CppunitTest_vcl_skia failing on tb68 with illegal instruction

Stephan Bergmann sbergman at redhat.com
Tue Mar 9 14:20:27 UTC 2021

On 09/03/2021 14:19, Luboš Luňák wrote:
>   That doesn't make sense to me. The crashing test calls normal Skia code that
> shouldn't be special WRT instruction sets, and it's normally compiled with
> clang-cl without explicit instruction set flags. The only plausible
> explanation I can think of is that clang-cl defaults to a higher instruction
> set default than cl's (or ours) and the relevant code is somehow unlucky to
> have clang-cl to actually use such an instruction there.

I tend to remember that clang-cl targeting x86 does indeed enable SSE2 
by default:

$ touch test.c && clang-cl -### -m32 -c test.c


... "-target-cpu" "pentium4" ...

(and e.g. LLVM's clang/include/clang/Basic/X86Target.def

> CPU_SPECIFIC("pentium_4", 'J', "+cmov,+mmx,+sse,+sse2")

appears to imply that pentium4 implies SSE2), and only an explicit

$ clang-cl -### -m32 -arch:SSE -c test.c

would output

... "-target-cpu" "pentium3" ...

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