[PATCH] D105207: [debuginfo][lsr] SCEV-based salvaging for LoopStrengthReduction

[Bjorn Pettersson via Phabricator via llvm-commits]

bjope added inline comments.


================
Comment at: llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp:6024
+    // Emit a simpler form if only a single location is referenced.
+    if (Values.size() == 1 && Expr[0] == llvm::dwarf::DW_OP_LLVM_arg &&
+        Expr[1] == 0) {
----------------
Is this some kind of optimization on IR/MIR level?

Seems like this can result in DBG_VALUE with DW_OP_LLVM_arg in the DIExpression (i.e. neither having a DIArgList or using DBG_VALUE_LIST). But it also seem like that particular scenario doesn't seem to be handled by DwarfDebug. See https://github.com/llvm/llvm-project/issues/55097

Maybe such things should be expected by all passes? Or is this just a pseudo optimization introducing a special case that complicate logic in other passes?

Well, I haven't analysed things so closely so maybe this choice is needed for some other reason.


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  https://reviews.llvm.org/D105207/new/

https://reviews.llvm.org/D105207