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| author | Jakub Jelinek <jakub@redhat.com> | 2021-07-23 19:55:16 +0200 |
|---|---|---|
| committer | Jakub Jelinek <jakub@redhat.com> | 2021-07-23 19:55:16 +0200 |
| commit | 8408d34570c9fe9f3d22a25a76df2a4c64f08477 (patch) | |
| tree | 56c44ee871ca7bc2356294cde1beea3f503b0c86 /gcc | |
| parent | 435f90187eb4b6ddd66df692320057f303841ed6 (diff) | |
| download | gcc-8408d34570c9fe9f3d22a25a76df2a4c64f08477.zip gcc-8408d34570c9fe9f3d22a25a76df2a4c64f08477.tar.gz gcc-8408d34570c9fe9f3d22a25a76df2a4c64f08477.tar.bz2 | |
expmed: Fix store_integral_bit_field [PR101562]
Our documentation says that paradoxical subregs shouldn't appear
in strict_low_part:
'(strict_low_part (subreg:M (reg:N R) 0))'
This expression code is used in only one context: as the
destination operand of a 'set' expression. In addition, the
operand of this expression must be a non-paradoxical 'subreg'
expression.
but on the testcase below that triggers UB at runtime
store_integral_bit_field emits exactly that.
The following patch fixes it by ensuring the requirement is satisfied.
2021-07-23 Jakub Jelinek <jakub@redhat.com>
PR rtl-optimization/101562
* expmed.c (store_integral_bit_field): Only use movstrict_optab
if the operand isn't paradoxical.
* gcc.c-torture/compile/pr101562.c: New test.
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/expmed.c | 5 | ||||
| -rw-r--r-- | gcc/testsuite/gcc.c-torture/compile/pr101562.c | 21 |
2 files changed, 25 insertions, 1 deletions
diff --git a/gcc/expmed.c b/gcc/expmed.c index 1fb6317..3143f38 100644 --- a/gcc/expmed.c +++ b/gcc/expmed.c @@ -921,7 +921,10 @@ store_integral_bit_field (rtx op0, opt_scalar_int_mode op0_mode, } subreg_off = bitnum / BITS_PER_UNIT; - if (validate_subreg (fieldmode, GET_MODE (arg0), arg0, subreg_off)) + if (validate_subreg (fieldmode, GET_MODE (arg0), arg0, subreg_off) + /* STRICT_LOW_PART must have a non-paradoxical subreg as + operand. */ + && !paradoxical_subreg_p (fieldmode, GET_MODE (arg0))) { arg0 = gen_rtx_SUBREG (fieldmode, arg0, subreg_off); diff --git a/gcc/testsuite/gcc.c-torture/compile/pr101562.c b/gcc/testsuite/gcc.c-torture/compile/pr101562.c new file mode 100644 index 0000000..ea4a5f7 --- /dev/null +++ b/gcc/testsuite/gcc.c-torture/compile/pr101562.c @@ -0,0 +1,21 @@ +/* PR rtl-optimization/101562 */ + +struct S { char c; }; +void baz (struct S a, struct S b); + +void +foo (void) +{ + struct S x[1]; + *(short *)&x[0] = 256; + baz (x[0], x[1]); +} + +void +bar (void) +{ + struct S x[1]; + x[0].c = 0; + x[1].c = 1; + baz (x[0], x[1]); +} |