diff options
Diffstat (limited to 'lib/verify.h')
| -rw-r--r-- | lib/verify.h | 16 |
1 files changed, 11 insertions, 5 deletions
diff --git a/lib/verify.h b/lib/verify.h index 6d7b961db71..ca2a1540736 100644 --- a/lib/verify.h +++ b/lib/verify.h @@ -320,7 +320,9 @@ template <int w> based on __builtin_unreachable does not. (GCC so far has only __builtin_unreachable.) */ #if _GL_HAS_BUILTIN_ASSUME -/* Use a temporary variable, to avoid a clang warning +/* Use __builtin_constant_p to help clang's data-flow analysis for the case + assume (0). + Use a temporary variable, to avoid a clang warning "the argument to '__builtin_assume' has side effects that will be discarded" if R contains invocations of functions not marked as 'const'. The type of the temporary variable can't be __typeof__ (R), because that @@ -328,12 +330,16 @@ template <int w> instead. */ # if defined __cplusplus # define assume(R) \ - ((void) ({ bool _gl_verify_temp = (R); \ - __builtin_assume (_gl_verify_temp); })) + (__builtin_constant_p (R) && !(R) \ + ? (void) __builtin_unreachable () \ + : (void) ({ bool _gl_verify_temp = (R); \ + __builtin_assume (_gl_verify_temp); })) # else # define assume(R) \ - ((void) ({ _Bool _gl_verify_temp = (R); \ - __builtin_assume (_gl_verify_temp); })) + (__builtin_constant_p (R) && !(R) \ + ? (void) __builtin_unreachable () \ + : (void) ({ _Bool _gl_verify_temp = (R); \ + __builtin_assume (_gl_verify_temp); })) # endif #elif _GL_HAS_BUILTIN_UNREACHABLE # define assume(R) ((R) ? (void) 0 : __builtin_unreachable ()) |