[llvm] [SelectionDAG] Add preliminary plumbing for `samesign` flag (PR #112354)

[via llvm-commits]

gulfemsavrun wrote:

This PR caused an assertion error:
```
[1321/5119](49) Building CXX object lib/Analysis/CMakeFiles/LLVMAnalysis.dir/BranchProbabilityInfo.cpp.o
FAILED: lib/Analysis/CMakeFiles/LLVMAnalysis.dir/BranchProbabilityInfo.cpp.o 
/b/s/w/ir/x/w/llvm_build/./bin/clang++ --sysroot=/b/s/w/ir/x/w/cipd/linux -DGTEST_HAS_RTTI=0 -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I/b/s/w/ir/x/w/llvm_build/tools/clang/stage2-bins/lib/Analysis -I/b/s/w/ir/x/w/llvm-llvm-project/llvm/lib/Analysis -I/b/s/w/ir/x/w/llvm_build/tools/clang/stage2-bins/include -I/b/s/w/ir/x/w/llvm-llvm-project/llvm/include -isystem /b/s/w/ir/x/w/zlib_install_target/include -isystem /b/s/w/ir/x/w/zstd_install/include -stdlib=libc++ -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror=date-time -Werror=unguarded-availability-new -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic -Wno-long-long -Wc++98-compat-extra-semi -Wimplicit-fallthrough -Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wsuggest-override -Wno-comment -Wstring-conversion -Wmisleading-indentation -Wctad-maybe-unsupported -fdiagnostics-color -ffunction-sections -fdata-sections -flto=full -ffat-lto-objects -ffile-prefix-map=/b/s/w/ir/x/w/llvm_build/tools/clang/stage2-bins=../../../../llvm-llvm-project -ffile-prefix-map=/b/s/w/ir/x/w/llvm-llvm-project/= -no-canonical-prefixes -O3 -DNDEBUG -std=c++17 -fvisibility=default  -fno-exceptions -fno-unwind-tables -fno-asynchronous-unwind-tables -fno-rtti -MD -MT lib/Analysis/CMakeFiles/LLVMAnalysis.dir/BranchProbabilityInfo.cpp.o -MF lib/Analysis/CMakeFiles/LLVMAnalysis.dir/BranchProbabilityInfo.cpp.o.d -o lib/Analysis/CMakeFiles/LLVMAnalysis.dir/BranchProbabilityInfo.cpp.o -c /b/s/w/ir/x/w/llvm-llvm-project/llvm/lib/Analysis/BranchProbabilityInfo.cpp
clang++: llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:16157: SDValue (anonymous namespace)::DAGCombiner::visitFREEZE(SDNode *): Assertion `DAG.isGuaranteedNotToBeUndefOrPoison(R, false) && "Can't create node that may be undef/poison!"' failed.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0.	Program arguments: /b/s/w/ir/x/w/llvm_build/./bin/clang++ --sysroot=/b/s/w/ir/x/w/cipd/linux -DGTEST_HAS_RTTI=0 -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I/b/s/w/ir/x/w/llvm_build/tools/clang/stage2-bins/lib/Analysis -I/b/s/w/ir/x/w/llvm-llvm-project/llvm/lib/Analysis -I/b/s/w/ir/x/w/llvm_build/tools/clang/stage2-bins/include -I/b/s/w/ir/x/w/llvm-llvm-project/llvm/include -isystem /b/s/w/ir/x/w/zlib_install_target/include -isystem /b/s/w/ir/x/w/zstd_install/include -stdlib=libc++ -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror=date-time -Werror=unguarded-availability-new -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic -Wno-long-long -Wc++98-compat-extra-semi -Wimplicit-fallthrough -Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wsuggest-override -Wno-comment -Wstring-conversion -Wmisleading-indentation -Wctad-maybe-unsupported -fdiagnostics-color -ffunction-sections -fdata-sections -flto=full -ffat-lto-objects -ffile-prefix-map=/b/s/w/ir/x/w/llvm_build/tools/clang/stage2-bins=../../../../llvm-llvm-project -ffile-prefix-map=/b/s/w/ir/x/w/llvm-llvm-project/= -no-canonical-prefixes -O3 -DNDEBUG -std=c++17 -fvisibility=default -fno-exceptions -fno-unwind-tables -fno-asynchronous-unwind-tables -fno-rtti -MD -MT lib/Analysis/CMakeFiles/LLVMAnalysis.dir/BranchProbabilityInfo.cpp.o -MF lib/Analysis/CMakeFiles/LLVMAnalysis.dir/BranchProbabilityInfo.cpp.o.d -o lib/Analysis/CMakeFiles/LLVMAnalysis.dir/BranchProbabilityInfo.cpp.o -c /b/s/w/ir/x/w/llvm-llvm-project/llvm/lib/Analysis/BranchProbabilityInfo.cpp
1.	<eof> parser at end of file
2.	Code generation
3.	Running pass 'Function Pass Manager' on module '/b/s/w/ir/x/w/llvm-llvm-project/llvm/lib/Analysis/BranchProbabilityInfo.cpp'.
4.	Running pass 'AArch64 Instruction Selection' on function '@_ZN4llvm21BranchProbabilityInfo19calcMetadataWeightsEPKNS_10BasicBlockE'
#0 0x0000aaaacdc240c0 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/b/s/w/ir/x/w/llvm_build/./bin/clang+++0x42040c0)
clang++: error: clang frontend command failed with exit code 134 (use -v to see invocation)
```
https://logs.chromium.org/logs/fuchsia/buildbucket/cr-buildbucket/8732522040154573889/+/u/clang/build/stdout

https://github.com/llvm/llvm-project/pull/112354