On Tue, 2016-01-26 at 05:35 -0800, Ian Lance Taylor wrote:
[...]
> Index: common.opt
> ===================================================================
> --- common.opt (revision 232580)
> +++ common.opt (working copy)
> @@ -1380,6 +1380,10 @@
> Enable hoisting adjacent loads to encourage generating conditional move
> instructions.
>
> +fkeep-gc-roots-live
> +Common Report Var(flag_keep_gc_roots_live) Optimization
> +Always keep a pointer to a live memory block
> +
> floop-parallelize-all
> Common Report Var(flag_loop_parallelize_all) Optimization
> Mark all loops as parallel.
> Index: doc/invoke.texi
> ===================================================================
> --- doc/invoke.texi (revision 232580)
> +++ doc/invoke.texi (working copy)
> @@ -359,7 +359,7 @@
> -fno-ira-share-spill-slots @gol
> -fisolate-erroneous-paths-dereference -fisolate-erroneous-paths-attribute
> @gol
> -fivopts -fkeep-inline-functions -fkeep-static-functions @gol
> --fkeep-static-consts -flive-range-shrinkage @gol
> +-fkeep-static-consts -fkeep-gc-roots-live -flive-range-shrinkage @gol
> -floop-block -floop-interchange -floop-strip-mine @gol
> -floop-unroll-and-jam -floop-nest-optimize @gol
> -floop-parallelize-all -flra-remat -flto -flto-compression-level @gol
> @@ -6621,6 +6621,17 @@
> If you use @option{-Wunsafe-loop-optimizations}, the compiler warns you
> if it finds this kind of loop.
>
> +@item -fkeep-gc-roots-live
> +@opindex fkeep-gc-roots-live
> +This option tells the compiler that a garbage collector will be used,
> +and that therefore the compiled code must retain a live pointer into
> +all memory blocks. The compiler is permitted to construct a pointer
> +that is outside the bounds of a memory block, but it must ensure that
> +given a pointer into memory, some pointer into that memory remains
> +live in the compiled code whenever it is live in the source code.
> +This option is disabled by default for most languages, enabled by
> +default for languages that use garbage collection.
Is the patch missing some logic to make the option be enabled by default
for gc-using languages? (presumably go, and maybe java?)
[...snip...]
