index on master: bf135f8 Merge pull request #502 from halide/split_rvar_bounds
On master: isnan
Fix minor bug in CSE.

Use counts are not transitive. E.g in (x*x + 1) + (x*x + 1), (x*x + 1) is
used twice, x*x is used once (not twice), because once we pull x*x + 1 into
a let, there will only be one x*x.

But use counts should be transitive for exprs we're not going to
extract as a let! E.g, in the above example, if we're not going to pull
x*x + 1 out as a let, then we should treat x*x as having a use count of 2!

So I've separate the use_count tracking from the global numbering, and made
exprs for which should_extract = false transitively increment the use_counts
of their children.
Clarify row-major vs column major in tutorials.
Fixed bug preventing gpu_tile from being used on a mix of Var and RVar.
isnan
Disable const simplification
Add Param::is_explicit_name()

This is mainly useful for certain use cases on the Generator branch,
where it is sometimes desirable to ensure that a Param is given an
explicit name (vs auto generated).
Remove -static-libstdc++ -static-libgcc
Merge pull request #513 from halide/is_autogen

Add Param::is_explicit_name()
Fix for Bug #516. Make the GlobalState instance and its constructor not WEAK
Fix Pull Request comments
Added a test for various uses of Select for the GLSL target.
Fix bug in bounds querying buffers used in extern stages.

Bounds querying on an input buffer wasn't respecting extern stages that
use the buffer. Each user of the buffer was just clobbering the fields
with its own requirements.

This also required:
Adding dimensionality to Parameter objects. This cleans up some other code.
Adding an intrinsic to copy a buffer_t struct
Merge branch 'master' of github.com:halide/Halide

Conflicts:
	src/Param.cpp
	src/Param.h
	src/Parameter.cpp
	src/Parameter.h
Add a test for bounds querying on buffers used in extern stages
Merge branch 'master' into glsl-select-tests
GLSL: Fix handling of select

the previous implementation erroneously assumed that the condition of a
select has the same vector width as the arguments, which is obviously
wrong for scalar conditions that don't involve the color dimension.
Add test for GLSL codegen of scalar select conditions
Use extract_lane() instead of custom visitor