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[Bug binutils/19054] New: wrong assembly and disassembly for fsubp/fsubr
From: |
mattiase at acm dot org |
Subject: |
[Bug binutils/19054] New: wrong assembly and disassembly for fsubp/fsubrp |
Date: |
Fri, 02 Oct 2015 08:16:45 +0000 |
https://sourceware.org/bugzilla/show_bug.cgi?id=19054
Bug ID: 19054
Summary: wrong assembly and disassembly for fsubp/fsubrp
Product: binutils
Version: 2.25
Status: NEW
Severity: normal
Priority: P2
Component: binutils
Assignee: unassigned at sourceware dot org
Reporter: mattiase at acm dot org
Target Milestone: ---
The x86 (x87) instructions fsubp and fsubrp seem to be swapped both in assembly
and disassembly. The assembly source:
fsubp %st, %st(5)
fsubrp %st, %st(5)
results in the following, after going through as and objdump:
0: de e5 fsubp %st,%st(5)
2: de ed fsubrp %st,%st(5)
However, according to the architecture reference (and Intel's XED tool), [de
ed] is fsubp and [de e5] fsubrp, so the "r" bit seems to have been flipped in
both as and objdump. For instance, XED on the same file outputs
XDIS 0: X87_ALU X87 DEE5 fsubrp st5, st0
XDIS 2: X87_ALU X87 DEED fsubp st5, st0
The binutils error does not depend on whether AT&T or Intel syntax is used.
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- [Bug binutils/19054] New: wrong assembly and disassembly for fsubp/fsubrp,
mattiase at acm dot org <=