ARM: fp16 Fix PR 67624 - Incorrect conversion of float Infinity to __fp16

PR libgcc/67624
	libgcc:
	* config/arm/fp16.c (__gnu_f2h_internal): Handle infinity correctly.
	gcc/testsuite:
	* gcc.target/arm/fp16-inf.c: New test.

From-SVN: r228082

gcc/testsuite/ChangeLog

@@ -1,3 +1,8 @@
+2015-09-24  Richard Earnshaw  <rearnsha@arm.com>
+
+	PR libgcc/67624
+	* gcc.target/arm/fp16-inf.c: New test.
+
 2015-09-24  Kirill Yukhin <kirill.yukhin@intel.com>
 
 	* gcc.target/i386/avx512vbmi-check.h (main): Fix register

gcc/testsuite/gcc.target/arm/fp16-inf.c

@@ -0,0 +1,14 @@
+/* { dg-do run } */
+/* { dg-options "-O -mfp16-format=ieee" } */
+
+/* Conversion of infinity to __fp16 and back again should preserve the
+   value.  */
+volatile float f = __builtin_inf ();
+
+int main ()
+{
+  __fp16 h = f;
+  if (h != __builtin_inf ())
+    __builtin_abort ();
+  return 0;
+}

libgcc/ChangeLog

@@ -1,3 +1,8 @@
+2015-09-24  Richard Earnshaw  <rearnsha@arm.com>
+
+	PR libgcc/67624
+	* config/arm/fp16.c (__gnu_f2h_internal): Handle infinity correctly.
+
 2015-09-24  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>
 
 	* config.host (*-*-solaris2*): Add t-crtstuff-pic to tmake_file.

libgcc/config/arm/fp16.c

@@ -35,6 +35,9 @@ __gnu_f2h_internal(unsigned int a, int ieee)
     {
       if (!ieee)
 	return sign;
+      if (mantissa == 0)
+	return sign | 0x7c00;	/* Infinity.  */
+      /* Remaining cases are NaNs.  Convert SNaN to QNaN.  */
       return sign | 0x7e00 | (mantissa >> 13);
     }
 
@@ -49,7 +52,7 @@ __gnu_f2h_internal(unsigned int a, int ieee)
     {
       mask = 0x00ffffff;
       if (aexp >= -25)
-        mask >>= 25 + aexp;
+	mask >>= 25 + aexp;
     }
   else
     mask = 0x00001fff;