+2016-10-12 Segher Boessenkool <segher@kernel.crashing.org>
+
+ * common.opt (-fshrink-wrap-separate): New flag.
+ * doc/invoke.texi: Document it.
+ * doc/tm.texi.in (Shrink-wrapping separate components): New subsection.
+ * doc/tm.texi: Regenerate.
+ * emit-rtl.h (struct rtl_data): New field shrink_wrapped_separate.
+ * target.def (shrink_wrap): New hook vector.
+ (get_separate_components, components_for_bb, disqualify_components,
+ emit_prologue_components, emit_epilogue_components,
+ set_handled_components): New hooks.
+
2016-10-12 Segher Boessenkool <segher@kernel.crashing.org>
* config/rs6000/rs6000.c (rs6000_return_in_memory): Warn for
Emit function prologues only before parts of the function that need it,
rather than at the top of the function.
+fshrink-wrap-separate
+Common Report Var(flag_shrink_wrap_separate) Init(1) Optimization
+Shrink-wrap parts of the prologue and epilogue separately.
+
fsignaling-nans
Common Report Var(flag_signaling_nans) Optimization SetByCombined
Disable optimizations observable by IEEE signaling NaNs.
-fschedule-insns -fschedule-insns2 -fsection-anchors @gol
-fselective-scheduling -fselective-scheduling2 @gol
-fsel-sched-pipelining -fsel-sched-pipelining-outer-loops @gol
--fsemantic-interposition -fshrink-wrap -fsignaling-nans @gol
+-fsemantic-interposition -fshrink-wrap -fshrink-wrap-separate @gol
+-fsignaling-nans @gol
-fsingle-precision-constant -fsplit-ivs-in-unroller @gol
-fsplit-paths @gol
-fsplit-wide-types -fssa-backprop -fssa-phiopt @gol
-fmove-loop-invariants @gol
-freorder-blocks @gol
-fshrink-wrap @gol
+-fshrink-wrap-separate @gol
-fsplit-wide-types @gol
-fssa-backprop @gol
-fssa-phiopt @gol
rather than at the top of the function. This flag is enabled by default at
@option{-O} and higher.
+@item -fshrink-wrap-separate
+@opindex fshrink-wrap-separate
+Shrink-wrap separate parts of the prologue and epilogue separately, so that
+those parts are only executed when needed.
+This option is on by default, but has no effect unless @option{-fshrink-wrap}
+is also turned on and the target supports this.
+
@item -fcaller-saves
@opindex fcaller-saves
Enable allocation of values to registers that are clobbered by
* Function Entry::
* Profiling::
* Tail Calls::
+* Shrink-wrapping separate components::
* Stack Smashing Protection::
* Miscellaneous Register Hooks::
@end menu
True if a function's return statements should be checked for matching the function's return type. This includes checking for falling off the end of a non-void function. Return false if no such check should be made.
@end deftypefn
+@node Shrink-wrapping separate components
+@subsection Shrink-wrapping separate components
+@cindex shrink-wrapping separate components
+
+The prologue may perform a variety of target dependent tasks such as
+saving callee-saved registers, saving the return address, aligning the
+stack, creating a stack frame, initializing the PIC register, setting
+up the static chain, etc.
+
+On some targets some of these tasks may be independent of others and
+thus may be shrink-wrapped separately. These independent tasks are
+referred to as components and are handled generically by the target
+independent parts of GCC.
+
+Using the following hooks those prologue or epilogue components can be
+shrink-wrapped separately, so that the initialization (and possibly
+teardown) those components do is not done as frequently on execution
+paths where this would unnecessary.
+
+What exactly those components are is up to the target code; the generic
+code treats them abstractly, as a bit in an @code{sbitmap}. These
+@code{sbitmap}s are allocated by the @code{shrink_wrap.get_separate_components}
+and @code{shrink_wrap.components_for_bb} hooks, and deallocated by the
+generic code.
+
+@deftypefn {Target Hook} sbitmap TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS (void)
+This hook should return an @code{sbitmap} with the bits set for those
+components that can be separately shrink-wrapped in the current function.
+Return @code{NULL} if the current function should not get any separate
+shrink-wrapping.
+Don't define this hook if it would always return @code{NULL}.
+If it is defined, the other hooks in this group have to be defined as well.
+@end deftypefn
+
+@deftypefn {Target Hook} sbitmap TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB (basic_block)
+This hook should return an @code{sbitmap} with the bits set for those
+components where either the prologue component has to be executed before
+the @code{basic_block}, or the epilogue component after it, or both.
+@end deftypefn
+
+@deftypefn {Target Hook} void TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS (sbitmap @var{components}, edge @var{e}, sbitmap @var{edge_components}, bool @var{is_prologue})
+This hook should clear the bits in the @var{components} bitmap for those
+components in @var{edge_components} that the target cannot handle on edge
+@var{e}, where @var{is_prologue} says if this is for a prologue or an
+epilogue instead.
+@end deftypefn
+
+@deftypefn {Target Hook} void TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS (sbitmap)
+Emit prologue insns for the components indicated by the parameter.
+@end deftypefn
+
+@deftypefn {Target Hook} void TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS (sbitmap)
+Emit epilogue insns for the components indicated by the parameter.
+@end deftypefn
+
+@deftypefn {Target Hook} void TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS (sbitmap)
+Mark the components in the parameter as handled, so that the
+@code{prologue} and @code{epilogue} named patterns know to ignore those
+components. The target code should not hang on to the @code{sbitmap}, it
+will be deleted after this call.
+@end deftypefn
+
@node Stack Smashing Protection
@subsection Stack smashing protection
@cindex stack smashing protection
* Function Entry::
* Profiling::
* Tail Calls::
+* Shrink-wrapping separate components::
* Stack Smashing Protection::
* Miscellaneous Register Hooks::
@end menu
@hook TARGET_WARN_FUNC_RETURN
+@node Shrink-wrapping separate components
+@subsection Shrink-wrapping separate components
+@cindex shrink-wrapping separate components
+
+The prologue may perform a variety of target dependent tasks such as
+saving callee-saved registers, saving the return address, aligning the
+stack, creating a stack frame, initializing the PIC register, setting
+up the static chain, etc.
+
+On some targets some of these tasks may be independent of others and
+thus may be shrink-wrapped separately. These independent tasks are
+referred to as components and are handled generically by the target
+independent parts of GCC.
+
+Using the following hooks those prologue or epilogue components can be
+shrink-wrapped separately, so that the initialization (and possibly
+teardown) those components do is not done as frequently on execution
+paths where this would unnecessary.
+
+What exactly those components are is up to the target code; the generic
+code treats them abstractly, as a bit in an @code{sbitmap}. These
+@code{sbitmap}s are allocated by the @code{shrink_wrap.get_separate_components}
+and @code{shrink_wrap.components_for_bb} hooks, and deallocated by the
+generic code.
+
+@hook TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS
+
+@hook TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB
+
+@hook TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS
+
+@hook TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS
+
+@hook TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS
+
+@hook TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS
+
@node Stack Smashing Protection
@subsection Stack smashing protection
@cindex stack smashing protection
/* True if we performed shrink-wrapping for the current function. */
bool shrink_wrapped;
+ /* True if we performed shrink-wrapping for separate components for
+ the current function. */
+ bool shrink_wrapped_separate;
+
/* Nonzero if function being compiled doesn't modify the stack pointer
(ignoring the prologue and epilogue). This is only valid after
pass_stack_ptr_mod has run. */
bool, (tree),
hook_bool_tree_true)
+#undef HOOK_PREFIX
+#define HOOK_PREFIX "TARGET_SHRINK_WRAP_"
+HOOK_VECTOR (TARGET_SHRINK_WRAP_HOOKS, shrink_wrap)
+
+DEFHOOK
+(get_separate_components,
+ "This hook should return an @code{sbitmap} with the bits set for those\n\
+components that can be separately shrink-wrapped in the current function.\n\
+Return @code{NULL} if the current function should not get any separate\n\
+shrink-wrapping.\n\
+Don't define this hook if it would always return @code{NULL}.\n\
+If it is defined, the other hooks in this group have to be defined as well.",
+ sbitmap, (void),
+ NULL)
+
+DEFHOOK
+(components_for_bb,
+ "This hook should return an @code{sbitmap} with the bits set for those\n\
+components where either the prologue component has to be executed before\n\
+the @code{basic_block}, or the epilogue component after it, or both.",
+ sbitmap, (basic_block),
+ NULL)
+
+DEFHOOK
+(disqualify_components,
+ "This hook should clear the bits in the @var{components} bitmap for those\n\
+components in @var{edge_components} that the target cannot handle on edge\n\
+@var{e}, where @var{is_prologue} says if this is for a prologue or an\n\
+epilogue instead.",
+ void, (sbitmap components, edge e, sbitmap edge_components, bool is_prologue),
+ NULL)
+
+DEFHOOK
+(emit_prologue_components,
+ "Emit prologue insns for the components indicated by the parameter.",
+ void, (sbitmap),
+ NULL)
+
+DEFHOOK
+(emit_epilogue_components,
+ "Emit epilogue insns for the components indicated by the parameter.",
+ void, (sbitmap),
+ NULL)
+
+DEFHOOK
+(set_handled_components,
+ "Mark the components in the parameter as handled, so that the\n\
+@code{prologue} and @code{epilogue} named patterns know to ignore those\n\
+components. The target code should not hang on to the @code{sbitmap}, it\n\
+will be deleted after this call.",
+ void, (sbitmap),
+ NULL)
+
+HOOK_VECTOR_END (shrink_wrap)
+#undef HOOK_PREFIX
+#define HOOK_PREFIX "TARGET_"
+
/* Determine the type of unwind info to emit for debugging. */
DEFHOOK
(debug_unwind_info,
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