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5671f9d0a9
We currently always vectorize induction variables. However, if an induction variable is only used for counting loop iterations or computing addresses with getelementptr instructions, we don't need to do this. Vectorizing these trivial induction variables can create vector code that is difficult to simplify later on. This is especially true when the unroll factor is greater than one, and we create vector arithmetic when computing step vectors. With this patch, we check if an induction variable is only used for counting iterations or computing addresses, and if so, scalarize the arithmetic when computing step vectors instead. This allows for greater simplification. This patch addresses the suboptimal pointer arithmetic sequence seen in PR27881. Reference: https://llvm.org/bugs/show_bug.cgi?id=27881 Differential Revision: http://reviews.llvm.org/D21620 llvm-svn: 274627
42 lines
1.5 KiB
LLVM
42 lines
1.5 KiB
LLVM
; RUN: opt -S -loop-vectorize -instcombine -force-vector-width=4 < %s | FileCheck %s
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target datalayout = "e-m:e-i64:64-i128:128-n32:64-S128"
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; Vectorization of loop with bitcast between GEP and load
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; Simplified source code:
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;void foo (double** __restrict__ in, bool * __restrict__ res) {
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;
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; for (int i = 0; i < 4096; ++i)
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; res[i] = ((unsigned long long)in[i] == 0);
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;}
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; CHECK-LABEL: @foo
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; CHECK: vector.body
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; CHECK: %[[IV:.+]] = phi i64 [ 0, %vector.ph ], [ %index.next, %vector.body ]
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; CHECK: %[[v0:.+]] = getelementptr inbounds double*, double** %in, i64 %[[IV]]
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; CHECK: %[[v1:.+]] = bitcast double** %[[v0]] to <4 x i64>*
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; CHECK: %wide.load = load <4 x i64>, <4 x i64>* %[[v1]], align 8
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; CHECK: icmp eq <4 x i64> %wide.load, zeroinitializer
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; CHECK: br i1
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define void @foo(double** noalias nocapture readonly %in, double** noalias nocapture readnone %out, i8* noalias nocapture %res) #0 {
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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 double*, double** %in, i64 %indvars.iv
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%tmp53 = bitcast double** %arrayidx to i64*
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%tmp54 = load i64, i64* %tmp53, align 8
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%cmp1 = icmp eq i64 %tmp54, 0
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%arrayidx3 = getelementptr inbounds i8, i8* %res, i64 %indvars.iv
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%frombool = zext i1 %cmp1 to i8
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store i8 %frombool, i8* %arrayidx3, align 1
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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, 4096
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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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