lib/i386/ashldi3.S

// 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 __ashldi3(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
DEFINE_COMPILERRT_FUNCTION(__ashldi3)
	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
	psllq		%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
DEFINE_COMPILERRT_FUNCTION(__ashldi3)
	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
	shldl		%cl, %eax,	%edx	// left shift high by count
	shll		%cl,		%eax	// left shift low by count
	ret

1:	movl		%eax,		%edx	// Move low to high
	xorl		%eax,		%eax	// clear low
	shll		%cl,		%edx	// shift high by count - 32
	ret
	
#endif // __SSE2__
#endif // __i386__