From e0d4123bbcfe6d85eb3130ded4478f2135d116f2 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Thu, 17 Feb 2022 22:45:34 -0500 Subject: 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 --- src/backend/tcop/postgres.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) (limited to 'src/backend/tcop/postgres.c') diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c index 361866ad7fb..1928cdd3c05 100644 --- a/src/backend/tcop/postgres.c +++ b/src/backend/tcop/postgres.c @@ -3210,7 +3210,9 @@ 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) @@ -3220,8 +3222,16 @@ 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 -- cgit v1.2.3