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Refine unreachable warnings. WIP. 

llvm-svn: 93500
This commit is contained in:
Mike Stump 2010-01-15 02:06:42 +00:00
parent 0e7e55da1d
commit 6a11229dc8
1 changed files with 87 additions and 4 deletions
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91
clang/lib/Sema/SemaDecl.cpp
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@ -1328,6 +1328,66 @@ static void MarkLive(CFGBlock *e, llvm::BitVector &live) {
}
}
static SourceLocation MarkLiveTop(CFGBlock *e, llvm::BitVector &live,
SourceManager &SM) {
std::queue<CFGBlock*> workq;
// Prep work queue
workq.push(e);
SourceLocation top;
if (!e->empty())
top = e[0][0].getStmt()->getLocStart();
bool FromMainFile = false;
bool FromSystemHeader = false;
bool TopValid = false;
if (top.isValid()) {
FromMainFile = SM.isFromMainFile(top);
FromSystemHeader = SM.isInSystemHeader(top);
TopValid = true;
}
// Solve
while (!workq.empty()) {
CFGBlock *item = workq.front();
workq.pop();
SourceLocation c;
if (!item->empty())
c = item[0][0].getStmt()->getLocStart();
else if (item->getTerminator())
c = item->getTerminator()->getLocStart();
if (c.isValid()
&& (!TopValid
|| (SM.isFromMainFile(c) && !FromMainFile)
|| (FromSystemHeader && !SM.isInSystemHeader(c))
|| SM.isBeforeInTranslationUnit(c, top))) {
top = c;
FromMainFile = SM.isFromMainFile(top);
FromSystemHeader = SM.isInSystemHeader(top);
}
live.set(item->getBlockID());
for (CFGBlock::succ_iterator I=item->succ_begin(),
E=item->succ_end();
I != E;
++I) {
if ((*I) && !live[(*I)->getBlockID()]) {
live.set((*I)->getBlockID());
workq.push(*I);
}
}
}
return top;
}
namespace {
class LineCmp {
SourceManager &SM;
public:
LineCmp(SourceManager &sm) : SM(sm) {
}
bool operator () (SourceLocation l1, SourceLocation l2) {
return l1 < l2;
}
};
}
/// CheckUnreachable - Check for unreachable code.
void Sema::CheckUnreachable(AnalysisContext &AC) {
// We avoid checking when there are errors, as the CFG won't faithfully match
@ -1345,15 +1405,38 @@ void Sema::CheckUnreachable(AnalysisContext &AC) {
// Mark all live things first.
MarkLive(&cfg->getEntry(), live);
llvm::SmallVector<SourceLocation, 24> lines;
// First, give warnings for blocks with no predecessors, as they
// can't be part of a loop.
for (CFG::iterator I = cfg->begin(), E = cfg->end(); I != E; ++I) {
CFGBlock &b = **I;
if (!live[b.getBlockID()]) {
if (!b.empty())
Diag(b[0].getStmt()->getLocStart(), diag::warn_unreachable);
// Avoid excessive errors by marking everything reachable from here
MarkLive(&b, live);
if (b.pred_begin() == b.pred_end()) {
if (!b.empty())
lines.push_back(b[0].getStmt()->getLocStart());
else if (b.getTerminator())
lines.push_back(b.getTerminator()->getLocStart());
// Avoid excessive errors by marking everything reachable from here
MarkLive(&b, live);
}
}
}
// And then give warnings for the tops of loops.
for (CFG::iterator I = cfg->begin(), E = cfg->end(); I != E; ++I) {
CFGBlock &b = **I;
if (!live[b.getBlockID()])
// Avoid excessive errors by marking everything reachable from here
lines.push_back(MarkLiveTop(&b, live, Context.getSourceManager()));
}
std::sort(lines.begin(), lines.end(), LineCmp(Context.getSourceManager()));
for (llvm::SmallVector<SourceLocation, 24>::iterator I = lines.begin(),
E = lines.end();
I != E;
++I)
if (I->isValid())
Diag(*I, diag::warn_unreachable);
}
/// CheckFallThrough - Check that we don't fall off the end of a