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* [DebugInfo] Delete TypedDINodeRefFangrui Song2019-05-071-4/+4
| | | | | | | | | | | | | TypedDINodeRef<T> is a redundant wrapper of Metadata * that is actually a T *. Accordingly, change DI{Node,Scope,Type}Ref uses to DI{Node,Scope,Type} * or their const variants. This allows us to delete many resolve() calls that clutter the code. Reviewed By: rnk Differential Revision: https://reviews.llvm.org/D61369 llvm-svn: 360108
* [DebugInfo] DW_OP_deref_size in PrologEpilogInserter.Markus Lavin2019-04-301-0/+4
| | | | | | | | | | | | | | | | | | | | The PrologEpilogInserter need to insert a DW_OP_deref_size before prepending a memory location expression to an already implicit expression to avoid having the existing expression act on the memory address instead of the value behind it. The reason for using DW_OP_deref_size and not plain DW_OP_deref is that big-endian targets need to read the right size as simply truncating a larger read would yield the wrong result (LSB bytes are not at the lower address). This re-commit fixes issues reported in the first one. Namely deref was inserted under wrong conditions and additionally the deref_size argument was incorrectly encoded. Differential Revision: https://reviews.llvm.org/D59687 llvm-svn: 359535
* DebugInfo: Emit only declarations (not whole definitions) of non-unit user ↵David Blaikie2019-04-241-0/+16
| | | | | | | | | | | | | | | | | | | | defined types into type units While this doesn't come up in reasonable cases currently (the only user defined types not in type units are ones without linkage - which makes for near-ODR violations, because it'd be a type with linkage referencing a type without linkage - such a type can't be validly defined in more than one TU, so arguably it shouldn't be in a type unit to begin with - but it's a convenient way to demonstrate an issue that will become more revalent with homed modular debug info type definitions - which also don't need to be in type units but more legitimately so). Precursor to the Clang change to de-type-unit (by omitting the 'identifier') types homed due to strong linkage vtables. (making that change without this one would lead to major type duplication in type units) llvm-svn: 359122
* Reapply: "DebugInfo: Emit only one kind of accelerated access/name table""David Blaikie2019-04-231-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | Originally committed in r358931 Reverted in r358997 Seems this change made Apple accelerator tables miss names (because names started respecting the CU NameTableKind GNU & assuming that shouldn't produce accelerated names too), which is never correct (apple accelerator tables don't have separators or CU lists - if present, they must describe all names in all CUs). Original Description: Currently to opt in to debug_names in DWARFv5, the IR must contain 'nameTableKind: Default' which also enables debug_pubnames. Instead, only allow one of {debug_names, apple_names, debug_pubnames, debug_gnu_pubnames}. nameTableKind: Default gives debug_names in DWARFv5 and greater, debug_pubnames in v4 and earlier - and apple_names when tuning for lldb on MachO. nameTableKind: GNU always gives gnu_pubnames llvm-svn: 359026
* Revert "DebugInfo: Emit only one kind of accelerated access/name table"David Blaikie2019-04-231-3/+0
| | | | | | | | Regresses some apple_names situations - still investigating. This reverts commit r358931. llvm-svn: 358997
* Use llvm::stable_sortFangrui Song2019-04-231-13/+12
| | | | | | While touching the code, simplify if feasible. llvm-svn: 358996
* DebugInfo: Emit only one kind of accelerated access/name tableDavid Blaikie2019-04-221-0/+3
| | | | | | | | | | | | | | | Currently to opt in to debug_names in DWARFv5, the IR must contain 'nameTableKind: Default' which also enables debug_pubnames. Instead, only allow one of {debug_names, apple_names, debug_pubnames, debug_gnu_pubnames}. nameTableKind: Default gives debug_names in DWARFv5 and greater, debug_pubnames in v4 and earlier - and apple_names when tuning for lldb on MachO. nameTableKind: GNU always gives gnu_pubnames llvm-svn: 358931
* [DebugInfo] Improve handling of clobbered fragmentsDavid Stenberg2019-04-101-47/+83
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: Currently the DbgValueHistorymap only keeps track of clobbered registers for the last debug value that it has encountered. This could lead to preceding register-described debug values living on longer in the location lists than they should. See PR40283 for an example. This patch does not introduce tracking of multiple registers, but changes the DbgValueHistoryMap structure to allow for that in a follow-up patch. This patch is not NFC, as it at least fixes two bugs in DwarfDebug (both are covered in the new clobbered-fragments.mir test): * If a debug value was clobbered (its End pointer set), the value would still be added to OpenRanges, meaning that the succeeding location list entries could potentially contain stale values. * If a debug value was clobbered, and there were non-overlapping fragments that were still live after the clobbering, DwarfDebug would not create a location list entry starting directly after the clobbering instruction. This meant that the location list could have a gap until the next debug value for the variable was encountered. Before this patch, the history map was represented by <Begin, End> pairs, where a new pair was created for each new debug value. When dealing with partially overlapping register-described debug values, such as in the following example: DBG_VALUE $reg2, $noreg, !1, !DIExpression(DW_OP_LLVM_fragment, 32, 32) [...] DBG_VALUE $reg3, $noreg, !1, !DIExpression(DW_OP_LLVM_fragment, 64, 32) [...] $reg2 = insn1 [...] $reg3 = insn2 the history map would then contain the entries `[<DV1, insn1>, [<DV2, insn2>]`. This would leave it up to the users of the map to be aware of the relative order of the instructions, which e.g. could make DwarfDebug::buildLocationList() needlessly complex. Instead, this patch makes the history map structure monotonically increasing by dropping the End pointer, and replacing that with explicit clobbering entries in the vector. Each debug value has an "end index", which if set, points to the entry in the vector that ends the debug value. The ending entry can either be an overlapping debug value, or an instruction which clobbers the register that the debug value is described by. The ending entry's instruction can thus either be excluded or included in the debug value's range. If the end index is not set, the debug value that the entry introduces is valid until the end of the function. Changes to test cases: * DebugInfo/X86/pieces-3.ll: The range of the first DBG_VALUE, which describes that the fragment (0, 64) is located in RDI, was incorrectly ended by the clobbering of RAX, which the second (non-overlapping) DBG_VALUE was described by. With this patch we get a second entry that only describes RDI after that clobbering. * DebugInfo/ARM/partial-subreg.ll: This test seems to indiciate a bug in LiveDebugValues that is caused by it not being aware of fragments. I have added some comments in the test case about that. Also, before this patch DwarfDebug would incorrectly include a register-described debug value from a preceding block in a location list entry. Reviewers: aprantl, probinson, dblaikie, rnk, bjope Reviewed By: aprantl Subscribers: javed.absar, kristof.beyls, jdoerfert, llvm-commits Tags: #debug-info, #llvm Differential Revision: https://reviews.llvm.org/D59941 llvm-svn: 358072
* [DebugInfo] Rename DbgValueHistoryMap::{InstrRange -> Entry}, NFCDavid Stenberg2019-04-101-14/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | Summary: In an upcoming commit the history map will be changed so that it contains explicit entries for instructions that clobber preceding debug values, rather than Begin- End range pairs, so generalize the name to "Entry". Also, prefix the iterator variable names in buildLocationList() with "E". In an upcoming commit the entry will have query functions such as "isD(e)b(u)gValue", which could at a glance make one confuse it for iterations over MachineInstrs, so make the iterator names a bit more distinct to avoid that. Reviewers: aprantl Reviewed By: aprantl Subscribers: llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D59939 llvm-svn: 358060
* [DebugInfo] Make InstrRange into a class, NFCDavid Stenberg2019-04-101-5/+5
| | | | | | | | | | | | | | | | | | | | Summary: Replace use of std::pair by creating a class for the debug value instruction ranges instead. This is a preparatory refactoring for improving handling of clobbered fragments. In an upcoming commit the Begin pointer will become a PointerIntPair, so it will be cleaner to have a getter for that. Reviewers: aprantl Subscribers: llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D59938 llvm-svn: 358059
* [DebugInfo] Pass all values in DebugLocEntry's constructor, NFCDavid Stenberg2019-04-091-18/+5
| | | | | | | | | | | | | | | | | | | | Summary: With MergeValues() removed, amend DebugLocEntry's constructor so that it takes multiple values rather than a single, and keep non-fragment values in OpenRanges, as this allows some cleanup of the code in buildLocationList(). Reviewers: aprantl, dblaikie, loladiro Reviewed By: aprantl Subscribers: hiraditya, llvm-commits Tags: #debug-info, #llvm Differential Revision: https://reviews.llvm.org/D59303 llvm-svn: 357988
* [DebugInfo] Remove redundant DebugLocEntry::MergeValues() function, NFCDavid Stenberg2019-04-091-50/+4
| | | | | | | | | | | | | | | | | | | | | | | Summary: The MergeValues() function would try to merge two entries if they shared the same beginning label. Having the same beginning label means that the former entry's range would be empty; however, after D55919 we no longer create entries for empty ranges, so we can no longer land in a situation where that check in MergeValues would succeed. Instead, the "merging" is done by keeping the live values from the preceding empty ranges in OpenRanges, and adding them to the first non-empty range. Reviewers: aprantl, dblaikie, loladiro Reviewed By: aprantl Subscribers: llvm-commits Tags: #debug-info, #llvm Differential Revision: https://reviews.llvm.org/D59301 llvm-svn: 357974
* Revert "[llvm] Reapply "Prevent duplicate files in debug line header in ↵Ali Tamur2019-03-261-1/+0
| | | | | | | | | | | | | dwarf 5."" This reverts commit rL357020. The commit broke the test llvm/test/tools/llvm-objdump/embedded-source.test on some builds including clang-ppc64be-linux-multistage, clang-s390x-linux, clang-with-lto-ubuntu, clang-x64-windows-msvc, llvm-clang-lld-x86_64-scei-ps4-windows10pro-fast (and others). llvm-svn: 357026
* [llvm] Reapply "Prevent duplicate files in debug line header in dwarf 5."Ali Tamur2019-03-261-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Reapply rL356941 after regenerating the object file in the failing test llvm/test/tools/llvm-objdump/embedded-source.test from source. Original commit message: [llvm] Prevent duplicate files in debug line header in dwarf 5. Motivation: In previous dwarf versions, file name indexes started from 1, and the primary source file was not explicit. Dwarf 5 standard (6.2.4) prescribes the primary source file to be explicitly given an entry with an index number 0. The current implementation honors the specification by just duplicating the main source file, once with index number 0, and later maybe with another index number. While this is compliant with the letter of the standard, the duplication causes problems for consumers of this information such as lldb. (Some files are duplicated, where only some of them have a line table although all refer to the same file) With this change, dwarf 5 debug line section files always start from 0, and the zeroth entry is not duplicated whenever possible. This requires different handling of dwarf 4 and dwarf 5 during generation (e.g. when a function returns an index zero for a file name, it signals an error in dwarf 4, but not in dwarf 5) However, I think the minor complication is worth it, because it enables all consumers (lldb, gdb, dwarfdump, objdump, and so on) to treat all files in the file name list homogenously. Tags: #llvm, #debug-info Differential Revision: https://reviews.llvm.org/D59515 llvm-svn: 357018
* Revert "[llvm] Prevent duplicate files in debug line header in dwarf 5."Ali Tamur2019-03-251-1/+0
| | | | | | | | This reverts commit 312ab05887d0e2caa29aaf843cefe39379a98d36. My commit broke the build; I will revert and find out what happened. llvm-svn: 356951
* [llvm] Prevent duplicate files in debug line header in dwarf 5.Ali Tamur2019-03-251-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: Motivation: In previous dwarf versions, file name indexes started from 1, and the primary source file was not explicit. Dwarf 5 standard (6.2.4) prescribes the primary source file to be explicitly given an entry with an index number 0. The current implementation honors the specification by just duplicating the main source file, once with index number 0, and later maybe with another index number. While this is compliant with the letter of the standard, the duplication causes problems for consumers of this information such as lldb. (Some files are duplicated, where only some of them have a line table although all refer to the same file) With this change, dwarf 5 debug line section files always start from 0, and the zeroth entry is not duplicated whenever possible. This requires different handling of dwarf 4 and dwarf 5 during generation (e.g. when a function returns an index zero for a file name, it signals an error in dwarf 4, but not in dwarf 5) However, I think the minor complication is worth it, because it enables all consumers (lldb, gdb, dwarfdump, objdump, and so on) to treat all files in the file name list homogenously. Reviewers: dblaikie, probinson, aprantl, espindola Reviewed By: probinson Subscribers: emaste, jvesely, nhaehnle, aprantl, javed.absar, arichardson, hiraditya, MaskRay, rupprecht, jdoerfert, llvm-commits Tags: #llvm, #debug-info Differential Revision: https://reviews.llvm.org/D59515 llvm-svn: 356941
* [DwarfDebug] Skip entries to big for 16 bit size field in Dwarf < 5.Florian Hahn2019-03-191-1/+7
| | | | | | | | | | | | | | | | Nothing prevents entries from being bigger than the 16 bit size field in Dwarf < 5. For entries that are too big, just emit an empty entry instead of crashing. This fixes PR41038. Reviewers: probinson, aprantl, davide Reviewed By: probinson Differential Revision: https://reviews.llvm.org/D59518 llvm-svn: 356514
* [DebugInfo] Introduce DW_OP_LLVM_convertMarkus Lavin2019-03-191-12/+69
| | | | | | | | | | | | | | | | | | | | | Introduce a DW_OP_LLVM_convert Dwarf expression pseudo op that allows for a convenient way to perform type conversions on the Dwarf expression stack. As an additional bonus it paves the way for using other Dwarf v5 ops that need to reference a base_type. The new DW_OP_LLVM_convert is used from lib/Transforms/Utils/Local.cpp to perform sext/zext on debug values but mainly the patch is about preparing terrain for adding other Dwarf v5 ops that need to reference a base_type. For Dwarf v5 the op maps to DW_OP_convert and for earlier versions a complex shift & mask pattern is generated to emulate sext/zext. This is a recommit of r356442 with trivial fixes for the failing tests. Differential Revision: https://reviews.llvm.org/D56587 llvm-svn: 356451
* Revert "[DebugInfo] Introduce DW_OP_LLVM_convert"Markus Lavin2019-03-191-69/+12
| | | | | | | | | | | | | This reverts commit 1cf4b593a7ebd666fc6775f3bd38196e8e65fafe. Build bots found failing tests not detected locally. Failing Tests (3): LLVM :: DebugInfo/Generic/convert-debugloc.ll LLVM :: DebugInfo/Generic/convert-inlined.ll LLVM :: DebugInfo/Generic/convert-linked.ll llvm-svn: 356444
* [DebugInfo] Introduce DW_OP_LLVM_convertMarkus Lavin2019-03-191-12/+69
| | | | | | | | | | | | | | | | | | | Introduce a DW_OP_LLVM_convert Dwarf expression pseudo op that allows for a convenient way to perform type conversions on the Dwarf expression stack. As an additional bonus it paves the way for using other Dwarf v5 ops that need to reference a base_type. The new DW_OP_LLVM_convert is used from lib/Transforms/Utils/Local.cpp to perform sext/zext on debug values but mainly the patch is about preparing terrain for adding other Dwarf v5 ops that need to reference a base_type. For Dwarf v5 the op maps to DW_OP_convert and for earlier versions a complex shift & mask pattern is generated to emulate sext/zext. Differential Revision: https://reviews.llvm.org/D56587 llvm-svn: 356442
* DebugInfo: Split DWARF + gmlt + no-split-dwarf-inlining shouldn't emit ↵David Blaikie2019-02-121-2/+2
| | | | | | | | | | | | | | | anything to the .dwo file This configuration (due to r349207) was intended not to emit any DWO CU, but a degenerate CU was still being emitted - containing a header and a DW_TAG_compile_unit with no attributes. Under that situation, emit nothing to the .dwo file. (since this is a dynamic property of the input the .dwo file is still emitted, just with nothing in it (so a valid, but empty, ELF file) - if some other CU didn't satisfy this criteria, its DWO CU would still go there, etc) llvm-svn: 353771
* [DWARF v5] Fix DWARF emitter and consumer to produce/expect a uleb for a ↵Wolfgang Pieb2019-02-011-2/+4
| | | | | | | | | | location description's length. Reviewer: davide, JDevliegere Differential Revision: https://reviews.llvm.org/D57550 llvm-svn: 352889
* [TEST][COMMIT] - fix comment typo in AsmPrinter/DwarfDebug.cpp - NFCTom Weaver2019-01-251-1/+1
| | | | llvm-svn: 352214
* [DEBUG_INFO, NVPTX] Fix relocation info.Alexey Bataev2019-01-221-22/+45
| | | | | | | | | | | | Summary: Initial function labels must follow the debug location for the correct relocation info generation. Reviewers: tra, jlebar, echristo Subscribers: jholewinski, llvm-commits Differential Revision: https://reviews.llvm.org/D45784 llvm-svn: 351843
* Update the file headers across all of the LLVM projects in the monorepoChandler Carruth2019-01-191-4/+3
| | | | | | | | | | | | | | | | | to reflect the new license. We understand that people may be surprised that we're moving the header entirely to discuss the new license. We checked this carefully with the Foundation's lawyer and we believe this is the correct approach. Essentially, all code in the project is now made available by the LLVM project under our new license, so you will see that the license headers include that license only. Some of our contributors have contributed code under our old license, and accordingly, we have retained a copy of our old license notice in the top-level files in each project and repository. llvm-svn: 351636
* [AsmPrinter] Collapse .loc 0 0 directivesJonas Devlieghere2019-01-161-1/+1
| | | | | | | | | | | | | | | | Currently we do not always collapse subsequent .loc 0 0 directives. The reason is that we were checking for a PrevInstLoc which is not set when we emit a line-0 record. We should only check the LastAsmLine, which seems to be created exactly for this purpose. // When we emit a line-0 record, we don't update PrevInstLoc; so look at // the last line number actually emitted, to see if it was line 0. unsigned LastAsmLine = Asm->OutStreamer->getContext().getCurrentDwarfLoc().getLine(); Differential revision: https://reviews.llvm.org/D56767 llvm-svn: 351395
* Give helper classes/functions local linkage. NFC.Benjamin Kramer2019-01-121-2/+2
| | | | llvm-svn: 351016
* [DebugInfo] Omit location list entries with empty rangesDavid Stenberg2019-01-091-0/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: This fixes PR39710. In that case we emitted a location list looking like this: .Ldebug_loc0: .quad .Lfunc_begin0-.Lfunc_begin0 .quad .Lfunc_begin0-.Lfunc_begin0 .short 1 # Loc expr size .byte 85 # DW_OP_reg5 .quad .Lfunc_begin0-.Lfunc_begin0 .quad .Lfunc_end0-.Lfunc_begin0 .short 1 # Loc expr size .byte 85 # super-register DW_OP_reg5 .quad 0 .quad 0 As seen, the first entry's beginning and ending addresses evalute to 0, which meant that the entry inadvertently became an "end of list" entry, resulting in the location list ending sooner than expected. To fix this, omit all entries with empty ranges. Location list entries with empty ranges do not have any effect, as specified by DWARF, so we might as well drop them: "A location list entry (but not a base address selection or end of list entry) whose beginning and ending addresses are equal has no effect because the size of the range covered by such an entry is zero." Reviewers: davide, aprantl, dblaikie Reviewed By: aprantl Subscribers: javed.absar, JDevlieghere, llvm-commits Tags: #debug-info Differential Revision: https://reviews.llvm.org/D55919 llvm-svn: 350698
* DebugInfo: Fix for missing comp_dir handling with r349207David Blaikie2018-12-201-9/+10
| | | | | | | | | | | When deciding lazily whether a CU would be split or non-split I accidentally dropped some handling for the line tables comp_dir (by doing it lazily it was too late to be handled properly by the MC line table code). Move that bit of the code back to the non-lazy place. llvm-svn: 349819
* DebugInfo: Fix missing local imported entities after r349207David Blaikie2018-12-181-3/+3
| | | | | | Post commit review/bug reported by Pavel Labath - thanks! llvm-svn: 349528
* DebugInfo: Avoid using split DWARF when the split unit would be empty.David Blaikie2018-12-141-28/+37
| | | | | | | | | | | | | | | | | | | | | In ThinLTO many split CUs may be effectively empty because of the lack of support for cross-unit references in split DWARF. Using a split unit in those cases is just a waste/overhead - and turned out to be one contributor to a significant symbolizer performance issue when global variable debug info was being imported (see r348416 for the primary fix) due to symbolizers seeing CUs with no ranges, assuming there might still be addresses covered and walking into the split CU to see if there are any ranges (when that split CU was in a DWP file, that meant loading the DWP and its index, the index was extra large because of all these fractured/empty CUs... and so was very expensive to load). (the 3rd fix which will follow, is to assume that a CU with no ranges is empty rather than merely missing its CU level range data - and to not walk into its DIEs (split or otherwise) in search of address information that is generally not present) llvm-svn: 349207
* [AsmPrinter] Rename a comment of .debug_gnu_pubnames entryFangrui Song2018-11-131-2/+2
| | | | | | | | | | | | | | | | | | | | Summary: The comment refers to the field as "Kind:". However, in gdb, https://sourceware.org/gdb//onlinedocs/gdb/Index-Section-Format.html names it "attributes", gdb/dwarf2read.c:dw2_symtab_iter_next refers to the whole value as "cu_index_and_attrs" Change it to `Attributes:` for consistency. Reviewers: dblaikie Reviewed By: dblaikie Subscribers: aprantl, JDevlieghere, arphaman, llvm-commits Differential Revision: https://reviews.llvm.org/D54480 llvm-svn: 346790
* DebugInfo: Add a CU metadata attribute for use of DWARF ranges base address ↵David Blaikie2018-11-131-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | specifiers Summary: Ranges base address specifiers can save a lot of object size in relocation records especially in optimized builds. For an optimized self-host build of Clang with split DWARF and debug info compression in object files, but uncompressed debug info in the executable, this change produces about 18% smaller object files and 6% larger executable. While it would've been nice to turn this on by default, gold's 32 bit gdb-index support crashes on this input & I don't think there's any perfect heuristic to implement solely in LLVM that would suffice - so we'll need a flag one way or another (also possible people might want to aggressively optimized for executable size that contains debug info (even with compression this would still come at some cost to executable size)) - so let's plumb it through. Differential Revision: https://reviews.llvm.org/D54242 llvm-svn: 346788
* [DWARFv5] Emit split type units in .debug_info.dwo.Paul Robinson2018-11-121-4/+7
| | | | | | Differential Revision: https://reviews.llvm.org/D54350 llvm-svn: 346674
* [DWARFv5] Emit normal type units in .debug_info comdats.Paul Robinson2018-11-091-1/+6
| | | | | | Differential Revision: https://reviews.llvm.org/D54282 llvm-svn: 346540
* NFC: DebugInfo: Track the origin CU rather than just the base address for ↵David Blaikie2018-11-081-1/+2
| | | | | | | | | | range lists Turns out knowing more than just the base address might be useful - specifically a future change to respect a DICompileUnit flag for the use of base address specifiers in DWARF < 5. llvm-svn: 346380
* MachineModuleInfo: Initialize DbgInfoAvailable depending on debug_cus existingMatthias Braun2018-10-311-2/+5
| | | | | | | | | | | | | | | | Before this patch DbgInfoAvailable was set to true in DwarfDebug::beginModule() or CodeViewDebug::CodeViewDebug(). This made MIR testing weird since passes would suddenly stop dealing with debug info just because we stopped the pipeline before the debug printers. This patch changes the logic to initialize DbgInfoAvailable based on the fact that debug_compile_units exist in the llvm Module. The debug printers may then override it with false in case of debug printing being disabled. Differential Revision: https://reviews.llvm.org/D53885 llvm-svn: 345740
* [Codegen] - Implement basic .debug_loclists section emission (DWARF5).George Rimar2018-10-261-51/+133
| | | | | | | | | .debug_loclists is the DWARF 5 version of the .debug_loc. With that patch, it will be emitted when DWARF 5 is used. Differential revision: https://reviews.llvm.org/D53365 llvm-svn: 345377
* DebugInfo: Explain why DW_LLE_(GNU_)startx_length is usedDavid Blaikie2018-10-251-4/+7
| | | | | | | | | | This isn't the most object-size efficient encoding, but it's the only one GDB supports for the pre-standard fission format. I've written fixes for this twice now... - so perhaps this comment will help me remember why neither of these have been committed and why I shouldn't try to write a third fix another year from now... llvm-svn: 345326
* DebugInfo: Reuse common addresses for rnglist base address selectionsDavid Blaikie2018-10-241-0/+9
| | | | | | | | | | | | | | | | | | This makes the offsets larger (since they are further from the base address) but those are in the .dwo - and allows removing addresses and relocations from the .o file. This could be built into the AddressPool more fundamentally, perhaps - when you ask for an AddressPool entry you could say "or give me some other entry and an offset I need to use" - though what to do about situations where the first use of an address in a section is not the earliest address in that section... is tricky. At least with range addresses we can be fairly sure we've seen the earliest address first because we see the start address for the function. llvm-svn: 345224
* [DWARF] Use a function-local offset for AT_call_return_pcVedant Kumar2018-10-221-3/+4
| | | | | | | | | | | | | | | | | | | Logs provided by @stella.stamenova indicate that on Linux, lldb adds a spurious slide offset to the return PC it loads from AT_call_return_pc attributes (see the list thread: "[PATCH] D50478: Add support for artificial tail call frames"). This patch side-steps the issue by getting rid of the load address calculation in lldb's CallEdge::GetReturnPCAddress. The idea is to have the DWARF writer emit function-local offsets to the instruction after a call. I.e. return-pc = label-after-call-insn - function-entry. LLDB can simply add this offset to the base address of a function to get the return PC. Differential Revision: https://reviews.llvm.org/D53469 llvm-svn: 344960
* DebugInfo: Use base address specifiers more aggressivelyDavid Blaikie2018-10-201-1/+1
| | | | | | | | | | Using a base address specifier even for a single-element range is a size win for object files (7 words versus 8 words - more significant savings if the debug info is compressed (since it's 3 words of uncompressable reloc + 4 compressable words compared to 6 uncompressable reloc + 2 compressable words) - does trade off executable size increase though. llvm-svn: 344841
* DebugInfo: Implement debug_rnglists.dwoDavid Blaikie2018-10-201-0/+26
| | | | | | | Save space/relocations in .o files by keeping dwo ranges in the dwo file rather than the .o file. llvm-svn: 344837
* DebugInfo: Use address pool forms in debug_rnglistsDavid Blaikie2018-10-201-58/+51
| | | | | | Save no relocations by reusing addresses from the address pool. llvm-svn: 344836
* DebugInfo: Use debug_addr for non-dwo addresses in DWARF 5David Blaikie2018-10-201-7/+9
| | | | | | | | Putting addresses in the address pool, even with non-fission, can reduce relocations - reusing the addresses from debug_info and debug_rnglists (the latter coming soon) llvm-svn: 344834
* Revert BTF commit series.Eli Friedman2018-10-121-10/+0
| | | | | | | | | | The initial patch was not reviewed, and does not have any tests; it should not have been merged. This reverts 344395, 344390, 344387, 344385, 344381, 344376, and 344366. llvm-svn: 344405
* [BPF] Add BTF generation for BPF targetYonghong Song2018-10-121-0/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BTF is the debug format for BPF, a kernel virtual machine and widely used for tracing, networking and security, etc ([1]). Currently only instruction streams are passed to kernel, the kernel verifier verifies them before execution. In order to provide better visibility of bpf programs to user space tools, some debug information, e.g., function names and debug line information are desirable for kernel so tools can get such information with better annotation for jited instructions for performance or other reasons. The dwarf is too complicated in kernel and for BPF. Hence, BTF is designed to be the debug format for BPF ([2]). Right now, pahole supports BTF for types, which are generated based on dwarf sections in the ELF file. In order to annotate performance metrics for jited bpf insns, it is necessary to pass debug line info to the kernel. Furthermore, we want to pass the actual code to the kernel because of the following reasons: . bpf program typically is small so storage overhead should be small. . in bpf land, it is totally possible that an application loads the bpf program into the kernel and then that application quits, so holding debug info by the user space application is not practical. . having source codes directly kept by kernel would ease deployment since the original source code does not need ship on every hosts and kernel-devel package does not need to be deployed even if kernel headers are used. The only reliable time to get the source code is during compilation time. This will result in both more accurate information and easier deployment as stated in the above. Another consideration is for JIT. The project like bcc use MCJIT to compile a C program into bpf insns and load them to the kernel ([3]). The generated BTF sections will be readily available for such cases as well. This patch implemented generation of BTF info in llvm compiler. The BTF related sections will be generated when both -target bpf and -g are specified. Two sections are generated: .BTF contains all the type and string information, and .BTF.ext contains the func_info and line_info. The separation is related to how two sections are used differently in bpf loader, e.g., linux libbpf ([4]). The .BTF section can be loaded into the kernel directly while .BTF.ext needs loader manipulation before loading to the kernel. The format of the each section is roughly defined in llvm:include/llvm/MC/MCBTFContext.h and from the implementation in llvm:lib/MC/MCBTFContext.cpp. A later example also shows the contents in each section. The type and func_info are gathered during CodeGen/AsmPrinter by traversing dwarf debug_info. The line_info is gathered in MCObjectStreamer before writing to the object file. After all the information is gathered, the two sections are emitted in MCObjectStreamer::finishImpl. With cmake CMAKE_BUILD_TYPE=Debug, the compiler can dump out all the tables except insn offset, which will be resolved later as relocation records. The debug type "btf" is used for BTFContext dump. Dwarf tests the debug info generation with llvm-dwarfdump to decode the binary sections and check whether the result is expected. Currently we do not have such a tool yet. We will implement btf dump functionality in bpftool ([5]) as the bpftool is considered the recommended tool for bpf introspection. The implementation for type and func_info is tested with linux kernel test cases. The line_info is visually checked with dump from linux kernel libbpf ([4]) and checked with readelf dumping section raw data. Note that the .BTF and .BTF.ext information will not be emitted to assembly code and there is no assembler support for BTF either. In the below, with a clang/llvm built with CMAKE_BUILD_TYPE=Debug, Each table contents are shown for a simple C program. -bash-4.2$ cat -n test.c 1 struct A { 2 int a; 3 char b; 4 }; 5 6 int test(struct A *t) { 7 return t->a; 8 } -bash-4.2$ clang -O2 -target bpf -g -mllvm -debug-only=btf -c test.c Type Table: [1] FUNC name_off=1 info=0x0c000001 size/type=2 param_type=3 [2] INT name_off=12 info=0x01000000 size/type=4 desc=0x01000020 [3] PTR name_off=0 info=0x02000000 size/type=4 [4] STRUCT name_off=16 info=0x04000002 size/type=8 name_off=18 type=2 bit_offset=0 name_off=20 type=5 bit_offset=32 [5] INT name_off=22 info=0x01000000 size/type=1 desc=0x02000008 String Table: 0 : 1 : test 6 : .text 12 : int 16 : A 18 : a 20 : b 22 : char 27 : test.c 34 : int test(struct A *t) { 58 : return t->a; FuncInfo Table: sec_name_off=6 insn_offset=<Omitted> type_id=1 LineInfo Table: sec_name_off=6 insn_offset=<Omitted> file_name_off=27 line_off=34 line_num=6 column_num=0 insn_offset=<Omitted> file_name_off=27 line_off=58 line_num=7 column_num=3 -bash-4.2$ readelf -S test.o ...... [12] .BTF PROGBITS 0000000000000000 0000028d 00000000000000c1 0000000000000000 0 0 1 [13] .BTF.ext PROGBITS 0000000000000000 0000034e 0000000000000050 0000000000000000 0 0 1 [14] .rel.BTF.ext REL 0000000000000000 00000648 0000000000000030 0000000000000010 16 13 8 ...... -bash-4.2$ The latest linux kernel ([6]) can already support .BTF with type information. The [7] has the reference implementation in linux kernel side to support .BTF.ext func_info. The .BTF.ext line_info support is not implemented yet. If you have difficulty accessing [6], you can manually do the following to access the code: git clone https://github.com/yonghong-song/bpf-next-linux.git cd bpf-next-linux git checkout btf The change will push to linux kernel soon once this patch is landed. References: [1]. https://www.kernel.org/doc/Documentation/networking/filter.txt [2]. https://lwn.net/Articles/750695/ [3]. https://github.com/iovisor/bcc [4]. https://github.com/torvalds/linux/tree/master/tools/lib/bpf [5]. https://github.com/torvalds/linux/tree/master/tools/bpf/bpftool [6]. https://github.com/torvalds/linux [7]. https://github.com/yonghong-song/bpf-next-linux/tree/btf Signed-off-by: Song Liu <songliubraving@fb.com> Signed-off-by: Yonghong Song <yhs@fb.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Differential Revision: https://reviews.llvm.org/D52950 llvm-svn: 344366
* Revert "DwarfDebug: Pick next location in case of missing location at block ↵Matthias Braun2018-10-111-71/+41
| | | | | | | | | | | | | | | begin" It originally triggered a stepping problem in the debugger, which could be fixed by adjusting CodeGen/LexicalScopes.cpp however it seems we prefer the previous behavior anyway. See the discussion for details: http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20181008/593833.html This reverts commit r343880. This reverts commit r343874. llvm-svn: 344318
* [DebugInfo] Add support for DWARF5 call site-related attributesVedant Kumar2018-10-051-1/+67
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | DWARF v5 introduces DW_AT_call_all_calls, a subprogram attribute which indicates that all calls (both regular and tail) within the subprogram have call site entries. The information within these call site entries can be used by a debugger to populate backtraces with synthetic tail call frames. Tail calling frames go missing in backtraces because the frame of the caller is reused by the callee. Call site entries allow a debugger to reconstruct a sequence of (tail) calls which led from one function to another. This improves backtrace quality. There are limitations: tail recursion isn't handled, variables within synthetic frames may not survive to be inspected, etc. This approach is not novel, see: https://gcc.gnu.org/wiki/summit2010?action=AttachFile&do=get&target=jelinek.pdf This patch adds an IR-level flag (DIFlagAllCallsDescribed) which lowers to DW_AT_call_all_calls. It adds the minimal amount of DWARF generation support needed to emit standards-compliant call site entries. For easier deployment, when the debugger tuning is LLDB, the DWARF requirement is adjusted to v4. Testing: Apart from check-{llvm, clang}, I built a stage2 RelWithDebInfo clang binary. Its dSYM passed verification and grew by 1.4% compared to the baseline. 151,879 call site entries were added. rdar://42001377 Differential Revision: https://reviews.llvm.org/D49887 llvm-svn: 343883
* DwarfDebug: Pick next location in case of missing location at block beginMatthias Braun2018-10-051-41/+71
| | | | | | | | | | | | | | | | | Context: Compiler generated instructions do not have a debug location assigned to them. However emitting 0-line records for all of them bloats the line tables for very little benefit so we usually avoid doing that. Not emitting anything will lead to the previous debug location getting applied to the locationless instructions. This is not desirable for block begin and after labels. Previously we would emit simply emit line-0 records in this case, this patch changes the behavior to do a forward search for a debug location in these cases before emitting a line-0 record to further reduce line table bloat. Inspired by the discussion in https://reviews.llvm.org/D52862 llvm-svn: 343874
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