llvm 21 Windows MSVC build failure (function too large)

[mcbarton]

I am building the llvm 21 release branch on a Windows Github runner with the following options (I am aware some options may be redundant, but these are the options picked for the instructions to cover many llvm versions for the project I help with)

cmake -DLLVM_ENABLE_PROJECTS="clang"                   `
          -DLLVM_TARGETS_TO_BUILD="host;NVPTX"          `
          -DCMAKE_BUILD_TYPE=Release                          `
          -DLLVM_ENABLE_ASSERTIONS=ON                         `
          -DCLANG_ENABLE_STATIC_ANALYZER=OFF                  `
          -DCLANG_ENABLE_ARCMT=OFF                            `
          -DCLANG_ENABLE_FORMAT=OFF                           `
          -DCLANG_ENABLE_BOOTSTRAP=OFF                        `
          ..\llvm
cmake --build . --config Release --target clang clangInterpreter clangStaticAnalyzerCore --parallel 4

and I get the following error

 C:\a\CppInterOp\CppInterOp\llvm-project\clang\lib\CodeGen\TargetBuiltins\RISCV.cpp(138,1): error C1053: '?EmitRISCVBuiltinExpr@CodeGenFunction@CodeGen@clang@@QEAAPEAVValue@llvm@@IPEBVCallExpr@3@VReturnValueSlot@23@@Z': function too large [C:\a\CppInterOp\CppInterOp\llvm-project\build\tools\clang\lib\CodeGen\clangCodeGen.vcxproj]

I have no idea how to fix, and was hoping by opening this issue that someone may know a solution.

ci run here https://github.com/compiler-research/CppInterOp/actions/runs/17740116555/job/50411736531?pr=672#step:9:5193

[efriedma-quic]

Dup of #88368. #158164 is currently under review to cherry-pick to the LLVM 21 branch.