params.def (ggc-min-expand, [...]): New parameters.

	* params.def (ggc-min-expand, ggc-min-heapsize): New parameters.
	* doc/invoke.texi: Document them.

	* ggc-page.c: Include params.h.  Remove definitions of
	GGC_MIN_EXPAND_FOR_GC, GGC_MIN_LAST_ALLOCATED.  Replace
	GGC_POISON with ENABLE_GC_CHECKING in ifdefs, delete #define.
	(init_gcc): Don't set G.allocated_last_gc here.
	(ggc_collect): Use PARAM_VALUE (GGC_MIN_HEAPSIZE) and
	PARAM_VALUE (GGC_MIN_EXPAND) to decide whether or not to
	perform collection.
	* ggc-simple.c: Similarly.
	* Makefile.in (ggc-common.o, ggc-simple.o): Add $(PARAMS_H) to
	dependencies.

From-SVN: r59034

1 files changed, 23 insertions, 0 deletions

diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index c3605a3..dc8a436 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -4233,6 +4233,29 @@ compilation for profile feedback and one for compilation without.  The value
 for compilation with profile feedback needs to be more conservative (higher) in
 order to make tracer effective.
 
+@item ggc-min-expand
+
+GCC uses a garbage collector to manage its own memory allocation.  This
+parameter specifies the minimum percentage by which the garbage
+collector's heap should be allowed to expand between collections.
+Tuning this may improve compilation speed; it has no effect on code
+generation.
+
+The default is 30%.  Setting this parameter to zero causes a full
+collection to occur at every opportunity.  This is extremely slow, but
+can be useful for debugging.
+
+@item ggc-min-heapsize
+
+Minimum size of the garbage collector's heap before it begins bothering
+to collect garbage.  The first collection occurs after the heap expands
+by @option{ggc-min-expand}% beyond @option{ggc-min-heapsize}.  Again,
+tuning this may improve compilation speed, and has no effect on code
+generation.
+
+The default is 4096 (four megabytes).  Setting this parameter very large
+effectively disables garbage collection.
+
 @end table
 @end table