diff options
| -rw-r--r-- | lib/Analysis/CheckDeadStores.cpp | 17 | ||||
| -rw-r--r-- | test/Analysis/dead-stores.c | 16 |
2 files changed, 31 insertions, 2 deletions
diff --git a/lib/Analysis/CheckDeadStores.cpp b/lib/Analysis/CheckDeadStores.cpp index d5e5f4c9b2..504de3c97d 100644 --- a/lib/Analysis/CheckDeadStores.cpp +++ b/lib/Analysis/CheckDeadStores.cpp @@ -195,8 +195,21 @@ public: // If x is EVER assigned a new value later, don't issue // a warning. This is because such initialization can be // due to defensive programming. - if (!E->isConstantInitializer(Ctx)) - Report(V, DeadInit, V->getLocation(), E->getSourceRange()); + if (E->isConstantInitializer(Ctx)) + return; + + // Special case: check for initializations from constant + // variables. + // + // e.g. extern const int MyConstant; + // int x = MyConstant; + // + if (DeclRefExpr *DRE=dyn_cast<DeclRefExpr>(E->IgnoreParenCasts())) + if (VarDecl *VD = dyn_cast<VarDecl>(DRE->getDecl())) + if (VD->hasGlobalStorage() && + VD->getType().isConstQualified()) return; + + Report(V, DeadInit, V->getLocation(), E->getSourceRange()); } } } diff --git a/test/Analysis/dead-stores.c b/test/Analysis/dead-stores.c index c72bdcf2b4..7d7b369637 100644 --- a/test/Analysis/dead-stores.c +++ b/test/Analysis/dead-stores.c @@ -147,3 +147,19 @@ int f18() { return (x = 10); // expected-warning{{Although the value stored to 'x' is used in the enclosing expression, the value is never actually read from 'x'}} } + +// PR 3514: false positive `dead initialization` warning for init to global +// http://llvm.org/bugs/show_bug.cgi?id=3514 +extern const int MyConstant; +int f19(void) { + int x = MyConstant; // no-warning + x = 1; + return x; +} + +int f19b(void) { // FIXME: Should this case be considered the same as f19? + const int MyConstant = 0; + int x = MyConstant; // expected-warning{{never read}} + x = 1; + return x; +} |