Turn SLOW_UNALIGNED_ACCESS into a target hook

2017-09-12  Richard Sandiford  <richard.sandiford@linaro.org>
	    Alan Hayward  <alan.hayward@arm.com>
	    David Sherwood <david.sherwood@arm.com>

gcc/
	* defaults.h (SLOW_UNALIGNED_ACCESS): Delete.
	* target.def (slow_unaligned_access): New hook.
	* targhooks.h (default_slow_unaligned_access): Declare.
	* targhooks.c (default_slow_unaligned_access): New function.
	* doc/tm.texi.in (SLOW_UNALIGNED_ACCESS): Replace with...
	(TARGET_SLOW_UNALIGNED_ACCESS): ...this.
	* doc/tm.texi: Regenerate.
	* config/alpha/alpha.h (SLOW_UNALIGNED_ACCESS): Delete.
	* config/arm/arm.h (SLOW_UNALIGNED_ACCESS): Delete.
	* config/i386/i386.h (SLOW_UNALIGNED_ACCESS): Delete commented-out
	definition.
	* config/powerpcspe/powerpcspe.h (SLOW_UNALIGNED_ACCESS): Delete.
	* config/powerpcspe/powerpcspe.c (TARGET_SLOW_UNALIGNED_ACCESS):
	Redefine.
	(rs6000_slow_unaligned_access): New function.
	(rs6000_emit_move): Use it instead of SLOW_UNALIGNED_ACCESS.
	(expand_block_compare): Likewise.
	(expand_strn_compare): Likewise.
	(rs6000_rtx_costs): Likewise.
	* config/riscv/riscv.h (SLOW_UNALIGNED_ACCESS): Delete.
	(riscv_slow_unaligned_access): Likewise.
	* config/riscv/riscv.c (riscv_slow_unaligned_access): Rename to...
	(riscv_slow_unaligned_access_p): ...this and make static.
	(riscv_option_override): Update accordingly.
	(riscv_slow_unaligned_access): New function.
	(TARGET_SLOW_UNALIGNED_ACCESS): Redefine.
	* config/rs6000/rs6000.h (SLOW_UNALIGNED_ACCESS): Delete.
	* config/rs6000/rs6000.c (TARGET_SLOW_UNALIGNED_ACCESS): Redefine.
	(rs6000_slow_unaligned_access): New function.
	(rs6000_emit_move): Use it instead of SLOW_UNALIGNED_ACCESS.
	(rs6000_rtx_costs): Likewise.
	* config/rs6000/rs6000-string.c (expand_block_compare)
	(expand_strn_compare): Use targetm.slow_unaligned_access instead
	of SLOW_UNALIGNED_ACCESS.
	* config/tilegx/tilegx.h (SLOW_UNALIGNED_ACCESS): Delete.
	* config/tilepro/tilepro.h (SLOW_UNALIGNED_ACCESS): Delete.
	* calls.c (expand_call): Use targetm.slow_unaligned_access instead
	of SLOW_UNALIGNED_ACCESS.
	* expmed.c (simple_mem_bitfield_p): Likewise.
	* expr.c (alignment_for_piecewise_move): Likewise.
	(emit_group_load_1): Likewise.
	(emit_group_store): Likewise.
	(copy_blkmode_from_reg): Likewise.
	(emit_push_insn): Likewise.
	(expand_assignment): Likewise.
	(store_field): Likewise.
	(expand_expr_real_1): Likewise.
	* gimple-fold.c (gimple_fold_builtin_memory_op): Likewise.
	* lra-constraints.c (simplify_operand_subreg): Likewise.
	* stor-layout.c (bit_field_mode_iterator::next_mode): Likewise.
	* gimple-ssa-store-merging.c: Likewise in block comment at start
	of file.
	* tree-ssa-strlen.c: Include target.h.
	(handle_builtin_memcmp): Use targetm.slow_unaligned_access instead
	of SLOW_UNALIGNED_ACCESS.
	* system.h (SLOW_UNALIGNED_ACCESS): Poison.

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

From-SVN: r252009

1 files changed, 11 insertions, 12 deletions

diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
index c29d249..eb8a618 100644
--- a/gcc/doc/tm.texi
+++ b/gcc/doc/tm.texi
@@ -6386,23 +6386,22 @@ may eliminate subsequent memory access if subsequent accesses occur to
 other fields in the same word of the structure, but to different bytes.
 @end defmac
 
-@defmac SLOW_UNALIGNED_ACCESS (@var{mode}, @var{alignment})
-Define this macro to be the value 1 if memory accesses described by the
+@deftypefn {Target Hook} bool TARGET_SLOW_UNALIGNED_ACCESS (machine_mode @var{mode}, unsigned int @var{align})
+This hook returns true if memory accesses described by the
 @var{mode} and @var{alignment} parameters have a cost many times greater
-than aligned accesses, for example if they are emulated in a trap
-handler.  This macro is invoked only for unaligned accesses, i.e. when
+than aligned accesses, for example if they are emulated in a trap handler.
+This hook is invoked only for unaligned accesses, i.e. when
 @code{@var{alignment} < GET_MODE_ALIGNMENT (@var{mode})}.
 
-When this macro is nonzero, the compiler will act as if
-@code{STRICT_ALIGNMENT} were nonzero when generating code for block
+When this hook returns true, the compiler will act as if
+@code{STRICT_ALIGNMENT} were true when generating code for block
 moves.  This can cause significantly more instructions to be produced.
-Therefore, do not set this macro nonzero if unaligned accesses only add a
-cycle or two to the time for a memory access.
+Therefore, do not make this hook return true if unaligned accesses only
+add a cycle or two to the time for a memory access.
 
-If the value of this macro is always zero, it need not be defined.  If
-this macro is defined, it should produce a nonzero value when
-@code{STRICT_ALIGNMENT} is nonzero.
-@end defmac
+The hook must return true whenever @code{STRICT_ALIGNMENT} is true.
+The default implementation returns @code{STRICT_ALIGNMENT}.
+@end deftypefn
 
 @defmac MOVE_RATIO (@var{speed})
 The threshold of number of scalar memory-to-memory move insns, @emph{below}