<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">Not sure if this helps but: I didn’t think about the boost file you were trying to compile at first, but now that I see it involves the boost preprocessor stuff, I bet the issue involves code somewhere that is written like <div class=""><br class=""><div class="">`<font face="Menlo" class="">BOOST_PP_IF(condition, HUGEMACROEXPANSION_A, HUGEMACROEXPANSION_B)</font>`</div><div class=""><br class=""></div><div class="">which should instead be written</div><div class=""><br class=""></div><div class="">`<font face="Menlo" class="">BOOST_PP_CAT(HUGEMACROEXPANSION, BOOST_PP_IF(0, _A, _B))</font>`</div><div class=""><br class=""></div><div class="">The former results in two huge expansions, one of which is thrown away, whereas the latter only results in one expansion.</div><div class=""><br class=""></div><div class="">I recall writing reasonably small but complex boost pp code that would take like 15 minutes just to preprocess, and now that I think about it, it might have resulted in the "ran out of source locations" a few times, before I finally figured out to always write those conditionals the second way. </div><div class=""><br class=""></div><div class="">Not sure if that’s the issue, but it’s a place to look.</div><div class=""><br class=""></div><div class="">Dave</div><div class=""><br class=""><div><br class=""><blockquote type="cite" class=""><div class="">On Feb 3, 2021, at 3:10 PM, Keane, Erich <<a href="mailto:erich.keane@intel.com" class="">erich.keane@intel.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div class="WordSection1" style="page: WordSection1; caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;"><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">Thanks for the response Richard! I’m working with my QA team to get a better reproducer to see if we can figure out what is the root-cause. It DOES include a couple of other files so I’m not sure all of what is entailed.<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">>There are also some relatively cheap things we could do to expand our capacity: we could remove the 'is macro location' bit without much effort (though this would slow down the current places that check the flag), which would double our available source location capacity.<span class="Apple-converted-space"> </span><o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">This seems like a useful and cheap thing to do, if find this is a legitimate issue, I’ll see if I can put a patch together to do this one.<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">>And we could allow the division between local and imported locations to be determined dynamically rather than fixing a 50/50 split, which would in practice be likely to double the available capacity again. But those would only be useful if we're just a little over the limit; they wouldn't help if there's an asymptotic problem in our source location usage.<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">I don’t have a great idea on how to do this, or how we use this, but based on your description it seems worth-while. At least in non-module TUs I’d assume that the “imported-from-ast-file” is relatively rare. Also, I would think these imports happen ‘first’, right? So we could figure out the split as soon as we’re done with imports and optimize our space.<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="border-style: solid none none; border-top-width: 1pt; border-top-color: rgb(225, 225, 225); padding: 3pt 0in 0in;" class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><b class="">From:</b><span class="Apple-converted-space"> </span>Richard Smith <<a href="mailto:richard@metafoo.co.uk" class="">richard@metafoo.co.uk</a>><span class="Apple-converted-space"> </span><br class=""><b class="">Sent:</b><span class="Apple-converted-space"> </span>Wednesday, February 3, 2021 11:54 AM<br class=""><b class="">To:</b><span class="Apple-converted-space"> </span>Keane, Erich <<a href="mailto:erich.keane@intel.com" class="">erich.keane@intel.com</a>><br class=""><b class="">Cc:</b><span class="Apple-converted-space"> </span>David Rector <<a href="mailto:davrecthreads@gmail.com" class="">davrecthreads@gmail.com</a>>; clang developer list <<a href="mailto:cfe-dev@lists.llvm.org" class="">cfe-dev@lists.llvm.org</a>><br class=""><b class="">Subject:</b><span class="Apple-converted-space"> </span>Re: [cfe-dev] [RFC] Clang SourceLocation overflow<o:p class=""></o:p></div></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div class=""><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">On Tue, 2 Feb 2021 at 10:41, Keane, Erich via cfe-dev <<a href="mailto:cfe-dev@lists.llvm.org" style="color: blue; text-decoration: underline;" class="">cfe-dev@lists.llvm.org</a>> wrote:<o:p class=""></o:p></div></div><div class=""><blockquote style="border-style: none none none solid; border-left-width: 1pt; border-left-color: rgb(204, 204, 204); padding: 0in 0in 0in 6pt; margin-left: 4.8pt; margin-right: 0in;" class=""><div class=""><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">Presumably, yes, we could hit that limit, and that limit is closer than we’d think.<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">Based on my understanding though, we currently stores the ‘offset’ into the buffer. If we were to go with your plan, we’d reduce the ‘SourceLocation’ space significantly, since we’d only have 1 value taken up by “ALongFunctionName” instead of ~15? Or, at least, only 1 instead of 3 in ‘int’.<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">I presume that anything short of expanding the size of SourceLocation is going to be a temporary measure at best. <o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">One consideration: What do we think about making SourceLocation have an underlying type of ‘bitfield’ that is a smaller size than 64 bits? Then at least we could make SourceRange be a packed value? So make SourceLocation be 40 bits (obviously would still be 64 if stored directly), but at least we could pack 2 of them into 80 bits for any type that does some sort of bit-packing? <o:p class=""></o:p></div></div></div></blockquote><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div></div><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">I doubt this would help in practice -- most of the storage in AST nodes tends to be SourceLocations and pointers.<o:p class=""></o:p></div></div><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div></div><blockquote style="border-style: none none none solid; border-left-width: 1pt; border-left-color: rgb(204, 204, 204); padding: 0in 0in 0in 6pt; margin-left: 4.8pt; margin-right: 0in;" class=""><div class=""><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">Alternatively, what about making SourceRange (instead of 2 SourceLocation objects) be a SourceLocation + unsigned? It would make it a little smaller? Then we could do similar optimizations over time to the ASTNodes. That is, all of the TypeLoc types could just store things like open/close parens as offsets-from-the-original rather than SourceLocations, then calculate them when needed? I would assume anything that required re-calculation would be acceptable, since SourceLocations are seemingly quite rarely used (except for the few cases that Richard mentioned below).<o:p class=""></o:p></div></div></div></blockquote><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div></div><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">That doesn't seem likely to work: we can't assume the beginning and end of a source range are close together in source location space (they could be in different SLocEntrys, which could be a long way apart from each other).<o:p class=""></o:p></div></div><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div></div><blockquote style="border-style: none none none solid; border-left-width: 1pt; border-left-color: rgb(204, 204, 204); padding: 0in 0in 0in 6pt; margin-left: 4.8pt; margin-right: 0in;" class=""><div class=""><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">My preference is obviously to just make SourceLocation be uint64_t instead, but the impact on AST size is going to be significant. So I guess I’m hoping that Richard Smith can comment and help us figure out how much pain we are willing to go through for this?<o:p class=""></o:p></div></div></div></blockquote><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div></div><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">We could do that, and having a build-time selector for 32/64-bit SourceLocations seems like it might not impose a huge cost. But I think we should first try to gain some confidence that we're addressing the right problem -- running out of source locations seems likely to indicate that there's something more fundamental wrong with the compilation. Currently we reserve one bit for an 'is macro location' flag, and divide the remaining addressable 2GB into a 1GB local region and a 1GB imported-from-AST-file region. The resulting "1GB of preprocessed source (including all intermediate stages of macro expansion)" implementation limit does not seem especially restrictive to me, so the first thing I think we should find out is how we're actually hitting that limit in the boost example. We can currently handle huge compilations without hitting the limit, so if a single header file can hit it, that seems indicative of a bug that's not just caused by the limit being too low.<o:p class=""></o:p></div></div><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div></div><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">One possible cause would be that a large header is included a *lot* and doesn't have a proper include guard. If that's the case, that seems like a problem that we should get fixed in boost -- or in Clang if it's a bug in include guard detection -- because that will contribute to long compile times too. I expect there are other cases where source location address space gets wasted that we could drill down into.<o:p class=""></o:p></div></div><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div></div><div class=""><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">If we find the problem is our location tracking for macro expansions (eg, pushing a large volume of tokens through deeply nested macro expansions), we could probably find a way to turn that off; there may even be ways we can intelligently turn it off selectively in cases where we think the intermediary information is unlikely to be useful. We could also look into throwing away source location address space for macro expansions that ended up producing no tokens. But we need to understand the nature of the problem first.<o:p class=""></o:p></div></div></div><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div></div><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">There are also some relatively cheap things we could do to expand our capacity: we could remove the 'is macro location' bit without much effort (though this would slow down the current places that check the flag), which would double our available source location capacity. And we could allow the division between local and imported locations to be determined dynamically rather than fixing a 50/50 split, which would in practice be likely to double the available capacity again. But those would only be useful if we're just a little over the limit; they wouldn't help if there's an asymptotic problem in our source location usage.<o:p class=""></o:p></div></div><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div></div><blockquote style="border-style: none none none solid; border-left-width: 1pt; border-left-color: rgb(204, 204, 204); padding: 0in 0in 0in 6pt; margin-left: 4.8pt; margin-right: 0in;" class=""><div class=""><div class=""><div class=""><div style="border-style: solid none none; border-top-width: 1pt; border-top-color: rgb(225, 225, 225); padding: 3pt 0in 0in;" class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><b class="">From:</b><span class="Apple-converted-space"> </span>David Rector <<a href="mailto:davrecthreads@gmail.com" target="_blank" style="color: blue; text-decoration: underline;" class="">davrecthreads@gmail.com</a>><span class="Apple-converted-space"> </span><br class=""><b class="">Sent:</b><span class="Apple-converted-space"> </span>Tuesday, February 2, 2021 10:28 AM<br class=""><b class="">To:</b><span class="Apple-converted-space"> </span>Keane, Erich <<a href="mailto:erich.keane@intel.com" target="_blank" style="color: blue; text-decoration: underline;" class="">erich.keane@intel.com</a>><br class=""><b class="">Cc:</b><span class="Apple-converted-space"> </span>clang developer list <<a href="mailto:cfe-dev@lists.llvm.org" target="_blank" style="color: blue; text-decoration: underline;" class="">cfe-dev@lists.llvm.org</a>><br class=""><b class="">Subject:</b><span class="Apple-converted-space"> </span>Re: [cfe-dev] [RFC] Clang SourceLocation overflow<o:p class=""></o:p></div></div></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">An additional consideration: if the files/buffers are so large that each SourceLocation cannot fit in 30 bits, does that imply that so many SourceLocations will be generated that the indices to them won’t be able to fit in 30 bits? That may be the case now that I think of it, in which case the only solution really would be 64 bit SourceLocations, or something still more creative/costly.<o:p class=""></o:p></div><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div></div><div class=""><blockquote style="margin-top: 5pt; margin-bottom: 5pt;" class=""><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">On Feb 2, 2021, at 11:53 AM, Keane, Erich <<a href="mailto:erich.keane@intel.com" target="_blank" style="color: blue; text-decoration: underline;" class="">erich.keane@intel.com</a>> wrote:<o:p class=""></o:p></div></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div><div class=""><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">Huh, that is an interesting idea! The issue ends up being the callers of getOffset though, since it is a previate method.<o:p class=""></o:p></div></div><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div></div><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">That said, I wonder if the extra bit-use is just putting off the inevitable, and we should just use the vector in SourceManager for everything. My initial thought is that we could do away with the ‘IsMacro’ bit as well, and just encode that in the vector too. It makes isFileID and isMacroID require the SourceManager as well, but I wonder if that is OK?<o:p class=""></o:p></div></div><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div></div><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div></div><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div></div><div class=""><div style="border-style: solid none none; border-top-width: 1pt; border-top-color: rgb(225, 225, 225); padding: 3pt 0in 0in;" class=""><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><b class="">From:</b><span class="gmail-m6785580962079825663apple-converted-space"> </span>David Rector <<a href="mailto:davrecthreads@gmail.com" target="_blank" style="color: blue; text-decoration: underline;" class="">davrecthreads@gmail.com</a>><span class="gmail-m6785580962079825663apple-converted-space"> </span><br class=""><b class="">Sent:</b><span class="gmail-m6785580962079825663apple-converted-space"> </span>Tuesday, February 2, 2021 8:46 AM<br class=""><b class="">To:</b><span class="gmail-m6785580962079825663apple-converted-space"> </span>Keane, Erich <<a href="mailto:erich.keane@intel.com" target="_blank" style="color: blue; text-decoration: underline;" class="">erich.keane@intel.com</a>><br class=""><b class="">Cc:</b><span class="gmail-m6785580962079825663apple-converted-space"> </span>clang developer list <<a href="mailto:cfe-dev@lists.llvm.org" target="_blank" style="color: blue; text-decoration: underline;" class="">cfe-dev@lists.llvm.org</a>><br class=""><b class="">Subject:</b><span class="gmail-m6785580962079825663apple-converted-space"> </span>Re: [cfe-dev] [RFC] Clang SourceLocation overflow<o:p class=""></o:p></div></div></div></div><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div></div><div class=""><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">A possible solution not mentioned: reserve a bit in SourceLocation for "IsBigLoc". When IsBigLoc = true, the remaining 30 bits of the "ID" field is not an offset but an index into a vector of uintptr_ts in SourceManager, each holding 64-bit offset data.<o:p class=""></o:p></div></div></div><div class=""><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div></div></div><div class=""><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">Only a few changes to private methods and isolated details would be needed I think: e.g. method `unsigned SourceLocation::getOffset()` would become `uintptr_t SourceLocation::getOffset(const SourceManager &SM)`, and would dereference and return the larger data when IsBigLoc. And more generally `unsigned` types should be changed to `uintptr_t` everywhere 32-bit encodings are currently assumed (mostly in SourceManager).<o:p class=""></o:p></div></div></div><div class=""><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div></div></div><div class=""><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">This might be easier and less intrusive than allowing 64-bit SourceLocations depending on a build flag, if I understand that proposal correctly, since that would require templating virtually everything with the SourceLocation type.<o:p class=""></o:p></div></div></div><div class=""><div class=""><p class="MsoNormal" style="margin: 0in 0in 12pt; font-size: 11pt; font-family: Calibri, sans-serif;"><br class=""><br class=""><o:p class=""></o:p></p></div><blockquote style="margin-top: 5pt; margin-bottom: 5pt;" class=""><div class=""><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">On Feb 2, 2021, at 9:21 AM, Keane, Erich via cfe-dev <<a href="mailto:cfe-dev@lists.llvm.org" target="_blank" style="color: blue; text-decoration: underline;" class="">cfe-dev@lists.llvm.org</a>> wrote:<o:p class=""></o:p></div></div></div><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div></div><div class=""><div class=""><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">Original thread here:<span class="gmail-m6785580962079825663apple-converted-space"> </span><a href="https://lists.llvm.org/pipermail/cfe-dev/2019-October/063459.html" target="_blank" style="color: blue; text-decoration: underline;" class=""><span style="color: rgb(5, 99, 193);" class="">https://lists.llvm.org/pipermail/cfe-dev/2019-October/063459.html</span></a><o:p class=""></o:p></div></div></div><div class=""><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div></div></div><div class=""><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">I’m bringing this back up since we have a reproduction of this in Boost now. We haven’t finished analyzing what boost is doing, but simply doing an include of:<o:p class=""></o:p></div></div></div><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">#include <libs/vmd/test/test_doc_modifiers_return_type.cxx><o:p class=""></o:p></pre><div class=""><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div></div></div><div class=""><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">Now causes us to run out of source locations, hitting:<o:p class=""></o:p></div></div></div><div class=""><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div></div></div><div class=""><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">/llvm/clang/lib/Basic/SourceManager.cpp:680: clang::SourceLocation clang::SourceManager::createExpansionLocImpl(const clang::SrcMgr::ExpansionInfo &, unsigned int, int, unsigned int): Assertion `NextLocalOffset + TokLength + 1 > NextLocalOffset && NextLocalOffset + TokLength + 1 <= CurrentLoadedOffset && "Ran out of source locations!"' failed.<o:p class=""></o:p></div></div></div><div class=""><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div></div></div><div class=""><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div></div></div><div class=""><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">From the last discussion, it seems that increasing our source-location size isn’t really acceptable due to how much it is stored in the AST( Multiple times per node), and giving up on location isn’t viable either. Additionally, the source location/source manager layout is quite complex and I don’t quite understand it yet, so I don’t have a good way of suggesting an alternative.<o:p class=""></o:p></div></div></div><div class=""><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div></div></div><div class=""><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">SO, I’d like to re-start the discussion into this, we need to find a way to make our compiler able to support more source-locations, as I can’t imagine this is going to be the only time we run into this.<o:p class=""></o:p></div></div></div><div class=""><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div></div></div><div class=""><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">-Erihc<span class="gmail-m6785580962079825663apple-converted-space"> </span><o:p class=""></o:p></div></div></div><div class=""><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div></div></div><div class=""><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">>>>>>>>>>>>>>>>>>>>> <o:p class=""></o:p></div></div></div><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">Hi Matt.<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class=""> <o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">Thanks for the offer. Whenever you’re back and have a moment is fine by me, I don’t think we’re in a massive hurry.<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class=""> <o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">Thanks,<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">Christof<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class=""> <o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">From: Matt Asplund <<a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" target="_blank" style="color: blue; text-decoration: underline;" class=""><span style="color: rgb(5, 99, 193);" class="">mwasplund at gmail.com</span></a>><o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">Sent: 10 October 2019 14:09<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">To: Christof Douma <<a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" target="_blank" style="color: blue; text-decoration: underline;" class=""><span style="color: rgb(5, 99, 193);" class="">Christof.Douma at arm.com</span></a>><o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">Cc: Richard Smith <<a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" target="_blank" style="color: blue; text-decoration: underline;" class=""><span style="color: rgb(5, 99, 193);" class="">richard at metafoo.co.uk</span></a>>; Mikhail Maltsev <<a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" target="_blank" style="color: blue; text-decoration: underline;" class=""><span style="color: rgb(5, 99, 193);" class="">Mikhail.Maltsev at arm.com</span></a>>; Clang Dev <<a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" target="_blank" style="color: blue; text-decoration: underline;" class=""><span style="color: rgb(5, 99, 193);" class="">cfe-dev at lists.llvm.org</span></a>>; nd <<a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" target="_blank" style="color: blue; text-decoration: underline;" class=""><span style="color: rgb(5, 99, 193);" class="">nd at arm.com</span></a>><o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">Subject: Re: [cfe-dev] [RFC] Clang SourceLocation overflow<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class=""> <o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">Sure, I can share my changes. In general my changes are very localized to the code paths I was hitting oveflow issues and tried to keep as much as possible using 32bit encodings. Is there an ETA for when you will start investigating, I am out of town for the next week but if needed can get access to my desktop.<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class=""> <o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">-Matt<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class=""> <o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">On Thu, Oct 10, 2019, 2:13 AM Christof Douma <<a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" target="_blank" style="color: blue; text-decoration: underline;" class=""><span style="color: rgb(5, 99, 193);" class="">Christof.Douma at arm.com</span></a><mailto:<a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" target="_blank" style="color: blue; text-decoration: underline;" class=""><span style="color: rgb(5, 99, 193);" class="">Christof.Douma at arm.com</span></a>>> wrote:<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">Hi Richard.<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class=""> <o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">Thanks for the clarification, I certainly had not realized that location tracking was needed for correctness of clang. Decoupling this sounds like a painful processes, and the only thing we get is errors without any location information. Sounds like not a great trade-off. We’ll go experiment a bit with the size impact of using 64-bits and will attempt to take the route of a cmake configuration option.<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class=""> <o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">If there are people that have already done some experiments on the size impact of 64-bits location pointers, we’re welcome your insights. @Matt Asplund<mailto:<a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" target="_blank" style="color: blue; text-decoration: underline;" class=""><span style="color: rgb(5, 99, 193);" class="">mwasplund at gmail.com</span></a>> I believe you said that you’ve done some prototyping, is there something you can share?<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class=""> <o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">Thanks,<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">Christof<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class=""> <o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">From: Richard Smith <<a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" target="_blank" style="color: blue; text-decoration: underline;" class=""><span style="color: rgb(5, 99, 193);" class="">richard at metafoo.co.uk</span></a><mailto:<a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" target="_blank" style="color: blue; text-decoration: underline;" class=""><span style="color: rgb(5, 99, 193);" class="">richard at metafoo.co.uk</span></a>>><o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">Sent: 08 October 2019 19:53<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">To: Christof Douma <<a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" target="_blank" style="color: blue; text-decoration: underline;" class=""><span style="color: rgb(5, 99, 193);" class="">Christof.Douma at arm.com</span></a><mailto:<a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" target="_blank" style="color: blue; text-decoration: underline;" class=""><span style="color: rgb(5, 99, 193);" class="">Christof.Douma at arm.com</span></a>>><o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">Cc: Mikhail Maltsev <<a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" target="_blank" style="color: blue; text-decoration: underline;" class=""><span style="color: rgb(5, 99, 193);" class="">Mikhail.Maltsev at arm.com</span></a><mailto:<a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" target="_blank" style="color: blue; text-decoration: underline;" class=""><span style="color: rgb(5, 99, 193);" class="">Mikhail.Maltsev at arm.com</span></a>>>; Clang Dev <<a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" target="_blank" style="color: blue; text-decoration: underline;" class=""><span style="color: rgb(5, 99, 193);" class="">cfe-dev at lists.llvm.org</span></a><mailto:<a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" target="_blank" style="color: blue; text-decoration: underline;" class=""><span style="color: rgb(5, 99, 193);" class="">cfe-dev at lists.llvm.org</span></a>>>; nd <<a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" target="_blank" style="color: blue; text-decoration: underline;" class=""><span style="color: rgb(5, 99, 193);" class="">nd at arm.com</span></a><mailto:<a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" target="_blank" style="color: blue; text-decoration: underline;" class=""><span style="color: rgb(5, 99, 193);" class="">nd at arm.com</span></a>>><o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">Subject: Re: [cfe-dev] [RFC] Clang SourceLocation overflow<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class=""> <o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">On Tue, 8 Oct 2019, 10:42 Christof Douma via cfe-dev, <<a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" target="_blank" style="color: blue; text-decoration: underline;" class=""><span style="color: rgb(5, 99, 193);" class="">cfe-dev at lists.llvm.org</span></a><mailto:<a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" target="_blank" style="color: blue; text-decoration: underline;" class=""><span style="color: rgb(5, 99, 193);" class="">cfe-dev at lists.llvm.org</span></a>>> wrote:<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">Hi Richard, Paul and other.<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class=""> <o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">Thanks for the input so far. I wanted to point out that it’s not our code-base. Rather, we’re seeing more use of the LLVM technology in the automotive market and as usual we’re faced with existing code bases that are tried and tested with other toolchains (gcc or others) and when LLVM comes along things don’t always work directly.<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class=""> <o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">We’ve suggested better ways of structuring their code and your suggestions are certainly good input. However, legacy code is especially sticky in any market that has to handle ‘safety’ concerns, like automotive, aerospace and medical markets. Code changes are pretty expensive in those fields. So while I hope that over time we see more sensible coding structures, I don’t expect that to happen any time soon. In the mean time, we’re searching for a solution for this coding pattern that doesn’t play well with clang.<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class=""> <o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">Hope that gave some more background of where this question comes from.<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class=""> <o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">Do all options that were suggested by Mikhail really require fundamental restructuring of major parts of clang? This surprised me, I had expected that the option 2 to be possible without a complete overhaul. (2 is “Track until an overflow occurs after that make the lexer output the <invalid location> special value for all subsequent tokens.”)<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">Clang uses source locations as part of the semantic representation of the AST in some cases (simple example: some forms of initialization might use parens or not, with different semantics, and we distinguish between them based on whether we have paren locations; there are also some checks that look at which of two source locations came first when determining which warnings or errors to produce, and so on). Maybe we could go through and fix all of those, but that's still a very large task and it'd be hard to check we got them all.<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">Not nice user experience but maybe doable? I was hoping there was something slightly better that still works without a major restructuring (maybe something that at least gives a rough location or something that only gives the location of the error and not the include stack under an option or using some kind of heuristic to detect that things go haywire).<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class=""> <o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">As an alternative, I was curious if it would be possible and acceptable to make the switch between 32-bit and 64-bit location tracking a build-time/cmake decision? I’ve not done any estimation on the memory size growth, so maybe this is a dead end.<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">If someone is prepared to do the work to add and maintain this build mode, I think this might be a feasible option.<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">Thanks,<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">Christof<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class=""> <o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">From: cfe-dev <<a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" target="_blank" style="color: blue; text-decoration: underline;" class=""><span style="color: rgb(5, 99, 193);" class="">cfe-dev-bounces at lists.llvm.org</span></a><mailto:<a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" target="_blank" style="color: blue; text-decoration: underline;" class=""><span style="color: rgb(5, 99, 193);" class="">cfe-dev-bounces at lists.llvm.org</span></a>>> On Behalf Of Richard Smith via cfe-dev<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">Sent: 07 October 2019 20:36<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">To: Mikhail Maltsev <<a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" target="_blank" style="color: blue; text-decoration: underline;" class=""><span style="color: rgb(5, 99, 193);" class="">Mikhail.Maltsev at arm.com</span></a><mailto:<a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" target="_blank" style="color: blue; text-decoration: underline;" class=""><span style="color: rgb(5, 99, 193);" class="">Mikhail.Maltsev at arm.com</span></a>>><o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">Cc: nd <<a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" target="_blank" style="color: blue; text-decoration: underline;" class=""><span style="color: rgb(5, 99, 193);" class="">nd at arm.com</span></a><mailto:<a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" target="_blank" style="color: blue; text-decoration: underline;" class=""><span style="color: rgb(5, 99, 193);" class="">nd at arm.com</span></a>>>; <a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" target="_blank" style="color: blue; text-decoration: underline;" class=""><span style="color: rgb(5, 99, 193);" class="">cfe-dev at lists.llvm.org</span></a><mailto:<a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" target="_blank" style="color: blue; text-decoration: underline;" class=""><span style="color: rgb(5, 99, 193);" class="">cfe-dev at lists.llvm.org</span></a>><o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">Subject: Re: [cfe-dev] [RFC] Clang SourceLocation overflow<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class=""> <o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">On Wed, 2 Oct 2019 at 09:26, Mikhail Maltsev via cfe-dev <<a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" target="_blank" style="color: blue; text-decoration: underline;" class=""><span style="color: rgb(5, 99, 193);" class="">cfe-dev at lists.llvm.org</span></a><mailto:<a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" target="_blank" style="color: blue; text-decoration: underline;" class=""><span style="color: rgb(5, 99, 193);" class="">cfe-dev at lists.llvm.org</span></a>>> wrote:<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">Hi all,<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class=""> <o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">We are experiencing a problem with Clang SourceLocation overflow.<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">Currently source locations are 32-bit values, one bit is a flag, which gives<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">a source location space of 2^31 characters.<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class=""> <o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">When the Clang lexer processes an #include directive it reserves the total size<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">of the file being included in the source location space. An overflow can occur<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">if a large file (which does not have include guards by design) is included many<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">times into a single TU.<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class=""> <o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">The pattern of including a file multiple times is for example required by<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">the AUTOSAR standard [1], which is widely used in the automotive industry.<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">Specifically the pattern is described in the Specification of Memory Mapping [2]:<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class=""> <o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">Section 8.2.1, MEMMAP003:<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">"The start and stop symbols for section control are configured with section<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">identifiers defined in MemMap.h [...] For instance:<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class=""> <o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">#define EEP_START_SEC_VAR_16BIT<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">#include "MemMap.h"<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">static uint16 EepTimer;<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">static uint16 EepRemainingBytes;<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">#define EEP_STOP_SEC_VAR_16BIT<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">#include "MemMap.h""<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class=""> <o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">Section 8.2.2, MEMMAP005:<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">"The file MemMap.h shall provide a mechanism to select different code, variable<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">or constant sections by checking the definition of the module specific memory<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">allocation key words for starting a section [...]"<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class=""> <o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">In practice MemMap.h can reach several MBs and can be included several thousand<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">times causing an overflow in the source location space.<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class=""> <o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">The problem does not occur with GCC because it tracks line numbers rather than<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">file offsets. Column numbers are tracked separately and are optional. I.e., in<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">GCC a source location can be either a (line+column) tuple packed into 32 bits or<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">(when the line number exceeds a certain threshold) a 32-bit line number.<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class=""> <o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">We are looking for an acceptable way of resolving the problem and propose the<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">following approaches for discussion:<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">1. Use 64 bits for source location tracking.<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">2. Track until an overflow occurs after that make the lexer output<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class=""> the <invalid location> special value for all subsequent tokens.<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">3. Implement an approach similar to the one used by GCC and start tracking line<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class=""> numbers instead of file offsets after a certain threshold. Resort to (2)<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class=""> when even line numbers overflow.<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">4. (?) Detect the multiple inclusion pattern and track it differently (for now<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class=""> we don't have specific ideas on how to implement this)<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class=""> <o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">Is any of these approaches viable? What caveats should we expect? (we already<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">know about static_asserts guarding the sizes of certain class fields which start<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">failing in the first approach).<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class=""> <o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">Other suggestions are welcome.<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class=""> <o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">I don't think any of the above approaches are reasonable; they would all require fundamental restructuring of major parts of Clang, an efficiency or memory size hit for all other users of Clang, or some combination of those.<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class=""> <o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">Your code pattern seems unreasonable; including a multi-megabyte file thousands of times is not a good idea. Can you split out parts of MemMap.h into a separate header that is only included once, and keep only the parts that actually change on repeated inclusion in MemMap.h itself?<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">_______________________________________________<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">cfe-dev mailing list<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class=""><a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" target="_blank" style="color: blue; text-decoration: underline;" class=""><span style="color: rgb(5, 99, 193);" class="">cfe-dev at lists.llvm.org</span></a><mailto:<a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" target="_blank" style="color: blue; text-decoration: underline;" class=""><span style="color: rgb(5, 99, 193);" class="">cfe-dev at lists.llvm.org</span></a>><o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class=""><a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" target="_blank" style="color: blue; text-decoration: underline;" class=""><span style="color: rgb(5, 99, 193);" class="">https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev</span></a><o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">-------------- next part --------------<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">An HTML attachment was scrubbed...<o:p class=""></o:p></pre><pre style="margin: 0in 0in 0.0001pt; font-size: 10pt; font-family: "Courier New";" class="">URL: <<a href="http://lists.llvm.org/pipermail/cfe-dev/attachments/20191010/bc5ff8cd/attachment.html" target="_blank" style="color: blue; text-decoration: underline;" class=""><span style="color: rgb(5, 99, 193);" class="">http://lists.llvm.org/pipermail/cfe-dev/attachments/20191010/bc5ff8cd/attachment.html</span></a>><o:p class=""></o:p></pre><div class=""><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div></div></div><div class=""><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span style="font-size: 9pt; font-family: Helvetica, sans-serif;" class="">_______________________________________________<br class="">cfe-dev mailing list<br class=""></span><a href="mailto:cfe-dev@lists.llvm.org" target="_blank" style="color: blue; text-decoration: underline;" class=""><span style="font-size: 9pt; font-family: Helvetica, sans-serif; color: rgb(5, 99, 193);" class="">cfe-dev@lists.llvm.org</span></a><span style="font-size: 9pt; font-family: Helvetica, sans-serif;" class=""><br class=""></span><a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" target="_blank" style="color: blue; text-decoration: underline;" class=""><span style="font-size: 9pt; font-family: Helvetica, sans-serif; color: rgb(5, 99, 193);" class="">https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev</span></a><o:p class=""></o:p></div></div></div></blockquote></div></div></blockquote></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> <o:p class=""></o:p></div></div></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">_______________________________________________<br class="">cfe-dev mailing list<br class=""><a href="mailto:cfe-dev@lists.llvm.org" target="_blank" style="color: blue; text-decoration: underline;" class="">cfe-dev@lists.llvm.org</a><br class=""><a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" target="_blank" style="color: blue; text-decoration: underline;" class="">https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev</a></div></blockquote></div></div></div></div></blockquote></div><br class=""></div></div></body></html>