Implement an indirect-goto optimization for goto *&&lbl and respect this
in the scope checker. With that done, turn an indirect goto into a
protected scope into a hard error; otherwise IR generation has to start
worrying about declarations not dominating their scopes, as exemplified
in PR8473.
If this really affects anyone, I can probably adjust this to only hard-error
on possible indirect gotos into VLA scopes rather than arbitrary scopes.
But we'll see how people cope with the aggressive change on the marginal
feature.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@117539 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/clang/AST/Stmt.h b/include/clang/AST/Stmt.h
index 3862cf3..ca42b3e 100644
--- a/include/clang/AST/Stmt.h
+++ b/include/clang/AST/Stmt.h
@@ -1005,10 +1005,17 @@
void setStarLoc(SourceLocation L) { StarLoc = L; }
SourceLocation getStarLoc() const { return StarLoc; }
- Expr *getTarget();
- const Expr *getTarget() const;
+ Expr *getTarget() { return reinterpret_cast<Expr*>(Target); }
+ const Expr *getTarget() const {return reinterpret_cast<const Expr*>(Target);}
void setTarget(Expr *E) { Target = reinterpret_cast<Stmt*>(E); }
+ /// getConstantTarget - Returns the fixed target of this indirect
+ /// goto, if one exists.
+ LabelStmt *getConstantTarget();
+ const LabelStmt *getConstantTarget() const {
+ return const_cast<IndirectGotoStmt*>(this)->getConstantTarget();
+ }
+
virtual SourceRange getSourceRange() const {
return SourceRange(GotoLoc, Target->getLocEnd());
}
diff --git a/include/clang/Basic/DiagnosticSemaKinds.td b/include/clang/Basic/DiagnosticSemaKinds.td
index 7efc7d5..17a6fe7 100644
--- a/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/include/clang/Basic/DiagnosticSemaKinds.td
@@ -1980,9 +1980,8 @@
"switch case is in protected scope">;
def err_indirect_goto_without_addrlabel : Error<
"indirect goto in function with no address-of-label expressions">;
-def warn_indirect_goto_in_protected_scope : Warning<
- "indirect goto might cross protected scopes">,
- InGroup<DiagGroup<"label-address-scope">>;
+def err_indirect_goto_in_protected_scope : Error<
+ "indirect goto might cross protected scopes">;
def note_indirect_goto_target : Note<"possible target of indirect goto">;
def note_protected_by_variable_init : Note<
"jump bypasses variable initialization">;
diff --git a/lib/AST/Stmt.cpp b/lib/AST/Stmt.cpp
index 4f46b35..09d889e 100644
--- a/lib/AST/Stmt.cpp
+++ b/lib/AST/Stmt.cpp
@@ -669,8 +669,12 @@
Stmt::child_iterator GotoStmt::child_end() { return child_iterator(); }
// IndirectGotoStmt
-Expr* IndirectGotoStmt::getTarget() { return cast<Expr>(Target); }
-const Expr* IndirectGotoStmt::getTarget() const { return cast<Expr>(Target); }
+LabelStmt *IndirectGotoStmt::getConstantTarget() {
+ if (AddrLabelExpr *E =
+ dyn_cast<AddrLabelExpr>(getTarget()->IgnoreParenImpCasts()))
+ return E->getLabel();
+ return 0;
+}
Stmt::child_iterator IndirectGotoStmt::child_begin() { return &Target; }
Stmt::child_iterator IndirectGotoStmt::child_end() { return &Target+1; }
diff --git a/lib/CodeGen/CGStmt.cpp b/lib/CodeGen/CGStmt.cpp
index 008c075..4de505a 100644
--- a/lib/CodeGen/CGStmt.cpp
+++ b/lib/CodeGen/CGStmt.cpp
@@ -297,6 +297,11 @@
void CodeGenFunction::EmitIndirectGotoStmt(const IndirectGotoStmt &S) {
+ if (const LabelStmt *Target = S.getConstantTarget()) {
+ EmitBranchThroughCleanup(getJumpDestForLabel(Target));
+ return;
+ }
+
// Ensure that we have an i8* for our PHI node.
llvm::Value *V = Builder.CreateBitCast(EmitScalarExpr(S.getTarget()),
llvm::Type::getInt8PtrTy(VMContext),
diff --git a/lib/Sema/JumpDiagnostics.cpp b/lib/Sema/JumpDiagnostics.cpp
index b23f615..bbe7bd5 100644
--- a/lib/Sema/JumpDiagnostics.cpp
+++ b/lib/Sema/JumpDiagnostics.cpp
@@ -186,6 +186,17 @@
break;
case Stmt::IndirectGotoStmtClass:
+ // "goto *&&lbl;" is a special case which we treat as equivalent
+ // to a normal goto. In addition, we don't calculate scope in the
+ // operand (to avoid recording the address-of-label use), which
+ // works only because of the restricted set of expressions which
+ // we detect as constant targets.
+ if (cast<IndirectGotoStmt>(S)->getConstantTarget()) {
+ LabelAndGotoScopes[S] = ParentScope;
+ Jumps.push_back(S);
+ return;
+ }
+
LabelAndGotoScopes[S] = ParentScope;
IndirectJumps.push_back(cast<IndirectGotoStmt>(S));
break;
@@ -341,6 +352,14 @@
continue;
}
+ // We only get indirect gotos here when they have a constant target.
+ if (IndirectGotoStmt *IGS = dyn_cast<IndirectGotoStmt>(Jump)) {
+ LabelStmt *Target = IGS->getConstantTarget();
+ CheckJump(IGS, Target, IGS->getGotoLoc(),
+ diag::err_goto_into_protected_scope);
+ continue;
+ }
+
SwitchStmt *SS = cast<SwitchStmt>(Jump);
for (SwitchCase *SC = SS->getSwitchCaseList(); SC;
SC = SC->getNextSwitchCase()) {
@@ -497,7 +516,7 @@
unsigned TargetScope) {
assert(JumpScope != TargetScope);
- S.Diag(Jump->getGotoLoc(), diag::warn_indirect_goto_in_protected_scope);
+ S.Diag(Jump->getGotoLoc(), diag::err_indirect_goto_in_protected_scope);
S.Diag(Target->getIdentLoc(), diag::note_indirect_goto_target);
unsigned Common = GetDeepestCommonScope(JumpScope, TargetScope);
diff --git a/test/Sema/scope-check.c b/test/Sema/scope-check.c
index 4ccb64c..1a2fc2b 100644
--- a/test/Sema/scope-check.c
+++ b/test/Sema/scope-check.c
@@ -133,7 +133,7 @@
void test9(int n, void *P) {
int Y;
int Z = 4;
- goto *P; // expected-warning {{indirect goto might cross protected scopes}}
+ goto *P; // expected-error {{indirect goto might cross protected scopes}}
L2: ;
int a[n]; // expected-note {{jump bypasses initialization of variable length array}}
@@ -199,3 +199,33 @@
a0: ;
static void *ps[] = { &&a0 };
}
+
+int test14(int n) {
+ static void *ps[] = { &&a0, &&a1 };
+ if (n < 0)
+ goto *&&a0;
+
+ if (n > 0) {
+ int vla[n];
+ a1:
+ vla[n-1] = 0;
+ }
+ a0:
+ return 0;
+}
+
+
+// PR8473: IR gen can't deal with indirect gotos past VLA
+// initialization, so that really needs to be a hard error.
+void test15(int n, void *pc) {
+ static const void *addrs[] = { &&L1, &&L2 };
+
+ goto *pc; // expected-error {{indirect goto might cross protected scope}}
+
+ L1:
+ {
+ char vla[n]; // expected-note {{jump bypasses initialization}}
+ L2: // expected-note {{possible target}}
+ vla[0] = 'a';
+ }
+}
diff --git a/test/SemaCXX/scope-check.cpp b/test/SemaCXX/scope-check.cpp
index cdc3868..d462af0 100644
--- a/test/SemaCXX/scope-check.cpp
+++ b/test/SemaCXX/scope-check.cpp
@@ -66,7 +66,7 @@
C c0;
- goto *ip; // expected-warning {{indirect goto might cross protected scopes}}
+ goto *ip; // expected-error {{indirect goto might cross protected scopes}}
C c1; // expected-note {{jump bypasses variable initialization}}
lbl1: // expected-note {{possible target of indirect goto}}
return 0;
@@ -90,7 +90,7 @@
if (ip[1]) {
D d; // expected-note {{jump exits scope of variable with non-trivial destructor}}
ip += 2;
- goto *ip; // expected-warning {{indirect goto might cross protected scopes}}
+ goto *ip; // expected-error {{indirect goto might cross protected scopes}}
}
return 1;
}