[PATCH][AArch64] Remove aarch64_cannot_change_mode_class

[PATCH][AArch64] Remove aarch64_cannot_change_mode_class

[Wilco Dijkstra]

Remove aarch64_cannot_change_mode_class as the underlying issue
(PR67609) has been resolved.  This avoids a few unnecessary lane
widening operations like:

faddp   d18, v18.2d
mov     d18, v18.d[0] 

Passes regress, OK for commit?

ChangeLog:
2016-05-19  Wilco Dijkstra  <wdijkstr@arm.com>

	* gcc/config/aarch64/aarch64.h
	(CANNOT_CHANGE_MODE_CLASS): Remove.
	* gcc/config/aarch64/aarch64.c
	(aarch64_cannot_change_mode_class): Remove function.
	* cc/config/aarch64/aarch64-protos.h
	(aarch64_cannot_change_mode_class): Remove.

--

diff --git a/gcc/config/aarch64/aarch64-protos.h b/gcc/config/aarch64/aarch64-protos.h
index 6a8a850673853a98e12496046ebdcf4a3cd37cf8..1b20cf9da9ef98119315bb7573c161bc71ed00ae 100644
--- a/gcc/config/aarch64/aarch64-protos.h
+++ b/gcc/config/aarch64/aarch64-protos.h
@@ -282,9 +282,6 @@ int aarch64_get_condition_code (rtx);
 bool aarch64_bitmask_imm (HOST_WIDE_INT val, machine_mode);
 int aarch64_branch_cost (bool, bool);
 enum aarch64_symbol_type aarch64_classify_symbolic_expression (rtx);
-bool aarch64_cannot_change_mode_class (machine_mode,
-				       machine_mode,
-				       enum reg_class);
 bool aarch64_const_vec_all_same_int_p (rtx, HOST_WIDE_INT);
 bool aarch64_constant_address_p (rtx);
 bool aarch64_expand_movmem (rtx *);
diff --git a/gcc/config/aarch64/aarch64.h b/gcc/config/aarch64/aarch64.h
index 6eb31e9537a01881d74e258ce159b5a2fb7e0e6f..8c7f2bde66840139e265b75923b1fcb3336436c5 100644
--- a/gcc/config/aarch64/aarch64.h
+++ b/gcc/config/aarch64/aarch64.h
@@ -832,9 +832,6 @@ typedef struct
   extern void  __aarch64_sync_cache_range (void *, void *);	\
   __aarch64_sync_cache_range (beg, end)
 
-#define CANNOT_CHANGE_MODE_CLASS(FROM, TO, CLASS)	\
-  aarch64_cannot_change_mode_class (FROM, TO, CLASS)
-
 #define SHIFT_COUNT_TRUNCATED !TARGET_SIMD
 
 /* Choose appropriate mode for caller saves, so we do the minimum
diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index 0bfaa2717c7940c08958c47381cd88e09ac28f24..8dec55606e4874c9263416e93c30646c68989261 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -12640,24 +12640,6 @@ aarch64_vectorize_vec_perm_const_ok (machine_mode vmode,
   return ret;
 }
 
-/* Implement target hook CANNOT_CHANGE_MODE_CLASS.  */
-bool
-aarch64_cannot_change_mode_class (machine_mode from,
-				  machine_mode to,
-				  enum reg_class rclass)
-{
-  /* We cannot allow word_mode subregs of full vector modes.
-     Otherwise the middle-end will assume it's ok to store to
-     (subreg:DI (reg:TI 100) 0) in order to modify only the low 64 bits
-     of the 128-bit register.  However, after reload the subreg will
-     be dropped leaving a plain DImode store.  See PR67609 for a more
-     detailed dicussion.  In all other cases, we want to be permissive
-     and return false.  */
-  return (reg_classes_intersect_p (FP_REGS, rclass)
-	  && GET_MODE_SIZE (to) == UNITS_PER_WORD
-	  && GET_MODE_SIZE (from) > UNITS_PER_WORD);
-}
-
 rtx
 aarch64_reverse_mask (enum machine_mode mode)
 {

Re: [PATCH][AArch64] Remove aarch64_cannot_change_mode_class

[James Greenhalgh]

On Thu, May 19, 2016 at 12:23:32PM +0100, Wilco Dijkstra wrote:
> Remove aarch64_cannot_change_mode_class as the underlying issue
> (PR67609) has been resolved.  This avoids a few unnecessary lane
> widening operations like:
> 
> faddp   d18, v18.2d
> mov     d18, v18.d[0] 
> 
> Passes regress, OK for commit?

Which targets did you check? I'd hope aarch64_be-none-elf in addition to
aarch64-none-linux-gnu.

OK if they're both clean.

Please refer to PR67609 in your ChangeLog so this gets tracked alongside
the other fixes in that bug.

Thanks,
James

> 
> ChangeLog:
> 2016-05-19  Wilco Dijkstra  <wdijkstr@arm.com>
> 
> 	* gcc/config/aarch64/aarch64.h
> 	(CANNOT_CHANGE_MODE_CLASS): Remove.
> 	* gcc/config/aarch64/aarch64.c
> 	(aarch64_cannot_change_mode_class): Remove function.
> 	* cc/config/aarch64/aarch64-protos.h
> 	(aarch64_cannot_change_mode_class): Remove.
> 

Re: [PATCH][AArch64] Remove aarch64_cannot_change_mode_class

[Wilco Dijkstra]

James Greenhalgh wrote:
> Which targets did you check? I'd hope aarch64_be-none-elf in addition to
> aarch64-none-linux-gnu.

I ran aarch64-none-elf, and just checked aarch64_be-none-elf passes too.

> Please refer to PR67609 in your ChangeLog so this gets tracked alongside
> the other fixes in that bug.

Sure.

>
> ChangeLog:
> 2016-05-19  Wilco Dijkstra  <wdijkstr@arm.com>
>
>       * gcc/config/aarch64/aarch64.h
>       (CANNOT_CHANGE_MODE_CLASS): Remove.
>       * gcc/config/aarch64/aarch64.c
>       (aarch64_cannot_change_mode_class): Remove function.
>       * cc/config/aarch64/aarch64-protos.h
>       (aarch64_cannot_change_mode_class): Remove.
>