[PATCH 1/8] math: Sync powf with Arm Optimized Routines

[Adhemerval Zanella]

Sync with commit 2175be4.  No functional change.

Checked on x86_64-linux-gnu, i686-linux-gnu, and aarch64-linux-gnu.
---
 sysdeps/ieee754/flt-32/e_powf.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/sysdeps/ieee754/flt-32/e_powf.c b/sysdeps/ieee754/flt-32/e_powf.c
index d2558ad172..1fa0a0befe 100644
--- a/sysdeps/ieee754/flt-32/e_powf.c
+++ b/sysdeps/ieee754/flt-32/e_powf.c
@@ -84,8 +84,8 @@ log2_inline (uint32_t ix)
 /* The output of log2 and thus the input of exp2 is either scaled by N
    (in case of fast toint intrinsics) or not.  The unscaled xd must be
    in [-1021,1023], sign_bias sets the sign of the result.  */
-static inline double
-exp2_inline (double_t xd, uint32_t sign_bias)
+static inline float
+exp2_inline (double xd, uint32_t sign_bias)
 {
   uint64_t ki, ski, t;
   double kd, z, r, r2, y, s;
@@ -99,8 +99,7 @@ exp2_inline (double_t xd, uint32_t sign_bias)
 # define C __exp2f_data.poly
 # define SHIFT __exp2f_data.shift_scaled
   /* x = k/N + r with r in [-1/(2N), 1/(2N)] */
-  xd = (double) xd; /* Force double precision if FLT_EVAL_METHOD == 2.  */
-  kd = (double) (xd + SHIFT); /* Rounding to double precision is required.  */
+  kd = (double) (xd + SHIFT);
   ki = asuint64 (kd);
   kd -= SHIFT; /* k/N */
 #endif
@@ -180,7 +179,9 @@ __powf (float x, float y)
 	  if (2 * ix == 0 && iy & 0x80000000)
 	    return __math_divzerof (sign_bias);
 #endif
-	  return iy & 0x80000000 ? 1 / x2 : x2;
+	  /* Without the barrier some versions of clang hoist the 1/x2 and
+	     thus division by zero exception can be signaled spuriously.  */
+	  return iy & 0x80000000 ? math_opt_barrier (1 / x2) : x2;
 	}
       /* x and y are non-zero finite.  */
       if (ix & 0x80000000)
@@ -236,7 +237,7 @@ __powf (float x, float y)
 	  return sign_bias ? -0x1.fffffep127 : 0x1.fffffep127;
 	}
     }
-  return (float) exp2_inline (ylogx, sign_bias);
+  return exp2_inline (ylogx, sign_bias);
 }
 #ifndef __powf
 strong_alias (__powf, __ieee754_powf)
-- 
2.43.0