1:%[a-zA-Z0-9.]+]], %vector.body ]
; CHECK: [[L1]] = load <4 x i32>
; CHECK: {{.*}} = shufflevector <4 x i32> %vector.recur, <4 x i32> [[L1]], <4 x i32> <i32 3, i32 4, i32 5, i32 6>
; CHECK: middle.block:
; CHECK: %vector.recur.extract = extractelement <4 x i32> [[L1]], i32 3
; CHECK: scalar.ph:
; CHECK: %scalar.recur.init = phi i32 [ %vector.recur.extract, %middle.block ], [ %.pre, %min.iters.checked ], [ %.pre, %for.preheader ]
; CHECK: scalar.body:
; CHECK: %scalar.recur = phi i32 [ %scalar.recur.init, %scalar.ph ], [ {{.*}}, %scalar.body ]
;
; UNROLL-LABEL: @recurrence_2(
; UNROLL: vector.body:
; UNROLL: %vector.recur = phi <4 x i32> [ %vector.recur.init, %vector.ph ], [ [[L2:%[a-zA-Z0-9.]+]], %vector.body ]
; UNROLL: [[L1:%[a-zA-Z0-9.]+]] = load <4 x i32>
; UNROLL: [[L2]] = load <4 x i32>
; UNROLL: {{.*}} = shufflevector <4 x i32> %vector.recur, <4 x i32> [[L1]], <4 x i32> <i32 3, i32 4, i32 5, i32 6>
; UNROLL: {{.*}} = shufflevector <4 x i32> [[L1]], <4 x i32> [[L2]], <4 x i32> <i32 3, i32 4, i32 5, i32 6>
; UNROLL: middle.block:
; UNROLL: %vector.recur.extract = extractelement <4 x i32> [[L2]], i32 3
;
define i32 @recurrence_2(i32* nocapture readonly %a, i32 %n) {
entry:
%cmp27 = icmp sgt i32 %n, 0
br i1 %cmp27, label %for.preheader, label %for.cond.cleanup
for.preheader:
%arrayidx2.phi.trans.insert = getelementptr inbounds i32, i32* %a, i64 -1
%.pre = load i32, i32* %arrayidx2.phi.trans.insert, align 4
br label %scalar.body
for.cond.cleanup.loopexit:
%minmax.0.cond.lcssa = phi i32 [ %minmax.0.cond, %scalar.body ]
br label %for.cond.cleanup
for.cond.cleanup:
%minmax.0.lcssa = phi i32 [ undef, %entry ], [ %minmax.0.cond.lcssa, %for.cond.cleanup.loopexit ]
ret i32 %minmax.0.lcssa
scalar.body:
%0 = phi i32 [ %.pre, %for.preheader ], [ %1, %scalar.body ]
%indvars.iv = phi i64 [ 0, %for.preheader ], [ %indvars.iv.next, %scalar.body ]
%minmax.028 = phi i32 [ undef, %for.preheader ], [ %minmax.0.cond, %scalar.body ]
%arrayidx = getelementptr inbounds i32, i32* %a, i64 %indvars.iv
%1 = load i32, i32* %arrayidx, align 4
%sub3 = sub nsw i32 %1, %0
%cmp4 = icmp sgt i32 %sub3, 0
%cond = select i1 %cmp4, i32 %sub3, i32 0
%cmp5 = icmp slt i32 %minmax.028, %cond
%minmax.0.cond = select i1 %cmp5, i32 %minmax.028, i32 %cond
%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.cond.cleanup.loopexit, label %scalar.body
}
; void recurrence_3(short *a, double *b, int n, float f, short p) {
; b[0] = (double)a[0] - f * (double)p;
; for (int i = 1; i < n; i++)
; b[i] = (double)a[i] - f * (double)a[i - 1];
; }
;
; CHECK-LABEL: @recurrence_3(
; CHECK: vector.ph:
; CHECK: %vector.recur.init = insertelement <4 x i16> undef, i16 %0, i32 3
; CHECK: vector.body:
; CHECK: %vector.recur = phi <4 x i16> [ %vector.recur.init, %vector.ph ], [ [[L1:%[a-zA-Z0-9.]+]], %vector.body ]
; CHECK: [[L1]] = load <4 x i16>
; CHECK: {{.*}} = shufflevector <4 x i16> %vector.recur, <4 x i16> [[L1]], <4 x i32> <i32 3, i32 4, i32 5, i32 6>
; CHECK: middle.block:
; CHECK: %vector.recur.extract = extractelement <4 x i16> [[L1]], i32 3
; CHECK: scalar.ph:
; CHECK: %scalar.recur.init = phi i16 [ %vector.recur.extract, %middle.block ], [ %0, %vector.memcheck ], [ %0, %min.iters.checked ], [ %0, %for.preheader ]
; CHECK: scalar.body:
; CHECK: %scalar.recur = phi i16 [ %scalar.recur.init, %scalar.ph ], [ {{.*}}, %scalar.body ]
;
; UNROLL-LABEL: @recurrence_3(
; UNROLL: vector.body:
; UNROLL: %vector.recur = phi <4 x i16> [ %vector.recur.init, %vector.ph ], [ [[L2:%[a-zA-Z0-9.]+]], %vector.body ]
; UNROLL: [[L1:%[a-zA-Z0-9.]+]] = load <4 x i16>
; UNROLL: [[L2]] = load <4 x i16>
; UNROLL: {{.*}} = shufflevector <4 x i16> %vector.recur, <4 x i16> [[L1]], <4 x i32> <i32 3, i32 4, i32 5, i32 6>
; UNROLL: {{.*}} = shufflevector <4 x i16> [[L1]], <4 x i16> [[L2]], <4 x i32> <i32 3, i32 4, i32 5, i32 6>
; UNROLL: middle.block:
; UNROLL: %vector.recur.extract = extractelement <4 x i16> [[L2]], i32 3
;
define void @recurrence_3(i16* nocapture readonly %a, double* nocapture %b, i32 %n, float %f, i16 %p) {
entry:
%0 = load i16, i16* %a, align 2
%conv = sitofp i16 %0 to double
%conv1 = fpext float %f to double
%conv2 = sitofp i16 %p to double
%mul = fmul fast double %conv2, %conv1
%sub = fsub fast double %conv, %mul
store double %sub, double* %b, align 8
%cmp25 = icmp sgt i32 %n, 1
br i1 %cmp25, label %for.preheader, label %for.end
for.preheader:
br label %scalar.body
scalar.body:
%1 = phi i16 [ %0, %for.preheader ], [ %2, %scalar.body ]
%advars.iv = phi i64 [ %advars.iv.next, %scalar.body ], [ 1, %for.preheader ]
%arrayidx5 = getelementptr inbounds i16, i16* %a, i64 %advars.iv
%2 = load i16, i16* %arrayidx5, align 2
%conv6 = sitofp i16 %2 to double
%conv11 = sitofp i16 %1 to double
%mul12 = fmul fast double %conv11, %conv1
%sub13 = fsub fast double %conv6, %mul12
%arrayidx15 = getelementptr inbounds double, double* %b, i64 %advars.iv
store double %sub13, double* %arrayidx15, align 8
%advars.iv.next = add nuw nsw i64 %advars.iv, 1
%lftr.wideiv = trunc i64 %advars.iv.next to i32
%exitcond = icmp eq i32 %lftr.wideiv, %n
br i1 %exitcond, label %for.end.loopexit, label %scalar.body
for.end.loopexit:
br label %for.end
for.end:
ret void
}
; void PR26734(short *a, int *b, int *c, int d, short *e) {
; for (; d != 21; d++) {
; *b &= *c;
; *e = *a - 6;
; *c = *e;
; }
; }
;
; CHECK-LABEL: @PR26734(
; CHECK-NOT: vector.ph:
; CHECK: }
;
define void @PR26734(i16* %a, i32* %b, i32* %c, i32 %d, i16* %e) {
entry:
%cmp4 = icmp eq i32 %d, 21
br i1 %cmp4, label %entry.for.end_crit_edge, label %for.body.lr.ph
entry.for.end_crit_edge:
%.pre = load i32, i32* %b, align 4
br label %for.end
for.body.lr.ph:
%0 = load i16, i16* %a, align 2
%sub = add i16 %0, -6
%conv2 = sext i16 %sub to i32
%c.promoted = load i32, i32* %c, align 4
%b.promoted = load i32, i32* %b, align 4
br label %for.body
for.body:
%inc7 = phi i32 [ %d, %for.body.lr.ph ], [ %inc, %for.body ]
%and6 = phi i32 [ %b.promoted, %for.body.lr.ph ], [ %and, %for.body ]
%conv25 = phi i32 [ %c.promoted, %for.body.lr.ph ], [ %conv2, %for.body ]
%and = and i32 %and6, %conv25
%inc = add nsw i32 %inc7, 1
%cmp = icmp eq i32 %inc, 21
br i1 %cmp, label %for.cond.for.end_crit_edge, label %for.body
for.cond.for.end_crit_edge:
%and.lcssa = phi i32 [ %and, %for.body ]
store i32 %conv2, i32* %c, align 4
store i32 %and.lcssa, i32* %b, align 4
store i16 %sub, i16* %e, align 2
br label %for.end
for.end:
ret void
}
; int PR27246() {
; unsigned int e, n;
; for (int i = 1; i < 49; ++i) {
; for (int k = i; k > 1; --k)
; e = k;
; n = e;
; }
; return n;
; }
;
; CHECK-LABEL: @PR27246(
; CHECK-NOT: vector.ph:
; CHECK: }
;
define i32 @PR27246() {
entry:
br label %for.cond1.preheader
for.cond1.preheader:
%i.016 = phi i32 [ 1, %entry ], [ %inc, %for.cond.cleanup3 ]
%e.015 = phi i32 [ undef, %entry ], [ %e.1.lcssa, %for.cond.cleanup3 ]
br label %for.cond1
for.cond.cleanup:
%e.1.lcssa.lcssa = phi i32 [ %e.1.lcssa, %for.cond.cleanup3 ]
ret i32 %e.1.lcssa.lcssa
for.cond1:
%e.1 = phi i32 [ %k.0, %for.cond1 ], [ %e.015, %for.cond1.preheader ]
%k.0 = phi i32 [ %dec, %for.cond1 ], [ %i.016, %for.cond1.preheader ]
%cmp2 = icmp sgt i32 %k.0, 1
%dec = add nsw i32 %k.0, -1
br i1 %cmp2, label %for.cond1, label %for.cond.cleanup3
for.cond.cleanup3:
%e.1.lcssa = phi i32 [ %e.1, %for.cond1 ]
%inc = add nuw nsw i32 %i.016, 1
%exitcond = icmp eq i32 %inc, 49
br i1 %exitcond, label %for.cond.cleanup, label %for.cond1.preheader
}
; UNROLL-NO-IC-LABEL: @PR30183(
; UNROLL-NO-IC: vector.ph:
; UNROLL-NO-IC-NEXT: [[VECTOR_RECUR_INIT:%.*]] = insertelement <4 x i32> undef, i32 [[PRE_LOAD:%.*]], i32 3
; UNROLL-NO-IC-NEXT: br label %vector.body
; UNROLL-NO-IC: vector.body:
; UNROLL-NO-IC-NEXT: [[INDEX:%.*]] = phi i64 [ 0, %vector.ph ], [ [[INDEX_NEXT:%.*]], %vector.body ]
; UNROLL-NO-IC-NEXT: [[VECTOR_RECUR:%.*]] = phi <4 x i32> [ [[VECTOR_RECUR_INIT]], %vector.ph ], [ [[TMP42:%.*]], %vector.body ]
; UNROLL-NO-IC: [[TMP27:%.*]] = load i32, i32* {{.*}}
; UNROLL-NO-IC-NEXT: [[TMP28:%.*]] = load i32, i32* {{.*}}
; UNROLL-NO-IC-NEXT: [[TMP29:%.*]] = load i32, i32* {{.*}}
; UNROLL-NO-IC-NEXT: [[TMP30:%.*]] = load i32, i32* {{.*}}
; UNROLL-NO-IC-NEXT: [[TMP31:%.*]] = load i32, i32* {{.*}}
; UNROLL-NO-IC-NEXT: [[TMP32:%.*]] = load i32, i32* {{.*}}
; UNROLL-NO-IC-NEXT: [[TMP33:%.*]] = load i32, i32* {{.*}}
; UNROLL-NO-IC-NEXT: [[TMP34:%.*]] = load i32, i32* {{.*}}
; UNROLL-NO-IC-NEXT: [[TMP35:%.*]] = insertelement <4 x i32> undef, i32 [[TMP27]], i32 0
; UNROLL-NO-IC-NEXT: [[TMP36:%.*]] = insertelement <4 x i32> [[TMP35]], i32 [[TMP28]], i32 1
; UNROLL-NO-IC-NEXT: [[TMP37:%.*]] = insertelement <4 x i32> [[TMP36]], i32 [[TMP29]], i32 2
; UNROLL-NO-IC-NEXT: [[TMP38:%.*]] = insertelement <4 x i32> [[TMP37]], i32 [[TMP30]], i32 3
; UNROLL-NO-IC-NEXT: [[TMP39:%.*]] = insertelement <4 x i32> undef, i32 [[TMP31]], i32 0
; UNROLL-NO-IC-NEXT: [[TMP40:%.*]] = insertelement <4 x i32> [[TMP39]], i32 [[TMP32]], i32 1
; UNROLL-NO-IC-NEXT: [[TMP41:%.*]] = insertelement <4 x i32> [[TMP40]], i32 [[TMP33]], i32 2
; UNROLL-NO-IC-NEXT: [[TMP42]] = insertelement <4 x i32> [[TMP41]], i32 [[TMP34]], i32 3
; UNROLL-NO-IC-NEXT: [[TMP43:%.*]] = shufflevector <4 x i32> [[VECTOR_RECUR]], <4 x i32> [[TMP38]], <4 x i32> <i32 3, i32 4, i32 5, i32 6>
; UNROLL-NO-IC-NEXT: [[TMP44:%.*]] = shufflevector <4 x i32> [[TMP38]], <4 x i32> [[TMP42]], <4 x i32> <i32 3, i32 4, i32 5, i32 6>
; UNROLL-NO-IC-NEXT: [[INDEX_NEXT]] = add i64 [[INDEX]], 8
; UNROLL-NO-IC: br i1 {{.*}}, label %middle.block, label %vector.body
;
define void @PR30183(i32 %pre_load, i32* %a, i32* %b, i64 %n) {
entry:
br label %scalar.body
scalar.body:
%i = phi i64 [ 0, %entry ], [ %i.next, %scalar.body ]
%tmp0 = phi i32 [ %pre_load, %entry ], [ %tmp2, %scalar.body ]
%i.next = add nuw nsw i64 %i, 2
%tmp1 = getelementptr inbounds i32, i32* %a, i64 %i.next
%tmp2 = load i32, i32* %tmp1
%cond = icmp eq i64 %i.next,%n
br i1 %cond, label %for.end, label %scalar.body
for.end:
ret void
}
; UNROLL-NO-IC-LABEL: @constant_folded_previous_value(
; UNROLL-NO-IC: vector.body:
; UNROLL-NO-IC: [[VECTOR_RECUR:%.*]] = phi <4 x i64> [ <i64 undef, i64 undef, i64 undef, i64 0>, %vector.ph ], [ <i64 1, i64 1, i64 1, i64 1>, %vector.body ]
; UNROLL-NO-IC-NEXT: [[TMP0:%.*]] = shufflevector <4 x i64> [[VECTOR_RECUR]], <4 x i64> <i64 1, i64 1, i64 1, i64 1>, <4 x i32> <i32 3, i32 4, i32 5, i32 6>
; UNROLL-NO-IC: br i1 {{.*}}, label %middle.block, label %vector.body
;
define void @constant_folded_previous_value() {
entry:
br label %scalar.body
scalar.body:
%i = phi i64 [ 0, %entry ], [ %i.next, %scalar.body ]
%tmp2 = phi i64 [ 0, %entry ], [ %tmp3, %scalar.body ]
%tmp3 = add i64 0, 1
%i.next = add nuw nsw i64 %i, 1
%cond = icmp eq i64 %i.next, undef
br i1 %cond, label %for.end, label %scalar.body
for.end:
ret void
}
; We vectorize this first order recurrence, by generating two
; extracts for the phi `val.phi` - one at the last index and
; another at the second last index. We need these 2 extracts because
; the first order recurrence phi is used outside the loop, so we require the phi
; itself and not its update (addx).
; UNROLL-NO-IC-LABEL: extract_second_last_iteration
; UNROLL-NO-IC: vector.body
; UNROLL-NO-IC: %step.add = add <4 x i32> %vec.ind, <i32 4, i32 4, i32 4, i32 4>
; UNROLL-NO-IC: %[[L1:.+]] = add <4 x i32> %vec.ind, %broadcast.splat
; UNROLL-NO-IC: %[[L2:.+]] = add <4 x i32> %step.add, %broadcast.splat
; UNROLL-NO-IC: %index.next = add i32 %index, 8
; UNROLL-NO-IC: icmp eq i32 %index.next, 96
; UNROLL-NO-IC: middle.block
; UNROLL-NO-IC: icmp eq i32 96, 96
; UNROLL-NO-IC: %vector.recur.extract = extractelement <4 x i32> %[[L2]], i32 3
; UNROLL-NO-IC: %vector.recur.extract.for.phi = extractelement <4 x i32> %[[L2]], i32 2
; UNROLL-NO-IC: for.end
; UNROLL-NO-IC: %val.phi.lcssa = phi i32 [ %scalar.recur, %for.body ], [ %vector.recur.extract.for.phi, %middle.block ]
; Check the case when unrolled but not vectorized.
; UNROLL-NO-VF-LABEL: extract_second_last_iteration
; UNROLL-NO-VF: vector.body:
; UNROLL-NO-VF: %induction = add i32 %index, 0
; UNROLL-NO-VF: %induction1 = add i32 %index, 1
; UNROLL-NO-VF: %[[L1:.+]] = add i32 %induction, %x
; UNROLL-NO-VF: %[[L2:.+]] = add i32 %induction1, %x
; UNROLL-NO-VF: %index.next = add i32 %index, 2
; UNROLL-NO-VF: icmp eq i32 %index.next, 96
; UNROLL-NO-VF: for.end:
; UNROLL-NO-VF: %val.phi.lcssa = phi i32 [ %scalar.recur, %for.body ], [ %[[L1]], %middle.block ]
define i32 @extract_second_last_iteration(i32* %cval, i32 %x) {
entry:
br label %for.body
for.body:
%inc.phi = phi i32 [ 0, %entry ], [ %inc, %for.body ]
%val.phi = phi i32 [ 0, %entry ], [ %addx, %for.body ]
%inc = add i32 %inc.phi, 1
%bc = zext i32 %inc.phi to i64
%addx = add i32 %inc.phi, %x
%cmp = icmp eq i32 %inc.phi, 95
br i1 %cmp, label %for.end, label %for.body
for.end:
ret i32 %val.phi
}
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