From: Taylor R Campbell <campbell@mumble.net>
Date: Fri, 23 Jul 2010 01:28:59 +0000 (+0000)
Subject: Unmask IEEE 754 floating-point exceptions on x86-64.
X-Git-Tag: 20101212-Gtk~135
X-Git-Url: https://birchwood-abbey.net/git?a=commitdiff_plain;h=367485b5c511e044c1d44146056bd2fcae9b944b;p=mit-scheme.git

Unmask IEEE 754 floating-point exceptions on x86-64.

Should this instead be part of Scheme's dynamic environment, like the
floating-point rounding mode?
---

diff --git a/src/microcode/cmpauxmd/x86-64.m4 b/src/microcode/cmpauxmd/x86-64.m4
index 5524b9a11..6d5a523c1 100644
--- a/src/microcode/cmpauxmd/x86-64.m4
+++ b/src/microcode/cmpauxmd/x86-64.m4
@@ -356,6 +356,24 @@ define_double(flonum_one,1.0)
 DECLARE_CODE_SEGMENT()
 declare_alignment(2)
 
+define_c_label(x86_64_fpe_reset_traps)
+	OP(push,q)	REG(rbp)
+	OP(mov,q)	TW(REG(rsp),REG(rbp))
+	OP(sub,q)	TW(IMM(8),REG(rsp))
+	stmxcsr		IND(REG(rsp))
+	# Clear 7 (invalid operation mask)
+	#       8 (denormalized operand mask)
+	#       9 (zero-divide exception mask)
+	#       10 (overflow exception mask)
+	#       11 (underflow exception mask)
+	#       15 (flush-to-zero (if set, gives non-IEEE semantics))
+	OP(and,l)	TW(IMM(HEX(ffff707f)),IND(REG(rsp)))
+	# Set   12 (precision exception mask)
+	OP(or,l)	TW(IMM(HEX(1000)),IND(REG(rsp)))
+	ldmxcsr		IND(REG(rsp))
+	leave
+	ret
+
 # C_to_interface passes control from C into Scheme.  To C it is a
 # unary procedure; its one argument is passed in rdi.  It saves the
 # state of the C world (the C frame pointer and stack pointer) and
diff --git a/src/microcode/cmpintmd/x86-64.c b/src/microcode/cmpintmd/x86-64.c
index 404abd402..86144a79a 100644
--- a/src/microcode/cmpintmd/x86-64.c
+++ b/src/microcode/cmpintmd/x86-64.c
@@ -223,6 +223,8 @@ x86_64_reset_hook (void)
   int offset = (COMPILER_REGBLOCK_N_FIXED * (sizeof (SCHEME_OBJECT)));
   unsigned char * rsi_value = ((unsigned char *) Registers);
 
+  x86_64_fpe_reset_traps ();
+
   /* These must match machines/x86-64/lapgen.scm */
 
   SETUP_REGISTER (asm_scheme_to_interface); 		/* 0 */
diff --git a/src/microcode/cmpintmd/x86-64.h b/src/microcode/cmpintmd/x86-64.h
index f296eab47..0a7548fce 100644
--- a/src/microcode/cmpintmd/x86-64.h
+++ b/src/microcode/cmpintmd/x86-64.h
@@ -117,6 +117,7 @@ entry	0		MOV	AL,code		0xB0, code-byte
 */
 
 #define ASM_RESET_HOOK x86_64_reset_hook
+#define FPE_RESET_TRAPS x86_64_fpe_reset_traps
 
 #define CMPINT_USE_STRUCS 1
 
@@ -173,7 +174,7 @@ typedef byte_t insn_t;
 #  define ASM_ENTRY_POINT(name) name
 #endif
 
-extern int ASM_ENTRY_POINT (x86_64_interface_initialize) (void);
+extern void ASM_ENTRY_POINT (x86_64_fpe_reset_traps) (void);
 
 extern void asm_assignment_trap (void);
 extern void asm_dont_serialize_cache (void);