Wed Jun 06 21:48:53 2012: Request 77677 was acted upon.
Transaction: Correspondence added by bulk88.
Queue: Win32-API
Subject: x64 asm is broken for ::API, >4 param crash
Broken in: 0.68
Severity: Normal
Owner: Nobody
Requestors: bul...@hotmail.com
Status: open
Ticket <URL: https://rt.cpan.org/Ticket/Display.html?id=77677 >
There are 2 separate problems here. MSVC doesn't save RSI, but it causes
no ill effects since MSVC (atleast my 2008) will not use nonvolatile
registers (and therefore use more stack memory) no matter what the -O
flag or LTCG setting. Ask MS about that one. The GCC code saves RSI and
restores it, and GCC uses RSI alot unlike MSVC, but if the stack
prototype has more than 4 args, the copystack loop runs and "corrupts"
RSP and then later when the POPs happen they POP garbage into RSI and
R10 (why R10 is saved, its volatile, and not a fastcall register, IDK),
RSP isn't the same when the PUSHes were done. Since MSVC code doesn't
ever call POP and uses 100% RBP addressing, the RSP position is
irrelevant but RSI is still not restored.
