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llvm-mirror/test/CodeGen/X86/bswap.ll
Evan Cheng 40adfc21f6 Teach dag combine to match halfword byteswap patterns.
1. (((x) & 0xFF00) >> 8) | (((x) & 0x00FF) << 8)
   => (bswap x) >> 16
2. ((x&0xff)<<8)|((x&0xff00)>>8)|((x&0xff000000)>>8)|((x&0x00ff0000)<<8))
   => (rotl (bswap x) 16)

This allows us to eliminate most of the def : Pat patterns for ARM rev16
revsh instructions. It catches many more cases for ARM and x86.

rdar://9609108

llvm-svn: 133503
2011-06-21 06:01:08 +00:00

60 lines
1.2 KiB
LLVM

; bswap should be constant folded when it is passed a constant argument
; RUN: llc < %s -march=x86 | FileCheck %s
declare i16 @llvm.bswap.i16(i16)
declare i32 @llvm.bswap.i32(i32)
declare i64 @llvm.bswap.i64(i64)
define i16 @W(i16 %A) {
; CHECK: W:
; CHECK: rolw $8, %ax
%Z = call i16 @llvm.bswap.i16( i16 %A ) ; <i16> [#uses=1]
ret i16 %Z
}
define i32 @X(i32 %A) {
; CHECK: X:
; CHECK: bswapl %eax
%Z = call i32 @llvm.bswap.i32( i32 %A ) ; <i32> [#uses=1]
ret i32 %Z
}
define i64 @Y(i64 %A) {
; CHECK: Y:
; CHECK: bswapl %eax
; CHECK: bswapl %edx
%Z = call i64 @llvm.bswap.i64( i64 %A ) ; <i64> [#uses=1]
ret i64 %Z
}
; rdar://9164521
define i32 @test1(i32 %a) nounwind readnone {
entry:
; CHECK: test1
; CHECK: bswapl %eax
; CHECK: shrl $16, %eax
%and = lshr i32 %a, 8
%shr3 = and i32 %and, 255
%and2 = shl i32 %a, 8
%shl = and i32 %and2, 65280
%or = or i32 %shr3, %shl
ret i32 %or
}
define i32 @test2(i32 %a) nounwind readnone {
entry:
; CHECK: test2
; CHECK: bswapl %eax
; CHECK: sarl $16, %eax
%and = lshr i32 %a, 8
%shr4 = and i32 %and, 255
%and2 = shl i32 %a, 8
%or = or i32 %shr4, %and2
%sext = shl i32 %or, 16
%conv3 = ashr exact i32 %sext, 16
ret i32 %conv3
}