Within each function that launches tasks, we now can easily track which
tasks that function launched, so that the sync at the end of the function
can just sync on the tasks launched by that function (not all tasks
launched by all functions.)
Implementing this led to a rework of the task system API that ispc generates
code to call; the example task systems in examples/tasksys.cpp have been
updated to conform to this API. (The updated API is also documented in
the ispc user's guide.)
As part of this, "launch[n]" syntax was added to launch a number of tasks
in a single launch statement, rather than requiring a loop over 'n' to
launch n tasks.
This commit thus fixes issue #84 (enhancement to launch multiple tasks from
a single launch statement) as well as issue #105 (recursive task launches
were broken).
Previously, we did a vector equal compare and then a movmsk, the
result of which we checked to see if it was on for all lanes.
Because masks are vectors of i32s, under AVX, the vector equal
compare required two 4-wide SSE compares and some shuffling.
Now, we do a movmsk of both masks first and then a scalar
equality comparison of those two values, which seems to generate
overall better code.
Fixes bug #55. A number of tests were crashing on Windows due to the task
launch code using alloca to allocate space for the tasks' parameters. On
Windows, the stack isn't generally big enough for this to be a good idea.
Also added an alignment parmaeter to ISPCMalloc() to pass the alignment
requirement along.
When creating function Symbols for functions that were defined in LLVM bitcode for the standard library, if any of the function parameters are integer types, create two ispc-side Symbols: one where the integer types are all signed and the other where they are all unsigned. This allows us to provide, for example, both store_to_int16(reference int a[], uniform int offset, int val) as well as store_to_int16(reference unsigned int a[], uniform int offset, unsigned int val). functions.
Added some additional tests to exercise the new variants of these.
Also fixed some cases where the __{load,store}_int{8,16} builtins would read from/write to memory even if the mask was all off (which could cause crashes in some cases.)
were expecting vector-width-aligned pointers where in point of fact,
there's no guarantee that they would have been in general.
Removed the aligned memory allocation routines from some of the examples;
they're no longer needed.
No perf. difference on Core2/Core i5 CPUs; older CPUs may see some
regressions.
Still need to update the documentation for this change and finish reviewing
alignment issues in Load/Store instructions generated by .cpp files.
