NoQ created this revision.
NoQ added reviewers: dcoughlin, xazax.hun, a.sidorin, george.karpenkov, szepet.
Herald added subscribers: cfe-commits, rnkovacs.
When a constructor with a single argument is treated as a functional cast
expression, skip the functional cast while finding the construction context.
Like https://reviews.llvm.org/D43477, this patch only adds new construction
contexts in cases where there is no destructor, which therefore has no
immediate effect on the analyzer. It allows us to find the
`MaterializeTemporaryExpr` in some extra cases, such as the newly added test
with `D &&d = D(1)`, which would help us with lifetime extension. But in case
of lifetime extension through a normal lvalue reference, we'd also have to
unwrap the no-op cast to `const`-object as well, which is something i'd follow
up with.
Repository:
rC Clang
https://reviews.llvm.org/D43480
Files:
lib/Analysis/CFG.cpp
test/Analysis/cfg-rich-constructors.cpp
Index: test/Analysis/cfg-rich-constructors.cpp
===================================================================
--- test/Analysis/cfg-rich-constructors.cpp
+++ test/Analysis/cfg-rich-constructors.cpp
@@ -105,7 +105,7 @@
C c = C::get();
}
-// TODO: Should find construction target for the three temporaries as well.
+// TODO: Should find construction target for the elidable constructors as well.
// CHECK: void simpleVariableWithTernaryOperator(bool coin)
// CHECK: [B1]
// CHECK-NEXT: 1: [B4.2] ? [B2.5] : [B3.6]
@@ -121,7 +121,7 @@
// CHECK: [B3]
// CHECK-NEXT: 1: 0
// CHECK-NEXT: 2: [B3.1] (ImplicitCastExpr, NullToPointer, class C *)
-// CHECK-NEXT: 3: [B3.2] (CXXConstructExpr, class C)
+// CHECK-NEXT: 3: [B3.2] (CXXConstructExpr, [B3.5], class C)
// CHECK-NEXT: 4: C([B3.3]) (CXXFunctionalCastExpr, ConstructorConversion, class C)
// CHECK-NEXT: 5: [B3.4]
// CHECK-NEXT: 6: [B3.5] (CXXConstructExpr, class C)
@@ -133,6 +133,18 @@
C c = coin ? C::get() : C(0);
}
+// CHECK: void simpleVariableWithElidableCopy()
+// CHECK: 1: 0
+// CHECK-NEXT: 2: [B1.1] (ImplicitCastExpr, NullToPointer, class C *)
+// CHECK-NEXT: 3: [B1.2] (CXXConstructExpr, [B1.5], class C)
+// CHECK-NEXT: 4: C([B1.3]) (CXXFunctionalCastExpr, ConstructorConversion, class C)
+// CHECK-NEXT: 5: [B1.4]
+// CHECK-NEXT: 6: [B1.5] (CXXConstructExpr, [B1.7], class C)
+// CHECK-NEXT: 7: C c = C(0);
+void simpleVariableWithElidableCopy() {
+ C c = C(0);
+}
+
// CHECK: void referenceVariableWithConstructor()
// CHECK: 1: 0
// CHECK-NEXT: 2: [B1.1] (ImplicitCastExpr, NullToPointer, class C *)
@@ -153,7 +165,7 @@
const C &c = C();
}
-// TODO: Should find construction targets here.
+// TODO: Should find construction targets for the elidable constructors as well.
// CHECK: void referenceVariableWithTernaryOperator(bool coin)
// CHECK: [B1]
// CHECK-NEXT: 1: [B4.2] ? [B2.5] : [B3.6]
@@ -169,7 +181,7 @@
// CHECK: [B3]
// CHECK-NEXT: 1: 0
// CHECK-NEXT: 2: [B3.1] (ImplicitCastExpr, NullToPointer, class C *)
-// CHECK-NEXT: 3: [B3.2] (CXXConstructExpr, class C)
+// CHECK-NEXT: 3: [B3.2] (CXXConstructExpr, [B3.5], class C)
// CHECK-NEXT: 4: C([B3.3]) (CXXFunctionalCastExpr, ConstructorConversion, class C)
// CHECK-NEXT: 5: [B3.4]
// CHECK-NEXT: 6: [B3.5] (CXXConstructExpr, class C)
@@ -275,11 +287,10 @@
return C();
}
-// TODO: Should find construction targets for the first constructor as well.
// CHECK: C returnTemporaryWithArgument()
// CHECK: 1: nullptr
// CHECK-NEXT: 2: [B1.1] (ImplicitCastExpr, NullToPointer, class C *)
-// CHECK-NEXT: 3: [B1.2] (CXXConstructExpr, class C)
+// CHECK-NEXT: 3: [B1.2] (CXXConstructExpr, [B1.5], class C)
// CHECK-NEXT: 4: C([B1.3]) (CXXFunctionalCastExpr, ConstructorConversion, class C)
// CHECK-NEXT: 5: [B1.4]
// CHECK-NEXT: 6: [B1.5] (CXXConstructExpr, [B1.7], class C)
@@ -299,13 +310,12 @@
return C::get();
}
-// TODO: Should find construction targets for the first constructor as well.
// CHECK: C returnChainOfCopies()
// CHECK: 1: C::get
// CHECK-NEXT: 2: [B1.1] (ImplicitCastExpr, FunctionToPointerDecay, class C (*)(void))
// CHECK-NEXT: 3: [B1.2]()
// CHECK-NEXT: 4: [B1.3]
-// CHECK-NEXT: 5: [B1.4] (CXXConstructExpr, class C)
+// CHECK-NEXT: 5: [B1.4] (CXXConstructExpr, [B1.7], class C)
// CHECK-NEXT: 6: C([B1.5]) (CXXFunctionalCastExpr, ConstructorConversion, class C)
// CHECK-NEXT: 7: [B1.6]
// CHECK-NEXT: 8: [B1.7] (CXXConstructExpr, [B1.9], class C)
@@ -450,4 +460,16 @@
void referenceVariableWithTernaryOperator(bool coin) {
const D &d = coin ? D::get() : D(0);
}
+
+// CHECK: void referenceWithFunctionalCast()
+// CHECK: 1: 1
+// CHECK-NEXT: 2: [B1.1] (CXXConstructExpr, [B1.3], [B1.5], class temporary_object_expr_with_dtors::D)
+// CHECK-NEXT: 3: [B1.2] (BindTemporary)
+// CHECK-NEXT: 4: temporary_object_expr_with_dtors::D([B1.3]) (CXXFunctionalCastExpr, ConstructorCon
+// CHECK-NEXT: 5: [B1.4]
+// CHECK-NEXT: 6: temporary_object_expr_with_dtors::D &&d = temporary_object_expr_with_dtors::D(1);
+// CHECK-NEXT: 7: [B1.6].~D() (Implicit destructor)
+void referenceWithFunctionalCast() {
+ D &&d = D(1);
+}
} // end namespace temporary_object_expr_with_dtors
Index: lib/Analysis/CFG.cpp
===================================================================
--- lib/Analysis/CFG.cpp
+++ lib/Analysis/CFG.cpp
@@ -1168,6 +1168,8 @@
}
} else if (auto *Cleanups = dyn_cast<ExprWithCleanups>(Child)) {
findConstructionContexts(ContextSoFar, Cleanups->getSubExpr());
+ } else if (auto *Cast = dyn_cast<CXXFunctionalCastExpr>(Child)) {
+ findConstructionContexts(ContextSoFar, Cast->getSubExpr());
} else if (auto *BTE = dyn_cast<CXXBindTemporaryExpr>(Child)) {
findConstructionContexts(
ConstructionContext::create(cfg->getBumpVectorContext(), BTE,
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