the issue comes from floating point stack being too precise on ix86.

for example the following

-------------------------------------
#include <stdio.h>

int f(double d) { d *= 100; return d; }

int main() {
  printf("%d\n", f(0.099999999999999992));
  return 0;
}
---------------------------------------
gives
- 9 with -02 on i586
- 10 on all other arches
- 10 with -02 -ffloat-store on i586

the patch uses "volatile" to ensure the equivalent of -ffloat-store on the
part of the code that needs it

Signed-off-by: Pascal Rigaux <pixel@mandriva.com>


diff -p -up php-5.2.5/Zend/zend_strtod.c.pix php-5.2.5/Zend/zend_strtod.c
--- php-5.2.5/Zend/zend_strtod.c.pix	2008-01-31 15:07:55.000000000 +0100
+++ php-5.2.5/Zend/zend_strtod.c	2008-02-01 12:07:28.000000000 +0100
@@ -984,7 +984,7 @@ static Bigint * diff(Bigint *a, Bigint *
 
 static double ulp (double _x)
 {
-	_double x;
+	volatile _double x;
 	register Long L;
 	_double a;
 
@@ -1092,7 +1092,7 @@ static Bigint * d2b(double _d, int *e, i
 	Bigint *b;
 	int de, i, k;
 	ULong *x, y, z;
-	_double d;
+	volatile _double d;
 #ifdef VAX
 	ULong d0, d1;
 #endif
@@ -1213,7 +1213,7 @@ static Bigint * d2b(double _d, int *e, i
 
 static double ratio (Bigint *a, Bigint *b)
 {
-	_double da, db;
+	volatile _double da, db;
 	int k, ka, kb;
 
 	value(da) = b2d(a, &ka);
@@ -1480,7 +1480,7 @@ ZEND_API char * zend_dtoa(double _d, int
 	Bigint *b, *b1, *delta, *mlo, *mhi, *S, *tmp;
 	double ds;
 	char *s, *s0;
-	_double d, d2, eps;
+	volatile _double d, d2, eps;
 
 	value(d) = _d;
 
@@ -2043,7 +2058,7 @@ ZEND_API double zend_strtod (CONST char 
 		e, e1, esign, i, j, k, nd, nd0, nf, nz, nz0, sign;
 	CONST char *s, *s0, *s1;
 	double aadj, aadj1, adj;
-	_double rv, rv0;
+	volatile _double rv, rv0;
 	Long L;
 	ULong y, z;
 	Bigint *bb, *bb1, *bd, *bd0, *bs, *delta, *tmp;