Fix PR 93044: extra cast is not removed

In this case we are not removing convert to a bigger size
back to the same size (or smaller) if signedness does not
match.
For an example:
```
  signed char _1;
...
  _1 = *a_4(D);
  b_5 = (short unsigned int) _1;
  _2 = (unsigned char) b_5;
```
The inner cast is not needed and can be removed but was not.
The match pattern for removing the extra cast is overly
complex so decided to add a new case for rather than trying
to modify the current if statement here.

Committed as approved. Bootstrapped and tested on x86_64-linux-gnu with no regressions.

gcc/ChangeLog:

	PR tree-optimization/93044
	* match.pd (nested int casts): A truncation (to the same size or smaller)
	can always remove the inner cast.

gcc/testsuite/ChangeLog:

	PR tree-optimization/93044
	* gcc.dg/tree-ssa/cast-1.c: New test.
	* gcc.dg/tree-ssa/cast-2.c: New test.

0 files changed, 0 insertions, 0 deletions