Commit Graph

2 Commits

Author SHA1 Message Date
John Stiles
b21fac2481 Detect cases in Metal where out params are swizzled.
We will need to emit a helper function to work around this case, as
GLSL supports swizzled out params, but Metal does not. In this CL, we
do not yet synthesize the helper function, but we annotate the code with
a comment indicating affected calls. (Of course, this will be replaced
with a helper function in a followup CL)

Even detecting a swizzle is actually an interesting problem, because
index expressions are sometimes actually swizzles, depending on the type
of the base expression. Also, the index or swizzle might be nested in
several other valid assignable expressions.

Change-Id: I8c74f9a7daec08eff1f32387f8b6b96851c1bd6e
Bug: skia:10855
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/341057
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
2020-12-07 17:12:09 +00:00
John Stiles
f2bd501ce3 Use references instead of pointers for Metal out params.
Pointers require decorating the variable with a * to read back the
value, which the code generator did not properly handle. There was a
special case to add the * but it only supported assignment into the
variable, not reading back. References require no special decoration.

This change fixes compile errors in Functions.sksl with the "bar"
function. (This test marks `x` as an inout but never actually mutates
it.) It also allows us to remove a special-case workaround for `frexp`,
an intrinsic function which uses a reference for its out-parameter.

Additionally, this CL adds a non-inlining copy of "OutParams.sksl" to
the Metal test directory, as most of our tests which use out-parameters
end up inlining all the code, which hides these sorts of bugs.

Change-Id: I31c4db04f6b512b4cd4fe65b3347b82bdbf039cd
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/341000
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
2020-12-04 20:22:55 +00:00