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Mark successors as reachable/unreachable instead of changing the CFG. 

As suggested by Ted, this makes a few warnings less aggressive.

llvm-svn: 215128
This commit is contained in:
Manuel Klimek 2014-08-07 18:44:19 +00:00
parent 1b9f936f91
commit edf925b935
2 changed files with 22 additions and 35 deletions
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51
clang/lib/Analysis/CFG.cpp
View File

@ -479,6 +479,7 @@ private:
AbstractConditionalOperator *E, bool BindToTemporary,
TempDtorContext &Context);
void InsertTempDtorDecisionBlock(const TempDtorContext &Context,
TryResult ConditionVal,
CFGBlock *FalseSucc = nullptr);
// NYS == Not Yet Supported
@ -3631,24 +3632,16 @@ CFGBlock *CFGBuilder::VisitBinaryOperatorForTemporaryDtors(
BinaryOperator *E, TempDtorContext &Context) {
if (E->isLogicalOp()) {
VisitForTemporaryDtors(E->getLHS(), false, Context);
TryResult LHSVal = tryEvaluateBool(E->getLHS());
bool RHSNotExecuted = (E->getOpcode() == BO_LAnd && LHSVal.isFalse()) ||
(E->getOpcode() == BO_LOr && LHSVal.isTrue());
if (RHSNotExecuted) {
return Block;
}
TryResult RHSExecuted = tryEvaluateBool(E->getLHS());
if (RHSExecuted.isKnown() && E->getOpcode() == BO_LOr)
RHSExecuted.negate();
// If the LHS is known, and the RHS is not executed, we returned above.
// Thus, once we arrive here, and the LHS is known, we also know that the
// RHS was executed and can execute the RHS unconditionally (that is, we
// don't insert a decision block).
if (LHSVal.isKnown()) {
VisitForTemporaryDtors(E->getRHS(), false, Context);
} else {
TempDtorContext RHSContext(/*IsConditional=*/true);
VisitForTemporaryDtors(E->getRHS(), false, RHSContext);
InsertTempDtorDecisionBlock(RHSContext);
}
// We do not know at CFG-construction time whether the right-hand-side was
// executed, thus we add a branch node that depends on the temporary
// constructor call.
TempDtorContext RHSContext(/*IsConditional=*/true);
VisitForTemporaryDtors(E->getRHS(), false, RHSContext);
InsertTempDtorDecisionBlock(RHSContext, RHSExecuted);
return Block;
}
@ -3705,6 +3698,7 @@ CFGBlock *CFGBuilder::VisitCXXBindTemporaryExprForTemporaryDtors(
}
void CFGBuilder::InsertTempDtorDecisionBlock(const TempDtorContext &Context,
TryResult ConditionVal,
CFGBlock *FalseSucc) {
if (!Context.TerminatorExpr) {
// If no temporary was found, we do not need to insert a decision point.
@ -3713,8 +3707,9 @@ void CFGBuilder::InsertTempDtorDecisionBlock(const TempDtorContext &Context,
assert(Context.TerminatorExpr);
CFGBlock *Decision = createBlock(false);
Decision->setTerminator(CFGTerminator(Context.TerminatorExpr, true));
addSuccessor(Decision, Block);
addSuccessor(Decision, FalseSucc ? FalseSucc : Context.Succ);
addSuccessor(Decision, Block, !ConditionVal.isFalse());
addSuccessor(Decision, FalseSucc ? FalseSucc : Context.Succ,
!ConditionVal.isTrue());
Block = Decision;
}
@ -3725,16 +3720,8 @@ CFGBlock *CFGBuilder::VisitConditionalOperatorForTemporaryDtors(
CFGBlock *ConditionBlock = Block;
CFGBlock *ConditionSucc = Succ;
TryResult ConditionVal = tryEvaluateBool(E->getCond());
if (ConditionVal.isKnown()) {
if (ConditionVal.isTrue()) {
VisitForTemporaryDtors(E->getTrueExpr(), BindToTemporary, Context);
} else {
assert(ConditionVal.isFalse());
VisitForTemporaryDtors(E->getFalseExpr(), BindToTemporary, Context);
}
return Block;
}
TryResult NegatedVal = ConditionVal;
if (NegatedVal.isKnown()) NegatedVal.negate();
TempDtorContext TrueContext(/*IsConditional=*/true);
VisitForTemporaryDtors(E->getTrueExpr(), BindToTemporary, TrueContext);
@ -3746,12 +3733,12 @@ CFGBlock *CFGBuilder::VisitConditionalOperatorForTemporaryDtors(
VisitForTemporaryDtors(E->getFalseExpr(), BindToTemporary, FalseContext);
if (TrueContext.TerminatorExpr && FalseContext.TerminatorExpr) {
InsertTempDtorDecisionBlock(FalseContext, TrueBlock);
InsertTempDtorDecisionBlock(FalseContext, NegatedVal, TrueBlock);
} else if (TrueContext.TerminatorExpr) {
Block = TrueBlock;
InsertTempDtorDecisionBlock(TrueContext);
InsertTempDtorDecisionBlock(TrueContext, ConditionVal);
} else {
InsertTempDtorDecisionBlock(FalseContext);
InsertTempDtorDecisionBlock(FalseContext, NegatedVal);
}
return Block;
}

6
clang/test/SemaCXX/return-noreturn.cpp
View File

@ -185,11 +185,11 @@ int testTernaryConditionalNoreturnFalseBranch(bool value) {
int testConditionallyExecutedComplexTernaryTrueBranch(bool value) {
value || (true ? NoReturn() : true);
} // expected-warning {{control may reach end of non-void function}}
}
int testConditionallyExecutedComplexTernaryFalseBranch(bool value) {
value || (false ? true : NoReturn());
} // expected-warning {{control may reach end of non-void function}}
}
int testStaticallyExecutedLogicalOrBranch() {
false || NoReturn();
@ -209,7 +209,7 @@ int testStaticallySkppedLogicalAndBranch() {
int testConditionallyExecutedComplexLogicalBranch(bool value) {
value || (true && NoReturn());
} // expected-warning {{control may reach end of non-void function}}
}
#if __cplusplus >= 201103L
namespace LambdaVsTemporaryDtor {