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.
<rdar://problem/8087431>

llvm-svn: 110163
This commit is contained in:
John McCall 2010-08-03 22:46:07 +00:00
parent 38321174e0
commit 8601a75118
3 changed files with 33 additions and 5 deletions

View File

@ -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<llvm::CallInst>(&*BI))
if (!Call->doesNotThrow())
return;
F->setDoesNotThrow(true);
}
void CodeGenFunction::GenerateCode(GlobalDecl GD, llvm::Function *Fn) {
const FunctionDecl *FD = cast<FunctionDecl>(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

View File

@ -1,6 +1,16 @@
// RUN: %clang_cc1 -fexceptions -emit-llvm -o - %s | grep "@foo()" | not grep nounwind
// RUN: %clang_cc1 -emit-llvm -o - %s | grep "@foo()" | grep nounwind
// RUN: %clang_cc1 -fexceptions -emit-llvm -o - %s | FileCheck %s
// RUN: %clang_cc1 -emit-llvm -o - %s | FileCheck -check-prefix NOEXC %s
int foo(void) {
return 0;
int opaque();
// CHECK: define [[INT:i.*]] @test0() {
// CHECK-NOEXC: define [[INT:i.*]] @test0() nounwind {
int test0(void) {
return opaque();
}
// <rdar://problem/8087431>: locally infer nounwind at -O0
// CHECK: define [[INT:i.*]] @test1() nounwind {
// CHECK-NOEXC: define [[INT:i.*]] @test1() nounwind {
int test1(void) {
}

View File

@ -36,7 +36,7 @@ namespace test1 {
const int y = x - 1; // This gets deferred.
const int z = ~y; // This also gets deferred, but gets "undeferred" before y.
int test() { return z; }
// CHECK: define i32 @_ZN5test14testEv() {
// CHECK: define i32 @_ZN5test14testEv()
// All of these initializers end up delayed, so we check them later.
}