From b121bfcc22660b1bdfb1183b191b6516988bcaf5 Mon Sep 17 00:00:00 2001 From: John McCall Date: Mon, 14 Mar 2011 22:41:50 +0000 Subject: Version N of the llvm_unreachable patch: VC++ doesn't recognize that abort() doesn't return, so just go back to using the old runtime function instead of trying to use abort() when __builtin_unreachable (or an equivalent) isn't supported. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127629 91177308-0d34-0410-b5e6-96231b3b80d8 --- include/llvm/Support/Compiler.h | 4 +--- include/llvm/Support/ErrorHandling.h | 17 ++++++++++------- 2 files changed, 11 insertions(+), 10 deletions(-) (limited to 'include') diff --git a/include/llvm/Support/Compiler.h b/include/llvm/Support/Compiler.h index 0df154b5d6..e092157218 100644 --- a/include/llvm/Support/Compiler.h +++ b/include/llvm/Support/Compiler.h @@ -128,12 +128,10 @@ // LLVM_BUILTIN_UNREACHABLE - On compilers which support it, expands // to an expression which states that it is undefined behavior for the -// compiler to reach this point. +// compiler to reach this point. Otherwise is not defined. #if defined(__clang__) || (__GNUC__ > 4) \ || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5) # define LLVM_BUILTIN_UNREACHABLE __builtin_unreachable() -#else -# define LLVM_BUILTIN_UNREACHABLE abort() #endif #endif diff --git a/include/llvm/Support/ErrorHandling.h b/include/llvm/Support/ErrorHandling.h index fb0c88d8d8..95b01095c1 100644 --- a/include/llvm/Support/ErrorHandling.h +++ b/include/llvm/Support/ErrorHandling.h @@ -86,18 +86,21 @@ namespace llvm { unsigned line=0); } -/// Prints the message and location info to stderr in !NDEBUG builds. -/// This is intended to be used for "impossible" situations that imply -/// a bug in the compiler. +/// Marks that the current location is not supposed to be reachable. +/// In !NDEBUG builds, prints the message and location info to stderr. +/// In NDEBUG builds, becomes an optimizer hint that the current location +/// is not supposed to be reachable. On compilers that don't support +/// such hints, prints a reduced message instead. /// -/// In NDEBUG mode it only prints "UNREACHABLE executed". -/// Use this instead of assert(0), so that the compiler knows this path -/// is not reachable even for NDEBUG builds. +/// Use this instead of assert(0). It conveys intent more clearly and +/// allows compilers to omit some unnecessary code. #ifndef NDEBUG #define llvm_unreachable(msg) \ ::llvm::llvm_unreachable_internal(msg, __FILE__, __LINE__) -#else +#elif defined(LLVM_BUILTIN_UNREACHABLE) #define llvm_unreachable(msg) LLVM_BUILTIN_UNREACHABLE +#else +#define llvm_unreachable(msg) ::llvm::llvm_unreachable_internal() #endif #endif -- cgit v1.2.3