From: Taylor R Campbell <campbell@mumble.net>
Date: Sat, 18 Jun 2011 23:37:06 +0000 (+0000)
Subject: On x86, align stack to 16 bytes for all calls to C.
X-Git-Tag: release-9.1.0~3^2~11
X-Git-Url: https://birchwood-abbey.net/git?a=commitdiff_plain;h=79026f35510cdc7ad676194a3fe33859b604f9a7;p=mit-scheme.git

On x86, align stack to 16 bytes for all calls to C.

Should fix random hangs on Mac OS X, whose ABI requires 16-byte
stack alignment.  Should be harmless on other operating systems.
---

diff --git a/src/microcode/cmpauxmd/i386.m4 b/src/microcode/cmpauxmd/i386.m4
index 9d1273e4d..c77fd3a33 100644
--- a/src/microcode/cmpauxmd/i386.m4
+++ b/src/microcode/cmpauxmd/i386.m4
@@ -559,12 +559,17 @@ define_c_label(within_c_stack)
 	OP(push,l)	REG(ebp)			# Save frame pointer
 	OP(mov,l)	TW(REG(esp),REG(ebp))
 	OP(mov,l)	TW(REG(eax),REG(esp))		# Switch to C stack
+	OP(mov,l)	TW(IMM(0),EVR(C_Stack_Pointer))
+	OP(push,l)	IMM(0)				# Align sp to 16 bytes
 	OP(push,l)	REG(ebp)			# Save stack pointer
 	OP(push,l)	LOF(HEX(c),REG(ebp))		# Push argument
 	call		IJMP(LOF(8,REG(ebp)))		# Call function
 
 define_debugging_label(within_c_stack_restore)
 	OP(pop,l)	REG(eax)			# Pop argument
+	OP(mov,l)	TW(REG(esp),REG(eax))		# Restore C stack ptr
+	OP(add,l)	TW(IMM(8),REG(eax))
+	OP(mov,l)	TW(REG(eax),EVR(C_Stack_Pointer))
 	OP(pop,l)	REG(esp)			# Restore stack pointer
 							#   and switch back to
 							#   Scheme stack
@@ -574,6 +579,7 @@ define_debugging_label(within_c_stack_restore)
 define_debugging_label(within_c_stack_from_c)
 	OP(push,l)	REG(ebp)			# Save a frame pointer,
 	OP(mov,l)	TW(REG(esp),REG(ebp))		#   for debuggers.
+	OP(push,l)	IMM(0)				# Align sp to 16 bytes
 	OP(push,l)	LOF(HEX(c),REG(ebp))		# Push argument
 	call		IJMP(LOF(8,REG(ebp)))
 	leave
diff --git a/src/microcode/cmpauxmd/x86-64.m4 b/src/microcode/cmpauxmd/x86-64.m4
index 2ae38405c..8f4b3ec39 100644
--- a/src/microcode/cmpauxmd/x86-64.m4
+++ b/src/microcode/cmpauxmd/x86-64.m4
@@ -392,12 +392,17 @@ define_c_label(within_c_stack)
 	OP(push,q)	REG(rbp)			# Save frame pointer
 	OP(mov,q)	TW(REG(rsp),REG(rbp))
 	OP(mov,q)	TW(REG(rax),REG(rsp))		# Switch to C stack
+	OP(mov,q)	TW(IMM(0),ABS(EVR(C_Stack_Pointer)))
+	OP(push,q)	IMM(0)				# Align sp to 16 bytes
 	OP(push,q)	REG(rbp)			# Save stack pointer
 	OP(mov,q)	TW(REG(rdi),REG(rax))		# arg1 (fn) -> rax
 	OP(mov,q)	TW(REG(rsi),REG(rdi))		# arg2 (arg) -> arg1
 	call		IJMP(REG(rax))			# call fn(arg)
 
 define_debugging_label(within_c_stack_restore)
+	OP(mov,q)	TW(REG(rsp),REG(rax))		# Restore C stack ptr
+	OP(add,q)	TW(IMM(16),REG(rax))
+	OP(mov,q)	TW(REG(rax),ABS(EVR(C_Stack_Pointer)))
 	OP(pop,q)	REG(rsp)			# Restore stack pointer
 							#   and switch back to
 							#   Scheme stack