Create and use SET_RESTORE_ROUND{,_NOEX,_53BIT}{,F,L}.

9 files changed, 213 insertions, 134 deletions

diff --git a/sysdeps/generic/math_private.h b/sysdeps/generic/math_private.h
index ab4b47bfe0..0b945f9afc 100644
--- a/sysdeps/generic/math_private.h
+++ b/sysdeps/generic/math_private.h
@@ -457,6 +457,75 @@ default_libc_feupdateenv (fenv_t *e)
 # define libc_feupdateenv_53bit libc_feupdateenv
 #endif
 
+/* Save and set the rounding mode.  The use of fenv_t to store the old mode
+   allows a target-specific version of this function to avoid converting the
+   rounding mode from the fpu format.  By default we have no choice but to
+   manipulate the entire env.  */
+
+#ifndef libc_feholdsetround
+# define libc_feholdsetround  libc_feholdexcept_setround
+#endif
+#ifndef libc_feholdsetroundf
+# define libc_feholdsetroundf libc_feholdexcept_setroundf
+#endif
+#ifndef libc_feholdsetroundl
+# define libc_feholdsetroundl libc_feholdexcept_setroundl
+#endif
+
+/* ... and the reverse.  */
+
+#ifndef libc_feresetround
+# define libc_feresetround  libc_feupdateenv
+#endif
+#ifndef libc_feresetroundf
+# define libc_feresetroundf libc_feupdateenvf
+#endif
+#ifndef libc_feresetroundl
+# define libc_feresetroundl libc_feupdateenvl
+#endif
+
+/* ... and a version that may also discard exceptions.  */
+
+#ifndef libc_feresetround_noex
+# define libc_feresetround_noex  libc_fesetenv
+#endif
+#ifndef libc_feresetround_noexf
+# define libc_feresetround_noexf libc_fesetenvf
+#endif
+#ifndef libc_feresetround_noexl
+# define libc_feresetround_noexl libc_fesetenvl
+#endif
+
+/* Save and restore the rounding mode within a lexical block.  */
+
+#define SET_RESTORE_ROUND(RM) \
+  fenv_t __libc_save_rm __attribute__((cleanup(libc_feresetround)));	\
+  libc_feholdsetround (&__libc_save_rm, (RM))
+#define SET_RESTORE_ROUNDF(RM) \
+  fenv_t __libc_save_rm __attribute__((cleanup(libc_feresetroundf)));	\
+  libc_feholdsetroundf (&__libc_save_rm, (RM))
+#define SET_RESTORE_ROUNDL(RM) \
+  fenv_t __libc_save_rm __attribute__((cleanup(libc_feresetroundl)));	\
+  libc_feholdsetroundl (&__libc_save_rm, (RM))
+
+/* Save and restore the rounding mode within a lexical block, and also
+   the set of exceptions raised within the block may be discarded.  */
+
+#define SET_RESTORE_ROUND_NOEX(RM) \
+  fenv_t __libc_save_rm __attribute__((cleanup(libc_feresetround_noex))); \
+  libc_feholdsetround (&__libc_save_rm, (RM))
+#define SET_RESTORE_ROUND_NOEXF(RM) \
+  fenv_t __libc_save_rm __attribute__((cleanup(libc_feresetround_noexf))); \
+  libc_feholdsetroundf (&__libc_save_rm, (RM))
+#define SET_RESTORE_ROUND_NOEXL(RM) \
+  fenv_t __libc_save_rm __attribute__((cleanup(libc_feresetround_noexl))); \
+  libc_feholdsetroundl (&__libc_save_rm, (RM))
+
+/* Like SET_RESTORE_ROUND, but also set rounding precision to 53 bits.  */
+#define SET_RESTORE_ROUND_53BIT(RM) \
+  fenv_t __libc_save_rm __attribute__((cleanup(libc_feupdateenv_53bit))); \
+  libc_feholdexcept_setround_53bit (&__libc_save_rm, (RM))
+
 #define __nan(str) \
   (__builtin_constant_p (str) && str[0] == '\0' ? NAN : __nan (str))
 #define __nanf(str) \
diff --git a/sysdeps/ieee754/dbl-64/e_exp.c b/sysdeps/ieee754/dbl-64/e_exp.c
index cb8d9e8d9d..5deba5e445 100644
--- a/sysdeps/ieee754/dbl-64/e_exp.c
+++ b/sysdeps/ieee754/dbl-64/e_exp.c
@@ -59,10 +59,9 @@ __ieee754_exp(double x) {
   int4 k;
 #endif
   int4 i,j,m,n,ex;
-  fenv_t env;
   double retval;
 
-  libc_feholdexcept_setround (&env, FE_TONEAREST);
+  SET_RESTORE_ROUND (FE_TONEAREST);
 
   junk1.x = x;
   m = junk1.i[HIGH_HALF];
@@ -157,7 +156,6 @@ __ieee754_exp(double x) {
     else { retval = __slowexp(x); goto ret; }
   }
  ret:
-  libc_feupdateenv (&env);
   return retval;
 }
 #ifndef __ieee754_exp
diff --git a/sysdeps/ieee754/dbl-64/e_exp2.c b/sysdeps/ieee754/dbl-64/e_exp2.c
index 4cf879b7f9..e57ec92116 100644
--- a/sysdeps/ieee754/dbl-64/e_exp2.c
+++ b/sysdeps/ieee754/dbl-64/e_exp2.c
@@ -61,57 +61,56 @@ __ieee754_exp2 (double x)
       int tval, unsafe;
       double rx, x22, result;
       union ieee754_double ex2_u, scale_u;
-      fenv_t oldenv;
-
-      libc_feholdexcept_setround (&oldenv, FE_TONEAREST);
-
-      /* 1. Argument reduction.
-	 Choose integers ex, -256 <= t < 256, and some real
-	 -1/1024 <= x1 <= 1024 so that
-	 x = ex + t/512 + x1.
-
-	 First, calculate rx = ex + t/512.  */
-      rx = x + THREEp42;
-      rx -= THREEp42;
-      x -= rx;  /* Compute x=x1. */
-      /* Compute tval = (ex*512 + t)+256.
-	 Now, t = (tval mod 512)-256 and ex=tval/512  [that's mod, NOT %; and
-	 /-round-to-nearest not the usual c integer /].  */
-      tval = (int) (rx * 512.0 + 256.0);
-
-      /* 2. Adjust for accurate table entry.
-	 Find e so that
-	 x = ex + t/512 + e + x2
-	 where -1e6 < e < 1e6, and
-	 (double)(2^(t/512+e))
-	 is accurate to one part in 2^-64.  */
-
-      /* 'tval & 511' is the same as 'tval%512' except that it's always
-	 positive.
-	 Compute x = x2.  */
-      x -= exp2_deltatable[tval & 511];
-
-      /* 3. Compute ex2 = 2^(t/512+e+ex).  */
-      ex2_u.d = exp2_accuratetable[tval & 511];
-      tval >>= 9;
-      unsafe = abs(tval) >= -DBL_MIN_EXP - 1;
-      ex2_u.ieee.exponent += tval >> unsafe;
-      scale_u.d = 1.0;
-      scale_u.ieee.exponent += tval - (tval >> unsafe);
-
-      /* 4. Approximate 2^x2 - 1, using a fourth-degree polynomial,
-	 with maximum error in [-2^-10-2^-30,2^-10+2^-30]
-	 less than 10^-19.  */
-
-      x22 = (((.0096181293647031180
-	       * x + .055504110254308625)
-	      * x + .240226506959100583)
-	     * x + .69314718055994495) * ex2_u.d;
-      math_opt_barrier (x22);
 
-      /* 5. Return (2^x2-1) * 2^(t/512+e+ex) + 2^(t/512+e+ex).  */
-      libc_fesetenv (&oldenv);
+      {
+	SET_RESTORE_ROUND_NOEX (FE_TONEAREST);
+
+	/* 1. Argument reduction.
+	   Choose integers ex, -256 <= t < 256, and some real
+	   -1/1024 <= x1 <= 1024 so that
+	   x = ex + t/512 + x1.
+
+	   First, calculate rx = ex + t/512.  */
+	rx = x + THREEp42;
+	rx -= THREEp42;
+	x -= rx;  /* Compute x=x1. */
+	/* Compute tval = (ex*512 + t)+256.
+	   Now, t = (tval mod 512)-256 and ex=tval/512  [that's mod, NOT %;
+	   and /-round-to-nearest not the usual c integer /].  */
+	tval = (int) (rx * 512.0 + 256.0);
+
+	/* 2. Adjust for accurate table entry.
+	   Find e so that
+	   x = ex + t/512 + e + x2
+	   where -1e6 < e < 1e6, and
+	   (double)(2^(t/512+e))
+	   is accurate to one part in 2^-64.  */
+
+	/* 'tval & 511' is the same as 'tval%512' except that it's always
+	   positive.
+	   Compute x = x2.  */
+	x -= exp2_deltatable[tval & 511];
+
+	/* 3. Compute ex2 = 2^(t/512+e+ex).  */
+	ex2_u.d = exp2_accuratetable[tval & 511];
+	tval >>= 9;
+	unsafe = abs(tval) >= -DBL_MIN_EXP - 1;
+	ex2_u.ieee.exponent += tval >> unsafe;
+	scale_u.d = 1.0;
+	scale_u.ieee.exponent += tval - (tval >> unsafe);
+
+	/* 4. Approximate 2^x2 - 1, using a fourth-degree polynomial,
+	   with maximum error in [-2^-10-2^-30,2^-10+2^-30]
+	   less than 10^-19.  */
+
+	x22 = (((.0096181293647031180
+		 * x + .055504110254308625)
+		* x + .240226506959100583)
+	       * x + .69314718055994495) * ex2_u.d;
+        math_opt_barrier (x22);
+      }
 
+      /* 5. Return (2^x2-1) * 2^(t/512+e+ex) + 2^(t/512+e+ex).  */
       result = x22 * x + ex2_u.d;
 
       if (!unsafe)
diff --git a/sysdeps/ieee754/dbl-64/e_pow.c b/sysdeps/ieee754/dbl-64/e_pow.c
index 550633cf9b..f936a72de7 100644
--- a/sysdeps/ieee754/dbl-64/e_pow.c
+++ b/sysdeps/ieee754/dbl-64/e_pow.c
@@ -85,10 +85,9 @@ __ieee754_pow(double x, double y) {
        (u.i[HIGH_HALF]==0 && u.i[LOW_HALF]!=0))  &&
 				      /*   2^-1023< x<= 2^-1023 * 0x1.0000ffffffff */
       (v.i[HIGH_HALF]&0x7fffffff) < 0x4ff00000) {              /* if y<-1 or y>1   */
-    fenv_t env;
     double retval;
 
-    libc_feholdexcept_setround (&env, FE_TONEAREST);
+    SET_RESTORE_ROUND (FE_TONEAREST);
 
     z = log1(x,&aa,&error);                                 /* x^y  =e^(y log (X)) */
     t = y*134217729.0;
@@ -105,7 +104,6 @@ __ieee754_pow(double x, double y) {
     t = __exp1(a1,a2,1.9e16*error);     /* return -10 or 0 if wasn't computed exactly */
     retval = (t>0)?t:power1(x,y);
 
-    libc_feupdateenv (&env);
     return retval;
   }
 
diff --git a/sysdeps/ieee754/dbl-64/s_sin.c b/sysdeps/ieee754/dbl-64/s_sin.c
index 4b4b67573d..7b9252f81e 100644
--- a/sysdeps/ieee754/dbl-64/s_sin.c
+++ b/sysdeps/ieee754/dbl-64/s_sin.c
@@ -108,10 +108,9 @@ __sin(double x){
 #if 0
 	int4 nn;
 #endif
-	fenv_t env;
 	double retval = 0;
 
-	libc_feholdexcept_setround_53bit (&env, FE_TONEAREST);
+	SET_RESTORE_ROUND_53BIT (FE_TONEAREST);
 
 	u.x = x;
 	m = u.i[HIGH_HALF];
@@ -365,7 +364,6 @@ __sin(double x){
 	}
 
  ret:
-	libc_feupdateenv_53bit (&env);
 	return retval;
 }
 
@@ -383,10 +381,9 @@ __cos(double x)
   mynumber u,v;
   int4 k,m,n;
 
-  fenv_t env;
   double retval = 0;
 
-  libc_feholdexcept_setround_53bit (&env, FE_TONEAREST);
+  SET_RESTORE_ROUND_53BIT (FE_TONEAREST);
 
   u.x = x;
   m = u.i[HIGH_HALF];
@@ -635,7 +632,6 @@ __cos(double x)
   }
 
  ret:
-  libc_feupdateenv_53bit (&env);
   return retval;
 }
 
diff --git a/sysdeps/ieee754/dbl-64/s_tan.c b/sysdeps/ieee754/dbl-64/s_tan.c
index 8eee383933..f8507eaa4c 100644
--- a/sysdeps/ieee754/dbl-64/s_tan.c
+++ b/sysdeps/ieee754/dbl-64/s_tan.c
@@ -68,13 +68,12 @@ tan(double x) {
   mp_no mpy;
 #endif
 
-  fenv_t env;
   double retval;
 
   int __branred(double, double *, double *);
   int __mpranred(double, mp_no *, int);
 
-  libc_feholdexcept_setround_53bit (&env, FE_TONEAREST);
+  SET_RESTORE_ROUND_53BIT (FE_TONEAREST);
 
   /* x=+-INF, x=NaN */
   num.d = x;  ux = num.i[HIGH_HALF];
@@ -503,7 +502,6 @@ tan(double x) {
   goto ret;
 
  ret:
-  libc_feupdateenv_53bit (&env);
   return retval;
 }
 
diff --git a/sysdeps/ieee754/flt-32/e_exp2f.c b/sysdeps/ieee754/flt-32/e_exp2f.c
index e728e6ec74..267d81b23f 100644
--- a/sysdeps/ieee754/flt-32/e_exp2f.c
+++ b/sysdeps/ieee754/flt-32/e_exp2f.c
@@ -54,53 +54,52 @@ __ieee754_exp2f (float x)
       int tval, unsafe;
       float rx, x22, result;
       union ieee754_float ex2_u, scale_u;
-      fenv_t oldenv;
-
-      libc_feholdexcept_setroundf (&oldenv, FE_TONEAREST);
-
-      /* 1. Argument reduction.
-	 Choose integers ex, -128 <= t < 128, and some real
-	 -1/512 <= x1 <= 1/512 so that
-	 x = ex + t/512 + x1.
-
-	 First, calculate rx = ex + t/256.  */
-      rx = x + THREEp14;
-      rx -= THREEp14;
-      x -= rx;  /* Compute x=x1. */
-      /* Compute tval = (ex*256 + t)+128.
-	 Now, t = (tval mod 256)-128 and ex=tval/256  [that's mod, NOT %; and
-	 /-round-to-nearest not the usual c integer /].  */
-      tval = (int) (rx * 256.0f + 128.0f);
-
-      /* 2. Adjust for accurate table entry.
-	 Find e so that
-	 x = ex + t/256 + e + x2
-	 where -7e-4 < e < 7e-4, and
-	 (float)(2^(t/256+e))
-	 is accurate to one part in 2^-64.  */
-
-      /* 'tval & 255' is the same as 'tval%256' except that it's always
-	 positive.
-	 Compute x = x2.  */
-      x -= __exp2f_deltatable[tval & 255];
-
-      /* 3. Compute ex2 = 2^(t/255+e+ex).  */
-      ex2_u.f = __exp2f_atable[tval & 255];
-      tval >>= 8;
-      unsafe = abs(tval) >= -FLT_MIN_EXP - 1;
-      ex2_u.ieee.exponent += tval >> unsafe;
-      scale_u.f = 1.0;
-      scale_u.ieee.exponent += tval - (tval >> unsafe);
-
-      /* 4. Approximate 2^x2 - 1, using a second-degree polynomial,
-	 with maximum error in [-2^-9 - 2^-14, 2^-9 + 2^-14]
-	 less than 1.3e-10.  */
-
-      x22 = (.24022656679f * x + .69314736128f) * ex2_u.f;
 
-      /* 5. Return (2^x2-1) * 2^(t/512+e+ex) + 2^(t/512+e+ex).  */
-      libc_fesetenv (&oldenv);
+      {
+	SET_RESTORE_ROUND_NOEXF (FE_TONEAREST);
+
+	/* 1. Argument reduction.
+	   Choose integers ex, -128 <= t < 128, and some real
+	   -1/512 <= x1 <= 1/512 so that
+	   x = ex + t/512 + x1.
+
+	   First, calculate rx = ex + t/256.  */
+	rx = x + THREEp14;
+	rx -= THREEp14;
+	x -= rx;  /* Compute x=x1. */
+	/* Compute tval = (ex*256 + t)+128.
+	   Now, t = (tval mod 256)-128 and ex=tval/256  [that's mod, NOT %;
+	   and /-round-to-nearest not the usual c integer /].  */
+	tval = (int) (rx * 256.0f + 128.0f);
+
+	/* 2. Adjust for accurate table entry.
+	   Find e so that
+	   x = ex + t/256 + e + x2
+	   where -7e-4 < e < 7e-4, and
+	   (float)(2^(t/256+e))
+	   is accurate to one part in 2^-64.  */
+
+	/* 'tval & 255' is the same as 'tval%256' except that it's always
+	   positive.
+	   Compute x = x2.  */
+	x -= __exp2f_deltatable[tval & 255];
+
+	/* 3. Compute ex2 = 2^(t/255+e+ex).  */
+	ex2_u.f = __exp2f_atable[tval & 255];
+	tval >>= 8;
+	unsafe = abs(tval) >= -FLT_MIN_EXP - 1;
+	ex2_u.ieee.exponent += tval >> unsafe;
+	scale_u.f = 1.0;
+	scale_u.ieee.exponent += tval - (tval >> unsafe);
+
+	/* 4. Approximate 2^x2 - 1, using a second-degree polynomial,
+	   with maximum error in [-2^-9 - 2^-14, 2^-9 + 2^-14]
+	   less than 1.3e-10.  */
+
+	x22 = (.24022656679f * x + .69314736128f) * ex2_u.f;
+      }
 
+      /* 5. Return (2^x2-1) * 2^(t/512+e+ex) + 2^(t/512+e+ex).  */
       result = x22 * x + ex2_u.f;
 
       if (!unsafe)
diff --git a/sysdeps/ieee754/flt-32/e_expf.c b/sysdeps/ieee754/flt-32/e_expf.c
index e69e7f6ae0..57aff16ab7 100644
--- a/sysdeps/ieee754/flt-32/e_expf.c
+++ b/sysdeps/ieee754/flt-32/e_expf.c
@@ -80,40 +80,39 @@ __ieee754_expf (float x)
       double x22, t, result, dx;
       float n, delta;
       union ieee754_double ex2_u;
-      fenv_t oldenv;
 
-      libc_feholdexcept_setroundf (&oldenv, FE_TONEAREST);
+      {
+	SET_RESTORE_ROUND_NOEXF (FE_TONEAREST);
 
-      /* Calculate n.  */
-      n = x * M_1_LN2 + THREEp22;
-      n -= THREEp22;
-      dx = x - n*M_LN2;
+	/* Calculate n.  */
+	n = x * M_1_LN2 + THREEp22;
+	n -= THREEp22;
+	dx = x - n*M_LN2;
 
-      /* Calculate t/512.  */
-      t = dx + THREEp42;
-      t -= THREEp42;
-      dx -= t;
+	/* Calculate t/512.  */
+	t = dx + THREEp42;
+	t -= THREEp42;
+	dx -= t;
 
-      /* Compute tval = t.  */
-      tval = (int) (t * 512.0);
+	/* Compute tval = t.  */
+	tval = (int) (t * 512.0);
 
-      if (t >= 0)
-	delta = - __exp_deltatable[tval];
-      else
-	delta = __exp_deltatable[-tval];
+	if (t >= 0)
+	  delta = - __exp_deltatable[tval];
+	else
+	  delta = __exp_deltatable[-tval];
 
-      /* Compute ex2 = 2^n e^(t/512+delta[t]).  */
-      ex2_u.d = __exp_atable[tval+177];
-      ex2_u.ieee.exponent += (int) n;
+	/* Compute ex2 = 2^n e^(t/512+delta[t]).  */
+	ex2_u.d = __exp_atable[tval+177];
+	ex2_u.ieee.exponent += (int) n;
 
-      /* Approximate e^(dx+delta) - 1, using a second-degree polynomial,
-	 with maximum error in [-2^-10-2^-28,2^-10+2^-28]
-	 less than 5e-11.  */
-      x22 = (0.5000000496709180453 * dx + 1.0000001192102037084) * dx + delta;
+	/* Approximate e^(dx+delta) - 1, using a second-degree polynomial,
+	   with maximum error in [-2^-10-2^-28,2^-10+2^-28]
+	   less than 5e-11.  */
+	x22 = (0.5000000496709180453 * dx + 1.0000001192102037084) * dx + delta;
+      }
 
       /* Return result.  */
-      libc_fesetenvf (&oldenv);
-
       result = x22 * ex2_u.d + ex2_u.d;
       return (float) result;
     }
diff --git a/sysdeps/x86_64/fpu/math_private.h b/sysdeps/x86_64/fpu/math_private.h
index 8b1fe70d2c..3289afc58b 100644
--- a/sysdeps/x86_64/fpu/math_private.h
+++ b/sysdeps/x86_64/fpu/math_private.h
@@ -119,6 +119,29 @@ libc_feupdateenv (fenv_t *e)
 #define libc_feupdateenv  libc_feupdateenv
 #define libc_feupdateenvf libc_feupdateenv
 
+static __always_inline void
+libc_feholdsetround (fenv_t *e, int r)
+{
+  unsigned int mxcsr;
+  asm (STMXCSR " %0" : "=m" (*&mxcsr));
+  e->__mxcsr = mxcsr;
+  mxcsr = (mxcsr & ~0x6000) | (r << 3);
+  asm volatile (LDMXCSR " %0" : : "m" (*&mxcsr));
+}
+#define libc_feholdsetround  libc_feholdsetround
+#define libc_feholdsetroundf libc_feholdsetround
+
+static __always_inline void
+libc_feresetround (fenv_t *e)
+{
+  unsigned int mxcsr;
+  asm (STMXCSR " %0" : "=m" (*&mxcsr));
+  mxcsr = (mxcsr & ~0x6000) | (e->__mxcsr & 0x6000);
+  asm volatile (LDMXCSR " %0" : : "m" (*&mxcsr));
+}
+#define libc_feresetround  libc_feresetround
+#define libc_feresetroundf libc_feresetround
+
 #include_next <math_private.h>
 
 extern __always_inline double