Support emitting debuginfo w.r.t. LLVM IR #56792
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This change adds two new environmental variables:
JULIA_DUMP_IR
- when provided, this is a path that all emitted LLVM IR (post-optimization, just before machine code generation) will be saved toJULIA_DEBUGINFO
- when set to "LLVM-IR" this will run an additional pass on any emitted functions to rewrite their debuginfo to refer to the LLVM source, rather than the Julia source it was generated fromThis allows
gdb
to open the dumped IR and means you can step through LLVM IR line-by-line, print SSA values, etc. which can be very useful for debugging segfaults, or issues in codegen:The
debugir
pass that rewrites the debuginfo is vendored from: https://github.com/vaivaswatha/debugir. For simplicity, this is just a copy of the one file that we need for the pass.