[all-commits] [llvm/llvm-project] ffe872: Reduce dependencies on llvm/BinaryFormat/Dwarf.h

[serge-sans-paille via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: ffe8720aa060d66297500f30bb8ad02114e40326
      https://github.com/llvm/llvm-project/commit/ffe8720aa060d66297500f30bb8ad02114e40326
  Author: serge-sans-paille <sguelton at redhat.com>
  Date:   2022-02-04 (Fri, 04 Feb 2022)

  Changed paths:
    M clang/tools/clang-linker-wrapper/OffloadWrapper.cpp
    M llvm/include/llvm/IR/DIBuilder.h
    M llvm/include/llvm/IR/DebugInfoMetadata.h
    M llvm/include/llvm/IR/IRBuilder.h
    M llvm/lib/Analysis/ModuleDebugInfoPrinter.cpp
    M llvm/lib/Bitcode/Reader/MetadataLoader.cpp
    M llvm/lib/CodeGen/LiveDebugVariables.cpp
    M llvm/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
    M llvm/lib/CodeGen/TargetInstrInfo.cpp
    M llvm/lib/CodeGen/TargetRegisterInfo.cpp
    M llvm/lib/IR/AutoUpgrade.cpp
    M llvm/lib/IR/DebugInfoMetadata.cpp
    M llvm/lib/IR/IRBuilder.cpp
    M llvm/lib/Target/AArch64/AArch64RegisterInfo.cpp
    M llvm/lib/Target/AArch64/GISel/AArch64InstructionSelector.cpp
    M llvm/lib/Target/AMDGPU/AMDGPUPrintfRuntimeBinding.cpp
    M llvm/lib/Target/BPF/BPFAbstractMemberAccess.cpp
    M llvm/lib/Target/BPF/BPFPreserveDIType.cpp
    M llvm/lib/Target/RISCV/RISCVRegisterInfo.cpp
    M llvm/lib/Transforms/Coroutines/CoroSplit.cpp
    M llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
    M llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp
    M llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
    M llvm/unittests/IR/DebugTypeODRUniquingTest.cpp
    M mlir/lib/Target/LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.cpp

  Log Message:
  -----------
  Reduce dependencies on llvm/BinaryFormat/Dwarf.h

This header is very large (3M Lines once expended) and was included in location
where dwarf-specific information were not needed.

More specifically, this commit suppresses the dependencies on
llvm/BinaryFormat/Dwarf.h in two headers: llvm/IR/IRBuilder.h and
llvm/IR/DebugInfoMetadata.h. As these headers (esp. the former) are widely used,
this has a decent impact on number of preprocessed lines generated during
compilation of LLVM, as showcased below.

This is achieved by moving some definitions back to the .cpp file, no
performance impact implied[0].

As a consequence of that patch, downstream user may need to manually some extra
files:

llvm/IR/IRBuilder.h no longer includes llvm/BinaryFormat/Dwarf.h
llvm/IR/DebugInfoMetadata.h no longer includes llvm/BinaryFormat/Dwarf.h

In some situations, codes maybe relying on the fact that
llvm/BinaryFormat/Dwarf.h was including llvm/ADT/Triple.h, this hidden
dependency now needs to be explicit.

$ clang++ -E  -Iinclude -I../llvm/include ../llvm/lib/Transforms/Scalar/*.cpp -std=c++14 -fno-rtti -fno-exceptions | wc -l
after:   10978519
before:  11245451

Related Discourse thread: https://llvm.discourse.group/t/include-what-you-use-include-cleanup
[0] https://llvm-compile-time-tracker.com/compare.php?from=fa7145dfbf94cb93b1c3e610582c495cb806569b&to=995d3e326ee1d9489145e20762c65465a9caeab4&stat=instructions

Differential Revision: https://reviews.llvm.org/D118781