[Issue 17940] bool function parameters loaded from struct sometimes miscompiled with -O

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=17940

--- Comment #2 from FeepingCreature <default_357-line at yahoo.de> ---
Hah! It tries to reload the cse into ESI, but since that's a 1-byte operation
(since bool), it actually becomes a move to DH. ESI is not even reachable with
1-byte ops, because those register values were used to address high regs. So
for reg8 opcodes like 0x8A, code->setReg should assert on reg & 4.

How to actually fix this though, no idea.

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