diff options
Diffstat (limited to 'lib/i386/lshrdi3.s')
-rw-r--r-- | lib/i386/lshrdi3.s | 65 |
1 files changed, 65 insertions, 0 deletions
diff --git a/lib/i386/lshrdi3.s b/lib/i386/lshrdi3.s new file mode 100644 index 00000000..5992c213 --- /dev/null +++ b/lib/i386/lshrdi3.s @@ -0,0 +1,65 @@ +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. + +// di_int __lshrdi3(di_int input, int count); + +// This routine has some extra memory traffic, loading the 64-bit input via two +// 32-bit loads, then immediately storing it back to the stack via a single 64-bit +// store. This is to avoid a write-small, read-large stall. +// However, if callers of this routine can be safely assumed to store the argument +// via a 64-bt store, this is unnecessary memory traffic, and should be avoided. +// It can be turned off by defining the TRUST_CALLERS_USE_64_BIT_STORES macro. + +#ifdef __i386__ +#ifdef __SSE2__ + +.text +.align 4 +.globl ___lshrdi3 +___lshrdi3: + movd 12(%esp), %xmm2 // Load count +#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 // shift input by count + movd %xmm0, %eax + psrlq $32, %xmm0 + movd %xmm0, %edx + ret + +#else // Use GPRs instead of SSE2 instructions, if they aren't available. + +.text +.align 4 +.globl ___lshrdi3 +___lshrdi3: + 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 2f // goto 2 + testl $0x1f, %ecx // If count == 0 + jz 1f // goto 1 + + pushl %ebx + movl %edx, %ebx // copy high + shrl %cl, %eax // right shift low by count + shrl %cl, %edx // right shift high by count + neg %cl + shll %cl, %ebx // left shift high by 32 - count + orl %ebx, %eax // or the result into the low word + popl %ebx +1: ret + +2: movl %edx, %eax // Move high to low + xorl %edx, %edx // clear high + shrl %cl, %eax // shift low by count - 32 + ret + +#endif // __SSE2__ +#endif // __i386__ |