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[PCC-82] invalid assembly on amd64 Created: 19/Aug/09 Updated: 03/Jun/10
|Reporter:||Daniel Dickman||Assignee:||Anders Magnusson|
[/usr/src/bin/cp] uname -msrvp
OpenBSD 4.6 GENERIC.MP#130 amd64 Intel(R) Core(TM)2 Duo CPU T7100 @ 1.80GHz
Compiling with -O2 on OpenBSD/amd64 produces the following error for some code
[/usr/src/bin/cp] pcc -O2 -c cp.c
/tmp/ctm.sE01ll: Assembler messages:
/tmp/ctm.sE01ll:488: Error: `(%eax,%r14d)' is not a valid 64 bit base/index expression
Leaving out the -O2 seems to work
[/usr/src/bin/cp] pcc -c cp.c
|Comment by Jonathan Gray [ 14/Sep/09 05:25 PM ]|
perhaps this wasn't noticed during development as NetBSD supports -m32 on amd64?
|Comment by Jonathan Gray [ 14/Sep/09 06:25 PM ]|
It is worth pointing out that OpenBSD currently uses binutils 2.15, there have been several noteable amd64 changes since
Changes from binutils 126.96.36.199.2:
2. Support x86-64 medium model.
Changes from binutils 188.8.131.52.1:
4. Add x86-64 new relocations for medium model.
When specifying -mcmodel=medium to gcc it will generate code with leal instructions that looks like that of pcc.
|Comment by Jonathan Gray [ 14/Sep/09 06:33 PM ]|
|I mistakenly used pcc in the last test not gcc, all leal instructions still use %r* registers with the different mcmodel it would seem.|
|Comment by Anders Magnusson [ 03/Jun/10 09:57 PM ]|
This is a bug in the old gas used in OpenBSD, it do not accept constructs like "leal (%eax,%ebx),%ecx" which does not have anything to do with addresses but in fact is a 3-operand addition. pcc may emit it to avoid an extra movl instruction.
It must be fixed in OpenBSD, it's not a compiler problem. Newer gas supports this.