On 7/23/2021 1:49 AM, Jakub Jelinek wrote:
Hi!
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.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2021-07-23 Jakub Jelinek <ja...@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.
OK
jeff
