Only the low bytes are compared. Originally, signed 16-bit compares were optimized into signed 8-bit compares. But, the sign bits are in the high bytes; and, they're equal. Therefore, the low bytes always must be compared as unsigned numbers.
Fixes#1348.
The old broken code defers the count until the end of the (parent function's) argument list. But, a nested function call clears the pointer to the deferred type. That leads to an access violation.
The new code defers only until the end of each argument. Fixes#1320.
Test expressions like `unsigned char x = ...; ... = x / 2;`
These use `int` constants with values representable by
`unsigned int` / `unsigned char`, so using unsigned codegen should
be possible.
Additional tests for #1308. These are things we want to generate better
code for, so add tests that the behavior doesn't change.
In g_typeadjust, before we apply the integral promotions, we check if
both types are unsigned char. If so, we promote to unsigned int, rather
than int, which would be chosen by the standard rules. This is only a
performance optimization and does not affect correctness, as the flags
returned by g_typeadjust are only used for code generation, and not to
determine types of other expressions containing this one. All unsigned
char bit-patterns are valid as both int and unsigned int and represent
the same value, so either signed or unsigned int operations can be used.
This special case part is not duplicated by ArithmeticConvert.
Partial fix for #1308.
Both signed and unsigned chars are promoted to int by C's evaluation
rules. It is more efficient to use unsigned operations when possible,
however. These tests will help test the correctness of optimizations
doing that. See #1308.
