Most ops use the common handling in emit_alu in order to convert NIR sources to bifrost sources, but the "special" math op lowering handrolls the conversion (due to needing to reference the same source multiple times).
Unfortunately, that handrolled lowering did not consider that there might be a non-identity swizzle on the source. In this case we would reference the wrong component of the source and generate garbage.
Fixes all but two of the remaining failures on G31 in: dEQP-GLES2.functional.shaders.operator.exponential.highp
The following tests are still broken due to some other issue: dEQP-GLES2.functional.shaders.operator.exponential.exp2.highp_float_fragment dEQP-GLES2.functional.shaders.operator.exponential.exp2.highp_vec2_fragment
Signed-off-by: Chris Forbes firstname.lastname@example.org