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https://github.com/c64scene-ar/llvm-6502.git
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8bde857088
Summary: Often filter-like loops will do memory accesses that are separated by constant offsets. In these cases it is common that we will exceed the threshold for the allowable number of checks. However, it should be possible to merge such checks, sice a check of any interval againt two other intervals separated by a constant offset (a,b), (a+c, b+c) will be equivalent with a check againt (a, b+c), as long as (a,b) and (a+c, b+c) overlap. Assuming the loop will be executed for a sufficient number of iterations, this will be true. If not true, checking against (a, b+c) is still safe (although not equivalent). As long as there are no dependencies between two accesses, we can merge their checks into a single one. We use this technique to construct groups of accesses, and then check the intervals associated with the groups instead of checking the accesses directly. Reviewers: anemet Subscribers: llvm-commits Differential Revision: http://reviews.llvm.org/D10386 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@241673 91177308-0d34-0410-b5e6-96231b3b80d8
111 lines
3.2 KiB
LLVM
111 lines
3.2 KiB
LLVM
; RUN: opt -basicaa -loop-distribute -verify-loop-info -verify-dom-info -S \
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; RUN: < %s | FileCheck %s
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; RUN: opt -basicaa -loop-distribute -loop-vectorize -force-vector-width=4 \
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; RUN: -verify-loop-info -verify-dom-info -S < %s | \
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; RUN: FileCheck --check-prefix=VECTORIZE %s
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; The memcheck version of basic.ll. We should distribute and vectorize the
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; second part of this loop with 5 memchecks (A+1 x {C, D, E} + C x {A, B})
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;
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; for (i = 0; i < n; i++) {
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; A[i + 1] = A[i] * B[i];
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; -------------------------------
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; C[i] = D[i] * E[i];
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; }
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target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
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target triple = "x86_64-apple-macosx10.10.0"
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@B = common global i32* null, align 8
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@A = common global i32* null, align 8
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@C = common global i32* null, align 8
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@D = common global i32* null, align 8
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@E = common global i32* null, align 8
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define void @f() {
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entry:
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%a = load i32*, i32** @A, align 8
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%b = load i32*, i32** @B, align 8
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%c = load i32*, i32** @C, align 8
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%d = load i32*, i32** @D, align 8
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%e = load i32*, i32** @E, align 8
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br label %for.body
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; We have two compares for each array overlap check.
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; Since the checks to A and A + 4 get merged, this will give us a
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; total of 8 compares.
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;
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; CHECK: for.body.lver.memcheck:
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; CHECK: = icmp
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; CHECK: = icmp
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; CHECK: = icmp
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; CHECK: = icmp
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; CHECK: = icmp
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; CHECK: = icmp
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; CHECK: = icmp
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; CHECK: = icmp
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; CHECK-NOT: = icmp
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; CHECK: br i1 %memcheck.conflict, label %for.body.ph.lver.orig, label %for.body.ph.ldist1
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; The non-distributed loop that the memchecks fall back on.
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; CHECK: for.body.ph.lver.orig:
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; CHECK: br label %for.body.lver.orig
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; CHECK: for.body.lver.orig:
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; CHECK: br i1 %exitcond.lver.orig, label %for.end, label %for.body.lver.orig
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; Verify the two distributed loops.
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; CHECK: for.body.ph.ldist1:
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; CHECK: br label %for.body.ldist1
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; CHECK: for.body.ldist1:
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; CHECK: %mulA.ldist1 = mul i32 %loadB.ldist1, %loadA.ldist1
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; CHECK: br i1 %exitcond.ldist1, label %for.body.ph, label %for.body.ldist1
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; CHECK: for.body.ph:
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; CHECK: br label %for.body
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; CHECK: for.body:
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; CHECK: %mulC = mul i32 %loadD, %loadE
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; CHECK: for.end:
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; VECTORIZE: mul <4 x i32>
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for.body: ; preds = %for.body, %entry
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%ind = phi i64 [ 0, %entry ], [ %add, %for.body ]
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%arrayidxA = getelementptr inbounds i32, i32* %a, i64 %ind
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%loadA = load i32, i32* %arrayidxA, align 4
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%arrayidxB = getelementptr inbounds i32, i32* %b, i64 %ind
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%loadB = load i32, i32* %arrayidxB, align 4
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%mulA = mul i32 %loadB, %loadA
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%add = add nuw nsw i64 %ind, 1
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%arrayidxA_plus_4 = getelementptr inbounds i32, i32* %a, i64 %add
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store i32 %mulA, i32* %arrayidxA_plus_4, align 4
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%arrayidxD = getelementptr inbounds i32, i32* %d, i64 %ind
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%loadD = load i32, i32* %arrayidxD, align 4
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%arrayidxE = getelementptr inbounds i32, i32* %e, i64 %ind
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%loadE = load i32, i32* %arrayidxE, align 4
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%mulC = mul i32 %loadD, %loadE
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%arrayidxC = getelementptr inbounds i32, i32* %c, i64 %ind
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store i32 %mulC, i32* %arrayidxC, align 4
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%exitcond = icmp eq i64 %add, 20
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br i1 %exitcond, label %for.end, label %for.body
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for.end: ; preds = %for.body
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ret void
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}
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