OpenCL.DebugInfo.100 information preservation in spirv-opt legalization passes

[jaebaek]

This is an umbrella bug for OpenCL.DebugInfo.100 information preservation in spirv-opt legalization passes. #3367 and #3366 are parts of the debug information preservation.

• wrap-opkill
• eliminate-dead-branches
• merge-return
• inline-entry-points-exhaustive
• eliminate-dead-functions
• private-to-local
• fix-storage-class
• eliminate-local-single-block
• eliminate-local-single-store
• eliminate-dead-code-aggressive
• scalar-replacement=0
• ssa-rewrite
• ccp
• loop-unroll
• simplify-instructions
• copy-propagate-arrays
• vector-dce
• eliminate-dead-inserts
• reduce-load-size

[jaebaek]

• infrastructure for OpenCL.DebugInfo.100 instructions: Add debug information analysis #3305 Add data structures for DebugScope, DebugNoScope, DebugDeclare, DebugValue #3183
• function inlining: [spirv-opt] refactor inlining pass #3328 Preserve debug info in inline pass #3349
• dead-function-elimination: Preserve debug info in eliminate-dead-functions #3251
• wrap-opkill: Preserve debug info for wrap-opkill #3331

[jaebaek]

Related spirv-val PRs: #3133 #3104 #3374

We have to add the validation for more OpenCL.DebugInfo.100 instructions: #3369

[jaebaek]

ssa-rewrite is WIP: #3356

[greg-lunarg]

I will start with eliminate-local-single-block and eliminate-local-single-store.

[jaebaek]

I just sent a PR for merge return pass: #3389

[jaebaek]

I created this kanban to easily check the progress: https://github.com/KhronosGroup/SPIRV-Tools/projects/6

[jaebaek]

For the fix-storage-class pass, we do not have to update the code for the debug information because it does not have any impact on the debug information.

[jaebaek]

The debug info preservation in the spirv-opt legalization passes is done \o/