[compiler-rt] [builtins] Support building the 128-bit float functions on i386 (PR #122658)

[Alexander Richardson via llvm-commits]

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@@ -906,7 +907,7 @@ else ()
 
       # For RISCV32, we must force enable int128 for compiling long
       # double routines.
-      if(COMPILER_RT_ENABLE_SOFTWARE_INT128 OR "${arch}" STREQUAL "riscv32")
+      if(COMPILER_RT_ENABLE_SOFTWARE_INT128 OR "${arch}" STREQUAL "riscv32" OR "${arch}" STREQUAL "i386")
         list(APPEND BUILTIN_CFLAGS_${arch} -fforce-enable-int128)
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arichardson wrote:

Do we support other compilers? If so enabling this unconditionally for i386 might break them?

https://github.com/llvm/llvm-project/pull/122658