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The new analysis is not yet ready for prime time. It has a *critical* flawed assumption, and some troubling shortages of testing. Until it's been hammered into better shape, let's stick with the working code. This should be easy to revert itself when the analysis is ready. Fixes PR14241, a miscompile of any memcpy-able loop which uses a pointer as the induction mechanism. If you have been seeing miscompiles in this revision range, you really want to test with this backed out. The results of this miscompile are a bit subtle as they can lead to downstream passes concluding things are impossible which are in fact possible. Thanks to David Blaikie for the majority of the reduction of this miscompile. I'll be checking in the test case in a non-revert commit. Revesions reverted here: r167045: LoopIdiom: Fix a serious missed optimization: we only turned top-level loops into memmove. r166877: LoopIdiom: Add checks to avoid turning memmove into an infinite loop. r166875: LoopIdiom: Recognize memmove loops. r166874: LoopIdiom: Replace custom dependence analysis with DependenceAnalysis. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@167286 91177308-0d34-0410-b5e6-96231b3b80d8
31 lines
1.1 KiB
LLVM
31 lines
1.1 KiB
LLVM
; RUN: opt -loop-idiom < %s -S | FileCheck %s
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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"
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target triple = "x86_64-apple-darwin10.0.0"
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; CHECK: @memset
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; CHECK-NOT: llvm.memset
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define i8* @memset(i8* %b, i32 %c, i64 %len) nounwind uwtable ssp {
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entry:
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%cmp1 = icmp ult i64 0, %len
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br i1 %cmp1, label %for.body.lr.ph, label %for.end
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for.body.lr.ph: ; preds = %entry
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%conv6 = trunc i32 %c to i8
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br label %for.body
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for.body: ; preds = %for.body.lr.ph, %for.body
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%indvar = phi i64 [ 0, %for.body.lr.ph ], [ %indvar.next, %for.body ]
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%p.02 = getelementptr i8* %b, i64 %indvar
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store i8 %conv6, i8* %p.02, align 1
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%indvar.next = add i64 %indvar, 1
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%exitcond = icmp ne i64 %indvar.next, %len
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br i1 %exitcond, label %for.body, label %for.cond.for.end_crit_edge
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for.cond.for.end_crit_edge: ; preds = %for.body
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br label %for.end
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for.end: ; preds = %for.cond.for.end_crit_edge, %entry
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ret i8* %b
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}
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