gcc/

	* target.def (can_use_doloop_p): New hook.
	* doc/tm.texi.in (TARGET_CAN_USE_DOLOOP_P): Add.
	* doc/tm.texi: Regenerate.
	* doc/md.texi (doloop_begin, doloop_end): Update documentation.
	* hooks.h (hook_bool_dint_dint_uint_true): Declare.
	* hooks.c (hook_bool_dint_dint_uint_true): New function.
	* targhooks.h (can_use_doloop_if_innermost): Declare.
	* targhooks.c (can_use_doloop_if_innermost): New function.
	* target.h: Include double-int.h.
	* loop-doloop.c (doloop_optimize): Call targetm.can_use_doloop_p.
	Remove iteration count, maximum iteration count, loop depth and
	enter-at-top inputs from doloop_begin and doloop_end.
	* config/arc/arc.md (doloop_begin, doloop_end): Update for new
	interface.
	* config/arc/arc.c (arc_can_use_doloop_p): New function.
	(TARGET_CAN_USE_DOLOOP_P): Define.
	* config/arm/thumb2.md (doloop_end): Update for new interface.
	* config/arm/arm.c (TARGET_CAN_USE_DOLOOP_P): Define.
	* config/bfin/bfin.md (doloop_end): Update for new interface.
	* config/bfin/bfin.c (bfin_can_use_doloop_p): New function.
	(TARGET_CAN_USE_DOLOOP_P): Define.
	* config/c6x/c6x.md (doloop_end): Update for new interface.
	* config/ia64/ia64.md (doloop_end): Update for new interface.
	* config/ia64/ia64.c (TARGET_CAN_USE_DOLOOP_P): Define.
	* config/mep/mep.md (doloop_begin, doloop_end): Update for new
	interface.
	* config/mep/mep.c (mep_emit_doloop): Likewise.
	(TARGET_CAN_USE_DOLOOP_P): Define.
	* config/rs6000/rs6000.md (doloop_end): Update for new interface.
	* config/rs6000/rs6000.c (TARGET_CAN_USE_DOLOOP_P): Define.
	* config/s390/s390.md (doloop_end): Update for new interface.
	* config/sh/sh.md (doloop_end): Likewise.
	* config/spu/spu.md (doloop_end): Likewise.
	* config/spu/spu.c (TARGET_CAN_USE_DOLOOP_P): Define.
	* config/tilegx/tilegx.md (doloop_end): Update for new interface.
	* config/tilegx/tilegx.c (TARGET_CAN_USE_DOLOOP_P): Define.
	* config/tilepro/tilepro.md (doloop_end): Update for new interface.
	* config/tilepro/tilepro.c (TARGET_CAN_USE_DOLOOP_P): Define.
	* config/v850/v850.md (doloop_begin, doloop_end): Update for new
	interface.
	* config/v850/v850.c (TARGET_CAN_USE_DOLOOP_P): Define.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@204614 138bc75d-0d04-0410-961f-82ee72b054a4

3 files changed, 28 insertions, 19 deletions

diff --git a/gcc/doc/md.texi b/gcc/doc/md.texi
index 1e22b88f608..1a06e3d6e74 100644
--- a/gcc/doc/md.texi
+++ b/gcc/doc/md.texi
@@ -5857,34 +5857,27 @@ reduction is enabled.
 
 @cindex @code{doloop_end} instruction pattern
 @item @samp{doloop_end}
-Conditional branch instruction that decrements a register and jumps if
-the register is nonzero.  This instruction takes five operands: Operand
-0 is the register to decrement and test; operand 1 is the number of loop
-iterations as a @code{const_int} or @code{const0_rtx} if this cannot be
-determined until run-time; operand 2 is the actual or estimated maximum
-number of iterations as a @code{const_int}; operand 3 is the number of
-enclosed loops as a @code{const_int} (an innermost loop has a value of
-1); operand 4 is the label to jump to if the register is nonzero;
-operand 5 is const1_rtx if the loop in entered at its top, const0_rtx
-otherwise.
+Conditional branch instruction that decrements a register and
+jumps if the register is nonzero.  Operand 0 is the register to
+decrement and test; operand 1 is the label to jump to if the
+register is nonzero.
 @xref{Looping Patterns}.
 
 This optional instruction pattern should be defined for machines with
 low-overhead looping instructions as the loop optimizer will try to
-modify suitable loops to utilize it.  If nested low-overhead looping is
-not supported, use a @code{define_expand} (@pxref{Expander Definitions})
-and make the pattern fail if operand 3 is not @code{const1_rtx}.
-Similarly, if the actual or estimated maximum number of iterations is
-too large for this instruction, make it fail.
+modify suitable loops to utilize it.  The target hook
+@code{TARGET_CAN_USE_DOLOOP_P} controls the conditions under which
+low-overhead loops can be used.
 
 @cindex @code{doloop_begin} instruction pattern
 @item @samp{doloop_begin}
 Companion instruction to @code{doloop_end} required for machines that
-need to perform some initialization, such as loading special registers
-used by a low-overhead looping instruction.  If initialization insns do
-not always need to be emitted, use a @code{define_expand}
-(@pxref{Expander Definitions}) and make it fail.
+need to perform some initialization, such as loading a special counter
+register.  Operand 1 is the associated @code{doloop_end} pattern and
+operand 0 is the register that it decrements.
 
+If initialization insns do not always need to be emitted, use a
+@code{define_expand} (@pxref{Expander Definitions}) and make it fail.
 
 @cindex @code{canonicalize_funcptr_for_compare} instruction pattern
 @item @samp{canonicalize_funcptr_for_compare}
diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
index 5e7910bdd20..35cfa995583 100644
--- a/gcc/doc/tm.texi
+++ b/gcc/doc/tm.texi
@@ -11091,6 +11091,20 @@ function version at run-time for a given set of function versions.
 body must be generated.
 @end deftypefn
 
+@deftypefn {Target Hook} bool TARGET_CAN_USE_DOLOOP_P (double_int @var{iterations}, double_int @var{iterations_max}, unsigned int @var{loop_depth}, bool @var{entered_at_top})
+Return true if it is possible to use low-overhead loops (@code{doloop_end}
+and @code{doloop_begin}) for a particular loop.  @var{iterations} gives the
+exact number of iterations, or 0 if not known.  @var{iterations_max} gives
+the maximum number of iterations, or 0 if not known.  @var{loop_depth} is
+the nesting depth of the loop, with 1 for innermost loops, 2 for loops that
+contain innermost loops, and so on.  @var{entered_at_top} is true if the
+loop is only entered from the top.
+
+This hook is only used if @code{doloop_end} is available.  The default
+implementation returns true.  You can use @code{can_use_doloop_if_innermost}
+if the loop must be the innermost, and if there are no other restrictions.
+@end deftypefn
+
 @deftypefn {Target Hook} {const char *} TARGET_INVALID_WITHIN_DOLOOP (const_rtx @var{insn})
 
 Take an instruction in @var{insn} and return NULL if it is valid within a
diff --git a/gcc/doc/tm.texi.in b/gcc/doc/tm.texi.in
index 4e60d48a337..b10ecd7dda8 100644
--- a/gcc/doc/tm.texi.in
+++ b/gcc/doc/tm.texi.in
@@ -8212,6 +8212,8 @@ to by @var{ce_info}.
 
 @hook TARGET_GENERATE_VERSION_DISPATCHER_BODY
 
+@hook TARGET_CAN_USE_DOLOOP_P
+
 @hook TARGET_INVALID_WITHIN_DOLOOP
 
 @hook TARGET_LEGITIMATE_COMBINED_INSN