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

3 files changed, 5 insertions, 12 deletions

diff --git a/gcc/config/powerpcspe/powerpcspe-protos.h b/gcc/config/powerpcspe/powerpcspe-protos.h
index 20587ba..f3aa41b 100644
--- a/gcc/config/powerpcspe/powerpcspe-protos.h
+++ b/gcc/config/powerpcspe/powerpcspe-protos.h
@@ -154,7 +154,6 @@ extern void rs6000_emit_le_vsx_move (rtx, rtx, machine_mode);
 extern bool valid_sf_si_move (rtx, rtx, machine_mode);
 extern void rs6000_emit_move (rtx, rtx, machine_mode);
 extern rtx rs6000_secondary_memory_needed_rtx (machine_mode);
-extern machine_mode rs6000_secondary_memory_needed_mode (machine_mode);
 extern rtx (*rs6000_legitimize_reload_address_ptr) (rtx, machine_mode,
 						    int, int, int, int *);
 extern bool rs6000_legitimate_offset_address_p (machine_mode, rtx,
diff --git a/gcc/config/powerpcspe/powerpcspe.c b/gcc/config/powerpcspe/powerpcspe.c
index 7784676..9b8d68b 100644
--- a/gcc/config/powerpcspe/powerpcspe.c
+++ b/gcc/config/powerpcspe/powerpcspe.c
@@ -1897,6 +1897,8 @@ static const struct attribute_spec rs6000_attribute_table[] =
 
 #undef TARGET_SECONDARY_RELOAD
 #define TARGET_SECONDARY_RELOAD rs6000_secondary_reload
+#undef TARGET_SECONDARY_MEMORY_NEEDED_MODE
+#define TARGET_SECONDARY_MEMORY_NEEDED_MODE rs6000_secondary_memory_needed_mode
 
 #undef TARGET_LEGITIMATE_ADDRESS_P
 #define TARGET_LEGITIMATE_ADDRESS_P rs6000_legitimate_address_p
@@ -21811,10 +21813,9 @@ rs6000_secondary_memory_needed_rtx (machine_mode mode)
   return ret;
 }
 
-/* Return the mode to be used for memory when a secondary memory
-   location is needed.  For SDmode values we need to use DDmode, in
-   all other cases we can use the same mode.  */
-machine_mode
+/* Implement TARGET_SECONDARY_MEMORY_NEEDED_MODE.  For SDmode values we
+   need to use DDmode, in all other cases we can use the same mode.  */
+static machine_mode
 rs6000_secondary_memory_needed_mode (machine_mode mode)
 {
   if (lra_in_progress && mode == SDmode)
diff --git a/gcc/config/powerpcspe/powerpcspe.h b/gcc/config/powerpcspe/powerpcspe.h
index c4b6dc3..5d1a138 100644
--- a/gcc/config/powerpcspe/powerpcspe.h
+++ b/gcc/config/powerpcspe/powerpcspe.h
@@ -1611,13 +1611,6 @@ extern enum reg_class rs6000_constraints[RS6000_CONSTRAINT_MAX];
 #define SECONDARY_MEMORY_NEEDED_RTX(MODE) \
   rs6000_secondary_memory_needed_rtx (MODE)
 
-/* Specify the mode to be used for memory when a secondary memory
-   location is needed.  For cpus that cannot load/store SDmode values
-   from the 64-bit FP registers without using a full 64-bit
-   load/store, we need a wider mode.  */
-#define SECONDARY_MEMORY_NEEDED_MODE(MODE)		\
-  rs6000_secondary_memory_needed_mode (MODE)
-
 /* Return the maximum number of consecutive registers
    needed to represent mode MODE in a register of class CLASS.