On 11/13/2021 6:10 AM, Iain Sandoe via Gcc-patches wrote:
When saving, if we cannot obtain a suitable memory segment there
is no point in continuing, so exit with an error.
When reading in the PCH, we have a situation that the read-in
data will replace the line tables used by the diagnostics output.
However, the state of the read-in line tables is indeterminate
at some points where diagnostics might be needed.
To make this more robust, we save the existing line tables at
the start and, once we have read in the pointer to the new one,
put that to one side and restore the original table. This
avoids compiler hangs if the read or memory acquisition code
issues an assert, fatal_error, segv etc.
Once the read is complete, we swap in the new line table that
came from the PCH.
If the read-in PCH is corrupted then we still have a broken
compilation w.r.t any future diagnostics - but there is little
that can be done about that without more careful validation of
the file.
I've tested this by hacking and rebuilding the compiler to
produce various kinds of failure. At present, it is hard to
see how to make testcases to do this. Now reg-testing on more
systems,
OK for master if reg-tests pass?
thanks
Iain
Signed-off-by: Iain Sandoe <i...@sandoe.co.uk>
gcc/ChangeLog:
* ggc-common.c (gt_pch_save): If we cannot find a suitable
memory segment for save, then error-out, do not try to
continue.
(gt_pch_restore): Save the existing line table, and when
the replacement is being read, use that when constructing
diagnostics.
OK if it passes.
Jeff
