[libcxxabi] Fix the long double demangling for PowerPC (llvm#135332)

mstorsjo · var-const · commit 1343812d2861 · 2025-04-17T03:22:46.000-07:00
PowerPC uses a slightly different type of floats for their 128 bit long doubles, as "double-double", with __LDBL_MANT_DIG__ == 106 rather than __LDBL_MANT_DIG__ == 113 for IEEE 128 bit floats. This fixes compiling libcxxabi for PowerPC after 3b70715.
diff --git a/libcxxabi/src/demangle/ItaniumDemangle.h b/libcxxabi/src/demangle/ItaniumDemangle.h
@@ -5741,7 +5741,7 @@ struct FloatData<double>
 template <>
 struct FloatData<long double>
 {
-#if __LDBL_MANT_DIG__ == 113
+#if __LDBL_MANT_DIG__ == 113 || __LDBL_MANT_DIG__ == 106
   static const size_t mangled_size = 32;
 #elif __LDBL_MANT_DIG__ == 53 || defined(_MSC_VER)
   // MSVC doesn't define __LDBL_MANT_DIG__, but it has long double equal to

Original file line number	Diff line number	Diff line change
`@@ -5741,7 +5741,7 @@ struct FloatData<double>`
`5741`	`5741`	`template <>`
`5742`	`5742`	`struct FloatData<long double>`
`5743`	`5743`	`{`
`5744`		`-#if __LDBL_MANT_DIG__ == 113`
	`5744`	`+#if __LDBL_MANT_DIG__ == 113 \|\| __LDBL_MANT_DIG__ == 106`
`5745`	`5745`	`static const size_t mangled_size = 32;`
`5746`	`5746`	`#elif __LDBL_MANT_DIG__ == 53 \|\| defined(_MSC_VER)`
`5747`	`5747`	`// MSVC doesn't define __LDBL_MANT_DIG__, but it has long double equal to`