Hello, after upgrading to gcc-4.4.3-r2 (the latest stable) I started to suffer from random crashes. Short analysis revealed that the reason is that with -O3 (maybe with lower optimization levels, too -- it's not that easy to catch the problem, I am not sure) gcc generates aligned accesses to arguments on stack which are not necessarily aligned. Depending on the model and stepping of the CPU, this can lead to an exception. A user sees a segfault. This is indeed what Bugs #301389 and #301819 are about. Reproducible: Always Steps to Reproduce: 1. CFLAGS="-march=core2 -O3 -ggdb" FEATURES="splitdebug installsources" emerge -1 sys-libs/zlib 2. Have a look at inflate_table() in inftrees.c 3. Run firefox, it may (depending on your CPU) crash Actual Results: inflate_table: .LFB45: .file 1 "inftrees.c" .loc 1 39 0 .LVL0: pushl %ebp .LCFI0: .loc 1 108 0 pxor %xmm0, %xmm0 .loc 1 39 0 movl %esp, %ebp .LCFI1: pushl %edi .LCFI2: pushl %esi .LCFI3: pushl %ebx .LCFI4: call .L101 .L101: popl %ebx addl $_GLOBAL_OFFSET_TABLE_+[.-.L101], %ebx subl $188, %esp .LCFI5: .loc 1 108 0 movdqa %xmm0, -56(%ebp) Note that %ebp on the last instruction is not necessarily aligned to 16 bytes (and it is not, in my very case it is 0xbffe710c). Expected Results: Another code (e.g. with movdqu) is generated. This is not the only occurence where I have got such a crash, some other were in glib, librsvg and in libxfce4util.
Created attachment 234861 [details] emerge --info
Duplicate of bug 270120 ?
Yes, I have isolated this to -ftree-vectorize. Sorry if this bug is already known. *** This bug has been marked as a duplicate of bug 270120 ***
