On 7/23/25 5:45 PM, Andrew Pinski via Gcc wrote:
Hi all,
When I improved DSE to remove stores where the rhs is known 100% to be an
uninitialized variables (ssa_undefined_value_p), I get a few regressions due to
an uninitialized warning does not happen:
gcc.dg/uninit-40.c for an example. (gcc.dg/analyzer/torture/boxed-int-1.c fails
also for a similar reason).
Does it make sense to warn at the same time as removing these stores that the
variable is uninitialized? Or should we delay to removing the stores until
right before the expansion of Gimple to RTL?
These stores show up more often with C++ code so removing them early as
possible would be a good idea.
I'll hopefully channel Richi correctly here ;-) Emitting this kind of
warning from an optimization pass should be avoided.
So the tradeoff is better optimization (concrete examples) vs missing
some uninit warnings. I tend to lean towards the former, but I realize
my views may be in the minority.
Jeff
