From: Chris Hanson <org/chris-hanson/cph>
Date: Sun, 26 Feb 1995 03:34:36 +0000 (+0000)
Subject: Guarantee that the floating-point register stack is empty when moving
X-Git-Tag: 20090517-FFI~6597
X-Git-Url: https://birchwood-abbey.net/git?a=commitdiff_plain;h=3c26beac30212aee55ae880ad4f73fefa78f17ab;p=mit-scheme.git

Guarantee that the floating-point register stack is empty when moving
from C to Scheme and vice-versa.  This appears to fix a floating-point
stack overflow exception that has been observed under unix and OS/2.
---

diff --git a/v7/src/microcode/cmpauxmd/i386.m4 b/v7/src/microcode/cmpauxmd/i386.m4
index 012d138c3..72e04715a 100644
--- a/v7/src/microcode/cmpauxmd/i386.m4
+++ b/v7/src/microcode/cmpauxmd/i386.m4
@@ -1,6 +1,6 @@
 ### -*-Midas-*-
 ###
-###	$Id: i386.m4,v 1.35 1995/01/06 17:39:39 cph Exp $
+###	$Id: i386.m4,v 1.36 1995/02/26 03:34:36 cph Exp $
 ###
 ###	Copyright (c) 1992-95 Massachusetts Institute of Technology
 ###
@@ -518,6 +518,18 @@ IFOS2(`	OP(pop,l)	REG(eax)	# Pop struct return into registers
 	jmp	IJMP(REG(eax))				# Invoke handler
 
 define_c_label(interface_to_scheme)
+IF387(`
+	OP(cmp,l)	TW(IMM(0),EDR(i387_presence))
+	je	interface_to_scheme_proceed
+	ffree	ST(0)					# Free floating "regs"
+	ffree	ST(1)
+	ffree	ST(2)
+	ffree	ST(3)
+	ffree	ST(4)
+	ffree	ST(5)
+	ffree	ST(6)
+	ffree	ST(7)
+interface_to_scheme_proceed:')
 ifdef(`WINNT',
 `	mov	edi,_Free				; Free pointer = %edi
 	sub	edi,_winnt_address_delta		; as a scheme offset
@@ -582,6 +594,7 @@ IF387(`
 	ffree	ST(4)
 	ffree	ST(5)
 	ffree	ST(6)
+	ffree	ST(7)
 interface_to_C_proceed:')
 
 	OP(mov,l)	TW(REG(edx),REG(eax))		# Set up result