3284775b70
When using clang with `-fno-unroll-loops` (implicitly added with `-O1`), the LoopUnrollPass is not not added to the (legacy) pass pipeline. This also means that it will not process any loop metadata such as llvm.loop.unroll.enable (which is generated by #pragma unroll or WarnMissedTransformationsPass emits a warning that a forced transformation has not been applied (see https://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20181210/610833.html). Such explicit transformations should take precedence over disabling heuristics. This patch unconditionally adds LoopUnrollPass to the optimizing pipeline (that is, it is still not added with `-O0`), but passes a flag indicating whether automatic unrolling is dis-/enabled. This is the same approach as LoopVectorize uses. The new pass manager's pipeline builder has no option to disable unrolling, hence the problem does not apply. Differential Revision: https://reviews.llvm.org/D55716 llvm-svn: 349509
31 lines
913 B
LLVM
31 lines
913 B
LLVM
; RUN: opt -disable-loop-unrolling -O1 -S < %s | FileCheck %s
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;
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; Check loop unrolling metadata is honored despite automatic unrolling
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; being disabled in the pass builder.
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;
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target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
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; CHECK-LABEL: @forced(
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; CHECK: load
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; CHECK: load
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define void @forced(i32* nocapture %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 [ 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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%inc = add nsw i32 %0, 1
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store i32 %inc, i32* %arrayidx, align 4
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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, 64
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br i1 %exitcond, label %for.end, label %for.body, !llvm.loop !0
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for.end:
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ret void
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}
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!0 = distinct !{!0, !{!"llvm.loop.unroll.enable"},
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!{!"llvm.loop.unroll.count", i32 2}}
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