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c197f50184
Several backends have instructions to reverse the order of bits in an integer. Conceptually matching such patterns is similar to @llvm.bswap, and it was mentioned in http://reviews.llvm.org/D14234 that it would be best if these patterns were matched in InstCombine instead of reimplemented in every different target. This patch introduces an intrinsic @llvm.bitreverse.i* that operates similarly to @llvm.bswap. For plumbing purposes there is also a new ISD node ISD::BITREVERSE, with simple expansion and promotion support. The intention is that InstCombine's BSWAP detection logic will be extended to support BITREVERSE too, and @llvm.bitreverse intrinsics emitted (if the backend supports lowering it efficiently). llvm-svn: 252878
24 lines
594 B
LLVM
24 lines
594 B
LLVM
; RUN: llc -march=ppc64 %s -o - | FileCheck %s
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; These tests just check that the plumbing is in place for @llvm.bitreverse. The
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; actual output is massive at the moment as llvm.bitreverse is not yet legal.
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declare <2 x i16> @llvm.bitreverse.v2i16(<2 x i16>) readnone
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define <2 x i16> @f(<2 x i16> %a) {
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; CHECK-LABEL: f:
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; CHECK: rlwinm
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%b = call <2 x i16> @llvm.bitreverse.v2i16(<2 x i16> %a)
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ret <2 x i16> %b
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}
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declare i8 @llvm.bitreverse.i8(i8) readnone
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define i8 @g(i8 %a) {
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; CHECK-LABEL: g:
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; CHECK: rlwinm
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; CHECK: rlwimi
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%b = call i8 @llvm.bitreverse.i8(i8 %a)
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ret i8 %b
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}
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