Turn TRULY_NOOP_TRUNCATION into a hook

I'm not sure the documentation is correct that outprec is always less
than inprec, and each non-default implementation tested for the case
in which it wasn't, but the patch leaves it as-is.

The SH port had a couple of TRULY_NOOP_TRUNCATION tests that were left
over from the old shmedia port.

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

gcc/
	* target.def (truly_noop_truncation): New hook.
	(mode_rep_extended): Refer to TARGET_TRULY_NOOP_TRUNCATION rather
	than TRULY_NOOP_TRUNCATION.
	* hooks.h (hook_bool_uint_uint_true): Declare.
	* hooks.c (hook_bool_uint_uint_true): New function.
	* doc/tm.texi.in (TRULY_NOOP_TRUNCATION): Replace with...
	(TARGET_TRULY_NOOP_TRUNCATION): ...this.
	* doc/tm.texi: Regenerate.
	* combine.c (make_extraction): Refer to TARGET_TRULY_NOOP_TRUNCATION
	rather than TRULY_NOOP_TRUNCATION in comments.
	(simplify_comparison): Likewise.
	(record_truncated_value): Likewise.
	* expmed.c (extract_bit_field_1): Likewise.
	(extract_split_bit_field): Likewise.
	* convert.c (convert_to_integer_1): Use targetm.truly_noop_truncation
	instead of TRULY_NOOP_TRUNCATION.
	* function.c (assign_parm_setup_block): Likewise.
	* machmode.h (TRULY_NOOP_TRUNCATION_MODES_P): Likewise.
	* rtlhooks.c: Include target.h.
	* config/aarch64/aarch64.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/alpha/alpha.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/arc/arc.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/arm/arm.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/avr/avr.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/bfin/bfin.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/c6x/c6x.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/cr16/cr16.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/cris/cris.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/epiphany/epiphany.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/fr30/fr30.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/frv/frv.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/ft32/ft32.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/h8300/h8300.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/i386/i386.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/ia64/ia64.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/iq2000/iq2000.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/lm32/lm32.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/m32c/m32c.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/m32r/m32r.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/m68k/m68k.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/mcore/mcore.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/microblaze/microblaze.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/mips/mips.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/mips/mips.c (mips_truly_noop_truncation): New function.
	(TARGET_TRULY_NOOP_TRUNCATION): Redefine.
	* config/mips/mips.md: Refer to TARGET_TRULY_NOOP_TRUNCATION
	rather than TRULY_NOOP_TRUNCATION in comments.
	* config/mmix/mmix.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/mn10300/mn10300.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/moxie/moxie.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/msp430/msp430.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/nds32/nds32.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/nios2/nios2.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/nvptx/nvptx.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/pa/pa.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/pdp11/pdp11.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/powerpcspe/powerpcspe.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/riscv/riscv.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/riscv/riscv.md: Refer to TARGET_TRULY_NOOP_TRUNCATION
	rather than TRULY_NOOP_TRUNCATION in comments.
	* config/rl78/rl78.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/rs6000/rs6000.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/rx/rx.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/s390/s390.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/sh/sh.h (MAYBE_BASE_REGISTER_RTX_P): Remove
	TRULY_NOOP_TRUNCATION condition.
	(MAYBE_INDEX_REGISTER_RTX_P): Likewise.
	(TRULY_NOOP_TRUNCATION): Delete.
	* config/sparc/sparc.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/spu/spu.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/spu/spu.c (spu_truly_noop_truncation): New function.
	(TARGET_TRULY_NOOP_TRUNCATION): Redefine.
	* config/stormy16/stormy16.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/tilegx/tilegx.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/tilegx/tilegx.c (tilegx_truly_noop_truncation): New fuction.
	(TARGET_TRULY_NOOP_TRUNCATION): Redefine.
	* config/tilegx/tilegx.md: Refer to TARGET_TRULY_NOOP_TRUNCATION
	rather than TRULY_NOOP_TRUNCATION in comments.
	* config/tilepro/tilepro.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/v850/v850.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/vax/vax.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/visium/visium.h (TRULY_NOOP_TRUNCATION): Delete.
	* config/xtensa/xtensa.h (TRULY_NOOP_TRUNCATION): Delete.
	* system.h (TRULY_NOOP_TRUNCATION): Poison.

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

From-SVN: r252818

2 files changed, 12 insertions, 30 deletions

diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
index 5b9e2b3..6277e88 100644
--- a/gcc/doc/tm.texi
+++ b/gcc/doc/tm.texi
@@ -10783,21 +10783,17 @@ nevertheless truncate the shift count, you may get better code
 by overriding it.
 @end deftypefn
 
-@defmac TRULY_NOOP_TRUNCATION (@var{outprec}, @var{inprec})
-A C expression which is nonzero if on this machine it is safe to
-``convert'' an integer of @var{inprec} bits to one of @var{outprec}
-bits (where @var{outprec} is smaller than @var{inprec}) by merely
-operating on it as if it had only @var{outprec} bits.
+@deftypefn {Target Hook} bool TARGET_TRULY_NOOP_TRUNCATION (unsigned int @var{outprec}, unsigned int @var{inprec})
+This hook returns true if it is safe to ``convert'' a value of
+@var{inprec} bits to one of @var{outprec} bits (where @var{outprec} is
+smaller than @var{inprec}) by merely operating on it as if it had only
+@var{outprec} bits.  The default returns true unconditionally, which
+is correct for most machines.
 
-On many machines, this expression can be 1.
-
-@c rearranged this, removed the phrase "it is reported that".  this was
-@c to fix an overfull hbox.  --mew 10feb93
-When @code{TRULY_NOOP_TRUNCATION} returns 1 for a pair of sizes for modes
-for which @code{TARGET_MODES_TIEABLE_P} is false, suboptimal code can result.
-If this is the case, making @code{TRULY_NOOP_TRUNCATION} return 0 in
-such cases may improve things.
-@end defmac
+If @code{TARGET_MODES_TIEABLE_P} returns false for a pair of modes,
+suboptimal code can result if this hook returns true for the corresponding
+mode sizes.  Making this hook return false in such cases may improve things.
+@end deftypefn
 
 @deftypefn {Target Hook} int TARGET_MODE_REP_EXTENDED (scalar_int_mode @var{mode}, scalar_int_mode @var{rep_mode})
 The representation of an integral mode can be such that the values
@@ -10823,7 +10819,7 @@ to define @code{LOAD_EXTEND_OP (mode)} to return the same type of
 extension.
 
 In order to enforce the representation of @code{mode},
-@code{TRULY_NOOP_TRUNCATION} should return false when truncating to
+@code{TARGET_TRULY_NOOP_TRUNCATION} should return false when truncating to
 @code{mode}.
 @end deftypefn
 
diff --git a/gcc/doc/tm.texi.in b/gcc/doc/tm.texi.in
index 57b017f..c66f8ce 100644
--- a/gcc/doc/tm.texi.in
+++ b/gcc/doc/tm.texi.in
@@ -7482,21 +7482,7 @@ You need not define this macro if it would always have the value of zero.
 @anchor{TARGET_SHIFT_TRUNCATION_MASK}
 @hook TARGET_SHIFT_TRUNCATION_MASK
 
-@defmac TRULY_NOOP_TRUNCATION (@var{outprec}, @var{inprec})
-A C expression which is nonzero if on this machine it is safe to
-``convert'' an integer of @var{inprec} bits to one of @var{outprec}
-bits (where @var{outprec} is smaller than @var{inprec}) by merely
-operating on it as if it had only @var{outprec} bits.
-
-On many machines, this expression can be 1.
-
-@c rearranged this, removed the phrase "it is reported that".  this was
-@c to fix an overfull hbox.  --mew 10feb93
-When @code{TRULY_NOOP_TRUNCATION} returns 1 for a pair of sizes for modes
-for which @code{TARGET_MODES_TIEABLE_P} is false, suboptimal code can result.
-If this is the case, making @code{TRULY_NOOP_TRUNCATION} return 0 in
-such cases may improve things.
-@end defmac
+@hook TARGET_TRULY_NOOP_TRUNCATION
 
 @hook TARGET_MODE_REP_EXTENDED