search for: dw_op_over

Currently, two patches undergoing review wish to add a new operator for LLVM's DIExpression: D70642[0], and D82363[1]. Though both of these cases use the same name, the operators have different meanings: in the former, it has the form `DW_OP_LLVM_argN` where N is in [0-7], and represents the Nth argument of the containing intrinsic; its purpose is to enable the intrinsic @llvm.dbg.derefval,

> To summarize my understanding: Neither of these operators is strictly necessary, since the same effect can be achieved by implicitly pushing all operands of a DBG_VALUE to the stack, followed by a combination of DW_OP_dup, DW_OP_pick, DW_OP_swap, DW_OP_rot, and DW_OP_over. However, the resulting expressions can get very long and unwieldy and it is easier to generate efficient DWARF from DIExpressions that explicitly refer to arguments. DW_OP_LLVM_argN has the advantage of using less memory, at the cost of limiting the number of arguments to a hardcoded value. I'...

...om> wrote: > > > >> To summarize my understanding: Neither of these operators is strictly necessary, since the same effect can be achieved by implicitly pushing all operands of a DBG_VALUE to the stack, followed by a combination of DW_OP_dup, DW_OP_pick, DW_OP_swap, DW_OP_rot, and DW_OP_over. However, the resulting expressions can get very long and unwieldy and it is easier to generate efficient DWARF from DIExpressions that explicitly refer to arguments. DW_OP_LLVM_argN has the advantage of using less memory, at the cost of limiting the number of arguments to a hardcoded value. > &...

...t; >>> > >>>> To summarize my understanding: Neither of these operators is strictly necessary, since the same effect can be achieved by implicitly pushing all operands of a DBG_VALUE to the stack, followed by a combination of DW_OP_dup, DW_OP_pick, DW_OP_swap, DW_OP_rot, and DW_OP_over. However, the resulting expressions can get very long and unwieldy and it is easier to generate efficient DWARF from DIExpressions that explicitly refer to arguments. DW_OP_LLVM_argN has the advantage of using less memory, at the cost of limiting the number of arguments to a hardcoded value. > &...