@Bruce Mitchener: Thank you sooo much for seeing that damn bug! Once this
has been fixed, compilation went smoothly with any optimization!
The JavaScript size went down from 3.5 MB to 680 KB with optimization level
-O3. Performance increased on Firefox browser by a factor of 2 compated to
-O0. Both are great results!
One thing I wonder about: Using Chrome, the O0-build is the fastest (with
very similar speed compared to Firefox) but when using -O3, Firefox gets
about 30% faster whereas Chrome takes 100% _more_ time. Are there any
optimization strategies to enable Chrome getting faster?
Best regards,
Björn
Am Donnerstag, 28. Mai 2015 15:45:07 UTC+2 schrieb Bruce Mitchener:
>
> I don't think this has anything to do with threads after looking at it a
> bit after dinner.
>
> The call stack looks clearly incorrect ... there's no reason for
> emit_message out of libjpeg to be calling __ZN10__cxxabiv112_GLOBAL__N_
> 19destruct_EPv
>
> If we look at the code in emit_message in JS, the line involved is:
>
> FUNCTION_TABLE_vi[HEAP32[(HEAP32[i6 >> 2] | 0) + 8 >> 2] & 63](HEAP32[i4
> >> 2] | 0);
>
> The line from C is:
>
> (*err->output_message) (cinfo);
>
> I really don't think this should be invoking what it is.
>
> So ... looking a bit further, we see this function in your C++ code:
>
> void DecodeImage::prepare(int sizeOfData, emscripten::val callback)
> {
> // create and assign libjpegs internal data structure
> struct jpeg_error_mgr jerr;
> struct jpeg_decompress_struct cinfo;
> this->cinfo = cinfo;
> this->sizeOfData = sizeOfData;
>
> // Allocate Memory
> this->imageData = (uint8_t*) malloc(this->sizeOfData);
> callback(emscripten::memory_view<uint8_t>(this->sizeOfData,
> this->imageData));
>
> // Allocate and initialize JPEG decompression object
> this->cinfo.err = jpeg_std_error(&jerr);
>
> // Now we can initialize the JPEG decompression object.
> jpeg_create_decompress(&this->cinfo);
>
> // Specify data source
> jpeg_mem_src(&this->cinfo, (unsigned char*)(this->imageData),
> this->sizeOfData);
> }
>
> That's creating jerr on the stack, saving a pointer to it, and then
> exiting, leaving that pointer invalid. You need to fix your memory
> allocation and then all will probably be well.
>
> Cheers,
>
> - Bruce
>
>
>
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