The compiler now supports an --emit-c++ option, which generates generic
vector C++ code. To actually compile this code, the user must provide
C++ code that implements a variety of types and operations (e.g. adding
two floating-point vector values together, comparing them, etc).
There are two examples of this required code in examples/intrinsics:
generic-16.h is a "generic" 16-wide implementation that does all required
with scalar math; it's useful for demonstrating the requirements of the
implementation. Then, sse4.h shows a simple implementation of a SSE4
target that maps the emitted function calls to SSE intrinsics.
When using these example implementations with the ispc test suite,
all but one or two tests pass with gcc and clang on Linux and OSX.
There are currently ~10 failures with icc on Linux, and ~50 failures with
MSVC 2010. (To be fixed in coming days.)
Performance varies: when running the examples through the sse4.h
target, some have the same performance as when compiled with --target=sse4
from ispc directly (options), while noise is 12% slower, rt is 26%
slower, and aobench is 2.2x slower. The details of this haven't yet been
carefully investigated, but will be in coming days as well.
Issue #92.
Pointers can be either uniform or varying, and behave correspondingly.
e.g.: "uniform float * varying" is a varying pointer to uniform float
data in memory, and "float * uniform" is a uniform pointer to varying
data in memory. Like other types, pointers are varying by default.
Pointer-based expressions, & and *, sizeof, ->, pointer arithmetic,
and the array/pointer duality all bahave as in C. Array arguments
to functions are converted to pointers, also like C.
There is a built-in NULL for a null pointer value; conversion from
compile-time constant 0 values to NULL still needs to be implemented.
Other changes:
- Syntax for references has been updated to be C++ style; a useful
warning is now issued if the "reference" keyword is used.
- It is now illegal to pass a varying lvalue as a reference parameter
to a function; references are essentially uniform pointers.
This case had previously been handled via special case call by value
return code. That path has been removed, now that varying pointers
are available to handle this use case (and much more).
- Some stdlib routines have been updated to take pointers as
arguments where appropriate (e.g. prefetch and the atomics).
A number of others still need attention.
- All of the examples have been updated
- Many new tests
TODO: documentation
If a flag along the lines of "--target=sse4,avx-x2" is provided on the command-line,
then the program will be compiled for each of the given targets, with a separate
output file generated for each one. Further, an output file with dispatch functions
that check the current system's CPU and then chooses the best available variant
is also created.
Issue #11.
We had been prohibiting Windows users from providing #definitions on the command
line, which is the wrong thing to do ever since we switched to using the
clang preprocessor.
If no CPU is specified, use the host CPU type, not just a default of "nehalem".
Provide better features strings to the LLVM target machinery.
-> Thus ensuring that LLVM doesn't generate SSE>2 instructions for the SSE2
target (Fixes issue #82).
-> Slight code improvements from using cmovs in generated code now
Use the llvm popcnt intrinsic for the SSE2 target now (it now generates code
that doesn't call the popcnt instruction now that we properly tell LLVM
which instructions are and aren't available for SSE2.)
Set the Module's target appropriately when it's first created.
Compile separate 32 and 64 bit versions of the builtins-c bitcocde
and load the appropriate one based on the target we're compiling
for.
Add optimization patterns to detect and simplify masked loads and stores
with the mask all on / all off.
Enable AVX for LLVM 3.0 builds (still generally hits bugs / unimplemented
stuff on the LLVM side, but it's getting there).
