[llvm] [flang-rt] Fix REAL(10)/COMPLEX(10) component sizes in runtime type info (PR #192049)

[Tarun Prabhu via llvm-commits]

================
@@ -280,3 +280,37 @@ TEST(Descriptor, Dump) {
   fclose(tmpf);
 }
 #endif // defined(__linux__) && !defined(__ANDROID__)
+
+// Verify that Descriptor::BytesFor returns the correct storage size
+// for Real and Complex types, especially for kind=10 where the x87
+// 80-bit extended precision value is stored in a 16-byte container.
+TEST(Descriptor, BytesForRealAndComplex) {
+  using TC = TypeCategory;
+  // Real kinds: storage size should account for container padding
+  EXPECT_EQ(Descriptor::BytesFor(TC::Real, 2), 2u);
+  EXPECT_EQ(Descriptor::BytesFor(TC::Real, 3), 2u);
+  EXPECT_EQ(Descriptor::BytesFor(TC::Real, 4), 4u);
+  EXPECT_EQ(Descriptor::BytesFor(TC::Real, 8), 8u);
+#if defined(__x86_64__) || defined(_M_X64) || defined(__i386__) || \
+    defined(_M_IX86)
+  EXPECT_EQ(Descriptor::BytesFor(TC::Real, 10),
+      16u); // x87: 80-bit in 128-bit container
+#endif
+  EXPECT_EQ(Descriptor::BytesFor(TC::Real, 16), 16u);
+  // Complex kinds: should be twice the Real storage size
+  EXPECT_EQ(Descriptor::BytesFor(TC::Complex, 2), 4u);
+  EXPECT_EQ(Descriptor::BytesFor(TC::Complex, 3), 4u);
+  EXPECT_EQ(Descriptor::BytesFor(TC::Complex, 4), 8u);
+  EXPECT_EQ(Descriptor::BytesFor(TC::Complex, 8), 16u);
+#if defined(__x86_64__) || defined(_M_X64) || defined(__i386__) || \
+    defined(_M_IX86)
+  EXPECT_EQ(Descriptor::BytesFor(TC::Complex, 10), 32u); // x87: 2 * 16 bytes
----------------
tarunprabhu wrote:

nit: Probably best to use leading comments here too for consistency

```suggestion
  // x87: 2 * 16 bytes
  EXPECT_EQ(Descriptor::BytesFor(TC::Complex, 10), 32u); 
```

https://github.com/llvm/llvm-project/pull/192049