PR go/60931
runtime: Fix garbage collector issue with non 4kB system page size
The go garbage collector tracks memory in terms of 4kB pages.
Most of the code checks getpagesize() at runtime and does the
right thing.
On a 64kB ppc64 box I see SEGVs in long running processes
which has been diagnosed as a bug in scavengelist.
scavengelist does a madvise(MADV_DONTNEED) without rounding
the arguments to the system page size. A strace of one of the
failures shows the problem:
madvise(0xc211030000, 4096, MADV_DONTNEED) = 0
The kernel rounds the length up to 64kB and we mark 60kB of
valid data as no longer needed.
Round start up to a system page and end down before calling
madvise.
From-SVN: r209777
The spans array is allocated in runtime_mallocinit. On a
32-bit system the number of entries in the spans array is
MaxArena32 / PageSize, which (2U << 30) / (1 << 12) == (1 << 19).
So we are allocating an array that can hold 19 bits for an
index that can hold 20 bits. According to the comment in the
function, this is intentional: we only allocate enough spans
(and bitmaps) for a 2G arena, because allocating more would
probably be wasteful.
But since the span index is simply the upper 20 bits of the
memory address, this scheme only works if memory addresses are
limited to the low 2G of memory. That would be OK if we were
careful to enforce it, but we're not. What we are careful to
enforce, in functions like runtime_MHeap_SysAlloc, is that we
always return addresses between the heap's arena_start and
arena_start + MaxArena32.
We generally get away with it because we start allocating just
after the program end, so we only run into trouble with
programs that allocate a lot of memory, enough to get past
address 0x80000000.
This changes the code that computes a span index to subtract
arena_start on 32-bit systems just as we currently do on
64-bit systems.
From-SVN: r206501
Update to current version of Go library.
Update testsuite for removed types.
* go-lang.c (go_langhook_init): Omit float_type_size when calling
go_create_gogo.
* go-c.h: Update declaration of go_create_gogo.
From-SVN: r169098
gcc/:
* gcc.c (default_compilers): Add entry for ".go".
* common.opt: Add -static-libgo as a driver option.
* doc/install.texi (Configuration): Mention libgo as an option for
--enable-shared. Mention go as an option for --enable-languages.
* doc/invoke.texi (Overall Options): Mention .go as a file name
suffix. Mention go as a -x option.
* doc/frontends.texi (G++ and GCC): Mention Go as a supported
language.
* doc/sourcebuild.texi (Top Level): Mention libgo.
* doc/standards.texi (Standards): Add section on Go language.
Move references for other languages into their own section.
* doc/contrib.texi (Contributors): Mention that I contributed the
Go frontend.
gcc/testsuite/:
* lib/go.exp: New file.
* lib/go-dg.exp: New file.
* lib/go-torture.exp: New file.
* lib/target-supports.exp (check_compile): Match // Go.
From-SVN: r167407
Ian Lance Taylor
Ian Lance Taylor