2016-08-04 02:17:35 +08:00
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; RUN: llc -verify-machineinstrs < %s -mtriple=powerpc64-unknown-linux-gnu -mcpu=a2 | FileCheck %s
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PPC: Optimize rldicl generation for masked shifts
Masking operations (where only some number of the low bits are being kept) are
selected to rldicl(x, 0, mb). If x is a logical right shift (which would become
rldicl(y, 64-n, n)), we might be able to fold the two instructions together:
rldicl(rldicl(x, 64-n, n), 0, mb) -> rldicl(x, 64-n, mb) for n <= mb
The right shift is really a left rotate followed by a mask, and if the explicit
mask is a more-restrictive sub-mask of the mask implied by the shift, only one
rldicl is needed.
llvm-svn: 195185
2013-11-20 09:10:15 +08:00
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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-f128:128:128-v128:128:128-n32:64"
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target triple = "powerpc64-unknown-linux-gnu"
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define i64 @foo(i64 %x) #0 {
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entry:
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; CHECK-LABEL: @foo
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%a = lshr i64 %x, 35
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%b = and i64 %a, 65535
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; CHECK: rldicl 3, 3, 29, 48
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ret i64 %b
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; CHECK: blr
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}
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attributes #0 = { nounwind }
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