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[Bug gas/30578] libavcodec/x86/mathops.h:125: Error: operand type mismat
From: |
jbeulich at suse dot com |
Subject: |
[Bug gas/30578] libavcodec/x86/mathops.h:125: Error: operand type mismatch for ` shr' |
Date: |
Thu, 20 Jul 2023 06:26:47 +0000 |
https://sourceware.org/bugzilla/show_bug.cgi?id=30578
Jan Beulich <jbeulich at suse dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Last reconfirmed| |2023-07-20
Ever confirmed|0 |1
Status|UNCONFIRMED |NEW
--- Comment #2 from Jan Beulich <jbeulich at suse dot com> ---
See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108941. The cast in
(uint8_t)(-s) isn't honored by gcc when s can be determined to be a plain
number, making it emit a negative value. Negative shift counts of course make
no sense (on x86 at least). See the description of the referenced binutils
patch as to the resulting misbehavior for RCL and RCR. For SHL/SHR etc the
behavior would still be correct, but (dis)allowing negative shift counts there
is a matter of consistency.
I won't mark this "invalid" right away, to allow for discussion to happen here
that should have happened on the patch submission (if need be).
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