[compiler-rt] [builtins] Generate __multc3 for z/OS (PR #77554)

[Sean Perry via llvm-commits]

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@@ -189,8 +189,10 @@ typedef long double tf_float;
 #define CRT_LDBL_IEEE_F128
 #endif
 #define TF_C(x) x##L
-#elif __LDBL_MANT_DIG__ == 113
-// Use long double instead of __float128 if it matches the IEEE 128-bit format.
+#elif __LDBL_MANT_DIG__ == 113 ||                                              \
+    (__FLT_RADIX__ == 16 && __LDBL_MANT_DIG__ == 28)
+// Use long double instead of __float128 if it matches the IEEE 128-bit format
+// or the IBM hexadecimal format.
 #define CRT_LDBL_128BIT
 #define CRT_HAS_F128
 #define CRT_HAS_IEEE_TF
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perry-ca wrote:

I double checked and Qcomplex is defined via CRT_LDBL_128BIT.  I can limit CRT_HAS_F128  to IEEE too.

https://github.com/llvm/llvm-project/pull/77554