Fix pr9614 by not emitting an available_externally function when it calls
itself via an asm label.
available_externally functions are supposed to correspond to an external
function, and that is not the case in the examples in pr9614.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@143049 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CodeGenModule.cpp b/lib/CodeGen/CodeGenModule.cpp
index 03fb181..86378a9 100644
--- a/lib/CodeGen/CodeGenModule.cpp
+++ b/lib/CodeGen/CodeGenModule.cpp
@@ -29,6 +29,7 @@
#include "clang/AST/DeclTemplate.h"
#include "clang/AST/Mangle.h"
#include "clang/AST/RecordLayout.h"
+#include "clang/AST/RecursiveASTVisitor.h"
#include "clang/Basic/Diagnostic.h"
#include "clang/Basic/SourceManager.h"
#include "clang/Basic/TargetInfo.h"
@@ -858,6 +859,62 @@
}
}
+namespace {
+ struct FunctionIsDirectlyRecursive :
+ public RecursiveASTVisitor<FunctionIsDirectlyRecursive> {
+ const StringRef Name;
+ bool Result;
+ FunctionIsDirectlyRecursive(const FunctionDecl *F) :
+ Name(F->getName()), Result(false) {
+ }
+ typedef RecursiveASTVisitor<FunctionIsDirectlyRecursive> Base;
+
+ bool TraverseCallExpr(CallExpr *E) {
+ const Decl *D = E->getCalleeDecl();
+ if (!D)
+ return true;
+ AsmLabelAttr *Attr = D->getAttr<AsmLabelAttr>();
+ if (!Attr)
+ return true;
+ if (Name == Attr->getLabel()) {
+ Result = true;
+ return false;
+ }
+ return true;
+ }
+ };
+}
+
+// isTriviallyRecursiveViaAsm - Check if this function calls another
+// decl that, because of the asm attribute, ends up pointing to itself.
+bool
+CodeGenModule::isTriviallyRecursiveViaAsm(const FunctionDecl *F) {
+ if (getCXXABI().getMangleContext().shouldMangleDeclName(F))
+ return false;
+
+ FunctionIsDirectlyRecursive Walker(F);
+ Walker.TraverseFunctionDecl(const_cast<FunctionDecl*>(F));
+ return Walker.Result;
+}
+
+bool
+CodeGenModule::shouldEmitFunction(const FunctionDecl *F) {
+ if (getFunctionLinkage(F) != llvm::Function::AvailableExternallyLinkage)
+ return true;
+ if (F->hasAttr<AlwaysInlineAttr>())
+ return true;
+ if (CodeGenOpts.OptimizationLevel == 0)
+ return false;
+ // PR9614. Avoid cases where the source code is lying to us. An available
+ // externally function should have an equivalent function somewhere else,
+ // but a function that calls itself is clearly not equivalent to the real
+ // implementation.
+ // This happens in glibc's btowc and in some configure checks.
+ if (isTriviallyRecursiveViaAsm(F))
+ return false;
+ return true;
+}
+
void CodeGenModule::EmitGlobalDefinition(GlobalDecl GD) {
const ValueDecl *D = cast<ValueDecl>(GD.getDecl());
@@ -868,10 +925,7 @@
if (const FunctionDecl *Function = dyn_cast<FunctionDecl>(D)) {
// At -O0, don't generate IR for functions with available_externally
// linkage.
- if (CodeGenOpts.OptimizationLevel == 0 &&
- !Function->hasAttr<AlwaysInlineAttr>() &&
- getFunctionLinkage(Function)
- == llvm::Function::AvailableExternallyLinkage)
+ if (!shouldEmitFunction(Function))
return;
if (const CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(D)) {