[compiler-rt] Found one more delta to unbreak build for z/os (PR #82789)

[Sean Perry via llvm-commits]

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@@ -756,8 +756,15 @@ set(riscv64_SOURCES
   ${riscv_SOURCES}
 )
 
-set(sparc_SOURCES ${GENERIC_SOURCES} ${GENERIC_TF_SOURCES})
-set(sparcv9_SOURCES ${GENERIC_SOURCES} ${GENERIC_TF_SOURCES})
+# Exclude the FT sources for 32-bit SPARC.  Clang doesn't
+# support 128-bit long double on 32-bit SPARC.
+if("${COMPILER_RT_DEFAULT_TARGET_ARCH}" MATCHES "sparc")
+  set(sparc_SOURCES ${GENERIC_SOURCES})
+  set(sparcv9_SOURCES ${GENERIC_SOURCES})
+else()
+  set(sparc_SOURCES ${GENERIC_SOURCES} ${GENERIC_TF_SOURCES})
+  set(sparcv9_SOURCES ${GENERIC_SOURCES} ${GENERIC_TF_SOURCES})
+endif()
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perry-ca wrote:

>Then for every change we need a detailed justification why the current code is wrong, while your proposed change is right, not just for s390x, but in general.

@arichardson has reviewed this and approves the change.  In this case the changes recently made to divtc3.c and multc3.c had a bad assumption connecting native 128-bit long double support to 128-bit int support.  That is not generally correct.  I could simply reverse that but I know that will break sparc hence the change to this file.

The answers to the other questions are in previous PRs.  I'll add the answers in the description of this one to save searching.

https://github.com/llvm/llvm-project/pull/82789