Fix compilation with old MSVC compiler

Old pre-4.0 MSVC does not support _ReturnAddress() intrinsic. Provide for
it simple implementation via inline assembly.

1 files changed, 12 insertions, 0 deletions

diff --git a/src/dlfcn.c b/src/dlfcn.c
index da9a37a..8dc0359 100644
--- a/src/dlfcn.c
+++ b/src/dlfcn.c
@@ -47,9 +47,21 @@ typedef ULONG ULONG_PTR;
 #endif

 

 #ifdef _MSC_VER

+#if _MSC_VER >= 1000

 /* https://docs.microsoft.com/en-us/cpp/intrinsics/returnaddress */

 #pragma intrinsic( _ReturnAddress )

 #else

+/* On older version read return address from the value on stack pointer + 4 of

+ * the caller. Caller stack pointer is stored in EBP register but only when

+ * the EBP register is not optimized out. Usage of _alloca() function prevent

+ * EBP register optimization. Read value of EBP + 4 via inline assembly. And

+ * because inline assembly does not have a return value, put it into naked

+ * function which does not have prologue and epilogue and preserve registers.

+ */

+__declspec( naked ) static void *_ReturnAddress( void ) { __asm mov eax, [ebp+4] __asm ret }

+#define _ReturnAddress( ) ( _alloca(1), _ReturnAddress( ) )

+#endif

+#else

 /* https://gcc.gnu.org/onlinedocs/gcc/Return-Address.html */

 #ifndef _ReturnAddress

 #define _ReturnAddress( ) ( __builtin_extract_return_addr( __builtin_return_address( 0 ) ) )