From 39dad53772c42eb36ebec1c81c56ba99d038fb94 Mon Sep 17 00:00:00 2001 From: John McCall Date: Tue, 3 Aug 2010 22:46:07 +0000 Subject: Do a very simple pass over every function we emit to infer whether we can mark it nounwind based on whether it contains any non-nounwind calls. git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@110163 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/CodeGen/CodeGenFunction.cpp | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) (limited to 'lib/CodeGen/CodeGenFunction.cpp') diff --git a/lib/CodeGen/CodeGenFunction.cpp b/lib/CodeGen/CodeGenFunction.cpp index 396ab4e6d2..35664af219 100644 --- a/lib/CodeGen/CodeGenFunction.cpp +++ b/lib/CodeGen/CodeGenFunction.cpp @@ -311,6 +311,19 @@ void CodeGenFunction::EmitFunctionBody(FunctionArgList &Args) { EmitStmt(FD->getBody()); } +/// Tries to mark the given function nounwind based on the +/// non-existence of any throwing calls within it. We believe this is +/// lightweight enough to do at -O0. +static void TryMarkNoThrow(llvm::Function *F) { + for (llvm::Function::iterator FI = F->begin(), FE = F->end(); FI != FE; ++FI) + for (llvm::BasicBlock::iterator + BI = FI->begin(), BE = FI->end(); BI != BE; ++BI) + if (llvm::CallInst *Call = dyn_cast(&*BI)) + if (!Call->doesNotThrow()) + return; + F->setDoesNotThrow(true); +} + void CodeGenFunction::GenerateCode(GlobalDecl GD, llvm::Function *Fn) { const FunctionDecl *FD = cast(GD.getDecl()); @@ -369,6 +382,11 @@ void CodeGenFunction::GenerateCode(GlobalDecl GD, llvm::Function *Fn) { // Emit the standard function epilogue. FinishFunction(BodyRange.getEnd()); + + // If we haven't marked the function nothrow through other means, do + // a quick pass now to see if we can. + if (!CurFn->doesNotThrow()) + TryMarkNoThrow(CurFn); } /// ContainsLabel - Return true if the statement contains a label in it. If -- cgit v1.2.3-70-g09d2