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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2022-02-17 22:45:34 -0500 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2022-02-17 22:46:01 -0500 |
| commit | de447bb8e6fbbad19f964a2d7f04c9ccc1d06903 (patch) | |
| tree | 95aad2cc5e0c44e8d3e1fb64dfa369772715b3c0 /src/backend/tcop/postgres.c | |
| parent | f927a6ec3ef710ad2bd7d9c63f524b7a22d7e664 (diff) | |
| download | postgresql-de447bb8e6fbbad19f964a2d7f04c9ccc1d06903.tar.gz postgresql-de447bb8e6fbbad19f964a2d7f04c9ccc1d06903.zip | |
Suppress warning about stack_base_ptr with late-model GCC.
GCC 12 complains that set_stack_base is storing the address of
a local variable in a long-lived pointer. This is an entirely
reasonable warning (indeed, it just helped us find a bug);
but that behavior is intentional here. We can work around it
by using __builtin_frame_address(0) instead of a specific local
variable; that produces an address a dozen or so bytes different,
in my testing, but we don't care about such a small difference.
Maybe someday a compiler lacking that function will start to issue
a similar warning, but we'll worry about that when it happens.
Patch by me, per a suggestion from Andres Freund. Back-patch to
v12, which is as far back as the patch will go without some pain.
(Recently-established project policy would permit a back-patch as
far as 9.2, but I'm disinclined to expend the work until GCC 12
is much more widespread.)
Discussion: https://postgr.es/m/3773792.1645141467@sss.pgh.pa.us
Diffstat (limited to 'src/backend/tcop/postgres.c')
| -rw-r--r-- | src/backend/tcop/postgres.c | 20 |
1 files changed, 14 insertions, 6 deletions
diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c index 38d8b97894c..3c7d08209f3 100644 --- a/src/backend/tcop/postgres.c +++ b/src/backend/tcop/postgres.c @@ -129,17 +129,15 @@ static long max_stack_depth_bytes = 100 * 1024L; /* * Stack base pointer -- initialized by PostmasterMain and inherited by - * subprocesses. This is not static because old versions of PL/Java modify - * it directly. Newer versions use set_stack_base(), but we want to stay - * binary-compatible for the time being. + * subprocesses (but see also InitPostmasterChild). */ -char *stack_base_ptr = NULL; +static char *stack_base_ptr = NULL; /* * On IA64 we also have to remember the register stack base. */ #if defined(__ia64__) || defined(__ia64) -char *register_stack_base_ptr = NULL; +static char *register_stack_base_ptr = NULL; #endif /* @@ -3416,7 +3414,9 @@ ia64_get_bsp(void) pg_stack_base_t set_stack_base(void) { +#ifndef HAVE__BUILTIN_FRAME_ADDRESS char stack_base; +#endif pg_stack_base_t old; #if defined(__ia64__) || defined(__ia64) @@ -3426,8 +3426,16 @@ set_stack_base(void) old = stack_base_ptr; #endif - /* Set up reference point for stack depth checking */ + /* + * Set up reference point for stack depth checking. On recent gcc we use + * __builtin_frame_address() to avoid a warning about storing a local + * variable's address in a long-lived variable. + */ +#ifdef HAVE__BUILTIN_FRAME_ADDRESS + stack_base_ptr = __builtin_frame_address(0); +#else stack_base_ptr = &stack_base; +#endif #if defined(__ia64__) || defined(__ia64) register_stack_base_ptr = ia64_get_bsp(); #endif |