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| author | Jakub Jelinek <jakub@redhat.com> | 2021-07-27 09:59:37 +0200 |
|---|---|---|
| committer | Jakub Jelinek <jakub@redhat.com> | 2021-07-27 09:59:37 +0200 |
| commit | a21bd3cebd6f54af70a37c18b8fbeae933fb6515 (patch) | |
| tree | 84262a34a51b1b3a9fc51ac12d9d6239bb737598 /gcc | |
| parent | 5485e820cd0554886af282265198c7433c64c7b9 (diff) | |
| download | gcc-a21bd3cebd6f54af70a37c18b8fbeae933fb6515.zip gcc-a21bd3cebd6f54af70a37c18b8fbeae933fb6515.tar.gz gcc-a21bd3cebd6f54af70a37c18b8fbeae933fb6515.tar.bz2 | |
gimple-fold: Fix up __builtin_clear_padding on classes with virtual inheritence [PR101586]
For the following testcase, B is 16-byte type, containing 8-byte
virtual pointer and 1-byte A member, and C contains two FIELD_DECLs,
one with B type and size of just 8-byte and then a field with type
A and 1-byte size.
The __builtin_clear_padding code was upset about the B typed FIELD_DECL
containing FIELD_DECLs beyond the field size and triggered
assertion failure.
This patch makes it ignore all FIELD_DECLs that are (fully) beyond the sz
passed from the caller (except for the flexible array member
diagnostics that is kept).
2021-07-27 Jakub Jelinek <jakub@redhat.com>
PR middle-end/101586
* gimple-fold.c (clear_padding_type): Ignore FIELD_DECLs with byte
positions above or equal to sz except for diagnostics of flexible
array members.
* g++.dg/torture/builtin-clear-padding-4.C: New test.
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/gimple-fold.c | 4 | ||||
| -rw-r--r-- | gcc/testsuite/g++.dg/torture/builtin-clear-padding-4.C | 44 |
2 files changed, 48 insertions, 0 deletions
diff --git a/gcc/gimple-fold.c b/gcc/gimple-fold.c index a3afe87..b6f6054 100644 --- a/gcc/gimple-fold.c +++ b/gcc/gimple-fold.c @@ -4697,6 +4697,8 @@ clear_padding_type (clear_padding_struct *buf, tree type, HOST_WIDE_INT sz) if (fldsz == 0) continue; HOST_WIDE_INT pos = int_byte_position (field); + if (pos >= sz) + continue; HOST_WIDE_INT bpos = tree_to_uhwi (DECL_FIELD_BIT_OFFSET (field)); bpos %= BITS_PER_UNIT; @@ -4772,6 +4774,8 @@ clear_padding_type (clear_padding_struct *buf, tree type, HOST_WIDE_INT sz) else { HOST_WIDE_INT pos = int_byte_position (field); + if (pos >= sz) + continue; HOST_WIDE_INT fldsz = tree_to_shwi (DECL_SIZE_UNIT (field)); gcc_assert (pos >= 0 && fldsz >= 0 && pos >= cur_pos); clear_padding_add_padding (buf, pos - cur_pos); diff --git a/gcc/testsuite/g++.dg/torture/builtin-clear-padding-4.C b/gcc/testsuite/g++.dg/torture/builtin-clear-padding-4.C new file mode 100644 index 0000000..5936cdf --- /dev/null +++ b/gcc/testsuite/g++.dg/torture/builtin-clear-padding-4.C @@ -0,0 +1,44 @@ +// PR middle-end/101586 + +struct A { char a; }; +struct B : virtual A {}; +struct C : B {}; +struct D : virtual A, C {}; + +__attribute__((noipa)) A * +baz (C *p, D *q) +{ + if (p) + return dynamic_cast <A *> (p); + else + return dynamic_cast <A *> (q); +} + +void +foo () +{ + C c; + c.a = 42; + __builtin_clear_padding (&c); + A *p = baz (&c, 0); + if (c.a != 42 || p->a != 42) + __builtin_abort (); +} + +void +bar () +{ + D d; + d.a = 42; + __builtin_clear_padding (&d); + A *p = baz (0, &d); + if (d.a != 42 || p->a != 42) + __builtin_abort (); +} + +int +main () +{ + foo (); + bar (); +} |