Add an LLVM_BUILTIN_DEBUGTRAP macro.

Summary:
This provides a macro that expands to __builtin_debugtrap() for clang,
and __debugbreak() for MSVC.

It intentionally expands to nothing for compilers that do not support a
similar mechanism that halts the debugger without otherwise crashing the
process.

Differential Revision: http://reviews.llvm.org/D18002

llvm-svn: 263095

diff --git a/llvm/include/llvm/Support/Compiler.h b/llvm/include/llvm/Support/Compiler.h
index 45a70bd815b581982d7972d945cf7048bf13f9a9..fae0d8f4419eed029dbc28b8c0fd9cd482708824 100644 (file)
--- a/llvm/include/llvm/Support/Compiler.h
+++ b/llvm/include/llvm/Support/Compiler.h
@@ -274,6 +274,23 @@
 # define LLVM_BUILTIN_TRAP *(volatile int*)0x11 = 0
 #endif
 
+/// LLVM_BUILTIN_DEBUGTRAP - On compilers which support it, expands to
+/// an expression which causes the program to break while running
+/// under a debugger.
+#if __has_builtin(__builtin_debugtrap)
+# define LLVM_BUILTIN_DEBUGTRAP __builtin_debugtrap()
+#elif defined(_MSC_VER)
+// The __debugbreak intrinsic is supported by MSVC and breaks while
+// running under the debugger, and also supports invoking a debugger
+// when the OS is configured appropriately.
+# define LLVM_BUILTIN_DEBUGTRAP __debugbreak()
+#else
+// Just continue execution when built with compilers that have no
+// support. This is a debugging aid and not intended to force the
+// program to abort if encountered.
+# define LLVM_BUILTIN_DEBUGTRAP
+#endif
+
 /// \macro LLVM_ASSUME_ALIGNED
 /// \brief Returns a pointer with an assumed alignment.
 #if __has_builtin(__builtin_assume_aligned) || LLVM_GNUC_PREREQ(4, 7, 0)