4684ddb6aa
- import libcxx - reduce targets to the one when compiled as a tools Change-Id: Iabb8427f80ff8e89463559a28bcb8b4f2bdbc496
99 lines
2.5 KiB
ArmAsm
99 lines
2.5 KiB
ArmAsm
// This file is dual licensed under the MIT and the University of Illinois Open
|
|
// Source Licenses. See LICENSE.TXT for details.
|
|
|
|
#include "../assembly.h"
|
|
|
|
// float __floatundisf(du_int a);
|
|
|
|
// Note that there is a hardware instruction, fildll, that does most of what
|
|
// this function needs to do. However, because of our ia32 ABI, it will take
|
|
// a write-small read-large stall, so the software implementation here is
|
|
// actually several cycles faster.
|
|
|
|
// This is a branch-free implementation. A branchy implementation might be
|
|
// faster for the common case if you know something a priori about the input
|
|
// distribution.
|
|
|
|
/* branch-free x87 implementation - one cycle slower than without x87.
|
|
|
|
#ifdef __i386__
|
|
|
|
.const
|
|
.align 3
|
|
|
|
.quad 0x43f0000000000000
|
|
twop64: .quad 0x0000000000000000
|
|
|
|
#define TWOp64 twop64-0b(%ecx,%eax,8)
|
|
|
|
.text
|
|
.align 4
|
|
DEFINE_COMPILERRT_FUNCTION(__floatundisf)
|
|
movl 8(%esp), %eax
|
|
movd 8(%esp), %xmm1
|
|
movd 4(%esp), %xmm0
|
|
punpckldq %xmm1, %xmm0
|
|
calll 0f
|
|
0: popl %ecx
|
|
sarl $31, %eax
|
|
movq %xmm0, 4(%esp)
|
|
fildll 4(%esp)
|
|
faddl TWOp64
|
|
fstps 4(%esp)
|
|
flds 4(%esp)
|
|
ret
|
|
|
|
#endif // __i386__
|
|
|
|
*/
|
|
|
|
/* branch-free, x87-free implementation - faster at the expense of code size */
|
|
|
|
#ifdef __i386__
|
|
|
|
#ifndef __ELF__
|
|
.const
|
|
.align 3
|
|
#else
|
|
.align 8
|
|
#endif
|
|
twop52: .quad 0x4330000000000000
|
|
.quad 0x0000000000000fff
|
|
sticky: .quad 0x0000000000000000
|
|
.long 0x00000012
|
|
twelve: .long 0x00000000
|
|
|
|
#define TWOp52 twop52-0b(%ecx)
|
|
#define STICKY sticky-0b(%ecx,%eax,8)
|
|
|
|
.text
|
|
.align 4
|
|
DEFINE_COMPILERRT_FUNCTION(__floatundisf)
|
|
movl 8(%esp), %eax
|
|
movd 8(%esp), %xmm1
|
|
movd 4(%esp), %xmm0
|
|
punpckldq %xmm1, %xmm0
|
|
|
|
calll 0f
|
|
0: popl %ecx
|
|
shrl %eax // high 31 bits of input as sint32
|
|
addl $0x7ff80000, %eax
|
|
sarl $31, %eax // (big input) ? -1 : 0
|
|
movsd STICKY, %xmm1 // (big input) ? 0xfff : 0
|
|
movl $12, %edx
|
|
andl %eax, %edx // (big input) ? 12 : 0
|
|
movd %edx, %xmm3
|
|
andpd %xmm0, %xmm1 // (big input) ? input & 0xfff : 0
|
|
movsd TWOp52, %xmm2 // 0x1.0p52
|
|
psrlq %xmm3, %xmm0 // (big input) ? input >> 12 : input
|
|
orpd %xmm2, %xmm1 // 0x1.0p52 + ((big input) ? input & 0xfff : input)
|
|
orpd %xmm1, %xmm0 // 0x1.0p52 + ((big input) ? (input >> 12 | input & 0xfff) : input)
|
|
subsd %xmm2, %xmm0 // (double)((big input) ? (input >> 12 | input & 0xfff) : input)
|
|
cvtsd2ss %xmm0, %xmm0 // (float)((big input) ? (input >> 12 | input & 0xfff) : input)
|
|
pslld $23, %xmm3
|
|
paddd %xmm3, %xmm0 // (float)input
|
|
movd %xmm0, 4(%esp)
|
|
flds 4(%esp)
|
|
ret
|
|
|
|
#endif // __i386__
|