1 files changed, 31 insertions, 0 deletions
diff --git a/lib/i386/floatdisf.S b/lib/i386/floatdisf.S
new file mode 100644
index 000000000000..741e4a6607fc
--- /dev/null
+++ b/lib/i386/floatdisf.S
@@ -0,0 +1,31 @@
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+
+#include "../assembly.h"
+
+// float __floatdisf(di_int a);
+
+// 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__
+
+.text
+.align 4
+DEFINE_COMPILERRT_FUNCTION(__floatdisf)
+#ifndef TRUST_CALLERS_USE_64_BIT_STORES
+	movd		4(%esp),	%xmm0
+	movd		8(%esp),	%xmm1
+	punpckldq	%xmm1,		%xmm0
+	movq		%xmm0,		4(%esp)
+#endif
+	fildll		4(%esp)
+	fstps		4(%esp)
+	flds		4(%esp)
+	ret
+
+#endif // __i386__