Subject: bug#16039: repeated emacs crashes (in GC?)

From: YAMAMOTO Mitsuharu <[email-masked]>
Date: Thu, 05 Dec 2013 09:35:21 +0900

>>>>> On Wed, 04 Dec 2013 10:48:11 +0900, YAMAMOTO Mitsuharu <[email-masked]> said:

>>> Having 136 thousand frames during GC is not unheard of.

>> (/ 8720000.0 (* 136 1000))
>> 64.11764705882354

>> If each frame consumes more than 64 bytes, then it will use up
>> 8720000B stack space.

> FWIW, the default compiler for Xcode 4.0.2 on Mac OS X 10.6 with the
> -O2 option seems to consume 64 bytes for each mark_object frame:

>   i686-apple-darwin10-gcc-4.2.1 (GCC) 4.2.1 (Apple Inc. build 5666) (dot 3)

>   _mark_object:
>   00000000000008a0	pushq	%rbp
>   00000000000008a1	movq	%rsp, %rbp
>   00000000000008a4	movq	%rbx, 0xffffffffffffffd8(%rbp)
>   00000000000008a8	movq	%r12, 0xffffffffffffffe0(%rbp)
>   00000000000008ac	movq	%r13, 0xffffffffffffffe8(%rbp)
>   00000000000008b0	movq	%r14, 0xfffffffffffffff0(%rbp)
>   00000000000008b4	movq	%r15, 0xfffffffffffffff8(%rbp)
>   00000000000008b8	subq	$0x40, %rsp

> And the one for Xcode 5.0.2 on OS X 10.9 with -O4 does 24 bytes:

>   Apple LLVM version 5.0 (clang-500.2.79) (based on LLVM 3.3svn)

>   _mark_object:
>   0000000000005c70	pushq	%rbp
>   0000000000005c71	movq	%rsp, %rbp
>   0000000000005c74	pushq	%r15
>   0000000000005c76	pushq	%r14
>   0000000000005c78	pushq	%r13
>   0000000000005c7a	pushq	%r12
>   0000000000005c7c	pushq	%rbx
>   0000000000005c7d	subq	$0x18, %rsp

I forgot to count the pushq instructions.  The correct value would be
72 bytes for each mark_object frame in both cases.

				     YAMAMOTO Mitsuharu
				[email-masked]