Alexandre Oliva <[EMAIL PROTECTED]> writes: > On Nov 7, 2007, Ian Lance Taylor <[EMAIL PROTECTED]> wrote: > > >> Does it really matter? Do we compromise standards compliance (and so > >> violently, while at that) in any aspect of the compiler? > > > What standards are you talking about? > > Debug information standards such as DWARF-3.
... > Incorrectness in the compiler output is always a bug. No matter how > hard it is to implement, or how resource-intensive the solution is, > arguing that we've made a trade-off and decided to generate wrong > output for this case is a clever decision. I'm sorry, I've thought about it, but I don't buy this argument. I'm certainly willing to talk about improving debug information for optimized code, and clearly it is more important to more people than I initially thought. However, I don't think your arguments that this is an issue comparable to code correctness are valid. Incorrect generated code is a fatal problem in a compiler. Incorrect debugging information is a quality of implementation issue. > >> > We've fixed many many bugs and misoptimizations over the years due to > >> > NOTEs. I'm concerned that adding DEBUG_INSN in RTL repeats a mistake > >> > we've made in the past. > >> > >> That's a valid concern. However, per this reasoning, we might as well > >> push every operand in our IL to separate representations, because > >> there have been so many bugs and misoptimizations over the years, > >> especially when the representation didn't make transformations > >> trivially correct. > > > Please don't use strawman arguments. > > It's not, really. A reference to an object within a debug stmt or > insn is very much like any other operand, in that most optimizer > passes must keep them up to date. If you argue for pushing them > outside the IL, why would any other operands be different? I think you misread me. I didn't argue for pushing debugging information outside the IL. I argued against a specific implementation--DEBUG_INSN--based on our experience with similar implementations. Ian
