91722a4a13
The main use for this patch is LTO. It is not (yet?) possible to set the size level (-Os, -Oz) in the linker, which means loops are still rotated even if -Oz is specified on the command line. Therefore, look at the function attribute instead of only at the size level to determine whether to rotate loops for a given function. For discussion, see: https://reviews.llvm.org/D119342 An older version of this patch was already approved at https://reviews.llvm.org/D119342 but I never got around to committing it. The code changed so I had to make some minor updates to this patch and in the meantime I also lost commit access because I wasn't really using it. So here is an updated patch.
33 lines
754 B
LLVM
33 lines
754 B
LLVM
; REQUIRES: asserts
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; RUN: opt < %s -S -passes=loop-rotate -debug -debug-only=loop-rotate 2>&1 | FileCheck %s
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; Loop should not be rotated for functions with the minsize attribute.
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; This is mostly useful for LTO which doesn't (yet) understand -Oz.
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; CHECK: LoopRotation: NOT rotating - contains 2 instructions, which is more
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@e = global i32 10
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declare void @use(i32)
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; Function attrs: minsize optsize
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define void @test() #0 {
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entry:
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%end = load i32, ptr @e
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br label %loop
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loop:
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%n.phi = phi i32 [ %n, %loop.fin ], [ 0, %entry ]
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%cond = icmp eq i32 %n.phi, %end
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br i1 %cond, label %exit, label %loop.fin
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loop.fin:
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%n = add i32 %n.phi, 1
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call void @use(i32 %n)
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br label %loop
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exit:
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ret void
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}
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attributes #0 = { minsize optsize }
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