1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
|
// This file is dual licensed under the MIT and the University of Illinois Open
// Source Licenses. See LICENSE.TXT for details.
#include "../assembly.h"
// di_int __ashrdi3(di_int input, int count);
#ifdef __i386__
#ifdef __SSE2__
.text
.balign 4
DEFINE_COMPILERRT_FUNCTION(__ashrdi3)
movd 12(%esp), %xmm2 // Load count
movl 8(%esp), %eax
#ifndef TRUST_CALLERS_USE_64_BIT_STORES
movd 4(%esp), %xmm0
movd 8(%esp), %xmm1
punpckldq %xmm1, %xmm0 // Load input
#else
movq 4(%esp), %xmm0 // Load input
#endif
psrlq %xmm2, %xmm0 // unsigned shift input by count
testl %eax, %eax // check the sign-bit of the input
jns 1f // early out for positive inputs
// If the input is negative, we need to construct the shifted sign bit
// to or into the result, as xmm does not have a signed right shift.
pcmpeqb %xmm1, %xmm1 // -1ULL
psrlq $58, %xmm1 // 0x3f
pandn %xmm1, %xmm2 // 63 - count
pcmpeqb %xmm1, %xmm1 // -1ULL
psubq %xmm1, %xmm2 // 64 - count
psllq %xmm2, %xmm1 // -1 << (64 - count) = leading sign bits
por %xmm1, %xmm0
// Move the result back to the general purpose registers and return
1: movd %xmm0, %eax
psrlq $32, %xmm0
movd %xmm0, %edx
ret
END_COMPILERRT_FUNCTION(__ashrdi3)
#else // Use GPRs instead of SSE2 instructions, if they aren't available.
.text
.balign 4
DEFINE_COMPILERRT_FUNCTION(__ashrdi3)
movl 12(%esp), %ecx // Load count
movl 8(%esp), %edx // Load high
movl 4(%esp), %eax // Load low
testl $0x20, %ecx // If count >= 32
jnz 1f // goto 1
shrdl %cl, %edx, %eax // right shift low by count
sarl %cl, %edx // right shift high by count
ret
1: movl %edx, %eax // Move high to low
sarl $31, %edx // clear high
sarl %cl, %eax // shift low by count - 32
ret
END_COMPILERRT_FUNCTION(__ashrdi3)
#endif // __SSE2__
#endif // __i386__
NO_EXEC_STACK_DIRECTIVE
|
