From: David Hildenbrand

Sent: 22 October 2020 10:25

...

... especially because I recall that clang and gcc behave slightly
differently:

https://github.com/hjl-tools/x86-psABI/issues/2

"Function args are different: narrow types are sign or zero extended to
32 bits, depending on their type. clang depends on this for incoming
args, but gcc doesn't make that assumption. But both compilers do it
when calling, so gcc code can call clang code.

It really is best to use 'int' (or even 'long') for all numeric
arguments (and results) regardless of the domain of the value.

Related, I've always worried about 'bool'....

The upper 32 bits of registers are always undefined garbage for types
smaller than 64 bits."

On x86-64 the high bits are zeroed by all 32bit loads.

	David

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