[PATCH] D67263: [DwarfExpression] Disallow some rewrites to avoid undefined behavior

[Bjorn Pettersson via Phabricator via llvm-commits]

bjope marked an inline comment as done.
bjope added inline comments.


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Comment at: llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp:650
     SmallVector<uint64_t, 8> Ops;
-    Ops.push_back(dwarf::DW_OP_plus_uconst);
-    Ops.push_back(Offset);
+    DIExpression::appendOffset(Ops, Offset);
     // According to
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This fix was (the minimum) needed to make other lit tests pass. I.e not ending up with huge unsigned offsets in DW_OP_plus_uconst or DW_OP_plus resulting in changes in DWARF output.

So the "regressions" seen in the added dw_op_constu.mir test case are not supposed to happen in reality (as long as we use DW_OP_minus when having negative offsets).


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D67263/new/

https://reviews.llvm.org/D67263