[ARM] Fix PR85261: ICE with FPSCR setter builtin

Instruction pattern for setting the FPSCR expects the input value to be
in a register. However, __builtin_arm_set_fpscr expander does not ensure
that this is the case and as a result GCC ICEs when the builtin is
called with a constant literal.

This commit fixes the builtin to force the input value into a register.
It also remove the unneeded volatile in the existing fpscr test and
fixes the function prototype.

2018-04-11  Thomas Preud'homme  <thomas.preudhomme@arm.com>

    gcc/
    PR target/85261
    * config/arm/arm-builtins.c (arm_expand_builtin): Force input operand
    into register.

    gcc/testsuite/
    PR target/85261
    * config/arm/arm-builtins.c (arm_expand_builtin): Force input operand
    into register.

From-SVN: r259310

gcc/ChangeLog

+2018-04-11  Thomas Preud'homme  <thomas.preudhomme@arm.com>
+
+	PR target/85261
+	* config/arm/arm-builtins.c (arm_expand_builtin): Force input operand
+	into register.
+
 2018-04-10  Aaron Sawdey  <acsawdey@linux.ibm.com>
 
 	PR target/85321

gcc/config/arm/arm-builtins.c

@@ -2592,7 +2592,7 @@ arm_expand_builtin (tree exp,
 	  icode = CODE_FOR_set_fpscr;
 	  arg0 = CALL_EXPR_ARG (exp, 0);
 	  op0 = expand_normal (arg0);
-	  pat = GEN_FCN (icode) (op0);
+	  pat = GEN_FCN (icode) (force_reg (SImode, op0));
 	}
       emit_insn (pat);
       return target;

gcc/testsuite/ChangeLog

+2018-04-11  Thomas Preud'homme  <thomas.preudhomme@arm.com>
+
+	PR target/85261
+	* config/arm/arm-builtins.c (arm_expand_builtin): Force input operand
+	into register.
+
 2018-04-10  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	PR c++/70808

gcc/testsuite/gcc.target/arm/fpscr.c

@@ -6,11 +6,14 @@
 /* { dg-add-options arm_fp } */
 
 void
-test_fpscr ()
+test_fpscr (void)
 {
-  volatile unsigned int status = __builtin_arm_get_fpscr ();
+  unsigned status;
+
+  __builtin_arm_set_fpscr (0);
+  status = __builtin_arm_get_fpscr ();
   __builtin_arm_set_fpscr (status);
 }
 
 /* { dg-final { scan-assembler "mrc\tp10, 7, r\[0-9\]+, cr1, cr0, 0" } } */
-/* { dg-final { scan-assembler "mcr\tp10, 7, r\[0-9\]+, cr1, cr0, 0" } } */
+/* { dg-final { scan-assembler-times "mcr\tp10, 7, r\[0-9\]+, cr1, cr0, 0" 2 } } */