ipa: Skip widening type conversions in jump function constructions

Originally, we did not stream any formal parameter types into WPA and
were generally very conservative when it came to type mismatches in
IPA-CP.  Over the time, mismatches that happen in code and blew up in
WPA made us to be much more resilient and also to stream the types of
the parameters which we now use commonly.

With that information, we can safely skip conversions when looking at
the IL from which we build jump functions and then simply fold convert
the constants and ranges to the resulting type, as long as we are
careful that performing the corresponding folding of constants gives
the corresponding results.  In order to do that, we must ensure that
the old value can be represented in the new one without any loss.
With this change, we can nicely propagate non-NULLness in IPA-VR as
demonstrated with the new test case.

I have gone through all other uses of (all components of) jump
functions which could be affected by this and verified they do indeed
check types and can handle mismatches.

gcc/ChangeLog:

2024-12-11  Martin Jambor  <mjambor@suse.cz>

	* ipa-prop.cc: Include vr-values.h.
	(skip_a_safe_conversion_op): New function.
	(ipa_compute_jump_functions_for_edge): Use it.

gcc/testsuite/ChangeLog:

2024-11-01  Martin Jambor  <mjambor@suse.cz>

	* gcc.dg/ipa/vrp9.c: New test.