baloghadamsoftware created this revision.
baloghadamsoftware added reviewers: NoQ, szepet, Szelethus.
baloghadamsoftware added a project: clang.
Herald added subscribers: Charusso, gamesh411, donat.nagy, mikhail.ramalho,
dmgreen, a.sidorin, zzheng, rnkovacs, xazax.hun, whisperity.
For-loops with a variable upper boundary do not differ very much from for-loops
with integer literals if the value of the variable is known. Unroll these loops
as well, similarly to them. This was a TODO anyway.
Repository:
rC Clang
https://reviews.llvm.org/D63279
Files:
lib/StaticAnalyzer/Core/LoopUnrolling.cpp
test/Analysis/loop-unrolling.cpp
Index: test/Analysis/loop-unrolling.cpp
===================================================================
--- test/Analysis/loop-unrolling.cpp
+++ test/Analysis/loop-unrolling.cpp
@@ -499,3 +499,15 @@
clang_analyzer_numTimesReached(); // expected-warning {{6}}
}
}
+
+int unroll_known_value_of_variable() {
+ int a[9];
+ int k = 42;
+ int n = 9;
+ for (int i = 0; i < n; i++) {
+ clang_analyzer_numTimesReached(); // expected-warning {{9}}
+ a[i] = 42;
+ }
+ int b = 22 / (k - 42); // expected-warning {{Division by zero}}
+ return 0;
+}
Index: lib/StaticAnalyzer/Core/LoopUnrolling.cpp
===================================================================
--- lib/StaticAnalyzer/Core/LoopUnrolling.cpp
+++ lib/StaticAnalyzer/Core/LoopUnrolling.cpp
@@ -84,9 +84,8 @@
hasOperatorName("<="), hasOperatorName(">="),
hasOperatorName("!=")),
hasEitherOperand(ignoringParenImpCasts(declRefExpr(
-
to(varDecl(hasType(isInteger())).bind(BindName))))),
- hasEitherOperand(ignoringParenImpCasts(
- integerLiteral().bind("boundNum"))))
+ to(varDecl(hasType(isInteger())).bind(BindName)))
+ .bind("boundVarOperand"))))
.bind("conditionOperator");
}
@@ -200,18 +199,40 @@
if (!isLoopStmt(LoopStmt))
return false;
- // TODO: Match the cases where the bound is not a concrete literal but an
- // integer with known value
auto Matches = match(forLoopMatcher(), *LoopStmt, ASTCtx);
if (Matches.empty())
return false;
+ const auto State = Pred->getState();
+ auto &SVB = State->getStateManager().getSValBuilder();
+
auto CounterVar = Matches[0].getNodeAs<VarDecl>("initVarName");
- llvm::APInt BoundNum =
- Matches[0].getNodeAs<IntegerLiteral>("boundNum")->getValue();
llvm::APInt InitNum =
Matches[0].getNodeAs<IntegerLiteral>("initNum")->getValue();
auto CondOp = Matches[0].getNodeAs<BinaryOperator>("conditionOperator");
+
+ const Expr *BoundExpr = CondOp->getLHS()->IgnoreParenImpCasts();
+ if (BoundExpr == Matches[0].getNodeAs<Expr>("boundVarOperand"))
+ BoundExpr = CondOp->getRHS()->IgnoreParenImpCasts();
+ SVal BoundNumVal = Pred->getSVal(BoundExpr);
+
+ // If the value of the expression is unknown and it is a declaration
+ // reference then try to get the value of the declaration instead
+ if (BoundNumVal.isUnknown()) {
+ if (const auto *BoundDeclRefExpr = dyn_cast<DeclRefExpr>(BoundExpr)) {
+ // FIXME: Add other declarations such as Objective-C fields
+ if (const auto *BoundVarDecl =
+ dyn_cast<VarDecl>(BoundDeclRefExpr->getDecl())) {
+ BoundNumVal = State->getSVal(
+ State->getLValue(BoundVarDecl, Pred->getLocationContext()));
+ }
+ }
+ }
+ const llvm::APSInt *BoundNumPtr = SVB.getKnownValue(State, BoundNumVal);
+ if (!BoundNumPtr)
+ return false;
+ llvm::APInt BoundNum = *BoundNumPtr;
+
if (InitNum.getBitWidth() != BoundNum.getBitWidth()) {
InitNum = InitNum.zextOrSelf(BoundNum.getBitWidth());
BoundNum = BoundNum.zextOrSelf(InitNum.getBitWidth());
Index: test/Analysis/loop-unrolling.cpp
===================================================================
--- test/Analysis/loop-unrolling.cpp
+++ test/Analysis/loop-unrolling.cpp
@@ -499,3 +499,15 @@
clang_analyzer_numTimesReached(); // expected-warning {{6}}
}
}
+
+int unroll_known_value_of_variable() {
+ int a[9];
+ int k = 42;
+ int n = 9;
+ for (int i = 0; i < n; i++) {
+ clang_analyzer_numTimesReached(); // expected-warning {{9}}
+ a[i] = 42;
+ }
+ int b = 22 / (k - 42); // expected-warning {{Division by zero}}
+ return 0;
+}
Index: lib/StaticAnalyzer/Core/LoopUnrolling.cpp
===================================================================
--- lib/StaticAnalyzer/Core/LoopUnrolling.cpp
+++ lib/StaticAnalyzer/Core/LoopUnrolling.cpp
@@ -84,9 +84,8 @@
hasOperatorName("<="), hasOperatorName(">="),
hasOperatorName("!=")),
hasEitherOperand(ignoringParenImpCasts(declRefExpr(
- to(varDecl(hasType(isInteger())).bind(BindName))))),
- hasEitherOperand(ignoringParenImpCasts(
- integerLiteral().bind("boundNum"))))
+ to(varDecl(hasType(isInteger())).bind(BindName)))
+ .bind("boundVarOperand"))))
.bind("conditionOperator");
}
@@ -200,18 +199,40 @@
if (!isLoopStmt(LoopStmt))
return false;
- // TODO: Match the cases where the bound is not a concrete literal but an
- // integer with known value
auto Matches = match(forLoopMatcher(), *LoopStmt, ASTCtx);
if (Matches.empty())
return false;
+ const auto State = Pred->getState();
+ auto &SVB = State->getStateManager().getSValBuilder();
+
auto CounterVar = Matches[0].getNodeAs<VarDecl>("initVarName");
- llvm::APInt BoundNum =
- Matches[0].getNodeAs<IntegerLiteral>("boundNum")->getValue();
llvm::APInt InitNum =
Matches[0].getNodeAs<IntegerLiteral>("initNum")->getValue();
auto CondOp = Matches[0].getNodeAs<BinaryOperator>("conditionOperator");
+
+ const Expr *BoundExpr = CondOp->getLHS()->IgnoreParenImpCasts();
+ if (BoundExpr == Matches[0].getNodeAs<Expr>("boundVarOperand"))
+ BoundExpr = CondOp->getRHS()->IgnoreParenImpCasts();
+ SVal BoundNumVal = Pred->getSVal(BoundExpr);
+
+ // If the value of the expression is unknown and it is a declaration
+ // reference then try to get the value of the declaration instead
+ if (BoundNumVal.isUnknown()) {
+ if (const auto *BoundDeclRefExpr = dyn_cast<DeclRefExpr>(BoundExpr)) {
+ // FIXME: Add other declarations such as Objective-C fields
+ if (const auto *BoundVarDecl =
+ dyn_cast<VarDecl>(BoundDeclRefExpr->getDecl())) {
+ BoundNumVal = State->getSVal(
+ State->getLValue(BoundVarDecl, Pred->getLocationContext()));
+ }
+ }
+ }
+ const llvm::APSInt *BoundNumPtr = SVB.getKnownValue(State, BoundNumVal);
+ if (!BoundNumPtr)
+ return false;
+ llvm::APInt BoundNum = *BoundNumPtr;
+
if (InitNum.getBitWidth() != BoundNum.getBitWidth()) {
InitNum = InitNum.zextOrSelf(BoundNum.getBitWidth());
BoundNum = BoundNum.zextOrSelf(InitNum.getBitWidth());
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