math.floats.env: detect +fp-x87-stack-fault+ during collect-fp-exceptions block

basis/math/floats/env/x86/tags.txt

@@ -1 +1,2 @@
 not loaded
+not tested

basis/math/floats/env/x86/x86-tests.factor

@@ -0,0 +1,21 @@
+USING: math.floats.env math.floats.env.x86 tools.test
+alien.c-types alien.syntax classes.struct compiler.test
+math kernel sequences ;
+IN: math.floats.env.x86.tests
+
+! the sqrtl function is really long double sqrtl ( long double x ) 
+! calling it as if it had a void return leaves the return value on
+! the x87 stack, so 9 calls will be guaranteed to cause a stack
+! fault
+STRUCT: fake-long-double { x char[20] } ;
+FUNCTION-ALIAS: busted-sqrtl
+    void sqrtl ( fake-long-double x ) ;
+
+[ t ] [
+    [
+        [
+            9 [ fake-long-double <struct> busted-sqrtl ] times
+        ] collect-fp-exceptions
+    ] compile-call
+    +fp-x87-stack-fault+ swap member?
+] unit-test

basis/math/floats/env/x86/x86.factor

@@ -88,7 +88,9 @@ M: sse-env (set-denormal-mode) ( register mode -- register' )
         } case
     ] curry change-mxcsr ; inline
 
-CONSTANT: x87-exception-bits HEX: 3f
+SINGLETON: +fp-x87-stack-fault+
+
+CONSTANT: x87-exception-bits HEX: 7f
 CONSTANT: x87-exception>bit
     H{
         { +fp-invalid-operation+ HEX: 01 }
@@ -96,6 +98,7 @@ CONSTANT: x87-exception>bit
         { +fp-underflow+         HEX: 10 }
         { +fp-zero-divide+       HEX: 04 }
         { +fp-inexact+           HEX: 20 }
+        { +fp-x87-stack-fault+   HEX: 40 }
     }
 
 CONSTANT: x87-rounding-mode-bits HEX: 0c00