Hello Michael,
On 2017-11-28 05:14, Michael Raab wrote:
we're trying to build the recent OpenSG source with vs2017 (vc141). We
noticed that the compiler produces faulty code for release builds when
optimization (/O2) is activated.
OSGTextVectorFace.cpp
Line 273:
indexEnd = tIt->second;
Here, the assignment to indexEnd nevers happens. Assembly looks like this:
000007FEE316324A mov r8d,dword ptr [r12+4]
000007FEE316324F mov dword ptr [index],r8d
Looks like the value is written to a variable 'index' instead of
indexEnd... :-(
Do you have any ideas how to fix this without deactivating
optimizations? Do you have experienced other similar problems?
hmm, from just staring at the code I don't see anything that jumps out
as wrong/suspicious to me.
That it seems to store to index instead of indexEnd in the assembly
could also be because the compiler has concluded that it can materialize
the value of one variable from the other in a way that is cheaper than
using a register or stack slot.
You could try these things and see if that helps:
- move the scope of indexBegin, indexEnd into the for loop. I notice
that there is another set of variables with the same name around line
319, perhaps that confuses the compiler?
- #define OSG_ASSERT() to assert() at the top of the file, so the
compiler sees the assertions - some compilers derive optimization
knowledge from assertions.
- I assume you've used other methods (than reading assembly ;) ) to
track the problem to this function/loop, i.e. it is fairly unlikely that
the problem is elsewhere?
Cheers,
Carsten
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