Author: arphaman Date: Tue Apr 11 10:36:06 2017 New Revision: 299951 URL: http://llvm.org/viewvc/llvm-project?rev=299951&view=rev Log: Fix PR13910: Don't warn that __builtin_unreachable() is unreachable
Differential Revision: https://reviews.llvm.org/D25321 Modified: cfe/trunk/lib/Analysis/ReachableCode.cpp cfe/trunk/test/Sema/warn-unreachable.c Modified: cfe/trunk/lib/Analysis/ReachableCode.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Analysis/ReachableCode.cpp?rev=299951&r1=299950&r2=299951&view=diff ============================================================================== --- cfe/trunk/lib/Analysis/ReachableCode.cpp (original) +++ cfe/trunk/lib/Analysis/ReachableCode.cpp Tue Apr 11 10:36:06 2017 @@ -58,6 +58,14 @@ static bool isTrivialDoWhile(const CFGBl return false; } +static bool isBuiltinUnreachable(const Stmt *S) { + if (const auto *DRE = dyn_cast<DeclRefExpr>(S)) + if (const auto *FDecl = dyn_cast<FunctionDecl>(DRE->getDecl())) + return FDecl->getIdentifier() && + FDecl->getBuiltinID() == Builtin::BI__builtin_unreachable; + return false; +} + static bool isDeadReturn(const CFGBlock *B, const Stmt *S) { // Look to see if the current control flow ends with a 'return', and see if // 'S' is a substatement. The 'return' may not be the last element in the @@ -592,8 +600,7 @@ void DeadCodeScan::reportDeadCode(const if (isa<BreakStmt>(S)) { UK = reachable_code::UK_Break; - } - else if (isTrivialDoWhile(B, S)) { + } else if (isTrivialDoWhile(B, S) || isBuiltinUnreachable(S)) { return; } else if (isDeadReturn(B, S)) { Modified: cfe/trunk/test/Sema/warn-unreachable.c URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/warn-unreachable.c?rev=299951&r1=299950&r2=299951&view=diff ============================================================================== --- cfe/trunk/test/Sema/warn-unreachable.c (original) +++ cfe/trunk/test/Sema/warn-unreachable.c Tue Apr 11 10:36:06 2017 @@ -461,3 +461,40 @@ void testTrueFalseMacros() { if (!true) // expected-note {{silence by adding parentheses to mark code as explicitly dead}} testTrueFalseMacros(); // expected-warning {{code will never be executed}} } + +int pr13910_foo(int x) { + if (x == 1) + return 0; + else + return x; + __builtin_unreachable(); // expected no warning +} + +int pr13910_bar(int x) { + switch (x) { + default: + return x + 1; + } + pr13910_foo(x); // expected-warning {{code will never be executed}} +} + +int pr13910_bar2(int x) { + if (x == 1) + return 0; + else + return x; + pr13910_foo(x); // expected-warning {{code will never be executed}} + __builtin_unreachable(); // expected no warning + pr13910_foo(x); // expected-warning {{code will never be executed}} +} + +void pr13910_noreturn() { + raze(); + __builtin_unreachable(); // expected no warning +} + +void pr13910_assert() { + myassert(0 && "unreachable"); + return; + __builtin_unreachable(); // expected no warning +} _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
