match.pd: Remove "+ 0x80000000" in int comparisons [PR94899]

Expressions of the form "X + CST < Y + CST" where:

* CST is an unsigned integer constant with only the MSB set, and
* X and Y's types have integer conversion ranks <= CST's

can be simplified to "(signed) X < (signed) Y".

This is because, assuming a 32-bit signed numbers,
(unsigned) INT_MIN + 0x80000000 is 0, and
(unsigned) INT_MAX + 0x80000000 is UINT_MAX.

i.e. the result increases monotonically with signed input.

This means:
((signed) X < (signed) Y) iff (X + 0x80000000 < Y + 0x80000000)

gcc/
	PR tree-optimization/94899
	* match.pd (X + C < Y + C -> (signed) X < (signed) Y, if C is
	0x80000000): New simplification.
gcc/testsuite/
	* gcc.dg/pr94899.c: New test.

0 files changed, 0 insertions, 0 deletions