This resulted from the addition of the signed-to-unsigned comparison optimization. Specifically, it calls TypeOf for the expressions on each side of the comparison, and this did not handle function calls. That support has now been added, and will give the proper return type for direct and indirect calls to C functions. The IR for tool calls doesn't include the return type (just the number of bytes), so we return cgVoid for them. This is OK for the present use case.
Without this fix, an expression of the form "0 * exp" would be reduced to simply "0" unless exp contained a function call; other side effects of exp (such as assignments or increments) would be removed.
A similar issue could occur with additions that use the same expression on both sides of the "+": after optimization, it would only be evaluated once. I think the cases addressed here are all undefined behavior under the C standards, so the old behavior wasn't technically wrong, but the new behavior is still less confusing.
Specifically, this ensures that the depth-first numbering of basic blocks starts from 1, which is what ReachingDefinitions expects. Without this fix, reaching definitions wouldn't be correctly computed for functions that contain unreachable basic blocks (including the implicit one to return at the end). This could result in invalid hoisting of operations out of the loop.
This fixes the compca26.c test case.
Specifically, convert signed word comparisons to unsigned if both sides were either unsigned byte values or non-negative constants. This is incorporated as part of intermediate code peephole optimization (bit 0).
This should alleviate some cases of performance regressions due to promoting char to int instead of unsigned int.
This fixes the compca22.c test case.
This optimization could be fixed and re-enabled, but to do so, you would have to check if the stored value is ever used subsequently, which is not information that's readily available in the peephole optimization pass. It would also be necessary to check if there are any stores to the same location within the right-side expression, which could kill the optimization.