fix 32 bit int simple return of riscv64 bridge

Sometimes we need to return a 32 bit integer into a 64 bit integer.
For example, in pyuno.cxx:PyUNO_bool(), an int(32bit) is returned in
type Py_ssize_t(64bit). We assume that this 32bit int was put in low
32 bit of register a0. The bridge may return with high 32 bit
uncleaned and compiler might directly bind this register to 64 bit
variable in error.

This bug produces when build pyuno with gcc-12 with -O2.
https://bugs.documentfoundation.org/show_bug.cgi?id=155937
https://lists.debian.org/debian-riscv/2023/07/msg00011.html

So we need to clean the high 32 bit in bridge.

Change-Id: I37aafb03ba9523cfb90912871308921fbeaf5f0c
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/154837
Tested-by: René Engelhard <[email protected]>
Reviewed-by: René Engelhard <[email protected]>
Reviewed-by: Stephan Bergmann <[email protected]>

bridges/source/cpp_uno/gcc3_linux_riscv64/cpp2uno.cxx

@@ -357,8 +357,6 @@ cpp2uno_call(bridges::cpp_uno::shared::CppInterfaceProxy* pThis,
                 {
                     case typelib_TypeClass_HYPER:
                     case typelib_TypeClass_UNSIGNED_HYPER:
-                    case typelib_TypeClass_LONG:
-                    case typelib_TypeClass_UNSIGNED_LONG:
                     case typelib_TypeClass_ENUM:
                     case typelib_TypeClass_CHAR:
                     case typelib_TypeClass_SHORT:
@@ -367,6 +365,28 @@ cpp2uno_call(bridges::cpp_uno::shared::CppInterfaceProxy* pThis,
                     case typelib_TypeClass_BYTE:
                         std::memcpy(pReturn, pUnoReturn, 8);
                         break;
+                    // Sometimes we need to return a 32 bit integer into a 64 bit integer.
+                    // For example, in pyuno.cxx:PyUNO_bool(), an int(32bit) is returned
+                    // in type Py_ssize_t(64bit)
+                    // We assume that this 32bit int was put in low 32 bit of register a0.
+                    // The bridge may return with high 32 bit uncleaned and compiler might
+                    // directly bind this register to 64 bit variable.
+                    //
+                    // This bug occurs when build pyuno with gcc-12 with -O2.
+                    // https://bugs.documentfoundation.org/show_bug.cgi?id=155937
+                    //
+                    // So we need to clean the high 32 bit in bridge.
+                    case typelib_TypeClass_UNSIGNED_LONG:
+                        std::memset(pReturn + 4, 0x0, 4);
+                        std::memcpy(pReturn, pUnoReturn, 4);
+                        break;
+                    case typelib_TypeClass_LONG:
+                        if (*reinterpret_cast<sal_uInt32*>(pUnoReturn) & 0x80000000)
+                            std::memset(pReturn + 4, 0xFF, 4);
+                        else
+                            std::memset(pReturn + 4, 0x0, 4);
+                        std::memcpy(pReturn, pUnoReturn, 4);
+                        break;
                     case typelib_TypeClass_FLOAT:
                         std::memcpy(pReturn, pUnoReturn, 4);
                         std::memset(pReturn + 4, 0xFF, 4);
@@ -628,7 +648,7 @@ unsigned char* codeSnippet(unsigned char* code, sal_Int32 functionIndex, sal_Int
 
     /* generate this code */
     /*
-       It is complex to load a 64bit address because uou cannot load
+       It is complex to load a 64bit address because you cannot load
        an unsigned number to register on RISC-V.
        # load functionIndex to t4
              00000eb7       lui  t4,0x0