From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 1666) id B3671385B507; Mon, 9 Jan 2023 12:31:54 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org B3671385B507 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1673267514; bh=52py4B7cMMS3kfGzPag8vqiIUJNmi+uFtzhqIv4LVwU=; h=From:To:Subject:Date:From; b=HY5MNIl5t9PPgdKqA1OStMtg2LM7bP9ksEm/+dUWXlUZCi71dpm7DaYiw8wumw3SD dNoiklLCT7V7feuwepyiniM+ljssudzU0LmiQLb3YxtHWHpQ4r/SOuLYcy19WeHudy 9yIVY7RDUeM6JVREtvbHE2MbWdXSfRGd/1vIBzjQ= MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="utf-8" From: Richard Biener To: gcc-cvs@gcc.gnu.org Subject: [gcc r13-5066] middle-end/69482 - not preserving volatile accesses X-Act-Checkin: gcc X-Git-Author: Richard Biener X-Git-Refname: refs/heads/master X-Git-Oldrev: fb082e3293d45d928ae107d8f351b04be89d1bc2 X-Git-Newrev: a5a8242153d078f1ebe60f00409415da260a29ee Message-Id: <20230109123154.B3671385B507@sourceware.org> Date: Mon, 9 Jan 2023 12:31:54 +0000 (GMT) List-Id: https://gcc.gnu.org/g:a5a8242153d078f1ebe60f00409415da260a29ee commit r13-5066-ga5a8242153d078f1ebe60f00409415da260a29ee Author: Richard Biener Date: Mon Jan 9 12:46:28 2023 +0100 middle-end/69482 - not preserving volatile accesses The following addresses a long standing issue with not preserving accesses to non-volatile objects through volatile qualified pointers in the case that object gets expanded to a register. The fix is to treat accesses to an object with a volatile qualified access as forcing that object to memory. This issue got more exposed recently so it regressed more since GCC 11. PR middle-end/69482 * cfgexpand.cc (discover_nonconstant_array_refs_r): Volatile qualified accesses also force objects to memory. * gcc.target/i386/pr69482-1.c: New testcase. * gcc.target/i386/pr69482-2.c: Likewise. Diff: --- gcc/cfgexpand.cc | 9 +++++++++ gcc/testsuite/gcc.target/i386/pr69482-1.c | 16 ++++++++++++++++ gcc/testsuite/gcc.target/i386/pr69482-2.c | 10 ++++++++++ 3 files changed, 35 insertions(+) diff --git a/gcc/cfgexpand.cc b/gcc/cfgexpand.cc index 86783a6b661..25b1558dcb9 100644 --- a/gcc/cfgexpand.cc +++ b/gcc/cfgexpand.cc @@ -6291,6 +6291,15 @@ discover_nonconstant_array_refs_r (tree * tp, int *walk_subtrees, if (IS_TYPE_OR_DECL_P (t)) *walk_subtrees = 0; + else if (REFERENCE_CLASS_P (t) && TREE_THIS_VOLATILE (t)) + { + t = get_base_address (t); + if (t && DECL_P (t) + && DECL_MODE (t) != BLKmode + && !TREE_ADDRESSABLE (t)) + bitmap_set_bit (forced_stack_vars, DECL_UID (t)); + *walk_subtrees = 0; + } else if (TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF) { while (((TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF) diff --git a/gcc/testsuite/gcc.target/i386/pr69482-1.c b/gcc/testsuite/gcc.target/i386/pr69482-1.c new file mode 100644 index 00000000000..f192261b104 --- /dev/null +++ b/gcc/testsuite/gcc.target/i386/pr69482-1.c @@ -0,0 +1,16 @@ +/* { dg-do compile } */ +/* { dg-options "-O3" } */ + +static inline void memset_s(void* s, int n) { + volatile unsigned char * p = s; + for(int i = 0; i < n; ++i) { + p[i] = 0; + } +} + +void test() { + unsigned char x[4]; + memset_s(x, sizeof x); +} + +/* { dg-final { scan-assembler-times "mov" 4 } } */ diff --git a/gcc/testsuite/gcc.target/i386/pr69482-2.c b/gcc/testsuite/gcc.target/i386/pr69482-2.c new file mode 100644 index 00000000000..58e89a79333 --- /dev/null +++ b/gcc/testsuite/gcc.target/i386/pr69482-2.c @@ -0,0 +1,10 @@ +/* { dg-do compile } */ +/* { dg-options "-O2" } */ + +void bar () +{ + int j; + *(volatile int *)&j = 0; +} + +/* { dg-final { scan-assembler-times "mov" 1 } } */