tree 775811dab1fa0cf7a95fec1d7252a9da35b9a45b
parent d0a827a9f313954935e3d9edb0c063fd8625a22e
author Diego Novillo <dnovillo@google.com> 1638459628 -0500
committer GitHub <noreply@github.com> 1638459628 -0500
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Fix https://github.com/KhronosGroup/SPIRV-Tools/issues/4462 (#4651)

This prevents CCP from making constant -> constant transitions when
evaluating instruction values.  In this case, FClamp is evaluated twice.
On the first evaluation, if computes FClamp(0.5, 0.5, -1) which returns
-1.  On the second evaluation, it computes FClamp(0.5, 0.5, VARYING)
which returns 0.5.

Both fold() computations are correct given the semantics of FClamp() but
this causes a lateral transition in the constant lattice which was not
being considered VARYING by CCP.