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| author | Richard Biener <rguenther@suse.de> | 2023-01-09 12:46:28 +0100 |
|---|---|---|
| committer | Richard Biener <rguenther@suse.de> | 2023-01-09 13:31:44 +0100 |
| commit | a5a8242153d078f1ebe60f00409415da260a29ee (patch) | |
| tree | 14727901463d84d5f0759cc663254cc77db12ce8 /gcc | |
| parent | fb082e3293d45d928ae107d8f351b04be89d1bc2 (diff) | |
| download | gcc-a5a8242153d078f1ebe60f00409415da260a29ee.zip gcc-a5a8242153d078f1ebe60f00409415da260a29ee.tar.gz gcc-a5a8242153d078f1ebe60f00409415da260a29ee.tar.bz2 | |
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.
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/cfgexpand.cc | 9 | ||||
| -rw-r--r-- | gcc/testsuite/gcc.target/i386/pr69482-1.c | 16 | ||||
| -rw-r--r-- | gcc/testsuite/gcc.target/i386/pr69482-2.c | 10 |
3 files changed, 35 insertions, 0 deletions
diff --git a/gcc/cfgexpand.cc b/gcc/cfgexpand.cc index 86783a6..25b1558 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 0000000..f192261 --- /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 0000000..58e89a7 --- /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 } } */ |