opt: invalid SPIR-V produced with --eliminate-dead-branches --merge-return. In OpPhi instruction, ID definition does not dominate its parent. (GraphicsFuzz ref: spirv-tools-use-not-dominated-from-swiftshader) #2702
Description
To reproduce:
spirv-opt --eliminate-dead-branches --merge-return shader_reduced_final.comp.spv -o temp.comp.spv
spirv-val temp.comp.spvspirv-tools-use-not-dominated-from-swiftshader.zip
Found by GraphicsFuzz.