================ @@ -6178,10 +6178,16 @@ The current supported opcode vocabulary is limited: the last entry from the second last entry and appends the result to the expression stack. - ``DW_OP_plus_uconst, 93`` adds ``93`` to the working expression. -- ``DW_OP_LLVM_fragment, 16, 8`` specifies the offset and size (``16`` and ``8`` - here, respectively) of the variable fragment from the working expression. Note - that contrary to DW_OP_bit_piece, the offset is describing the location - within the described source variable. +- ``DW_OP_LLVM_fragment, 16, 8`` specifies that the top of the expression stack + is a fragment of the source language variable with the given offset and size + (``16`` and ``8`` here, respectively). Note that the offset and size are the + opposite way around to ``DW_OP_bit_piece``, and the offset is within the + source language variable. +- ``DW_OP_bit_piece, 8, 16`` specifies that the source language variable can be + found in the sequence of bits at the given size and offset (``8`` and ``16`` + here, respectively) within the top of the expression stack. Note that the + offset and size are the opposite way around to ``DW_OP_LLVM_fragment``, and the + offset is within the LLVM variable (if that's at the top of the stack). ---------------- adrian-prantl wrote:
> DW_OP_bit_piece is like every other standard dwarf expression Not it's not. It's a composite location description delimiter and cannot appear inside a DWARF expression. (See DWARF 5 section 2.6.1.2). That's why it's important that all LLVM algorithms that need to reason about fragments (the LLVM equivalent of composite location descriptions) are aware of them. https://github.com/llvm/llvm-project/pull/85665 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
