egcs-1.1: fix for volatile bug

Mark Powell
Tue Jan 12 02:10:00 GMT 1999

On Mon, 11 Jan 1999, Mark Powell wrote:
>  The following bug was observed in egcs-1.1b and egcs-1.1.1 configured
>  for m68k-coff.
>  Assignment operations through a pointer variable declared volatile
>  produce multiple accesses. This can cause incorrect behaviour when the
>  destination of the write is a register in a peripheral device and the
>  device expects a series of values to be written to the same address.
>  The bug is triggered when compiling with no optimisation. Optimisation
>  levels of -O1 and above do not exhibit the bug.

For info, the bug is fixed in current snapshots.

The fix was well commented so I was able to narrow it down very quickly.
A patch for egcs-1.1.1 is attached. It should apply to egcs-1.1b
equally well.


Mark Powell, Senior Software Engineer, Primagraphics Limited
New Cambridge House, Litlington, nr.Royston, Herts, SG8 0SS, UK
Tel. +44 1763 852222, Fax. 853324,,

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