a45f301f7a
It caused assertions to fire when building Chromium:
lib/CodeGen/LiveDebugValues.cpp:331: bool
{anonymous}::LiveDebugValues::OpenRangesSet::empty() const: Assertion
`Vars.empty() == VarLocs.empty() && "open ranges are inconsistent"' failed.
See https://crbug.com/992871#c3 for how to reproduce.
> Patch https://reviews.llvm.org/D43256 introduced more aggressive loop layout optimization which depends on profile information. If profile information is not available, the statically estimated profile information(generated by BranchProbabilityInfo.cpp) is used. If user program doesn't behave as BranchProbabilityInfo.cpp expected, the layout may be worse.
>
> To be conservative this patch restores the original layout algorithm in plain mode. But user can still try the aggressive layout optimization with -force-precise-rotation-cost=true.
>
> Differential Revision: https://reviews.llvm.org/D65673
llvm-svn: 368579
121 lines
2.0 KiB
LLVM
121 lines
2.0 KiB
LLVM
; RUN: llc -mtriple=i686-linux < %s | FileCheck %s
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; Don't rotate the loop if the number of fall through to exit is not larger
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; than the number of fall through to header.
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define void @no_rotate() {
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; CHECK-LABEL: no_rotate
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; CHECK: %entry
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; CHECK: %header
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; CHECK: %middle
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; CHECK: %latch1
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; CHECK: %latch2
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; CHECK: %end
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entry:
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br label %header
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header:
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%val1 = call i1 @foo()
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br i1 %val1, label %middle, label %end
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middle:
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%val2 = call i1 @foo()
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br i1 %val2, label %latch1, label %end
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latch1:
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%val3 = call i1 @foo()
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br i1 %val3, label %latch2, label %header
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latch2:
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%val4 = call i1 @foo()
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br label %header
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end:
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ret void
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}
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define void @do_rotate() {
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; CHECK-LABEL: do_rotate
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; CHECK: %entry
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; CHECK: %then
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; CHECK: %else
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; CHECK: %latch1
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; CHECK: %latch2
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; CHECK: %header
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; CHECK: %end
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entry:
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%val0 = call i1 @foo()
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br i1 %val0, label %then, label %else
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then:
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call void @a()
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br label %header
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else:
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call void @b()
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br label %header
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header:
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%val1 = call i1 @foo()
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br i1 %val1, label %latch1, label %end
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latch1:
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%val3 = call i1 @foo()
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br i1 %val3, label %latch2, label %header
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latch2:
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%val4 = call i1 @foo()
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br label %header
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end:
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ret void
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}
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; The loop structure is same as in @no_rotate, but the loop header's predecessor
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; doesn't fall through to it, so it should be rotated to get exit fall through.
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define void @do_rotate2() {
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; CHECK-LABEL: do_rotate2
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; CHECK: %entry
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; CHECK: %then
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; CHECK: %middle
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; CHECK: %latch1
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; CHECK: %latch2
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; CHECK: %header
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; CHECK: %exit
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entry:
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%val0 = call i1 @foo()
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br i1 %val0, label %then, label %header, !prof !1
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then:
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call void @a()
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br label %end
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header:
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%val1 = call i1 @foo()
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br i1 %val1, label %middle, label %exit
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middle:
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%val2 = call i1 @foo()
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br i1 %val2, label %latch1, label %exit
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latch1:
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%val3 = call i1 @foo()
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br i1 %val3, label %latch2, label %header
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latch2:
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%val4 = call i1 @foo()
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br label %header
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exit:
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call void @b()
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br label %end
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end:
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ret void
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}
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declare i1 @foo()
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declare void @a()
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declare void @b()
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!1 = !{!"branch_weights", i32 10, i32 1}
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