x86-64 stub calling convention (original) (raw)

Deneau, Tom tom.deneau at amd.com
Sat Jun 30 19:08:35 PDT 2012

OK, thanks, Vladimir. Is there a good reason for using the OS's C calling convention for stubs? (as opposed to, say, using whatever makes the most sense for Java).

-- Tom

-----Original Message----- From: Vladimir Kozlov [mailto:vladimir.kozlov at oracle.com] Sent: Friday, June 29, 2012 10:46 PM To: Krystal Mok Cc: Deneau, Tom; hotspot-compiler-dev at openjdk.java.net Subject: Re: x86-64 stub calling convention

I was not right that you can use all XMM registers. On windows64 only xmm0-xmm5 are available free, the rest are SOE (save on entry). For stabs calls we use C calling convention. It is described in .ad file where XMM registers are defined (second parameter):

// Linux ABI: No register preserved across function calls // XMM0-XMM7 might hold parameters // Windows ABI: XMM6-XMM15 preserved across function calls // XMM0-XMM3 might hold parameters

reg_def XMM5 (SOC, SOC, Op_RegF, 5, xmm5->as_VMReg()); reg_def XMM5_H (SOC, SOC, Op_RegF, 5, xmm5->as_VMReg()->next());

#ifdef _WIN64

reg_def XMM6 (SOC, SOE, Op_RegF, 6, xmm6->as_VMReg()); reg_def XMM6_H (SOC, SOE, Op_RegF, 6, xmm6->as_VMReg()->next()); ...

#else

reg_def XMM6 (SOC, SOC, Op_RegF, 6, xmm6->as_VMReg()); reg_def XMM6_H (SOC, SOC, Op_RegF, 6, xmm6->as_VMReg()->next());

Vladimir

On 6/29/12 7:25 PM, Krystal Mok wrote:

Hi Tom,

This is something I'd like to get an answer to, too. I did see in a comment in one of the older changes [1][2] that: + // Spill because stubs can use any register they like and it's + // easier to restore just those that we care about. Which doesn't really sound reassuring... - Kris [1]: http://hg.openjdk.java.net/hsx/hotspot-comp/hotspot/rev/28263a73ebfb [2]: http://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/2011-May/005623.html On Sat, Jun 30, 2012 at 9:27 AM, Deneau, Tom <tom.deneau at amd.com <mailto:tom.deneau at amd.com>> wrote: Hi -- Can someone point me to the x86-64 calling convention for stubs created by stubGenerator? In particular, which xmm registers if any must be preserved and which are volatile. -- Tom Deneau

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