Author: jamesm Date: Thu Nov 12 09:36:04 2015 New Revision: 252902 URL: http://llvm.org/viewvc/llvm-project?rev=252902&view=rev Log: [C++] Add the "norecurse" attribute to main() if in C++ mode
The C++ spec (3.6.1.3) says "The function `main` shall not be used within a program". This implies that it cannot recurse, so add the norecurse attribute to help the midend out a bit. Added: cfe/trunk/test/CodeGenCXX/main-norecurse.cpp Modified: cfe/trunk/lib/CodeGen/CodeGenFunction.cpp cfe/trunk/test/CodeGenObjC/objc-literal-tests.m Modified: cfe/trunk/lib/CodeGen/CodeGenFunction.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CodeGenFunction.cpp?rev=252902&r1=252901&r2=252902&view=diff ============================================================================== --- cfe/trunk/lib/CodeGen/CodeGenFunction.cpp (original) +++ cfe/trunk/lib/CodeGen/CodeGenFunction.cpp Thu Nov 12 09:36:04 2015 @@ -716,6 +716,14 @@ void CodeGenFunction::StartFunction(Glob } } + // If we're in C++ mode and the function name is "main", it is guaranteed + // to be norecurse by the standard (3.6.1.3 "The function main shall not be + // used within a program"). + if (getLangOpts().CPlusPlus) + if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D)) + if (FD->isMain()) + Fn->addFnAttr(llvm::Attribute::NoRecurse); + llvm::BasicBlock *EntryBB = createBasicBlock("entry", CurFn); // Create a marker to make it easy to insert allocas into the entryblock Added: cfe/trunk/test/CodeGenCXX/main-norecurse.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/main-norecurse.cpp?rev=252902&view=auto ============================================================================== --- cfe/trunk/test/CodeGenCXX/main-norecurse.cpp (added) +++ cfe/trunk/test/CodeGenCXX/main-norecurse.cpp Thu Nov 12 09:36:04 2015 @@ -0,0 +1,8 @@ +// RUN: %clang_cc1 -emit-llvm %s -o - | FileCheck %s + +// CHECK: define i{{.*}} @main({{.*}}) #0 +int main(int argc, char **argv) { + return 1; +} + +// CHECK: attributes #0 = { norecurse{{.*}} } Modified: cfe/trunk/test/CodeGenObjC/objc-literal-tests.m URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenObjC/objc-literal-tests.m?rev=252902&r1=252901&r2=252902&view=diff ============================================================================== --- cfe/trunk/test/CodeGenObjC/objc-literal-tests.m (original) +++ cfe/trunk/test/CodeGenObjC/objc-literal-tests.m Thu Nov 12 09:36:04 2015 @@ -94,4 +94,4 @@ void baz(void) { bar(^(void) { return YES; }); } -// CHECK: attributes [[NUW]] = { nounwind{{.*}} } +// CHECK: attributes [[NUW]] = { {{(norecurse )?}}nounwind{{.*}} } _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits