tree ae684f5f845316e8b932f45d0d79cbe468cec643
parent bab4e5911b1bfa5a86bc80006b7301ae48363844
author Bill Hollings <bill.hollings@brenwill.com> 1629127395 -0400
committer Bill Hollings <bill.hollings@brenwill.com> 1629127395 -0400

MSL: Fix duplicate gl_Position outputs when gl_Position defined but unused.

When gl_Position is defined by SPIR-V, but neither used nor initialized,
it appeared twice in the MSL output, as gl_Position and glPosition_1.

The existing tests for whether an output is active check only that it is
used by an op, or initialized. Adding the implicit gl_Position also marked
the existing gl_Position as active, duplicating the output variable.

Fix is that when checking for the need to add an implicit gl_Position
output, also check if the var is already defined in the shader,
and just needs to be marked as active.
Add test shader.