[PATCH] libm/math: Use __math_xflow in obsolete math code

C compilers may fold const values at compile time, so expressions
which try to elicit underflow/overflow by performing simple
arithemetic on suitable values will not generate the required
exceptions.

Work around this by replacing code which does these arithmetic
operations with calls to the existing __math_xflow functions that are
designed to do this correctly.

Signed-off-by: Keith Packard <[email protected]>
---
 newlib/libm/common/math_errf.c |  2 +-
 newlib/libm/math/e_cosh.c      |  9 +++++----
 newlib/libm/math/e_exp.c       |  5 +++--
 newlib/libm/math/e_pow.c       | 18 ++++++++----------
 newlib/libm/math/ef_cosh.c     |  7 ++++---
 newlib/libm/math/ef_exp.c      |  5 +++--
 newlib/libm/math/ef_pow.c      | 14 ++++++--------
 newlib/libm/math/s_erf.c       |  3 ++-
 newlib/libm/math/sf_erf.c      |  3 ++-
 9 files changed, 34 insertions(+), 32 deletions(-)

diff --git a/newlib/libm/common/math_errf.c b/newlib/libm/common/math_errf.c
index 53c68b1cf..bb8273b8d 100644
--- a/newlib/libm/common/math_errf.c
+++ b/newlib/libm/common/math_errf.c
@@ -51,13 +51,13 @@ xflowf (uint32_t sign, float y)
   return with_errnof (y, ERANGE);
 }
 
-#if !__OBSOLETE_MATH
 HIDDEN float
 __math_uflowf (uint32_t sign)
 {
   return xflowf (sign, 0x1p-95f);
 }
 
+#if !__OBSOLETE_MATH
 #if WANT_ERRNO_UFLOW
 /* Underflows to zero in some non-nearest rounding mode, setting errno
    is valid even if the result is non-zero, but in the subnormal range.  */
diff --git a/newlib/libm/math/e_cosh.c b/newlib/libm/math/e_cosh.c
index a6310bd07..7b258ffef 100644
--- a/newlib/libm/math/e_cosh.c
+++ b/newlib/libm/math/e_cosh.c
@@ -25,7 +25,7 @@
  *			       			          2
  *	    22       <= x <= lnovft :  cosh(x) := exp(x)/2 
  *	    lnovft   <= x <= ln2ovft:  cosh(x) := exp(x/2)/2 * exp(x/2)
- *	    ln2ovft  <  x	    :  cosh(x) := huge*huge (overflow)
+ *	    ln2ovft  <  x	    :  cosh(x) := overflow
  *
  * Special cases:
  *	cosh(x) is |x| if x is +INF, -INF, or NaN.
@@ -33,13 +33,14 @@
  */
 
 #include "fdlibm.h"
+#include "math_config.h"
 
 #ifndef _DOUBLE_IS_32BITS
 
 #ifdef __STDC__
-static const double one = 1.0, half=0.5, huge = 1.0e300;
+static const double one = 1.0, half=0.5;
 #else
-static double one = 1.0, half=0.5, huge = 1.0e300;
+static double one = 1.0, half=0.5;
 #endif
 
 #ifdef __STDC__
@@ -87,7 +88,7 @@ static double one = 1.0, half=0.5, huge = 1.0e300;
 	}
 
     /* |x| > overflowthresold, cosh(x) overflow */
-	return huge*huge;
+	return __math_oflow(0);
 }
 
 #endif /* defined(_DOUBLE_IS_32BITS) */
diff --git a/newlib/libm/math/e_exp.c b/newlib/libm/math/e_exp.c
index d23b1162b..ec26c2099 100644
--- a/newlib/libm/math/e_exp.c
+++ b/newlib/libm/math/e_exp.c
@@ -75,6 +75,7 @@
  */
 
 #include "fdlibm.h"
+#include "math_config.h"
 #if __OBSOLETE_MATH
 
 #ifndef _DOUBLE_IS_32BITS
@@ -126,8 +127,8 @@ P5   =  4.13813679705723846039e-08; /* 0x3E663769, 0x72BEA4D0 */
 		     return x+x; 		/* NaN */
 		else return (xsb==0)? x:0.0;	/* exp(+-inf)={inf,0} */
 	    }
-	    if(x > o_threshold) return huge*huge; /* overflow */
-	    if(x < u_threshold) return twom1000*twom1000; /* underflow */
+	    if(x > o_threshold) return __math_oflow(0); /* overflow */
+	    if(x < u_threshold) return __math_uflow(0); /* underflow */
 	}
 
     /* argument reduction */
diff --git a/newlib/libm/math/e_pow.c b/newlib/libm/math/e_pow.c
index 4c450ec05..e68a76e06 100644
--- a/newlib/libm/math/e_pow.c
+++ b/newlib/libm/math/e_pow.c
@@ -76,8 +76,6 @@ zero    =  0.0,
 one	=  1.0,
 two	=  2.0,
 two53	=  9007199254740992.0,	/* 0x43400000, 0x00000000 */
-huge	=  1.0e300,
-tiny    =  1.0e-300,
 	/* poly coefs for (3/2)*(log(x)-2s-2/3*s**3 */
 L1  =  5.99999999999994648725e-01, /* 0x3FE33333, 0x33333303 */
 L2  =  4.28571428578550184252e-01, /* 0x3FDB6DB6, 0xDB6FABFF */
@@ -197,12 +195,12 @@ ivln2_l  =  1.92596299112661746887e-08; /* 0x3E54AE0B, 0xF85DDF44 =1/ln2 tail*/
     /* |y| is huge */
 	if(iy>0x41e00000) { /* if |y| > 2**31 */
 	    if(iy>0x43f00000){	/* if |y| > 2**64, must o/uflow */
-		if(ix<=0x3fefffff) return (hy<0)? huge*huge:tiny*tiny;
-		if(ix>=0x3ff00000) return (hy>0)? huge*huge:tiny*tiny;
+		if(ix<=0x3fefffff) return (hy<0)? __math_oflow(0):__math_uflow(0);
+		if(ix>=0x3ff00000) return (hy>0)? __math_oflow(0):__math_uflow(0);
 	    }
 	/* over/underflow if x is not close to one */
-	    if(ix<0x3fefffff) return (hy<0)? huge*huge:tiny*tiny;
-	    if(ix>0x3ff00000) return (hy>0)? huge*huge:tiny*tiny;
+	    if(ix<0x3fefffff) return (hy<0)? __math_oflow(0):__math_uflow(0);
+	    if(ix>0x3ff00000) return (hy>0)? __math_oflow(0):__math_uflow(0);
 	/* now |1-x| is tiny <= 2**-20, suffice to compute 
 	   log(x) by x-x^2/2+x^3/3-x^4/4 */
 	    t = ax-1;		/* t has 20 trailing zeros */
@@ -275,15 +273,15 @@ ivln2_l  =  1.92596299112661746887e-08; /* 0x3E54AE0B, 0xF85DDF44 =1/ln2 tail*/
 	EXTRACT_WORDS(j,i,z);
 	if (j>=0x40900000) {				/* z >= 1024 */
 	    if(((j-0x40900000)|i)!=0)			/* if z > 1024 */
-		return s*huge*huge;			/* overflow */
+		return s*__math_oflow(0);			/* overflow */
 	    else {
-		if(p_l+ovt>z-p_h) return s*huge*huge;	/* overflow */
+		if(p_l+ovt>z-p_h) return s*__math_oflow(0);	/* overflow */
 	    }
 	} else if((j&0x7fffffff)>=0x4090cc00 ) {	/* z <= -1075 */
 	    if(((j-0xc090cc00)|i)!=0) 		/* z < -1075 */
-		return s*tiny*tiny;		/* underflow */
+		return s*__math_uflow(0);		/* underflow */
 	    else {
-		if(p_l<=z-p_h) return s*tiny*tiny;	/* underflow */
+		if(p_l<=z-p_h) return s*__math_uflow(0);	/* underflow */
 	    }
 	}
     /*
diff --git a/newlib/libm/math/ef_cosh.c b/newlib/libm/math/ef_cosh.c
index bdce61a00..5690bd7a4 100644
--- a/newlib/libm/math/ef_cosh.c
+++ b/newlib/libm/math/ef_cosh.c
@@ -14,15 +14,16 @@
  */
 
 #include "fdlibm.h"
+#include "math_config.h"
 
 #ifdef __v810__
 #define const
 #endif
 
 #ifdef __STDC__
-static const float one = 1.0, half=0.5, huge = 1.0e30;
+static const float one = 1.0, half=0.5;
 #else
-static float one = 1.0, half=0.5, huge = 1.0e30;
+static float one = 1.0, half=0.5;
 #endif
 
 #ifdef __STDC__
@@ -67,5 +68,5 @@ static float one = 1.0, half=0.5, huge = 1.0e30;
 	}
 
     /* |x| > overflowthresold, cosh(x) overflow */
-	return huge*huge;
+	return __math_oflowf(0);
 }
diff --git a/newlib/libm/math/ef_exp.c b/newlib/libm/math/ef_exp.c
index fb3e2ffe6..0cd0c00b3 100644
--- a/newlib/libm/math/ef_exp.c
+++ b/newlib/libm/math/ef_exp.c
@@ -14,6 +14,7 @@
  */
 
 #include "fdlibm.h"
+#include "math_config.h"
 
 #if __OBSOLETE_MATH
 #ifdef __v810__
@@ -61,9 +62,9 @@ P5   =  4.1381369442e-08; /* 0x3331bb4c */
         if(FLT_UWORD_IS_INFINITE(hx))
 	    return (xsb==0)? x:0.0;		/* exp(+-inf)={inf,0} */
 	if(sx > FLT_UWORD_LOG_MAX)
-	    return huge*huge; /* overflow */
+	    return __math_oflowf(0); /* overflow */
 	if(sx < 0 && hx > FLT_UWORD_LOG_MIN)
-	    return twom100*twom100; /* underflow */
+	    return __math_uflow(0); /* underflow */
 	
     /* argument reduction */
 	if(hx > 0x3eb17218) {		/* if  |x| > 0.5 ln2 */ 
diff --git a/newlib/libm/math/ef_pow.c b/newlib/libm/math/ef_pow.c
index d4ea4c5e8..3f5c5c7e1 100644
--- a/newlib/libm/math/ef_pow.c
+++ b/newlib/libm/math/ef_pow.c
@@ -33,8 +33,6 @@ zero    =  0.0,
 one	=  1.0,
 two	=  2.0,
 two24	=  16777216.0,	/* 0x4b800000 */
-huge	=  1.0e30,
-tiny    =  1.0e-30,
 	/* poly coefs for (3/2)*(log(x)-2s-2/3*s**3 */
 L1  =  6.0000002384e-01, /* 0x3f19999a */
 L2  =  4.2857143283e-01, /* 0x3edb6db7 */
@@ -140,8 +138,8 @@ ivln2_l  =  7.0526075433e-06; /* 0x36eca570 =1/ln2 tail*/
     /* |y| is huge */
 	if(iy>0x4d000000) { /* if |y| > 2**27 */
 	/* over/underflow if x is not close to one */
-	    if(ix<0x3f7ffff8) return (hy<0)? huge*huge:tiny*tiny;
-	    if(ix>0x3f800007) return (hy>0)? huge*huge:tiny*tiny;
+	    if(ix<0x3f7ffff8) return (hy<0)? __math_oflowf(0):__math_uflowf(0);
+	    if(ix>0x3f800007) return (hy>0)? __math_oflowf(0):__math_uflowf(0);
 	/* now |1-x| is tiny <= 2**-20, suffice to compute 
 	   log(x) by x-x^2/2+x^3/3-x^4/4 */
 	    t = ax-1;		/* t has 20 trailing zeros */
@@ -219,14 +217,14 @@ ivln2_l  =  7.0526075433e-06; /* 0x36eca570 =1/ln2 tail*/
 	i = j&0x7fffffff;
 	if (j>0) {
 	    if (i>FLT_UWORD_EXP_MAX)
-	        return s*huge*huge;			/* overflow */
+	        return s*__math_oflowf(0);			/* overflow */
 	    else if (i==FLT_UWORD_EXP_MAX)
-	        if(p_l+ovt>z-p_h) return s*huge*huge;	/* overflow */
+	        if(p_l+ovt>z-p_h) return s*__math_oflowf(0);	/* overflow */
         } else {
 	    if (i>FLT_UWORD_EXP_MIN)
-	        return s*tiny*tiny;			/* underflow */
+	        return s*__math_uflowf(0);			/* underflow */
 	    else if (i==FLT_UWORD_EXP_MIN)
-	        if(p_l<=z-p_h) return s*tiny*tiny;	/* underflow */
+	        if(p_l<=z-p_h) return s*__math_uflowf(0);	/* underflow */
 	}
     /*
      * compute 2**(p_h+p_l)
diff --git a/newlib/libm/math/s_erf.c b/newlib/libm/math/s_erf.c
index eb288fc73..9e2333c11 100644
--- a/newlib/libm/math/s_erf.c
+++ b/newlib/libm/math/s_erf.c
@@ -152,6 +152,7 @@ PORTABILITY
 
 
 #include "fdlibm.h"
+#include "math_config.h"
 
 #ifndef _DOUBLE_IS_32BITS
 
@@ -352,7 +353,7 @@ sb7  = -2.24409524465858183362e+01; /* 0xC03670E2, 0x42712D62 */
 			__ieee754_exp((z-x)*(z+x)+R/S);
 	    if(hx>0) return r/x; else return two-r/x;
 	} else {
-	    if(hx>0) return tiny*tiny; else return two-tiny;
+	    if(hx>0) return __math_uflow(0); else return two-tiny;
 	}
 }
 
diff --git a/newlib/libm/math/sf_erf.c b/newlib/libm/math/sf_erf.c
index 0329c60fa..f3d0de97a 100644
--- a/newlib/libm/math/sf_erf.c
+++ b/newlib/libm/math/sf_erf.c
@@ -14,6 +14,7 @@
  */
 
 #include "fdlibm.h"
+#include "math_config.h"
 
 #ifdef __v810__
 #define const
@@ -217,7 +218,7 @@ sb7  = -2.2440952301e+01; /* 0xc1b38712 */
 			__ieee754_expf((z-x)*(z+x)+R/S);
 	    if(hx>0) return r/x; else return two-r/x;
 	} else {
-	    if(hx>0) return tiny*tiny; else return two-tiny;
+	    if(hx>0) return __math_uflow(0); else return two-tiny;
 	}
 }
 
-- 
2.28.0.rc2