[PATCH] D114848: [Analysis] Ignore casts and unary ops for uninitialized values
Bill Wendling via Phabricator via cfe-commits
cfe-commits at lists.llvm.org
Tue Dec 7 11:49:44 PST 2021
This revision was automatically updated to reflect the committed changes.
Closed by commit rGc4582a689c2c: [Analysis] Ignore casts and unary ops for uninitialized values (authored by void).
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D114848/new/
https://reviews.llvm.org/D114848
Files:
clang/lib/Analysis/UninitializedValues.cpp
clang/test/Analysis/uninit-asm-goto.cpp
Index: clang/test/Analysis/uninit-asm-goto.cpp
===================================================================
--- clang/test/Analysis/uninit-asm-goto.cpp
+++ clang/test/Analysis/uninit-asm-goto.cpp
@@ -57,3 +57,15 @@
indirect:
return -2;
}
+
+// test6: Expect no diagnostics.
+int test6(unsigned int *x) {
+ unsigned int val;
+
+ // See through casts and unary operators.
+ asm goto("nop" : "=r" (*(unsigned int *)(&val)) ::: indirect);
+ *x = val;
+ return 0;
+indirect:
+ return -1;
+}
Index: clang/lib/Analysis/UninitializedValues.cpp
===================================================================
--- clang/lib/Analysis/UninitializedValues.cpp
+++ clang/lib/Analysis/UninitializedValues.cpp
@@ -591,8 +591,8 @@
if (AtPredExit == MayUninitialized) {
// If the predecessor's terminator is an "asm goto" that initializes
- // the variable, then it won't be counted as "initialized" on the
- // non-fallthrough paths.
+ // the variable, then don't count it as "initialized" on the indirect
+ // paths.
CFGTerminator term = Pred->getTerminator();
if (const auto *as = dyn_cast_or_null<GCCAsmStmt>(term.getStmt())) {
const CFGBlock *fallthrough = *Pred->succ_begin();
@@ -810,13 +810,22 @@
if (!as->isAsmGoto())
return;
- for (const Expr *o : as->outputs())
- if (const VarDecl *VD = findVar(o).getDecl())
+ ASTContext &C = ac.getASTContext();
+ for (const Expr *O : as->outputs()) {
+ const Expr *Ex = stripCasts(C, O);
+
+ // Strip away any unary operators. Invalid l-values are reported by other
+ // semantic analysis passes.
+ while (const auto *UO = dyn_cast<UnaryOperator>(Ex))
+ Ex = stripCasts(C, UO->getSubExpr());
+
+ if (const VarDecl *VD = findVar(Ex).getDecl())
if (vals[VD] != Initialized)
// If the variable isn't initialized by the time we get here, then we
// mark it as potentially uninitialized for those cases where it's used
// on an indirect path, where it's not guaranteed to be defined.
vals[VD] = MayUninitialized;
+ }
}
void TransferFunctions::VisitObjCMessageExpr(ObjCMessageExpr *ME) {
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