Re: [PATCH] Tiny -fssa-ccp fix

[law at redhat dot com]

In message <20020304151156.N2204@sunsite.ms.mff.cuni.cz>, Jakub Jelinek writes:
 > Hi!
 > 
 > The following testcase ICEs because VARRAY_RTX (ssa_definition, i) is NULL.
 > All other users of this seem to check for NULL and if it
 > is not single_set, it skips it anyway.
 > 
 > 2002-03-04  Jakub Jelinek  <jakub@redhat.com>
 > 
 > 	* ssa-ccp.c (ssa_ccp_substitute_constants): Don't crash if def
 > 	is NULL.
 > 	* gcc.dg/20020304-1.c: New test.
This isn't correct.  Please revert the ssa-ccp part of the patch.

The root of the problem is we have deleted insns in various data structures
such as the def-use chains due to various changes elsewhere in the compiler.

It seems to me this should be fixed by updating the def-use chains at the
end of ssa_fast_dce.

jeff