Internal compiler error while cross-compiling LLVM 20.1.5 with GCC 8.1.0

[Sangeetha-E]

While cross-compiling LLVM 20.1.5 using GCC 8.1.0, I am encountering the following issues:

Initial Error:

llvm-20.1.5.src/lib/Support/APFloat.cpp:130:61: error: 'const llvm::fltSemantics{15, -14, 11, 16, IEEE754, IEEE, true, true}' is not a constant expression
 static constexpr fltSemantics semIEEEhalf = {15, -14, 11, 16};

Reference Fix Applied:

I followed the suggestion in this GitHub issue:
#81013 (comment)

Subsequent Error After Applying Fix:

llvm-20.1.5.src/lib/Analysis/CtxProfAnalysis.cpp:233:5: internal compiler error: in tsubst_decomp_names, at cp/pt.c:16535
    for (auto &[_, SubCtxSet] : Ctx.callsites())

Note:

• These issues occur when using GCC 8.1.0.

• When I compile LLVM 20.1.5 with GCC 13, the build completes successfully.

• This suggests that newer versions of LLVM (including 20.1.5) may require GCC >= 13 for successful compilation.

Request:

Please confirm:

• Whether LLVM 20.1.5 officially requires GCC 13 or later.

• Are there any known workarounds to build LLVM 20.1.5 with GCC 8.x?

Thank you.