r204430 - [-Wunreachable-code] add a specialized diagnostic for unreachable increment expressions of loops.
Ted Kremenek
kremenek at apple.com
Thu Mar 20 23:02:36 PDT 2014
Author: kremenek
Date: Fri Mar 21 01:02:36 2014
New Revision: 204430
URL: http://llvm.org/viewvc/llvm-project?rev=204430&view=rev
Log:
[-Wunreachable-code] add a specialized diagnostic for unreachable increment expressions of loops.
Modified:
cfe/trunk/include/clang/Analysis/Analyses/ReachableCode.h
cfe/trunk/include/clang/Basic/DiagnosticGroups.td
cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
cfe/trunk/lib/Analysis/ReachableCode.cpp
cfe/trunk/lib/Sema/AnalysisBasedWarnings.cpp
cfe/trunk/test/SemaCXX/unreachable-code.cpp
cfe/trunk/test/SemaCXX/warn-unreachable.cpp
cfe/trunk/test/SemaObjC/warn-unreachable.m
Modified: cfe/trunk/include/clang/Analysis/Analyses/ReachableCode.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Analysis/Analyses/ReachableCode.h?rev=204430&r1=204429&r2=204430&view=diff
==============================================================================
--- cfe/trunk/include/clang/Analysis/Analyses/ReachableCode.h (original)
+++ cfe/trunk/include/clang/Analysis/Analyses/ReachableCode.h Fri Mar 21 01:02:36 2014
@@ -41,6 +41,7 @@ namespace reachable_code {
enum UnreachableKind {
UK_Return,
UK_Break,
+ UK_Loop_Increment,
UK_Other
};
Modified: cfe/trunk/include/clang/Basic/DiagnosticGroups.td
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticGroups.td?rev=204430&r1=204429&r2=204430&view=diff
==============================================================================
--- cfe/trunk/include/clang/Basic/DiagnosticGroups.td (original)
+++ cfe/trunk/include/clang/Basic/DiagnosticGroups.td Fri Mar 21 01:02:36 2014
@@ -430,7 +430,9 @@ def DuplicateArgDecl : DiagGroup<"duplic
// least actively used, with more noisy versions of the warning covered
// under separate flags.
//
-def UnreachableCode : DiagGroup<"unreachable-code">;
+def UnreachableCodeLoopIncrement : DiagGroup<"unreachable-code-loop-increment">;
+def UnreachableCode : DiagGroup<"unreachable-code",
+ [UnreachableCodeLoopIncrement]>;
def UnreachableCodeBreak : DiagGroup<"unreachable-code-break">;
def UnreachableCodeReturn : DiagGroup<"unreachable-code-return">;
def UnreachableCodeAggressive : DiagGroup<"unreachable-code-aggressive",
Modified: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td?rev=204430&r1=204429&r2=204430&view=diff
==============================================================================
--- cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td (original)
+++ cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td Fri Mar 21 01:02:36 2014
@@ -370,6 +370,9 @@ def warn_unreachable_break : Warning<
def warn_unreachable_return : Warning<
"'return' will never be executed">,
InGroup<UnreachableCodeReturn>, DefaultIgnore;
+def warn_unreachable_loop_increment : Warning<
+ "loop will run at most once (loop increment never executed)">,
+ InGroup<UnreachableCodeLoopIncrement>, DefaultIgnore;
/// Built-in functions.
def ext_implicit_lib_function_decl : ExtWarn<
Modified: cfe/trunk/lib/Analysis/ReachableCode.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Analysis/ReachableCode.cpp?rev=204430&r1=204429&r2=204430&view=diff
==============================================================================
--- cfe/trunk/lib/Analysis/ReachableCode.cpp (original)
+++ cfe/trunk/lib/Analysis/ReachableCode.cpp Fri Mar 21 01:02:36 2014
@@ -529,6 +529,26 @@ void DeadCodeScan::reportDeadCode(const
UK = reachable_code::UK_Return;
}
+ if (UK == reachable_code::UK_Other) {
+ // Check if the dead code is part of the "loop target" of
+ // a for/for-range loop. This is the block that contains
+ // the increment code.
+ if (const Stmt *LoopTarget = B->getLoopTarget()) {
+ SourceLocation Loc = LoopTarget->getLocStart();
+ SourceRange R1(Loc, Loc), R2;
+
+ if (const ForStmt *FS = dyn_cast<ForStmt>(LoopTarget)) {
+ const Expr *Inc = FS->getInc();
+ Loc = Inc->getLocStart();
+ R2 = Inc->getSourceRange();
+ }
+
+ CB.HandleUnreachable(reachable_code::UK_Loop_Increment,
+ Loc, SourceRange(Loc, Loc), R2);
+ return;
+ }
+ }
+
SourceRange R1, R2;
SourceLocation Loc = GetUnreachableLoc(S, R1, R2);
CB.HandleUnreachable(UK, Loc, R1, R2);
Modified: cfe/trunk/lib/Sema/AnalysisBasedWarnings.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/AnalysisBasedWarnings.cpp?rev=204430&r1=204429&r2=204430&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/AnalysisBasedWarnings.cpp (original)
+++ cfe/trunk/lib/Sema/AnalysisBasedWarnings.cpp Fri Mar 21 01:02:36 2014
@@ -76,6 +76,9 @@ namespace {
case reachable_code::UK_Return:
diag = diag::warn_unreachable_return;
break;
+ case reachable_code::UK_Loop_Increment:
+ diag = diag::warn_unreachable_loop_increment;
+ break;
case reachable_code::UK_Other:
break;
}
@@ -1688,7 +1691,8 @@ clang::sema::AnalysisBasedWarnings::Anal
DefaultPolicy.enableCheckUnreachable =
isEnabled(D, warn_unreachable) ||
isEnabled(D, warn_unreachable_break) ||
- isEnabled(D, warn_unreachable_return);
+ isEnabled(D, warn_unreachable_return) ||
+ isEnabled(D, warn_unreachable_loop_increment);
DefaultPolicy.enableThreadSafetyAnalysis =
isEnabled(D, warn_double_lock);
Modified: cfe/trunk/test/SemaCXX/unreachable-code.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/unreachable-code.cpp?rev=204430&r1=204429&r2=204430&view=diff
==============================================================================
--- cfe/trunk/test/SemaCXX/unreachable-code.cpp (original)
+++ cfe/trunk/test/SemaCXX/unreachable-code.cpp Fri Mar 21 01:02:36 2014
@@ -5,7 +5,7 @@ int bar();
int test1() {
for (int i = 0;
i != 10;
- ++i) { // expected-warning {{will never be executed}}
+ ++i) { // expected-warning {{loop will run at most once (loop increment never executed)}}
if (j == 23) // missing {}'s
bar();
return 1;
@@ -17,7 +17,7 @@ int test1() {
int test1_B() {
for (int i = 0;
i != 10;
- ++i) { // expected-warning {{will never be executed}}
+ ++i) { // expected-warning {{loop will run at most once (loop increment never executed)}}
if (j == 23) // missing {}'s
bar();
return 1;
Modified: cfe/trunk/test/SemaCXX/warn-unreachable.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/warn-unreachable.cpp?rev=204430&r1=204429&r2=204430&view=diff
==============================================================================
--- cfe/trunk/test/SemaCXX/warn-unreachable.cpp (original)
+++ cfe/trunk/test/SemaCXX/warn-unreachable.cpp Fri Mar 21 01:02:36 2014
@@ -282,3 +282,15 @@ void test_static_class_var(Frodo &F) {
somethingToCall(); // no-warning
}
+void test_unreachable_for_null_increment() {
+ for (unsigned i = 0; i < 10 ; ) // no-warning
+ break;
+}
+
+void test_unreachable_forrange_increment() {
+ int x[10] = { 0 };
+ for (auto i : x) { // expected-warning {{loop will run at most once (loop increment never executed)}}
+ break;
+ }
+}
+
Modified: cfe/trunk/test/SemaObjC/warn-unreachable.m
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaObjC/warn-unreachable.m?rev=204430&r1=204429&r2=204430&view=diff
==============================================================================
--- cfe/trunk/test/SemaObjC/warn-unreachable.m (original)
+++ cfe/trunk/test/SemaObjC/warn-unreachable.m Fri Mar 21 01:02:36 2014
@@ -40,3 +40,12 @@ int test_CONFIG() {
else
return 0;
}
+
+// FIXME: This should at some point report a warning
+// that the loop increment is unreachable.
+void test_loop_increment(id container) {
+ for (id x in container) { // no-warning
+ break;
+ }
+}
+
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