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Hash : 853dc1ab
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Date : 2014-11-06T17:25:48
Add mediump and lowp precision emulation support for GLSL output This implements the rounding as specified in WEBGL_debug_shader_precision extension proposal for desktop GLSL and ESSL output. The bulk of the new functionality is added in the form of a new EmulatePrecision AST traverser, which inserts calls to the rounding routines angle_frm and angle_frl in the appropriate places, and writes the rounding routines themselves to the shader. Compound assignments which are subject to emulation are transformed from "x op= y" to "angle_compound_op_frm(x, y)", a call to a function which does the appropriate rounding and places the result of the operation to x. The angle_ prefixed names should not clash with user-defined names if name hashing is on. If name hashing is not on, the precision emulation can only be used if the angle_ prefix is reserved for use by ANGLE. To support the rounding routines in output, a new operator type is added for internal helper function calls, which are not subject to name hashing. In ESSL output, all variables are forced to highp when precision emulation is on to ensure consistency with how precision emulation performs on desktop. Comprehensive tests for the added code generation are included. BUG=angle:787 Change-Id: I0d0ad9327888f803a32e79b64b08763c654c913b Reviewed-on: https://chromium-review.googlesource.com/229631 Reviewed-by: Jamie Madill <jmadill@chromium.org> Tested-by: Olli Etuaho <oetuaho@nvidia.com>
