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https://github.com/RPCS3/llvm-mirror.git
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f5b825ae49
This patch fixes pr34283, which exposed that the computation of maximum legal width for vectorization was wrong, because it relied on MaxInterleaveFactor to obtain the maximum stride used in the loop, however not all strided accesses in the loop have an interleave-group associated with them. Instead of recording the maximum stride in the loop, which can be over conservative (e.g. if the access with the maximum stride is not involved in the dependence limitation), this patch tracks the actual maximum legal width imposed by accesses that are involved in dependencies. Differential Revision: https://reviews.llvm.org/D37507 llvm-svn: 313237
274 lines
8.1 KiB
LLVM
274 lines
8.1 KiB
LLVM
; RUN: opt < %s -loop-vectorize -force-vector-width=2 -force-vector-interleave=1 -S | FileCheck %s
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; RUN: opt < %s -loop-vectorize -force-vector-width=4 -force-vector-interleave=1 -S | FileCheck %s -check-prefix=WIDTH
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; RUN: opt -S -loop-vectorize -force-vector-width=4 < %s | FileCheck %s -check-prefix=RIGHTVF
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; RUN: opt -S -loop-vectorize -force-vector-width=8 < %s | FileCheck %s -check-prefix=WRONGVF
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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"
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; Vectorization with dependence checks.
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; No plausible dependence - can be vectorized.
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; for (i = 0; i < 1024; ++i)
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; A[i] = A[i + 1] + 1;
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; CHECK-LABEL: @f1_vec(
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; CHECK: <2 x i32>
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define void @f1_vec(i32* %A) {
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entry:
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br label %for.body
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for.body:
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%indvars.iv = phi i32 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
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%indvars.iv.next = add i32 %indvars.iv, 1
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%arrayidx = getelementptr inbounds i32, i32* %A, i32 %indvars.iv.next
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%0 = load i32, i32* %arrayidx, align 4
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%add1 = add nsw i32 %0, 1
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%arrayidx3 = getelementptr inbounds i32, i32* %A, i32 %indvars.iv
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store i32 %add1, i32* %arrayidx3, align 4
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%exitcond = icmp ne i32 %indvars.iv.next, 1024
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br i1 %exitcond, label %for.body, label %for.end
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for.end:
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ret void
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}
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; Plausible dependence of distance 1 - can't be vectorized.
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; for (i = 0; i < 1024; ++i)
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; A[i+1] = A[i] + 1;
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; CHECK-LABEL: @f2_novec(
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; CHECK-NOT: <2 x i32>
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define void @f2_novec(i32* %A) {
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entry:
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br label %for.body
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for.body:
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%indvars.iv = phi i32 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
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%arrayidx = getelementptr inbounds i32, i32* %A, i32 %indvars.iv
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%0 = load i32, i32* %arrayidx, align 4
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%add = add nsw i32 %0, 1
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%indvars.iv.next = add i32 %indvars.iv, 1
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%arrayidx3 = getelementptr inbounds i32, i32* %A, i32 %indvars.iv.next
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store i32 %add, i32* %arrayidx3, align 4
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%exitcond = icmp ne i32 %indvars.iv.next, 1024
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br i1 %exitcond, label %for.body, label %for.end
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for.end:
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ret void
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}
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; Plausible dependence of distance 2 - can be vectorized with a width of 2.
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; for (i = 0; i < 1024; ++i)
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; A[i+2] = A[i] + 1;
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; CHECK-LABEL: @f3_vec_len(
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; CHECK: <2 x i32>
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; WIDTH: f3_vec_len
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; WIDTH-NOT: <4 x i32>
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define void @f3_vec_len(i32* %A) {
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entry:
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br label %for.body
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for.body:
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%i.01 = phi i32 [ 0, %entry ], [ %inc, %for.body ]
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%idxprom = sext i32 %i.01 to i64
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%arrayidx = getelementptr inbounds i32, i32* %A, i64 %idxprom
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%0 = load i32, i32* %arrayidx, align 4
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%add = add nsw i32 %0, 1
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%add1 = add nsw i32 %i.01, 2
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%idxprom2 = sext i32 %add1 to i64
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%arrayidx3 = getelementptr inbounds i32, i32* %A, i64 %idxprom2
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store i32 %add, i32* %arrayidx3, align 4
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%inc = add nsw i32 %i.01, 1
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%cmp = icmp slt i32 %inc, 1024
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br i1 %cmp, label %for.body, label %for.end
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for.end:
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ret void
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}
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; Plausible dependence of distance 1 - cannot be vectorized (without reordering
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; accesses).
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; for (i = 0; i < 1024; ++i) {
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; B[i] = A[i];
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; A[i] = B[i + 1];
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; }
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; CHECK-LABEL: @f5(
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; CHECK-NOT: <2 x i32>
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define void @f5(i32* %A, i32* %B) {
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entry:
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br label %for.body
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for.body:
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%indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
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%arrayidx = getelementptr inbounds i32, i32* %A, i64 %indvars.iv
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%0 = load i32, i32* %arrayidx, align 4
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%arrayidx2 = getelementptr inbounds i32, i32* %B, i64 %indvars.iv
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store i32 %0, i32* %arrayidx2, align 4
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%indvars.iv.next = add nsw i64 %indvars.iv, 1
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%arrayidx4 = getelementptr inbounds i32, i32* %B, i64 %indvars.iv.next
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%1 = load i32, i32* %arrayidx4, align 4
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store i32 %1, i32* %arrayidx, align 4
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%lftr.wideiv = trunc i64 %indvars.iv.next to i32
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%exitcond = icmp ne i32 %lftr.wideiv, 1024
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br i1 %exitcond, label %for.body, label %for.end
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for.end:
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ret void
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}
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; Dependence through a phi node - must not vectorize.
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; for (i = 0; i < 1024; ++i) {
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; a[i+1] = tmp;
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; tmp = a[i];
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; }
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; CHECK-LABEL: @f6
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; CHECK-NOT: <2 x i32>
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define i32 @f6(i32* %a, i32 %tmp) {
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entry:
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br label %for.body
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for.body:
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%indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
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%tmp.addr.08 = phi i32 [ %tmp, %entry ], [ %0, %for.body ]
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%indvars.iv.next = add nsw i64 %indvars.iv, 1
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%arrayidx = getelementptr inbounds i32, i32* %a, i64 %indvars.iv.next
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store i32 %tmp.addr.08, i32* %arrayidx, align 4
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%arrayidx3 = getelementptr inbounds i32, i32* %a, i64 %indvars.iv
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%0 = load i32, i32* %arrayidx3, align 4
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%lftr.wideiv = trunc i64 %indvars.iv.next to i32
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%exitcond = icmp ne i32 %lftr.wideiv, 1024
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br i1 %exitcond, label %for.body, label %for.end
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for.end:
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ret i32 undef
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}
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; Don't vectorize true loop carried dependencies that are not a multiple of the
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; vector width.
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; Example:
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; for (int i = ...; ++i) {
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; a[i] = a[i-3] + ...;
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; It is a bad idea to vectorize this loop because store-load forwarding will not
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; happen.
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;
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; CHECK-LABEL: @nostoreloadforward(
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; CHECK-NOT: <2 x i32>
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define void @nostoreloadforward(i32* %A) {
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entry:
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br label %for.body
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for.body:
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%indvars.iv = phi i64 [ 16, %entry ], [ %indvars.iv.next, %for.body ]
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%0 = add nsw i64 %indvars.iv, -3
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%arrayidx = getelementptr inbounds i32, i32* %A, i64 %0
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%1 = load i32, i32* %arrayidx, align 4
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%2 = add nsw i64 %indvars.iv, 4
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%arrayidx2 = getelementptr inbounds i32, i32* %A, i64 %2
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%3 = load i32, i32* %arrayidx2, align 4
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%add3 = add nsw i32 %3, %1
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%arrayidx5 = getelementptr inbounds i32, i32* %A, i64 %indvars.iv
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store i32 %add3, i32* %arrayidx5, align 4
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%indvars.iv.next = add i64 %indvars.iv, 1
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%lftr.wideiv = trunc i64 %indvars.iv.next to i32
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%exitcond = icmp ne i32 %lftr.wideiv, 128
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br i1 %exitcond, label %for.body, label %for.end
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for.end:
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ret void
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}
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; Example:
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; for (int i = ...; ++i) {
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; a[i] = b[i];
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; c[i] = a[i-3] + ...;
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; It is a bad idea to vectorize this loop because store-load forwarding will not
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; happen.
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;
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; CHECK-LABEL: @nostoreloadforward2(
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; CHECK-NOT: <2 x i32>
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define void @nostoreloadforward2(i32* noalias %A, i32* noalias %B, i32* noalias %C) {
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entry:
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br label %for.body
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for.body:
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%indvars.iv = phi i64 [ 16, %entry ], [ %indvars.iv.next, %for.body ]
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%arrayidx = getelementptr inbounds i32, i32* %B, i64 %indvars.iv
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%0 = load i32, i32* %arrayidx, align 4
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%arrayidx2 = getelementptr inbounds i32, i32* %A, i64 %indvars.iv
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store i32 %0, i32* %arrayidx2, align 4
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%1 = add nsw i64 %indvars.iv, -3
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%arrayidx4 = getelementptr inbounds i32, i32* %A, i64 %1
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%2 = load i32, i32* %arrayidx4, align 4
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%arrayidx6 = getelementptr inbounds i32, i32* %C, i64 %indvars.iv
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store i32 %2, i32* %arrayidx6, align 4
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%indvars.iv.next = add i64 %indvars.iv, 1
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%lftr.wideiv = trunc i64 %indvars.iv.next to i32
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%exitcond = icmp ne i32 %lftr.wideiv, 128
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br i1 %exitcond, label %for.body, label %for.end
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for.end:
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ret void
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}
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;Check the new calculation of the maximum safe distance in bits which can be vectorized.
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;The previous behavior did not take account that the stride was 2.
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;Therefore the maxVF was computed as 8 instead of 4, as the dependence distance here is 6 iterations, given by |N-(N-12)|/2.
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;#define M 32
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;#define N 2 * M
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;unsigned int a [N];
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;void pr34283(){
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; unsigned int j=0;
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; for (j = 0; j < M - 6; ++j)
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; {
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; a[N - 2 * j] = 69;
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; a[N - 12 - 2 * j] = 7;
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; }
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;
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;}
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; RIGHTVF-LABEL: @pr34283
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; RIGHTVF: <4 x i64>
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; WRONGVF-LABLE: @pr34283
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; WRONGVF-NOT: <8 x i64>
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@a = common local_unnamed_addr global [64 x i32] zeroinitializer, align 16
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; Function Attrs: norecurse nounwind uwtable
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define void @pr34283() local_unnamed_addr {
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entry:
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br label %for.body
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for.body:
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%indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
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%0 = shl i64 %indvars.iv, 1
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%1 = sub nuw nsw i64 64, %0
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%arrayidx = getelementptr inbounds [64 x i32], [64 x i32]* @a, i64 0, i64 %1
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store i32 69, i32* %arrayidx, align 8
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%2 = sub nuw nsw i64 52, %0
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%arrayidx4 = getelementptr inbounds [64 x i32], [64 x i32]* @a, i64 0, i64 %2
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store i32 7, i32* %arrayidx4, align 8
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%indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
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%exitcond = icmp eq i64 %indvars.iv.next, 26
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br i1 %exitcond, label %for.end, label %for.body
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for.end:
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ret void
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}
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