1 files changed, 69 insertions, 0 deletions
diff --git a/lib/builtins/i386/ashrdi3.S b/lib/builtins/i386/ashrdi3.S
new file mode 100644
index 000000000000..8f4742481b42
--- /dev/null
+++ b/lib/builtins/i386/ashrdi3.S
@@ -0,0 +1,69 @@
+// 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__