[7/77] Add scalar_float_mode

This patch adds a scalar_float_mode class, which wraps a mode enum
that is known to satisfy SCALAR_FLOAT_MODE_P.  Things like "SFmode"
now give a scalar_float_mode object instead of a machine_mode.
This in turn needs a change to the real.h format_helper, so that
it can accept both machine_modes and scalar_float_modes.

2017-08-30  Richard Sandiford  <richard.sandiford@linaro.org>
	    Alan Hayward  <alan.hayward@arm.com>
	    David Sherwood  <david.sherwood@arm.com>

gcc/
	* coretypes.h (scalar_float_mode): New type.
	* machmode.h (mode_traits::from_int): Use machine_mode if
	USE_ENUM_MODES is defined.
	(is_a): New function.
	(as_a): Likewise.
	(dyn_cast): Likewise.
	(scalar_float_mode): New class.
	(scalar_float_mode::includes_p): New function.
	(is_float_mode): Likewise.
	* gdbhooks.py (MachineModePrinter): New class.
	(build_pretty_printer): Use it for scalar_float_mode.
	* real.h (FLOAT_MODE_FORMAT): Use as_a <scalar_float_mode>.
	(format_helper::format_helper): Turn into a template.
	* genmodes.c (get_mode_class): New function.
	(emit_insn_modes_h): Give modes the class returned by get_mode_class,
	or machine_mode if none.
	* config/aarch64/aarch64.c (aarch64_simd_valid_immediate): Use
	as_a <scalar_float_mode>.
	* dwarf2out.c (mem_loc_descriptor): Likewise.
	(insert_float): Likewise.
	(add_const_value_attribute): Likewise.
	* simplify-rtx.c (simplify_immed_subreg): Likewise.
	* optabs.c (expand_absneg_bit): Take a scalar_float_mode.
	(expand_unop): Update accordingly.
	(expand_abs_nojump): Likewise.
	(expand_copysign_absneg): Take a scalar_float_mode.
	(expand_copysign_bit): Likewise.
	(expand_copysign): Update accordingly.

gcc/ada/
	* gcc-interface/utils.c (gnat_type_for_mode): Use is_a
	<scalar_float_mode> instead of SCALAR_FLOAT_MODE_P.

gcc/go/
	* go-lang.c (go_langhook_type_for_mode): Use is_float_mode.

Co-Authored-By: Alan Hayward <alan.hayward@arm.com>
Co-Authored-By: David Sherwood <david.sherwood@arm.com>

From-SVN: r251458

14 files changed, 228 insertions, 44 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 9d8c1f0..6f5107f 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -2,6 +2,39 @@
 	    Alan Hayward  <alan.hayward@arm.com>
 	    David Sherwood  <david.sherwood@arm.com>
 
+	* coretypes.h (scalar_float_mode): New type.
+	* machmode.h (mode_traits::from_int): Use machine_mode if
+	USE_ENUM_MODES is defined.
+	(is_a): New function.
+	(as_a): Likewise.
+	(dyn_cast): Likewise.
+	(scalar_float_mode): New class.
+	(scalar_float_mode::includes_p): New function.
+	(is_float_mode): Likewise.
+	* gdbhooks.py (MachineModePrinter): New class.
+	(build_pretty_printer): Use it for scalar_float_mode.
+	* real.h (FLOAT_MODE_FORMAT): Use as_a <scalar_float_mode>.
+	(format_helper::format_helper): Turn into a template.
+	* genmodes.c (get_mode_class): New function.
+	(emit_insn_modes_h): Give modes the class returned by get_mode_class,
+	or machine_mode if none.
+	* config/aarch64/aarch64.c (aarch64_simd_valid_immediate): Use
+	as_a <scalar_float_mode>.
+	* dwarf2out.c (mem_loc_descriptor): Likewise.
+	(insert_float): Likewise.
+	(add_const_value_attribute): Likewise.
+	* simplify-rtx.c (simplify_immed_subreg): Likewise.
+	* optabs.c (expand_absneg_bit): Take a scalar_float_mode.
+	(expand_unop): Update accordingly.
+	(expand_abs_nojump): Likewise.
+	(expand_copysign_absneg): Take a scalar_float_mode.
+	(expand_copysign_bit): Likewise.
+	(expand_copysign): Update accordingly.
+
+2017-08-30  Richard Sandiford  <richard.sandiford@linaro.org>
+	    Alan Hayward  <alan.hayward@arm.com>
+	    David Sherwood  <david.sherwood@arm.com>
+
 	* coretypes.h (opt_mode): New class.
 	* machmode.h (opt_mode): Likewise.
 	(opt_mode::else_void): New function.
diff --git a/gcc/ada/ChangeLog b/gcc/ada/ChangeLog
index 769546c..9aab131 100644
--- a/gcc/ada/ChangeLog
+++ b/gcc/ada/ChangeLog
@@ -2,6 +2,13 @@
 	    Alan Hayward  <alan.hayward@arm.com>
 	    David Sherwood  <david.sherwood@arm.com>
 
+	* gcc-interface/utils.c (gnat_type_for_mode): Use is_a
+	<scalar_float_mode> instead of SCALAR_FLOAT_MODE_P.
+
+2017-08-30  Richard Sandiford  <richard.sandiford@linaro.org>
+	    Alan Hayward  <alan.hayward@arm.com>
+	    David Sherwood  <david.sherwood@arm.com>
+
 	* gcc-interface/decl.c (validate_size): Update use of
 	GET_MODE_WIDER_MODE, forcing a wider mode to exist.
 
diff --git a/gcc/ada/gcc-interface/utils.c b/gcc/ada/gcc-interface/utils.c
index 475261b..23127aa 100644
--- a/gcc/ada/gcc-interface/utils.c
+++ b/gcc/ada/gcc-interface/utils.c
@@ -3464,8 +3464,10 @@ gnat_type_for_mode (machine_mode mode, int unsignedp)
   if (COMPLEX_MODE_P (mode))
     return NULL_TREE;
 
-  if (SCALAR_FLOAT_MODE_P (mode))
-    return float_type_for_precision (GET_MODE_PRECISION (mode), mode);
+  scalar_float_mode float_mode;
+  if (is_a <scalar_float_mode> (mode, &float_mode))
+    return float_type_for_precision (GET_MODE_PRECISION (float_mode),
+				     float_mode);
 
   if (SCALAR_INT_MODE_P (mode))
     return gnat_type_for_size (GET_MODE_BITSIZE (mode), unsignedp);
diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index ced6f9b..88373dd 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -11473,8 +11473,12 @@ aarch64_simd_valid_immediate (rtx op, machine_mode mode, bool inverse,
 
       if (info)
 	{
-	  info->value = CONST_VECTOR_ELT (op, 0);
-	  info->element_width = GET_MODE_BITSIZE (GET_MODE (info->value));
+	  rtx elt = CONST_VECTOR_ELT (op, 0);
+	  scalar_float_mode elt_mode
+	    = as_a <scalar_float_mode> (GET_MODE (elt));
+
+	  info->value = elt;
+	  info->element_width = GET_MODE_BITSIZE (elt_mode);
 	  info->mvn = false;
 	  info->shift = 0;
 	}
diff --git a/gcc/coretypes.h b/gcc/coretypes.h
index 4de0611..216c29f 100644
--- a/gcc/coretypes.h
+++ b/gcc/coretypes.h
@@ -55,6 +55,7 @@ typedef const struct simple_bitmap_def *const_sbitmap;
 struct rtx_def;
 typedef struct rtx_def *rtx;
 typedef const struct rtx_def *const_rtx;
+class scalar_float_mode;
 template<typename> class opt_mode;
 
 /* Subclasses of rtx_def, using indentation to show the class
@@ -311,6 +312,8 @@ union _dont_use_tree_here_;
 #define tree union _dont_use_tree_here_ *
 #define const_tree union _dont_use_tree_here_ *
 
+typedef struct scalar_float_mode scalar_float_mode;
+
 #endif
 
 /* Classes of functions that compiler needs to check
diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c
index e17b58a..aafacf4 100644
--- a/gcc/dwarf2out.c
+++ b/gcc/dwarf2out.c
@@ -15324,7 +15324,8 @@ mem_loc_descriptor (rtx rtl, machine_mode mode,
 	  else
 #endif
 	    {
-	      unsigned int length = GET_MODE_SIZE (mode);
+	      scalar_float_mode float_mode = as_a <scalar_float_mode> (mode);
+	      unsigned int length = GET_MODE_SIZE (float_mode);
 	      unsigned char *array = ggc_vec_alloc<unsigned char> (length);
 
 	      insert_float (rtl, array);
@@ -18621,11 +18622,12 @@ insert_float (const_rtx rtl, unsigned char *array)
 {
   long val[4];
   int i;
+  scalar_float_mode mode = as_a <scalar_float_mode> (GET_MODE (rtl));
 
-  real_to_target (val, CONST_DOUBLE_REAL_VALUE (rtl), GET_MODE (rtl));
+  real_to_target (val, CONST_DOUBLE_REAL_VALUE (rtl), mode);
 
   /* real_to_target puts 32-bit pieces in each long.  Pack them.  */
-  for (i = 0; i < GET_MODE_SIZE (GET_MODE (rtl)) / 4; i++)
+  for (i = 0; i < GET_MODE_SIZE (mode) / 4; i++)
     {
       insert_int (val[i], 4, array);
       array += 4;
@@ -18669,21 +18671,19 @@ add_const_value_attribute (dw_die_ref die, rtx rtl)
 	 floating-point constant.  A CONST_DOUBLE is used whenever the
 	 constant requires more than one word in order to be adequately
 	 represented.  */
-      {
-	machine_mode mode = GET_MODE (rtl);
-
-	if (TARGET_SUPPORTS_WIDE_INT == 0 && !SCALAR_FLOAT_MODE_P (mode))
-	  add_AT_double (die, DW_AT_const_value,
-			 CONST_DOUBLE_HIGH (rtl), CONST_DOUBLE_LOW (rtl));
-	else
-	  {
-	    unsigned int length = GET_MODE_SIZE (mode);
-	    unsigned char *array = ggc_vec_alloc<unsigned char> (length);
+      if (TARGET_SUPPORTS_WIDE_INT == 0
+	  && !SCALAR_FLOAT_MODE_P (GET_MODE (rtl)))
+	add_AT_double (die, DW_AT_const_value,
+		       CONST_DOUBLE_HIGH (rtl), CONST_DOUBLE_LOW (rtl));
+      else
+	{
+	  scalar_float_mode mode = as_a <scalar_float_mode> (GET_MODE (rtl));
+	  unsigned int length = GET_MODE_SIZE (mode);
+	  unsigned char *array = ggc_vec_alloc<unsigned char> (length);
 
-	    insert_float (rtl, array);
-	    add_AT_vec (die, DW_AT_const_value, length / 4, 4, array);
-	  }
-      }
+	  insert_float (rtl, array);
+	  add_AT_vec (die, DW_AT_const_value, length / 4, 4, array);
+	}
       return true;
 
     case CONST_VECTOR:
diff --git a/gcc/gdbhooks.py b/gcc/gdbhooks.py
index 847cd08..4cbcefc 100644
--- a/gcc/gdbhooks.py
+++ b/gcc/gdbhooks.py
@@ -422,6 +422,16 @@ class VecPrinter:
 
 ######################################################################
 
+class MachineModePrinter:
+    def __init__(self, gdbval):
+        self.gdbval = gdbval
+
+    def to_string (self):
+        name = str(self.gdbval['m_mode'])
+        return name[2:] if name.startswith('E_') else name
+
+######################################################################
+
 class OptMachineModePrinter:
     def __init__(self, gdbval):
         self.gdbval = gdbval
@@ -532,6 +542,8 @@ def build_pretty_printer():
 
     pp.add_printer_for_regex(r'opt_mode<(\S+)>',
                              'opt_mode', OptMachineModePrinter)
+    pp.add_printer_for_types(['scalar_float_mode'],
+                             'scalar_float_mode', MachineModePrinter)
 
     return pp
 
diff --git a/gcc/genmodes.c b/gcc/genmodes.c
index 96b6ece..8c27b42 100644
--- a/gcc/genmodes.c
+++ b/gcc/genmodes.c
@@ -1129,6 +1129,23 @@ mode_unit_precision_inline (machine_mode mode)\n\
 }\n");
 }
 
+/* Return the best machine mode class for MODE, or null if machine_mode
+   should be used.  */
+
+static const char *
+get_mode_class (struct mode_data *mode)
+{
+  switch (mode->cl)
+    {
+    case MODE_FLOAT:
+    case MODE_DECIMAL_FLOAT:
+      return "scalar_float_mode";
+
+    default:
+      return NULL;
+    }
+}
+
 static void
 emit_insn_modes_h (void)
 {
@@ -1158,8 +1175,12 @@ enum machine_mode\n{");
 	printf ("#ifdef USE_ENUM_MODES\n");
 	printf ("#define %smode E_%smode\n", m->name, m->name);
 	printf ("#else\n");
-	printf ("#define %smode ((void) 0, E_%smode)\n",
-		m->name, m->name);
+	if (const char *mode_class = get_mode_class (m))
+	  printf ("#define %smode (%s ((%s::from_int) E_%smode))\n",
+		  m->name, mode_class, mode_class, m->name);
+	else
+	  printf ("#define %smode ((void) 0, E_%smode)\n",
+		  m->name, m->name);
 	printf ("#endif\n");
       }
 
diff --git a/gcc/go/ChangeLog b/gcc/go/ChangeLog
index f62fdd7..f65a1d4 100644
--- a/gcc/go/ChangeLog
+++ b/gcc/go/ChangeLog
@@ -1,3 +1,9 @@
+2017-08-30  Richard Sandiford  <richard.sandiford@linaro.org>
+	    Alan Hayward  <alan.hayward@arm.com>
+	    David Sherwood  <david.sherwood@arm.com>
+
+	* go-lang.c (go_langhook_type_for_mode): Use is_float_mode.
+
 2017-08-07  Martin Liska  <mliska@suse.cz>
 
 	* go-gcc.cc (Gcc_backend::function): Look up for no_split_stack
diff --git a/gcc/go/go-lang.c b/gcc/go/go-lang.c
index 09e4fea..614d890 100644
--- a/gcc/go/go-lang.c
+++ b/gcc/go/go-lang.c
@@ -382,12 +382,13 @@ go_langhook_type_for_mode (machine_mode mode, int unsignedp)
       return NULL_TREE;
     }
 
+  scalar_float_mode fmode;
   enum mode_class mc = GET_MODE_CLASS (mode);
   if (mc == MODE_INT)
     return go_langhook_type_for_size (GET_MODE_BITSIZE (mode), unsignedp);
-  else if (mc == MODE_FLOAT)
+  else if (is_float_mode (mode, &fmode))
     {
-      switch (GET_MODE_BITSIZE (mode))
+      switch (GET_MODE_BITSIZE (fmode))
 	{
 	case 32:
 	  return float_type_node;
@@ -396,7 +397,7 @@ go_langhook_type_for_mode (machine_mode mode, int unsignedp)
 	default:
 	  // We have to check for long double in order to support
 	  // i386 excess precision.
-	  if (mode == TYPE_MODE(long_double_type_node))
+	  if (fmode == TYPE_MODE(long_double_type_node))
 	    return long_double_type_node;
 	}
     }
diff --git a/gcc/machmode.h b/gcc/machmode.h
index 3b06f6d..3b71b9d 100644
--- a/gcc/machmode.h
+++ b/gcc/machmode.h
@@ -46,9 +46,15 @@ struct mode_traits
        res = T (typename mode_traits<T>::from_int (mode));
 
      when assigning to a value RES that must be assignment-compatible
-     with (but possibly not the same as) T.
-
-     Here we use an enum type distinct from machine_mode but with the
+     with (but possibly not the same as) T.  */
+#ifdef USE_ENUM_MODES
+  /* Allow direct conversion of enums to specific mode classes only
+     when USE_ENUM_MODES is defined.  This is only intended for use
+     by gencondmd, so that it can tell more easily when .md conditions
+     are always false.  */
+  typedef machine_mode from_int;
+#else
+  /* Here we use an enum type distinct from machine_mode but with the
      same range as machine_mode.  T should have a constructor that
      accepts this enum type; it should not have a constructor that
      accepts machine_mode.
@@ -58,6 +64,7 @@ struct mode_traits
      unoptimized code, the return statement above would construct the
      returned T directly from the numerical value of MODE.  */
   enum from_int { dummy = MAX_MACHINE_MODE };
+#endif
 };
 
 template<>
@@ -286,6 +293,75 @@ opt_mode<T>::exists (U *mode) const
   return false;
 }
 
+/* Return true if mode M has type T.  */
+
+template<typename T>
+inline bool
+is_a (machine_mode m)
+{
+  return T::includes_p (m);
+}
+
+/* Assert that mode M has type T, and return it in that form.  */
+
+template<typename T>
+inline T
+as_a (machine_mode m)
+{
+  gcc_checking_assert (T::includes_p (m));
+  return typename mode_traits<T>::from_int (m);
+}
+
+/* Convert M to an opt_mode<T>.  */
+
+template<typename T>
+inline opt_mode<T>
+dyn_cast (machine_mode m)
+{
+  if (T::includes_p (m))
+    return T (typename mode_traits<T>::from_int (m));
+  return opt_mode<T> ();
+}
+
+/* Return true if mode M has type T, storing it as a T in *RESULT
+   if so.  */
+
+template<typename T, typename U>
+inline bool
+is_a (machine_mode m, U *result)
+{
+  if (T::includes_p (m))
+    {
+      *result = T (typename mode_traits<T>::from_int (m));
+      return true;
+    }
+  return false;
+}
+
+/* Represents a machine mode that is known to be a SCALAR_FLOAT_MODE_P.  */
+class scalar_float_mode
+{
+public:
+  typedef mode_traits<scalar_float_mode>::from_int from_int;
+
+  ALWAYS_INLINE scalar_float_mode () {}
+  ALWAYS_INLINE scalar_float_mode (from_int m) : m_mode (machine_mode (m)) {}
+  ALWAYS_INLINE operator machine_mode () const { return m_mode; }
+
+  static bool includes_p (machine_mode);
+
+protected:
+  machine_mode m_mode;
+};
+
+/* Return true if M is a scalar_float_mode.  */
+
+inline bool
+scalar_float_mode::includes_p (machine_mode m)
+{
+  return SCALAR_FLOAT_MODE_P (m);
+}
+
 /* Return the base GET_MODE_SIZE value for MODE.  */
 
 ALWAYS_INLINE unsigned short
@@ -547,6 +623,21 @@ struct int_n_data_t {
 extern bool int_n_enabled_p[NUM_INT_N_ENTS];
 extern const int_n_data_t int_n_data[NUM_INT_N_ENTS];
 
+/* Return true if MODE has class MODE_FLOAT, storing it as a
+   scalar_float_mode in *FLOAT_MODE if so.  */
+
+template<typename T>
+inline bool
+is_float_mode (machine_mode mode, T *float_mode)
+{
+  if (GET_MODE_CLASS (mode) == MODE_FLOAT)
+    {
+      *float_mode = scalar_float_mode (scalar_float_mode::from_int (mode));
+      return true;
+    }
+  return false;
+}
+
 namespace mode_iterator
 {
   /* Start mode iterator *ITER at the first mode in class MCLASS, if any.  */
diff --git a/gcc/optabs.c b/gcc/optabs.c
index c6ad64b..5c9cd34 100644
--- a/gcc/optabs.c
+++ b/gcc/optabs.c
@@ -2552,7 +2552,7 @@ lowpart_subreg_maybe_copy (machine_mode omode, rtx val,
    logical operation on the sign bit.  */
 
 static rtx
-expand_absneg_bit (enum rtx_code code, machine_mode mode,
+expand_absneg_bit (enum rtx_code code, scalar_float_mode mode,
 		   rtx op0, rtx target)
 {
   const struct real_format *fmt;
@@ -2698,6 +2698,7 @@ expand_unop (machine_mode mode, optab unoptab, rtx op0, rtx target,
 {
   enum mode_class mclass = GET_MODE_CLASS (mode);
   machine_mode wider_mode;
+  scalar_float_mode float_mode;
   rtx temp;
   rtx libfunc;
 
@@ -2888,9 +2889,9 @@ expand_unop (machine_mode mode, optab unoptab, rtx op0, rtx target,
   if (optab_to_code (unoptab) == NEG)
     {
       /* Try negating floating point values by flipping the sign bit.  */
-      if (SCALAR_FLOAT_MODE_P (mode))
+      if (is_a <scalar_float_mode> (mode, &float_mode))
 	{
-	  temp = expand_absneg_bit (NEG, mode, op0, target);
+	  temp = expand_absneg_bit (NEG, float_mode, op0, target);
 	  if (temp)
 	    return temp;
 	}
@@ -3087,9 +3088,10 @@ expand_abs_nojump (machine_mode mode, rtx op0, rtx target,
     return temp;
 
   /* For floating point modes, try clearing the sign bit.  */
-  if (SCALAR_FLOAT_MODE_P (mode))
+  scalar_float_mode float_mode;
+  if (is_a <scalar_float_mode> (mode, &float_mode))
     {
-      temp = expand_absneg_bit (ABS, mode, op0, target);
+      temp = expand_absneg_bit (ABS, float_mode, op0, target);
       if (temp)
 	return temp;
     }
@@ -3244,7 +3246,7 @@ expand_one_cmpl_abs_nojump (machine_mode mode, rtx op0, rtx target)
    and not playing with subregs so much, will help the register allocator.  */
 
 static rtx
-expand_copysign_absneg (machine_mode mode, rtx op0, rtx op1, rtx target,
+expand_copysign_absneg (scalar_float_mode mode, rtx op0, rtx op1, rtx target,
 		        int bitpos, bool op0_is_abs)
 {
   machine_mode imode;
@@ -3328,7 +3330,7 @@ expand_copysign_absneg (machine_mode mode, rtx op0, rtx op1, rtx target,
    is true if op0 is known to have its sign bit clear.  */
 
 static rtx
-expand_copysign_bit (machine_mode mode, rtx op0, rtx op1, rtx target,
+expand_copysign_bit (scalar_float_mode mode, rtx op0, rtx op1, rtx target,
 		     int bitpos, bool op0_is_abs)
 {
   machine_mode imode;
@@ -3426,12 +3428,12 @@ expand_copysign_bit (machine_mode mode, rtx op0, rtx op1, rtx target,
 rtx
 expand_copysign (rtx op0, rtx op1, rtx target)
 {
-  machine_mode mode = GET_MODE (op0);
+  scalar_float_mode mode;
   const struct real_format *fmt;
   bool op0_is_abs;
   rtx temp;
 
-  gcc_assert (SCALAR_FLOAT_MODE_P (mode));
+  mode = as_a <scalar_float_mode> (GET_MODE (op0));
   gcc_assert (GET_MODE (op1) == mode);
 
   /* First try to do it with a special instruction.  */
diff --git a/gcc/real.h b/gcc/real.h
index e7248e3..95104b0 100644
--- a/gcc/real.h
+++ b/gcc/real.h
@@ -183,8 +183,7 @@ extern const struct real_format *
 			: (gcc_unreachable (), 0)])
 
 #define FLOAT_MODE_FORMAT(MODE) \
-  (REAL_MODE_FORMAT (SCALAR_FLOAT_MODE_P (MODE)? (MODE) \
-					       : GET_MODE_INNER (MODE)))
+  (REAL_MODE_FORMAT (as_a <scalar_float_mode> (GET_MODE_INNER (MODE))))
 
 /* The following macro determines whether the floating point format is
    composite, i.e. may contain non-consecutive mantissa bits, in which
@@ -212,7 +211,7 @@ class format_helper
 {
 public:
   format_helper (const real_format *format) : m_format (format) {}
-  format_helper (machine_mode m);
+  template<typename T> format_helper (const T &);
   const real_format *operator-> () const { return m_format; }
   operator const real_format *() const { return m_format; }
 
@@ -222,7 +221,8 @@ private:
   const real_format *m_format;
 };
 
-inline format_helper::format_helper (machine_mode m)
+template<typename T>
+inline format_helper::format_helper (const T &m)
   : m_format (m == VOIDmode ? 0 : REAL_MODE_FORMAT (m))
 {}
 
diff --git a/gcc/simplify-rtx.c b/gcc/simplify-rtx.c
index 0133d43..60ffdbd 100644
--- a/gcc/simplify-rtx.c
+++ b/gcc/simplify-rtx.c
@@ -5811,9 +5811,11 @@ simplify_immed_subreg (machine_mode outermode, rtx op,
 	    {
 	      /* This is big enough for anything on the platform.  */
 	      long tmp[MAX_BITSIZE_MODE_ANY_MODE / 32];
-	      int bitsize = GET_MODE_BITSIZE (GET_MODE (el));
+	      scalar_float_mode el_mode;
+
+	      el_mode = as_a <scalar_float_mode> (GET_MODE (el));
+	      int bitsize = GET_MODE_BITSIZE (el_mode);
 
-	      gcc_assert (SCALAR_FLOAT_MODE_P (GET_MODE (el)));
 	      gcc_assert (bitsize <= elem_bitsize);
 	      gcc_assert (bitsize % value_bit == 0);