[llvm] [NFC] Switch a number of DenseMaps to SmallDenseMaps for speedup (PR #109417)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-clang-x86_64-sie-ubuntu-fast` running on `sie-linux-worker` while building `llvm` at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/144/builds/7942

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

```
Step 6 (test-build-unified-tree-check-all) failure: test (failure)
...
3.992 [2/12/73] Linking CXX executable tools/clang/unittests/Tooling/ToolingTests
4.002 [2/11/74] Linking CXX executable unittests/tools/llvm-mca/LLVMMCATests
4.009 [2/10/75] Linking CXX executable unittests/ExecutionEngine/Orc/OrcJITTests
4.071 [2/9/76] Linking CXX executable unittests/IR/IRTests
4.112 [2/8/77] Linking CXX executable unittests/tools/llvm-exegesis/LLVMExegesisTests
4.117 [2/7/78] Linking CXX executable unittests/Transforms/Scalar/ScalarTests
4.149 [2/6/79] Linking CXX executable unittests/Passes/Plugins/PluginsTests
4.208 [2/5/80] Linking CXX executable unittests/Target/X86/X86Tests
4.246 [2/4/81] Linking CXX executable tools/clang/unittests/Frontend/FrontendTests
4.304 [2/3/82] Building CXX object unittests/Analysis/CMakeFiles/AnalysisTests.dir/SparsePropagation.cpp.o
FAILED: unittests/Analysis/CMakeFiles/AnalysisTests.dir/SparsePropagation.cpp.o 
CCACHE_CPP2=yes CCACHE_HASHDIR=yes /usr/bin/ccache /usr/bin/g++ -DGTEST_HAS_RTTI=0 -DLLVM_BUILD_STATIC -D_DEBUG -D_GLIBCXX_ASSERTIONS -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I/home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/build/unittests/Analysis -I/home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/llvm-project/llvm/unittests/Analysis -I/home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/build/include -I/home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/llvm-project/llvm/include -I/home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/llvm-project/third-party/unittest/googletest/include -I/home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/llvm-project/third-party/unittest/googlemock/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 -Wctad-maybe-unsupported -fdiagnostics-color -ffunction-sections -fdata-sections -O3 -DNDEBUG  -Wno-variadic-macros -fno-exceptions -funwind-tables -fno-rtti -UNDEBUG -Wno-suggest-override -std=c++17 -MD -MT unittests/Analysis/CMakeFiles/AnalysisTests.dir/SparsePropagation.cpp.o -MF unittests/Analysis/CMakeFiles/AnalysisTests.dir/SparsePropagation.cpp.o.d -o unittests/Analysis/CMakeFiles/AnalysisTests.dir/SparsePropagation.cpp.o -c /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/llvm-project/llvm/unittests/Analysis/SparsePropagation.cpp
/home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/llvm-project/llvm/unittests/Analysis/SparsePropagation.cpp:141:8: error: ‘void {anonymous}::TestLatticeFunc::ComputeInstructionState(llvm::Instruction&, llvm::DenseMap<llvm::PointerIntPair<llvm::Value*, 2, {anonymous}::IPOGrouping>, {anonymous}::TestLatticeVal>&, llvm::SparseSolver<llvm::PointerIntPair<llvm::Value*, 2, {anonymous}::IPOGrouping>, {anonymous}::TestLatticeVal, llvm::LatticeKeyInfo<llvm::PointerIntPair<llvm::Value*, 2, {anonymous}::IPOGrouping> > >&)’ marked ‘override’, but does not override
  141 |   void ComputeInstructionState(
      |        ^~~~~~~~~~~~~~~~~~~~~~~
/home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/llvm-project/llvm/unittests/Analysis/SparsePropagation.cpp:230:19: error: cannot declare field ‘{anonymous}::SparsePropagationTest::Lattice’ to be of abstract type ‘{anonymous}::TestLatticeFunc’
  230 |   TestLatticeFunc Lattice;
      |                   ^~~~~~~
/home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/llvm-project/llvm/unittests/Analysis/SparsePropagation.cpp:98:7: note:   because the following virtual functions are pure within ‘{anonymous}::TestLatticeFunc’:
   98 | class TestLatticeFunc
      |       ^~~~~~~~~~~~~~~
In file included from /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/llvm-project/llvm/unittests/Analysis/SparsePropagation.cpp:9:
/home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/llvm-project/llvm/include/llvm/Analysis/SparsePropagation.h:90:16: note:     ‘void llvm::AbstractLatticeFunction<LatticeKey, LatticeVal>::ComputeInstructionState(llvm::Instruction&, llvm::SmallDenseMap<LatticeKey, LatticeVal, 16>&, llvm::SparseSolver<LatticeKey, LatticeVal>&) [with LatticeKey = llvm::PointerIntPair<llvm::Value*, 2, {anonymous}::IPOGrouping>; LatticeVal = {anonymous}::TestLatticeVal]’
   90 |   virtual void ComputeInstructionState(
      |                ^~~~~~~~~~~~~~~~~~~~~~~
5.006 [2/2/83] Linking CXX executable tools/clang/unittests/Interpreter/ExceptionTests/ClangReplInterpreterExceptionTests
5.191 [2/1/84] Linking CXX executable tools/clang/unittests/Interpreter/ClangReplInterpreterTests
ninja: build stopped: subcommand failed.

```

</details>

https://github.com/llvm/llvm-project/pull/109417