AIX 3.1: Problems with strcpy and optimizer

[Bjorn Engsig]

During normal compilation with optimization, all calls to strcpy expand via
a macro __strcpy to inline lscbx and stcx instructions.  We have some examples
of cases where one of the addresses used by lscbx is stored in a register that
is the same used to do the copy, which leads to a bad copy.

If you generate the assembly listning, look for lines like:

 1795| 001B98 lscbx. 7C6C 222B         LSCBX    r3,r4,r5,r6,r7,r8,r9,r10,cr0=ormnam(r4,r12)

where one of the registers in the first list is the same as in the second
paranthesized list, here r4 occurs in both places.  A workaround is to give
the -U__STR__ option to the C compiler.

This note is for your information only to use when hunting optimizer problems.
It has been reported to IBM.
-- 
Bjorn Engsig,	       E-mail: bengsig at oracle.com, bengsig at oracle.nl
ORACLE Corporation   From IBM: auschs!ibmaus!cs.utexas.edu!uunet!oracle!bengsig

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