diff --git a/clang/lib/Analysis/UninitializedValues.cpp b/clang/lib/Analysis/UninitializedValues.cpp --- a/clang/lib/Analysis/UninitializedValues.cpp +++ b/clang/lib/Analysis/UninitializedValues.cpp @@ -576,6 +576,28 @@ continue; } + 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. + CFGTerminator term = Pred->getTerminator(); + if (const auto *as = dyn_cast_or_null(term.getStmt())) { + const CFGBlock *fallthrough = *Pred->succ_begin(); + if (as->isAsmGoto() && + llvm::any_of(as->outputs(), [&](const Expr *output) { + return vd == findVar(output).getDecl() && + llvm::any_of(as->labels(), + [&](const AddrLabelExpr *label) { + return label->getLabel()->getStmt() == B->Label && + B != fallthrough; + }); + })) { + Use.setUninitAfterDecl(); + continue; + } + } + } + unsigned &SV = SuccsVisited[Pred->getBlockID()]; if (!SV) { // When visiting the first successor of a block, mark all NULL @@ -768,7 +790,11 @@ for (const Expr *o : as->outputs()) if (const VarDecl *VD = findVar(o).getDecl()) - vals[VD] = Initialized; + 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) { @@ -809,7 +835,7 @@ tf.Visit(const_cast(cs->getStmt())); } CFGTerminator terminator = block->getTerminator(); - if (GCCAsmStmt *as = dyn_cast_or_null(terminator.getStmt())) + if (auto *as = dyn_cast_or_null(terminator.getStmt())) if (as->isAsmGoto()) tf.Visit(as); return vals.updateValueVectorWithScratch(block); diff --git a/clang/test/Analysis/uninit-asm-goto.cpp b/clang/test/Analysis/uninit-asm-goto.cpp --- a/clang/test/Analysis/uninit-asm-goto.cpp +++ b/clang/test/Analysis/uninit-asm-goto.cpp @@ -1,6 +1,6 @@ // RUN: %clang_cc1 -std=c++11 -Wuninitialized -verify %s -// expected-no-diagnostics +// test1: Expect no diagnostics int test1(int x) { int y; asm goto("nop" : "=r"(y) : "r"(x) : : err); @@ -8,3 +8,52 @@ err: return -1; } + +int test2(int x) { + int y; // expected-warning {{variable 'y' is used uninitialized whenever its declaration is reached}} \ + // expected-note {{initialize the variable}} + if (x < 42) + asm volatile goto("testl %0, %0; testl %1, %2; jne %l3" : "+S"(x), "+D"(y) : "r"(x) :: indirect_1, indirect_2); + else + asm volatile goto("testl %0, %1; testl %2, %3; jne %l5" : "+S"(x), "+D"(y) : "r"(x), "r"(y) :: indirect_1, indirect_2); + return x + y; +indirect_1: + return -42; +indirect_2: + return y; // expected-note {{uninitialized use occurs here}} +} + +int test3(int x) { + int y; // expected-warning {{variable 'y' is used uninitialized whenever its declaration is reached}} \ + // expected-note {{initialize the variable}} + asm goto("xorl %1, %0; jmp %l2" : "=&r"(y) : "r"(x) : : fail); +normal: + y += x; + return y; + if (x) { +fail: + return y; // expected-note {{uninitialized use occurs here}} + } + return 0; +} + +int test4(int x) { + int y; // expected-warning {{variable 'y' is used uninitialized whenever its declaration is reached}} \ + // expected-note {{initialize the variable}} + goto forward; +backward: + return y; // expected-note {{uninitialized use occurs here}} +forward: + asm goto("# %0 %1 %2" : "=r"(y) : "r"(x) : : backward); + return y; +} + +// test5: Expect no diagnostics +int test5(int x) { + int y; + asm volatile goto("testl %0, %0; testl %1, %2; jne %l3" : "+S"(x), "+D"(y) : "r"(x) :: indirect, fallthrough); +fallthrough: + return y; +indirect: + return -2; +}