Comment 47 for bug 1711337

They at chromium say they use clang when they cross compile chromium .And they had exactly same problem like firefox have ,when they build chromium native using gcc .
You can read a irc log :

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[16:17:16] <msanchez> This has been puzzling us for a few weeks already because we can't get that crash when we cross compile chromium, but only when running a version built natively in an arm7 machine
[16:18:55] <lizeb> Does gdb tell you which instruction is causing trouble? It should
[16:19:36] <msanchez> the only differences we could spot are that in the native build we pass use_sysroot=false and is_clang=false (we build with gcc 4.9), while in the cross-build we pass is_clang=true and use_sysroot=true
[16:19:54] <msanchez> #0 0xb629b9e6 in _sk_xor__vfp4 () from /usr/lib/chromium-browser/libskia.so
[16:20:00] <msanchez> is that what you mean?
[16:20:17] <msanchez> sorry, I'm not deep in ARM-internals, feel free to ask anything even if it sounds dumb :)
[16:21:05] <lizeb> try "disas 0xb629b9e6,0xb629b100"
[16:21:27] <lizeb> it will give you the assembly at these addresses
[16:21:49] <lizeb> since the issue is "illegal instruction", it might be that the instruction executed isn't supported by your target
[16:22:08] <msanchez> that makes sense
[16:22:12] * msanchez boots up the ARM device
[16:22:34] <msanchez> At the moment my theories were pointing to some compiler-specific thing
[16:22:49] <msanchez> because of the difference between using clang (cross-build) vs gcc 4.9 (native build)
[16:23:30] <lizeb> It's likely that different compiler will generate different instructions, especially if for some reason they don't get the same flags
[16:24:15] <msanchez> so I was not that off-track. Just wild guessing :)
[16:33:58] <ricea> I think the function you're crashing in comes from here: https://cs.chromium.org/codesearch/f/chromium/src/third_party/skia/src/jumper/SkJumper_generated.S
[16:47:39] <lizeb> So line 684 in your dump maps to _sk_xor__vfp4:
[16:47:47] <lizeb> in the file linked by ricea
[16:48:33] <lizeb> The problem is that the address on which you crash is not an actual instruction address...
[16:49:40] <msanchez> oops! I see
[16:49:52] <msanchez> yeah, it's like in between instructions
[16:50:10] <lizeb> This is not thumb code, so instructions are 4 bytes long
[16:51:15] <msanchez> not sure if it's related, but fwiw this is building with target_cpu="arm" arm_float_abi="hard" arm_use_neon=true arm_use_thumb=true
[16:56:29] <lizeb> I don't think we've ever built chrome on android with GCC 6 as Android doesn't support it, AFAIK. And we now use clang.
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