Compiling a Sascha Willems shader with dxc then passing through spirv-opt legalization gives:

Assertion failed: GetDebugFunction(dbg_inst->GetSingleWordOperand( kDebugFunctionOperandFunctionIndex)) == nullptr && "Two DebugFunction instruction exists for a single OpFunction.", file C:\Users\Greg\valve5\spirv-tools\source\opt\debug_info_manager.cpp, line 571

The dxc compile was:

dxc.exe -spirv -E main -T ps_6_1 -fspv-target-env=vulkan1.2 -fcgl -fspv-debug=rich -Vd -Fo genbrdflut.frag.rdbg.Od.spv genbrdflut.frag

The spirv-opt command is:

spirv-opt.exe --skip-validation --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 --eliminate-local-single-block --eliminate-local-single-store --eliminate-dead-code-aggressive --eliminate-local-multi-store --eliminate-dead-code-aggressive --ccp --loop-unroll --eliminate-dead-branches --simplify-instructions --eliminate-dead-code-aggressive --copy-propagate-arrays --vector-dce --eliminate-dead-inserts --reduce-load-size --eliminate-dead-code-aggressive -o genbrdflut.frag.rdbg.lgl.spv genbrdflut.frag.rdbg.Od.spv

FWIW, I have discovered that the inlining is pass is introducing invalid code. Here is the spirv-opt command:

spirv-opt.exe --wrap-opkill --eliminate-dead-branches --merge-return --inline-entry-points-exhaustive -o genbrdflut.frag.rdbg.inl.spv genbrdflut.frag.rdbg.Od.spv

Here is the spirv-val command:

spirv-val.exe genbrdflut.frag.rdbg.inl.spv
error: line 390: Invalid instruction word count: 0

I am also seeing this with the Sascha Willems shader pbrtexture.frag. These are the only two I have looked at so far.

@jaebaek I am assigning this to myself.