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ddbc274169
I followed three heuristics for deciding whether to set 'true' or 'false': - Everything target independent got 'true' as that is the expected common output of the GCC builtins. - If the target arch only has one way of implementing this operation, set the flag in the way that exercises the most of codegen. For most architectures this is also the likely path from a GCC builtin, with 'true' being set. It will (eventually) require lowering away that difference, and then lowering to the architecture's operation. - Otherwise, set the flag differently dependending on which target operation should be tested. Let me know if anyone has any issue with this pattern or would like specific tests of another form. This should allow the x86 codegen to just iteratively improve as I teach the backend how to differentiate between the two forms, and everything else should remain exactly the same. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@146370 91177308-0d34-0410-b5e6-96231b3b80d8
49 lines
1.0 KiB
LLVM
49 lines
1.0 KiB
LLVM
; RUN: llc < %s -march=x86 -mcpu=yonah | FileCheck %s
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define i32 @t1(i32 %x) nounwind {
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%tmp = tail call i32 @llvm.ctlz.i32( i32 %x, i1 true )
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ret i32 %tmp
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; CHECK: t1:
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; CHECK: bsrl
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; CHECK: cmov
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}
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declare i32 @llvm.ctlz.i32(i32, i1) nounwind readnone
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define i32 @t2(i32 %x) nounwind {
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%tmp = tail call i32 @llvm.cttz.i32( i32 %x, i1 true )
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ret i32 %tmp
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; CHECK: t2:
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; CHECK: bsfl
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; CHECK: cmov
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}
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declare i32 @llvm.cttz.i32(i32, i1) nounwind readnone
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define i16 @t3(i16 %x, i16 %y) nounwind {
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entry:
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%tmp1 = add i16 %x, %y
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%tmp2 = tail call i16 @llvm.ctlz.i16( i16 %tmp1, i1 true ) ; <i16> [#uses=1]
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ret i16 %tmp2
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; CHECK: t3:
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; CHECK: bsrw
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; CHECK: cmov
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}
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declare i16 @llvm.ctlz.i16(i16, i1) nounwind readnone
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; Don't generate the cmovne when the source is known non-zero (and bsr would
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; not set ZF).
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; rdar://9490949
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define i32 @t4(i32 %n) nounwind {
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entry:
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; CHECK: t4:
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; CHECK: bsrl
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; CHECK-NOT: cmov
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; CHECK: ret
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%or = or i32 %n, 1
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%tmp1 = tail call i32 @llvm.ctlz.i32(i32 %or, i1 true)
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ret i32 %tmp1
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}
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