[6/77] Make GET_MODE_WIDER return an opt_mode

GET_MODE_WIDER previously returned VOIDmode if no wider mode existed.
That would cause problems with stricter mode classes, since VOIDmode
isn't for example a valid scalar integer or floating-point mode.
This patch instead makes it return a new opt_mode<T> class, which
holds either a T or nothing.

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

gcc/
	* coretypes.h (opt_mode): New class.
	* machmode.h (opt_mode): Likewise.
	(opt_mode::else_void): New function.
	(opt_mode::require): Likewise.
	(opt_mode::exists): Likewise.
	(GET_MODE_WIDER_MODE): Turn into a function and return an opt_mode.
	(GET_MODE_2XWIDER_MODE): Likewise.
	(mode_iterator::get_wider): Update accordingly.
	(mode_iterator::get_2xwider): Likewise.
	(mode_iterator::get_known_wider): Likewise, turning into a template.
	* combine.c (make_extraction): Update use of GET_MODE_WIDER_MODE,
	forcing a wider mode to exist.
	* config/cr16/cr16.h (LONG_REG_P): Likewise.
	* rtlanal.c (init_num_sign_bit_copies_in_rep): Likewise.
	* config/c6x/c6x.c (c6x_rtx_costs): Update use of
	GET_MODE_2XWIDER_MODE, forcing a wider mode to exist.
	* lower-subreg.c (init_lower_subreg): Likewise.
	* optabs-libfuncs.c (init_sync_libfuncs_1): Likewise, but not
	on the final iteration.
	* config/i386/i386.c (ix86_expand_set_or_movmem): Check whether
	a wider mode exists before asking for a move pattern.
	(get_mode_wider_vector): Update use of GET_MODE_WIDER_MODE,
	forcing a wider mode to exist.
	(expand_vselect_vconcat): Update use of GET_MODE_2XWIDER_MODE,
	returning false if no such mode exists.
	* config/ia64/ia64.c (expand_vselect_vconcat): Likewise.
	* config/mips/mips.c (mips_expand_vselect_vconcat): Likewise.
	* expmed.c (init_expmed_one_mode): Update use of GET_MODE_WIDER_MODE.
	Avoid checking for a MODE_INT if we already know the mode is not a
	SCALAR_INT_MODE_P.
	(extract_high_half): Update use of GET_MODE_WIDER_MODE,
	forcing a wider mode to exist.
	(expmed_mult_highpart_optab): Likewise.
	(expmed_mult_highpart): Likewise.
	* expr.c (expand_expr_real_2): Update use of GET_MODE_WIDER_MODE,
	using else_void.
	* lto-streamer-in.c (lto_input_mode_table): Likewise.
	* optabs-query.c (find_widening_optab_handler_and_mode): Likewise.
	* stor-layout.c (bit_field_mode_iterator::next_mode): Likewise.
	* internal-fn.c (expand_mul_overflow): Update use of
	GET_MODE_2XWIDER_MODE.
	* omp-low.c (omp_clause_aligned_alignment): Likewise.
	* tree-ssa-math-opts.c (convert_mult_to_widen): Update use of
	GET_MODE_WIDER_MODE.
	(convert_plusminus_to_widen): Likewise.
	* tree-switch-conversion.c (array_value_type): Likewise.
	* var-tracking.c (emit_note_insn_var_location): Likewise.
	* tree-vrp.c (simplify_float_conversion_using_ranges): Likewise.
	Return false inside rather than outside the loop if no wider mode
	exists
	* optabs.c (expand_binop): Update use of GET_MODE_WIDER_MODE
	and GET_MODE_2XWIDER_MODE
	(can_compare_p): Use else_void.
	* gdbhooks.py (OptMachineModePrinter): New class.
	(build_pretty_printer): Use it for opt_mode.

gcc/ada/
	* gcc-interface/decl.c (validate_size): Update use of
	GET_MODE_WIDER_MODE, forcing a wider mode to exist.

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

From-SVN: r251457

1 files changed, 83 insertions, 9 deletions

diff --git a/gcc/machmode.h b/gcc/machmode.h
index c272888..3b06f6d 100644
--- a/gcc/machmode.h
+++ b/gcc/machmode.h
@@ -221,6 +221,71 @@ extern const unsigned char mode_class[NUM_MACHINE_MODES];
 #define POINTER_BOUNDS_MODE_P(MODE)      \
   (GET_MODE_CLASS (MODE) == MODE_POINTER_BOUNDS)
 
+/* An optional T (i.e. a T or nothing), where T is some form of mode class.  */
+template<typename T>
+class opt_mode
+{
+public:
+  enum from_int { dummy = MAX_MACHINE_MODE };
+
+  ALWAYS_INLINE opt_mode () : m_mode (E_VOIDmode) {}
+  ALWAYS_INLINE opt_mode (const T &m) : m_mode (m) {}
+  ALWAYS_INLINE opt_mode (from_int m) : m_mode (machine_mode (m)) {}
+
+  machine_mode else_void () const;
+  T require () const;
+
+  bool exists () const;
+  template<typename U> bool exists (U *) const;
+
+private:
+  machine_mode m_mode;
+};
+
+/* If the object contains a T, return its enum value, otherwise return
+   E_VOIDmode.  */
+
+template<typename T>
+ALWAYS_INLINE machine_mode
+opt_mode<T>::else_void () const
+{
+  return m_mode;
+}
+
+/* Assert that the object contains a T and return it.  */
+
+template<typename T>
+inline T
+opt_mode<T>::require () const
+{
+  gcc_checking_assert (m_mode != E_VOIDmode);
+  return typename mode_traits<T>::from_int (m_mode);
+}
+
+/* Return true if the object contains a T rather than nothing.  */
+
+template<typename T>
+ALWAYS_INLINE bool
+opt_mode<T>::exists () const
+{
+  return m_mode != E_VOIDmode;
+}
+
+/* Return true if the object contains a T, storing it in *MODE if so.  */
+
+template<typename T>
+template<typename U>
+inline bool
+opt_mode<T>::exists (U *mode) const
+{
+  if (m_mode != E_VOIDmode)
+    {
+      *mode = T (typename mode_traits<T>::from_int (m_mode));
+      return true;
+    }
+  return false;
+}
+
 /* Return the base GET_MODE_SIZE value for MODE.  */
 
 ALWAYS_INLINE unsigned short
@@ -352,13 +417,22 @@ extern const unsigned HOST_WIDE_INT mode_mask_array[NUM_MACHINE_MODES];
 
 /* Get the next wider natural mode (eg, QI -> HI -> SI -> DI -> TI).  */
 
-extern const unsigned char mode_wider[NUM_MACHINE_MODES];
-#define GET_MODE_WIDER_MODE(MODE) ((machine_mode) mode_wider[MODE])
+template<typename T>
+ALWAYS_INLINE opt_mode<T>
+GET_MODE_WIDER_MODE (const T &m)
+{
+  return typename opt_mode<T>::from_int (mode_wider[m]);
+}
 
 /* For scalars, this is a mode with twice the precision.  For vectors,
    this is a mode with the same inner mode but with twice the elements.  */
-extern const unsigned char mode_2xwider[NUM_MACHINE_MODES];
-#define GET_MODE_2XWIDER_MODE(MODE) ((machine_mode) mode_2xwider[MODE])
+
+template<typename T>
+ALWAYS_INLINE opt_mode<T>
+GET_MODE_2XWIDER_MODE (const T &m)
+{
+  return typename opt_mode<T>::from_int (mode_2xwider[m]);
+}
 
 /* Get the complex mode from the component mode.  */
 extern const unsigned char mode_complex[NUM_MACHINE_MODES];
@@ -497,17 +571,17 @@ namespace mode_iterator
   inline void
   get_wider (machine_mode *iter)
   {
-    *iter = GET_MODE_WIDER_MODE (*iter);
+    *iter = GET_MODE_WIDER_MODE (*iter).else_void ();
   }
 
   /* Set mode iterator *ITER to the next widest mode in the same class.
      Such a mode is known to exist.  */
 
+  template<typename T>
   inline void
-  get_known_wider (machine_mode *iter)
+  get_known_wider (T *iter)
   {
-    *iter = GET_MODE_WIDER_MODE (*iter);
-    gcc_checking_assert (*iter != VOIDmode);
+    *iter = GET_MODE_WIDER_MODE (*iter).require ();
   }
 
   /* Set mode iterator *ITER to the mode that is two times wider than the
@@ -516,7 +590,7 @@ namespace mode_iterator
   inline void
   get_2xwider (machine_mode *iter)
   {
-    *iter = GET_MODE_2XWIDER_MODE (*iter);
+    *iter = GET_MODE_2XWIDER_MODE (*iter).else_void ();
   }
 }