[llvm] [Utils] Consolidate `LockstepReverseIterator` into own header (NFC) (PR #116657)

Fri Feb 21 12:58:28 PST 2025

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `ml-opt-devrel-x86-64` running on `ml-opt-devrel-x86-64-b1` while building `llvm` at step 5 "build-unified-tree".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/175/builds/13585

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 5 (build-unified-tree) failure: build (failure)
...
78.482 [1523/29/2285] Building CXX object lib/Target/AArch64/Utils/CMakeFiles/LLVMAArch64Utils.dir/AArch64BaseInfo.cpp.o
78.570 [1522/29/2286] Linking CXX static library lib/libLLVMAArch64Utils.a
78.688 [1521/29/2287] Linking CXX static library lib/libLLVMAArch64Desc.a
78.758 [1520/29/2288] Linking CXX static library lib/libLLVMAArch64Disassembler.a
78.807 [1520/28/2289] Building AMDGPUGenRegBankGICombiner.inc...
79.284 [1520/27/2290] Building AMDGPUGenCallingConv.inc...
79.627 [1520/26/2291] Building AMDGPUGenPreLegalizeGICombiner.inc...
79.769 [1520/25/2292] Building CXX object tools/obj2yaml/CMakeFiles/obj2yaml.dir/elf2yaml.cpp.o
80.143 [1519/25/2293] Building AMDGPUGenMCPseudoLowering.inc...
80.454 [1519/24/2294] Building CXX object lib/Transforms/Utils/CMakeFiles/LLVMTransformUtils.dir/SimplifyCFG.cpp.o
FAILED: lib/Transforms/Utils/CMakeFiles/LLVMTransformUtils.dir/SimplifyCFG.cpp.o 
ccache /usr/bin/c++ -DCPUINFO_SUPPORTED_PLATFORM=1 -DGTEST_HAS_RTTI=0 -D_DEBUG -D_GLIBCXX_ASSERTIONS -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I/b/ml-opt-devrel-x86-64-b1/build/lib/Transforms/Utils -I/b/ml-opt-devrel-x86-64-b1/llvm-project/llvm/lib/Transforms/Utils -I/var/lib/buildbot/.local/lib/python3.7/site-packages/tensorflow/include -I/b/ml-opt-devrel-x86-64-b1/build/include -I/b/ml-opt-devrel-x86-64-b1/llvm-project/llvm/include -isystem /tmp/tflitebuild/tensorflow/include -isystem /tmp/tflitebuild/eigen/include/eigen3 -isystem /tmp/tflitebuild/abseil-cpp/include -isystem /tmp/tflitebuild/flatbuffers/include -isystem /tmp/tflitebuild/gemmlowp/include/gemmlowp -isystem /tmp/tflitebuild/ml_dtypes/src/ml_dtypes -isystem /tmp/tflitebuild/ml_dtypes/src/ml_dtypes/ml_dtypes -isystem /tmp/tflitebuild/ruy/include -isystem /tmp/tflitebuild/cpuinfo/include -isystem /tmp/tflitebuild/ARM_NEON_2_x86_SSE/include -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror=date-time -fno-lifetime-dse -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wno-missing-field-initializers -pedantic -Wno-long-long -Wimplicit-fallthrough -Wno-uninitialized -Wno-nonnull -Wno-class-memaccess -Wno-redundant-move -Wno-pessimizing-move -Wno-noexcept-type -Wdelete-non-virtual-dtor -Wsuggest-override -Wno-comment -Wno-misleading-indentation -fdiagnostics-color -ffunction-sections -fdata-sections -O3 -DNDEBUG  -fno-exceptions -funwind-tables -fno-rtti -UNDEBUG -DEIGEN_NEON_GEBP_NR=4 -DTFL_STATIC_LIBRARY_BUILD -std=c++17 -MD -MT lib/Transforms/Utils/CMakeFiles/LLVMTransformUtils.dir/SimplifyCFG.cpp.o -MF lib/Transforms/Utils/CMakeFiles/LLVMTransformUtils.dir/SimplifyCFG.cpp.o.d -o lib/Transforms/Utils/CMakeFiles/LLVMTransformUtils.dir/SimplifyCFG.cpp.o -c /b/ml-opt-devrel-x86-64-b1/llvm-project/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
/b/ml-opt-devrel-x86-64-b1/llvm-project/llvm/lib/Transforms/Utils/SimplifyCFG.cpp: In function ‘bool sinkCommonCodeFromPredecessors(llvm::BasicBlock*, llvm::DomTreeUpdater*)’:
/b/ml-opt-devrel-x86-64-b1/llvm-project/llvm/lib/Transforms/Utils/SimplifyCFG.cpp:2503:3: error: reference to ‘LockstepReverseIterator’ is ambiguous
 2503 |   LockstepReverseIterator<true> LRI(UnconditionalPreds);
      |   ^~~~~~~~~~~~~~~~~~~~~~~
/b/ml-opt-devrel-x86-64-b1/llvm-project/llvm/lib/Transforms/Utils/SimplifyCFG.cpp:1787:7: note: candidates are: ‘class {anonymous}::LockstepReverseIterator’
 1787 | class LockstepReverseIterator {
      |       ^~~~~~~~~~~~~~~~~~~~~~~
In file included from /b/ml-opt-devrel-x86-64-b1/llvm-project/llvm/lib/Transforms/Utils/SimplifyCFG.cpp:77:
/b/ml-opt-devrel-x86-64-b1/llvm-project/llvm/include/llvm/Transforms/Utils/LockstepReverseIterator.h:41:7: note:                 ‘template<bool EarlyFailure> class llvm::LockstepReverseIterator’
   41 | class LockstepReverseIterator
      |       ^~~~~~~~~~~~~~~~~~~~~~~
/b/ml-opt-devrel-x86-64-b1/llvm-project/llvm/lib/Transforms/Utils/SimplifyCFG.cpp:2503:33: error: ‘LRI’ was not declared in this scope
 2503 |   LockstepReverseIterator<true> LRI(UnconditionalPreds);
      |                                 ^~~
/b/ml-opt-devrel-x86-64-b1/llvm-project/llvm/lib/Transforms/Utils/SimplifyCFG.cpp:2533:44: error: reference to ‘LockstepReverseIterator’ is ambiguous
 2533 |     auto ProfitableToSinkInstruction = [&](LockstepReverseIterator<true> &LRI) {
      |                                            ^~~~~~~~~~~~~~~~~~~~~~~
/b/ml-opt-devrel-x86-64-b1/llvm-project/llvm/lib/Transforms/Utils/SimplifyCFG.cpp:1787:7: note: candidates are: ‘class {anonymous}::LockstepReverseIterator’
 1787 | class LockstepReverseIterator {
      |       ^~~~~~~~~~~~~~~~~~~~~~~
In file included from /b/ml-opt-devrel-x86-64-b1/llvm-project/llvm/lib/Transforms/Utils/SimplifyCFG.cpp:77:
/b/ml-opt-devrel-x86-64-b1/llvm-project/llvm/include/llvm/Transforms/Utils/LockstepReverseIterator.h:41:7: note:                 ‘template<bool EarlyFailure> class llvm::LockstepReverseIterator’
   41 | class LockstepReverseIterator
      |       ^~~~~~~~~~~~~~~~~~~~~~~
/b/ml-opt-devrel-x86-64-b1/llvm-project/llvm/lib/Transforms/Utils/SimplifyCFG.cpp:2533:44: error: ‘LockstepReverseIterator’ has not been declared
 2533 |     auto ProfitableToSinkInstruction = [&](LockstepReverseIterator<true> &LRI) {
      |                                            ^~~~~~~~~~~~~~~~~~~~~~~
/b/ml-opt-devrel-x86-64-b1/llvm-project/llvm/lib/Transforms/Utils/SimplifyCFG.cpp:2533:67: error: expected ‘,’ or ‘...’ before ‘<’ token
 2533 |     auto ProfitableToSinkInstruction = [&](LockstepReverseIterator<true> &LRI) {
      |                                                                   ^
/b/ml-opt-devrel-x86-64-b1/llvm-project/llvm/lib/Transforms/Utils/SimplifyCFG.cpp: At global scope:
/b/ml-opt-devrel-x86-64-b1/llvm-project/llvm/lib/Transforms/Utils/SimplifyCFG.cpp:2206:13: warning: ‘bool canSinkInstructions(llvm::ArrayRef<llvm::Instruction*>, llvm::DenseMap<const llvm::Use*, llvm::SmallVector<llvm::Value*, 4> >&)’ defined but not used [-Wunused-function]
 2206 | static bool canSinkInstructions(
      |             ^~~~~~~~~~~~~~~~~~~
80.630 [1519/23/2295] Building CXX object lib/Frontend/Offloading/CMakeFiles/LLVMFrontendOffloading.dir/Utility.cpp.o
80.656 [1519/22/2296] Linking CXX executable bin/obj2yaml
80.919 [1519/21/2297] Building CXX object tools/llvm-readobj/CMakeFiles/llvm-readobj.dir/COFFDumper.cpp.o

```

</details>

https://github.com/llvm/llvm-project/pull/116657