[PATCH] D71314: Emit a warning if a variable is uninitialized in indirect ASM goto destination.
Bill Wendling via Phabricator via cfe-commits
cfe-commits at lists.llvm.org
Thu Dec 12 23:19:49 PST 2019
void updated this revision to Diff 233738.
void marked 3 inline comments as done.
void added a comment.
Use "any_of" and improve tests.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D71314/new/
https://reviews.llvm.org/D71314
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
@@ -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("# %0 %1 %2" : "=r"(y) : "r"(x) : : err);
@@ -8,3 +8,42 @@
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;
+}
Index: clang/lib/Analysis/UninitializedValues.cpp
===================================================================
--- clang/lib/Analysis/UninitializedValues.cpp
+++ clang/lib/Analysis/UninitializedValues.cpp
@@ -637,6 +637,26 @@
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 (GCCAsmStmt *as = dyn_cast_or_null<GCCAsmStmt>(term.getStmt())) {
+ 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;
+ });
+ })) {
+ Use.setUninitAfterDecl();
+ continue;
+ }
+ }
+ }
+
unsigned &SV = SuccsVisited[Pred->getBlockID()];
if (!SV) {
// When visiting the first successor of a block, mark all NULL
@@ -829,7 +849,8 @@
for (const auto &o : as->outputs())
if (const VarDecl *VD = findVar(o).getDecl())
- vals[VD] = Initialized;
+ if (vals[VD] != Initialized)
+ vals[VD] = MayUninitialized;
}
void TransferFunctions::VisitObjCMessageExpr(ObjCMessageExpr *ME) {
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