r370406 - [CFG] Fix CFG for statement-expressions in return values.
Artem Dergachev via cfe-commits
cfe-commits at lists.llvm.org
Thu Aug 29 13:37:28 PDT 2019
Author: dergachev
Date: Thu Aug 29 13:37:28 2019
New Revision: 370406
URL: http://llvm.org/viewvc/llvm-project?rev=370406&view=rev
Log:
[CFG] Fix CFG for statement-expressions in return values.
We're building the CFG from bottom to top, so when the return-value expression
has a non-trivial CFG on its own, we need to continue building from the entry
to the return-value expression CFG rather than from the block to which
we've just appended the return statement.
Fixes a false positive warning "control may reach end of non-void function".
Modified:
cfe/trunk/lib/Analysis/CFG.cpp
cfe/trunk/test/Analysis/cfg.cpp
cfe/trunk/test/Sema/return.c
Modified: cfe/trunk/lib/Analysis/CFG.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Analysis/CFG.cpp?rev=370406&r1=370405&r2=370406&view=diff
==============================================================================
--- cfe/trunk/lib/Analysis/CFG.cpp (original)
+++ cfe/trunk/lib/Analysis/CFG.cpp Thu Aug 29 13:37:28 2019
@@ -2994,9 +2994,8 @@ CFGBlock *CFGBuilder::VisitReturnStmt(St
// Visit children
if (ReturnStmt *RS = dyn_cast<ReturnStmt>(S)) {
- Expr *O = RS->getRetValue();
- if (O)
- Visit(O, AddStmtChoice::AlwaysAdd, /*ExternallyDestructed=*/true);
+ if (Expr *O = RS->getRetValue())
+ return Visit(O, AddStmtChoice::AlwaysAdd, /*ExternallyDestructed=*/true);
return Block;
} else { // co_return
return VisitChildren(S);
Modified: cfe/trunk/test/Analysis/cfg.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Analysis/cfg.cpp?rev=370406&r1=370405&r2=370406&view=diff
==============================================================================
--- cfe/trunk/test/Analysis/cfg.cpp (original)
+++ cfe/trunk/test/Analysis/cfg.cpp Thu Aug 29 13:37:28 2019
@@ -499,6 +499,54 @@ void foo() {
} // end namespace pr37688_deleted_union_destructor
+namespace return_statement_expression {
+int unknown();
+
+// CHECK-LABEL: int foo()
+// CHECK: [B6 (ENTRY)]
+// CHECK-NEXT: Succs (1): B5
+// CHECK: [B1]
+// CHECK-NEXT: 1: 0
+// CHECK-NEXT: 2: return [B1.1];
+// CHECK-NEXT: Preds (1): B5
+// CHECK-NEXT: Succs (1): B0
+// CHECK: [B2]
+// CHECK-NEXT: 1: 0
+// CHECK-NEXT: 2: ({ ... ; [B2.1] })
+// CHECK-NEXT: 3: return [B2.2];
+// CHECK-NEXT: Preds (1): B4
+// CHECK-NEXT: Succs (1): B0
+// FIXME: Why do we have [B3] at all?
+// CHECK: [B3]
+// CHECK-NEXT: Succs (1): B4
+// CHECK: [B4]
+// CHECK-NEXT: 1: 0
+// CHECK-NEXT: 2: [B4.1] (ImplicitCastExpr, IntegralToBoolean, _Bool)
+// CHECK-NEXT: T: while [B4.2]
+// CHECK-NEXT: Preds (2): B3 B5
+// CHECK-NEXT: Succs (2): NULL B2
+// CHECK: [B5]
+// CHECK-NEXT: 1: unknown
+// CHECK-NEXT: 2: [B5.1] (ImplicitCastExpr, FunctionToPointerDecay, int (*)(void))
+// CHECK-NEXT: 3: [B5.2]()
+// CHECK-NEXT: 4: [B5.3] (ImplicitCastExpr, IntegralToBoolean, _Bool)
+// CHECK-NEXT: T: if [B5.4]
+// CHECK-NEXT: Preds (1): B6
+// CHECK-NEXT: Succs (2): B4 B1
+// CHECK: [B0 (EXIT)]
+// CHECK-NEXT: Preds (2): B1 B2
+int foo() {
+ if (unknown())
+ return ({
+ while (0)
+ ;
+ 0;
+ });
+ else
+ return 0;
+}
+} // namespace statement_expression_in_return
+
// CHECK-LABEL: template<> int *PR18472<int>()
// CHECK: [B2 (ENTRY)]
// CHECK-NEXT: Succs (1): B1
@@ -522,4 +570,3 @@ template <class T> T *PR18472() {
void PR18472_helper() {
PR18472<int>();
}
-
Modified: cfe/trunk/test/Sema/return.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/return.c?rev=370406&r1=370405&r2=370406&view=diff
==============================================================================
--- cfe/trunk/test/Sema/return.c (original)
+++ cfe/trunk/test/Sema/return.c Thu Aug 29 13:37:28 2019
@@ -328,3 +328,14 @@ int sizeof_long() {
if (sizeof(long) == 8)
return 2;
} // no-warning
+
+int return_statement_expression() {
+ if (unknown())
+ return ({
+ while (0)
+ ;
+ 0;
+ });
+ else
+ return 0;
+} // no-warning (used to be "control may reach end of non-void function")
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