Turn SECONDARY_MEMORY_NEEDED_MODE into a target hook

This includes a change to LRA.  Previously the code was:

    if (sclass == NO_REGS && dclass == NO_REGS)
      return false;
  #ifdef SECONDARY_MEMORY_NEEDED
    if (SECONDARY_MEMORY_NEEDED (sclass, dclass, GET_MODE (src))
  #ifdef SECONDARY_MEMORY_NEEDED_MODE
        && ((sclass != NO_REGS && dclass != NO_REGS)
            || GET_MODE (src) != SECONDARY_MEMORY_NEEDED_MODE (GET_MODE (src)))
  #endif
        )
      {
        *sec_mem_p = true;
        return false;
      }
  #endif

in which the positioning of the second ifdef meant that defining
SECONDARY_MEMORY_NEEDED_MODE to its default value was not a no-op:
without a definition, we would consider using secondary reloads for
mem<-reg and reg<-mem reloads even if the secondary memory has the
same mode as the original mem, while defining it would avoid this.
The latter behaviour seems correct.

The default is different for reload and LRA.  For LRA the default is
to use the original mode, while reload promotes smaller-than-word
integral modes to word mode:

  if (GET_MODE_BITSIZE (mode) < BITS_PER_WORD && INTEGRAL_MODE_P (mode))
    mode = mode_for_size (BITS_PER_WORD,
                          GET_MODE_CLASS (mode), 0).require ();

Some of the ports that have switched to LRA seemed to have
SECONDARY_MEMORY_NEEDED_MDOEs based on the old reload definition,
and still referred to the reload.c:get_secondary_mem function in
the comments.  The patch just keeps them as-is.

2017-09-13  Richard Sandiford  <richard.sandiford@linaro.org>
	    Alan Hayward  <alan.hayward@arm.com>
	    David Sherwood  <david.sherwood@arm.com>

gcc/
	* target.def (secondary_memory_needed_mode): New hook:
	* targhooks.c (default_secondary_memory_needed_mode): Declare.
	* targhooks.h (default_secondary_memory_needed_mode): New function.
	* doc/tm.texi.in (SECONDARY_MEMORY_NEEDED_MODE): Replace with...
	(TARGET_SECONDARY_MEMORY_NEEDED_MODE): ...this.
	* doc/tm.texi: Regenerate.
	* lra-constraints.c (check_and_process_move): Use
	targetm.secondary_memory_needed_mode instead of
	TARGET_SECONDARY_MEMORY_NEEDED_MODE.
	(curr_insn_transform): Likewise.
	* reload.c (get_secondary_mem): Likewise.
	* config/alpha/alpha.h (SECONDARY_MEMORY_NEEDED_MODE): Delete.
	* config/alpha/alpha.c (alpha_secondary_memory_needed_mode): New
	function.
	(TARGET_SECONDARY_MEMORY_NEEDED_MODE): Redefine.
	* config/i386/i386.h (SECONDARY_MEMORY_NEEDED_MODE): Delete.
	* config/i386/i386.c (ix86_secondary_memory_needed_mode): New function.
	(TARGET_SECONDARY_MEMORY_NEEDED_MODE): Redefine.
	* config/powerpcspe/powerpcspe.h (SECONDARY_MEMORY_NEEDED_MODE):
	Delete.
	* config/powerpcspe/powerpcspe-protos.h
	(rs6000_secondary_memory_needed_mode): Delete.
	* config/powerpcspe/powerpcspe.c
	(TARGET_SECONDARY_MEMORY_NEEDED_MODE): Redefine.
	(rs6000_secondary_memory_needed_mode): Make static.
	* config/rs6000/rs6000.h (SECONDARY_MEMORY_NEEDED_MODE): Delete.
	* config/rs6000/rs6000-protos.h (rs6000_secondary_memory_needed_mode):
	Delete.
	* config/rs6000/rs6000.c (TARGET_SECONDARY_MEMORY_NEEDED_MODE):
	Redefine.
	(rs6000_secondary_memory_needed_mode): Make static.
	* config/s390/s390.h (SECONDARY_MEMORY_NEEDED_MODE): Delete.
	* config/s390/s390.c (s390_secondary_memory_needed_mode): New function.
	(TARGET_SECONDARY_MEMORY_NEEDED_MODE): Redefine.
	* config/sparc/sparc.h (SECONDARY_MEMORY_NEEDED_MODE): Delete.
	* config/sparc/sparc.c (TARGET_SECONDARY_MEMORY_NEEDED_MODE):
	Redefine.
	(sparc_secondary_memory_needed_mode): New function.
	* system.h (TARGET_SECONDARY_MEMORY_NEEDED_MODE): Poison.

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

From-SVN: r252455

2 files changed, 27 insertions, 12 deletions

diff --git a/gcc/config/sparc/sparc.c b/gcc/config/sparc/sparc.c
index 9a7e467..469b03d 100644
--- a/gcc/config/sparc/sparc.c
+++ b/gcc/config/sparc/sparc.c
@@ -672,6 +672,7 @@ static void sparc_print_operand_address (FILE *, machine_mode, rtx);
 static reg_class_t sparc_secondary_reload (bool, rtx, reg_class_t,
 					   machine_mode,
 					   secondary_reload_info *);
+static machine_mode sparc_secondary_memory_needed_mode (machine_mode);
 static scalar_int_mode sparc_cstore_mode (enum insn_code icode);
 static void sparc_atomic_assign_expand_fenv (tree *, tree *, tree *);
 static bool sparc_fixed_condition_code_regs (unsigned int *, unsigned int *);
@@ -859,6 +860,8 @@ char sparc_hard_reg_printed[8];
 
 #undef TARGET_SECONDARY_RELOAD
 #define TARGET_SECONDARY_RELOAD sparc_secondary_reload
+#undef TARGET_SECONDARY_MEMORY_NEEDED_MODE
+#define TARGET_SECONDARY_MEMORY_NEEDED_MODE sparc_secondary_memory_needed_mode
 
 #undef TARGET_CONDITIONAL_REGISTER_USAGE
 #define TARGET_CONDITIONAL_REGISTER_USAGE sparc_conditional_register_usage
@@ -13050,6 +13053,30 @@ sparc_secondary_reload (bool in_p, rtx x, reg_class_t rclass_i,
   return NO_REGS;
 }
 
+/* Implement TARGET_SECONDARY_MEMORY_NEEDED_MODE.
+
+   get_secondary_mem widens its argument to BITS_PER_WORD which loses on v9
+   because the movsi and movsf patterns don't handle r/f moves.
+   For v8 we copy the default definition.  */
+
+static machine_mode
+sparc_secondary_memory_needed_mode (machine_mode mode)
+{
+  if (TARGET_ARCH64)
+    {
+      if (GET_MODE_BITSIZE (mode) < 32)
+	return mode_for_size (32, GET_MODE_CLASS (mode), 0).require ();
+      return mode;
+    }
+  else
+    {
+      if (GET_MODE_BITSIZE (mode) < BITS_PER_WORD)
+	return mode_for_size (BITS_PER_WORD,
+			      GET_MODE_CLASS (mode), 0).require ();
+      return mode;
+    }
+}
+
 /* Emit code to conditionally move either OPERANDS[2] or OPERANDS[3] into
    OPERANDS[0] in MODE.  OPERANDS[1] is the operator of the condition.  */
 
diff --git a/gcc/config/sparc/sparc.h b/gcc/config/sparc/sparc.h
index e037897..51bc318 100644
--- a/gcc/config/sparc/sparc.h
+++ b/gcc/config/sparc/sparc.h
@@ -1055,18 +1055,6 @@ extern char leaf_reg_remap[];
        || GET_MODE_SIZE (MODE) > 8 \
        || GET_MODE_SIZE (MODE) < 4))
 
-/* Get_secondary_mem widens its argument to BITS_PER_WORD which loses on v9
-   because the movsi and movsf patterns don't handle r/f moves.
-   For v8 we copy the default definition.  */
-#define SECONDARY_MEMORY_NEEDED_MODE(MODE)				   \
-  (TARGET_ARCH64							   \
-   ? (GET_MODE_BITSIZE (MODE) < 32					   \
-      ? mode_for_size (32, GET_MODE_CLASS (MODE), 0).require ()		   \
-      : MODE)								   \
-   : (GET_MODE_BITSIZE (MODE) < BITS_PER_WORD				   \
-      ? mode_for_size (BITS_PER_WORD, GET_MODE_CLASS (MODE), 0).require () \
-      : MODE))
-
 /* Return the maximum number of consecutive registers
    needed to represent mode MODE in a register of class CLASS.  */
 /* On SPARC, this is the size of MODE in words.  */