Fixes #140362
This is an attempt to reland https://github.com/llvm/llvm-project/pull/159104 with the fix for https://github.com/llvm/llvm-project/issues/160197. The original patch had the following problem: when an abstract subprogram DIE is constructed from within `DwarfDebug::endFunctionImpl()`, `DwarfDebug::constructAbstractSubprogramScopeDIE()` acknowledges `unit:` field of DISubprogram. But an abstract subprogram DIE constructed from `DwarfDebug::beginModule()` was put in the same compile unit to which global variable referencing the subprogram belonged, regardless of subprogram's `unit:`. This is fixed by adding `DwarfDebug::getOrCreateAbstractSubprogramCU()` used by both`DwarfDebug:: constructAbstractSubprogramScopeDIE()` and `DwarfCompileUnit::getOrCreateSubprogramDIE()` when abstract subprogram is queried during the creation of DIEs for globals in `DwarfDebug::beginModule()`. The fix and the already-reviewed code from https://github.com/llvm/llvm-project/pull/159104 are two separate commits in this PR. ===== The original commit message follows: With this change, construction of abstract subprogram DIEs is split in two stages/functions: creation of DIE (in DwarfCompileUnit::getOrCreateAbstractSubprogramDIE) and its population with children (in DwarfCompileUnit::constructAbstractSubprogramScopeDIE). With that, abstract subprograms can be created/referenced from DwarfDebug::beginModule, which should solve the issue with static local variables DIE creation of inlined functons with optimized-out definitions. It fixes https://github.com/llvm/llvm-project/issues/29985. LexicalScopes class now stores mapping from DISubprograms to their corresponding llvm::Function's. It is supposed to be built before processing of each function (so, now LexicalScopes class has a method for "module initialization" alongside the method for "function initialization"). It is used by DwarfCompileUnit to determine whether a DISubprogram needs an abstract DIE before DwarfDebug::beginFunction is invoked. DwarfCompileUnit::getOrCreateSubprogramDIE method is added, which can create an abstract or a concrete DIE for a subprogram. It accepts llvm::Function* argument to determine whether a concrete DIE must be created. This is a temporary fix for https://github.com/llvm/llvm-project/issues/29985. Ideally, it will be fixed by moving global variables and types emission to DwarfDebug::endModule (https://reviews.llvm.org/D144007, https://reviews.llvm.org/D144005). Some code proposed by Ellis Hoag <ellis.sparky.hoag@gmail.com> in https://github.com/llvm/llvm-project/pull/90523 was taken for this commit.
Reverts llvm/llvm-project#159104 due to the issues reported in https://github.com/llvm/llvm-project/issues/160197.
With this change, construction of abstract subprogram DIEs is split in two stages/functions: creation of DIE (in DwarfCompileUnit::getOrCreateAbstractSubprogramDIE) and its population with children (in DwarfCompileUnit::constructAbstractSubprogramScopeDIE). With that, abstract subprograms can be created/referenced from DwarfDebug::beginModule, which should solve the issue with static local variables DIE creation of inlined functons with optimized-out definitions. It fixes https://github.com/llvm/llvm-project/issues/29985. LexicalScopes class now stores mapping from DISubprograms to their corresponding llvm::Function's. It is supposed to be built before processing of each function (so, now LexicalScopes class has a method for "module initialization" alongside the method for "function initialization"). It is used by DwarfCompileUnit to determine whether a DISubprogram needs an abstract DIE before DwarfDebug::beginFunction is invoked. DwarfCompileUnit::getOrCreateSubprogramDIE method is added, which can create an abstract or a concrete DIE for a subprogram. It accepts llvm::Function* argument to determine whether a concrete DIE must be created. This is a temporary fix for https://github.com/llvm/llvm-project/issues/29985. Ideally, it will be fixed by moving global variables and types emission to DwarfDebug::endModule (https://reviews.llvm.org/D144007, https://reviews.llvm.org/D144005). Some code proposed by Ellis Hoag <ellis.sparky.hoag@gmail.com> in https://github.com/llvm/llvm-project/pull/90523 was taken for this commit.
An Ada program can have types that are subranges of other types. This
patch adds a new DIType node, DISubrangeType, to represent this concept.
I considered extending the existing DISubrange to do this, but as
DISubrange does not derive from DIType, that approach seemed more
disruptive.
A DISubrangeType can be used both as an ordinary type, but also as the
type of an array index. This is also important for Ada.
Ada subrange types can also be stored using a bias. Representing this in
the DWARF required the use of an extension. GCC has been emitting this
extension for years, so I've reused it here.
This avoids another unserializable field. Move the DbgInfoAvailable field into the AsmPrinter, which is only really a cache/convenience bit for checking a direct IR module metadata check.
I assume getSubprogram will do the correct thing in hasDebugInfo, and this is redundant with the debug_compile_units distance check. This is in preparation for removing the field.
Currently, an AsmPrinterHandler has several methods that allow to
dynamically hook in unwind or debug info emission, e.g. at begin/end of
every function or instruction. The class hierarchy and the actually
overridden functions are as follows:
(SymSz=setSymbolSize, mFE=markFunctionEnd, BBS=BasicBlockSection,
FL=Funclet; b=beginX, e=endX)
SymSz Mod Fn mFE BBS FL Inst
AsmPrinterHandler - - - - - - -
` PseudoProbeHandler - - - - - - -
` WinCFGuard - e e - - - -
` EHStreamer - - - - - - -
` DwarfCFIException - e be - be - -
` ARMException - - be e - - -
` AIXException - - e - - - -
` WinException - e be e - be -
` WasmException - e be - - - -
` DebugHandlerBase - b be - be - be
` BTFDebug - e - - - - b
` CodeViewDebug - be - - - - b
` DWARFDebug yes be - - - - b
Doing virtual function calls per instruction is costly and useless when
the called function does nothing.
This commit performs the following clean-up/improvements:
- PseudoProbeHandler is no longer an AsmPrinterHandler -- it used
nothing of its functionality to hook in at the possible points. This
avoids virtual function calls when a pseudo probe printer is present.
- DebugHandlerBase is no longer an AsmPrinterHandler, but a separate
base class. DebugHandlerBase is the only remaining "hook" for begin/end
instruction and setSymbolSize (only used by DWARFDebug). begin/end for
function and basic block sections are never overriden and therefore are
no longer virtual. (Originally I intended there to be only one debug
handler, but BPF as the only target supports two at the same time: DWARF
and BTF.)
- AsmPrinterHandler no longer has begin/end instruction and
setSymbolSize hooks -- these were only used by DebugHandlerBase. This
avoid iterating over handlers in every instruction.
AsmPrinterHandler Mod Fn mFE BBS FL
` WinCFGuard e e - - -
` EHStreamer - - - - -
` DwarfCFIException e be - be -
` ARMException - be e - -
` AIXException - e - - -
` WinException e be e - be
` WasmException e be - - -
SymSz Mod Fn BBS Inst
DebugHandlerBase - b be be be
` BTFDebug - e b
` CodeViewDebug - be b
` DWARFDebug yes be b
PseudoProbeHandler (no shared methods)
To continue allowing external users (e.g., Julia) to hook in at every
instruction, a new method addDebugHandler is exposed.
This results in a performance improvement, especially in the -O0 -g0
case with unwind information (e.g., JIT baseline).
Replace it with a forward declaration instead. Analysis.h is pulled in by all passes, but not all passes need to access the module.