[analyzer] Teach constraint managers about unsigned comparisons.
In C, comparisons between signed and unsigned numbers are always done in
unsigned-space. Thus, we should know that "i >= 0U" is always true, even
if 'i' is signed. Similarly, "u >= 0" is also always true, even though '0'
is signed.
Part of <rdar://problem/13239003> (false positives related to std::vector)
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177806 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/clang/StaticAnalyzer/Core/PathSensitive/APSIntType.h b/include/clang/StaticAnalyzer/Core/PathSensitive/APSIntType.h
index 27f3677..9502900 100644
--- a/include/clang/StaticAnalyzer/Core/PathSensitive/APSIntType.h
+++ b/include/clang/StaticAnalyzer/Core/PathSensitive/APSIntType.h
@@ -81,9 +81,12 @@
/// Tests whether a given value is losslessly representable using this type.
///
- /// Note that signedness conversions will be rejected, even with the same bit
- /// pattern. For example, -1s8 is not in range for 'unsigned char' (u8).
- RangeTestResultKind testInRange(const llvm::APSInt &Val) const LLVM_READONLY;
+ /// \param Val The value to test.
+ /// \param AllowMixedSign Whether or not to allow signedness conversions.
+ /// This determines whether -1s8 is considered in range
+ /// for 'unsigned char' (u8).
+ RangeTestResultKind testInRange(const llvm::APSInt &Val,
+ bool AllowMixedSign) const LLVM_READONLY;
bool operator==(const APSIntType &Other) const {
return BitWidth == Other.BitWidth && IsUnsigned == Other.IsUnsigned;
diff --git a/lib/StaticAnalyzer/Core/APSIntType.cpp b/lib/StaticAnalyzer/Core/APSIntType.cpp
index 884b0fa..c7e9526 100644
--- a/lib/StaticAnalyzer/Core/APSIntType.cpp
+++ b/lib/StaticAnalyzer/Core/APSIntType.cpp
@@ -13,20 +13,31 @@
using namespace ento;
APSIntType::RangeTestResultKind
-APSIntType::testInRange(const llvm::APSInt &Value) const {
+APSIntType::testInRange(const llvm::APSInt &Value,
+ bool AllowSignConversions) const {
+
// Negative numbers cannot be losslessly converted to unsigned type.
- if (IsUnsigned && Value.isSigned() && Value.isNegative())
+ if (IsUnsigned && !AllowSignConversions &&
+ Value.isSigned() && Value.isNegative())
return RTR_Below;
- // Signed integers can be converted to signed integers of the same width
- // or (if positive) unsigned integers with one fewer bit.
- // Unsigned integers can be converted to unsigned integers of the same width
- // or signed integers with one more bit.
unsigned MinBits;
- if (Value.isSigned())
- MinBits = Value.getMinSignedBits() - IsUnsigned;
- else
- MinBits = Value.getActiveBits() + !IsUnsigned;
+ if (AllowSignConversions) {
+ if (Value.isSigned() && !IsUnsigned)
+ MinBits = Value.getMinSignedBits();
+ else
+ MinBits = Value.getActiveBits();
+
+ } else {
+ // Signed integers can be converted to signed integers of the same width
+ // or (if positive) unsigned integers with one fewer bit.
+ // Unsigned integers can be converted to unsigned integers of the same width
+ // or signed integers with one more bit.
+ if (Value.isSigned())
+ MinBits = Value.getMinSignedBits() - IsUnsigned;
+ else
+ MinBits = Value.getActiveBits() + !IsUnsigned;
+ }
if (MinBits <= BitWidth)
return RTR_Within;
diff --git a/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp b/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp
index 216fb3d..3606e09 100644
--- a/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp
+++ b/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp
@@ -153,8 +153,8 @@
// The function returns false if the described range is entirely outside
// the range of values for the associated symbol.
APSIntType Type(getMinValue());
- APSIntType::RangeTestResultKind LowerTest = Type.testInRange(Lower);
- APSIntType::RangeTestResultKind UpperTest = Type.testInRange(Upper);
+ APSIntType::RangeTestResultKind LowerTest = Type.testInRange(Lower, true);
+ APSIntType::RangeTestResultKind UpperTest = Type.testInRange(Upper, true);
switch (LowerTest) {
case APSIntType::RTR_Below:
@@ -419,7 +419,7 @@
const llvm::APSInt &Adjustment) {
// Before we do any real work, see if the value can even show up.
APSIntType AdjustmentType(Adjustment);
- if (AdjustmentType.testInRange(Int) != APSIntType::RTR_Within)
+ if (AdjustmentType.testInRange(Int, true) != APSIntType::RTR_Within)
return St;
llvm::APSInt Lower = AdjustmentType.convert(Int) - Adjustment;
@@ -439,7 +439,7 @@
const llvm::APSInt &Adjustment) {
// Before we do any real work, see if the value can even show up.
APSIntType AdjustmentType(Adjustment);
- if (AdjustmentType.testInRange(Int) != APSIntType::RTR_Within)
+ if (AdjustmentType.testInRange(Int, true) != APSIntType::RTR_Within)
return NULL;
// [Int-Adjustment, Int-Adjustment]
@@ -454,7 +454,7 @@
const llvm::APSInt &Adjustment) {
// Before we do any real work, see if the value can even show up.
APSIntType AdjustmentType(Adjustment);
- switch (AdjustmentType.testInRange(Int)) {
+ switch (AdjustmentType.testInRange(Int, true)) {
case APSIntType::RTR_Below:
return NULL;
case APSIntType::RTR_Within:
@@ -483,7 +483,7 @@
const llvm::APSInt &Adjustment) {
// Before we do any real work, see if the value can even show up.
APSIntType AdjustmentType(Adjustment);
- switch (AdjustmentType.testInRange(Int)) {
+ switch (AdjustmentType.testInRange(Int, true)) {
case APSIntType::RTR_Below:
return St;
case APSIntType::RTR_Within:
@@ -512,7 +512,7 @@
const llvm::APSInt &Adjustment) {
// Before we do any real work, see if the value can even show up.
APSIntType AdjustmentType(Adjustment);
- switch (AdjustmentType.testInRange(Int)) {
+ switch (AdjustmentType.testInRange(Int, true)) {
case APSIntType::RTR_Below:
return St;
case APSIntType::RTR_Within:
@@ -541,7 +541,7 @@
const llvm::APSInt &Adjustment) {
// Before we do any real work, see if the value can even show up.
APSIntType AdjustmentType(Adjustment);
- switch (AdjustmentType.testInRange(Int)) {
+ switch (AdjustmentType.testInRange(Int, true)) {
case APSIntType::RTR_Below:
return NULL;
case APSIntType::RTR_Within:
diff --git a/lib/StaticAnalyzer/Core/SimpleConstraintManager.cpp b/lib/StaticAnalyzer/Core/SimpleConstraintManager.cpp
index 4ff2487..f6404f0 100644
--- a/lib/StaticAnalyzer/Core/SimpleConstraintManager.cpp
+++ b/lib/StaticAnalyzer/Core/SimpleConstraintManager.cpp
@@ -264,10 +264,14 @@
APSIntType ComparisonType = std::max(WraparoundType, APSIntType(Int));
llvm::APSInt ConvertedInt = ComparisonType.convert(Int);
+ // Prefer unsigned comparisons.
+ if (ComparisonType.getBitWidth() == WraparoundType.getBitWidth() &&
+ ComparisonType.isUnsigned() && !WraparoundType.isUnsigned())
+ Adjustment.setIsSigned(false);
+
switch (op) {
default:
- // No logic yet for other operators. assume the constraint is feasible.
- return state;
+ llvm_unreachable("invalid operation not caught by assertion above");
case BO_EQ:
return assumeSymEQ(state, Sym, ConvertedInt, Adjustment);
diff --git a/test/Analysis/additive-folding-range-constraints.c b/test/Analysis/additive-folding-range-constraints.c
index 7eb55ab..b22eb2a 100644
--- a/test/Analysis/additive-folding-range-constraints.c
+++ b/test/Analysis/additive-folding-range-constraints.c
@@ -170,3 +170,135 @@
clang_analyzer_eval(a == 0x7F); // expected-warning{{UNKNOWN}}
clang_analyzer_eval(a == -0x80); // expected-warning{{UNKNOWN}}
}
+
+
+void mixedSignedness1(int a) {
+ unsigned max = UINT_MAX;
+ clang_analyzer_eval(a < max); // expected-warning{{UNKNOWN}}
+ clang_analyzer_eval((a + 2) < max); // expected-warning{{UNKNOWN}}
+ clang_analyzer_eval((a + 2U) < max); // expected-warning{{UNKNOWN}}
+}
+
+void mixedSignedness2(int a) {
+ unsigned max = UINT_MAX;
+ clang_analyzer_eval(a <= max); // expected-warning{{TRUE}}
+ clang_analyzer_eval((a + 2) <= max); // expected-warning{{TRUE}}
+ clang_analyzer_eval((a + 2U) <= max); // expected-warning{{TRUE}}
+}
+
+void mixedSignedness3(unsigned a) {
+ int max = INT_MAX;
+ clang_analyzer_eval(a < max); // expected-warning{{UNKNOWN}}
+ clang_analyzer_eval((a + 2) < max); // expected-warning{{UNKNOWN}}
+ clang_analyzer_eval((a + 2U) < max); // expected-warning{{UNKNOWN}}
+}
+
+void mixedSignedness4(unsigned a) {
+ int max = INT_MAX;
+ clang_analyzer_eval(a <= max); // expected-warning{{UNKNOWN}}
+ clang_analyzer_eval((a + 2) <= max); // expected-warning{{UNKNOWN}}
+ clang_analyzer_eval((a + 2U) <= max); // expected-warning{{UNKNOWN}}
+}
+
+void mixedSignedness5(unsigned a) {
+ int min = INT_MIN;
+ clang_analyzer_eval(a < min); // expected-warning{{UNKNOWN}}
+ clang_analyzer_eval((a + 2) < min); // expected-warning{{UNKNOWN}}
+ clang_analyzer_eval((a + 2U) < min); // expected-warning{{UNKNOWN}}
+}
+
+void mixedSignedness6(unsigned a) {
+ int min = INT_MIN;
+ clang_analyzer_eval(a <= min); // expected-warning{{UNKNOWN}}
+ clang_analyzer_eval((a + 2) <= min); // expected-warning{{UNKNOWN}}
+ clang_analyzer_eval((a + 2U) <= min); // expected-warning{{UNKNOWN}}
+}
+
+void mixedSignedness7(unsigned a) {
+ unsigned min = 0;
+ clang_analyzer_eval(a < min); // expected-warning{{FALSE}}
+ clang_analyzer_eval((a + 2) < min); // expected-warning{{FALSE}}
+ clang_analyzer_eval((a + 2U) < min); // expected-warning{{FALSE}}
+}
+
+void mixedSignedness8(unsigned a) {
+ unsigned min = 0;
+ clang_analyzer_eval(a <= min); // expected-warning{{UNKNOWN}}
+ clang_analyzer_eval((a + 2) <= min); // expected-warning{{UNKNOWN}}
+ clang_analyzer_eval((a + 2U) <= min); // expected-warning{{UNKNOWN}}
+}
+
+void mixedSignedness9(unsigned a) {
+ int min = 0;
+ clang_analyzer_eval(a < min); // expected-warning{{FALSE}}
+ clang_analyzer_eval((a + 2) < min); // expected-warning{{FALSE}}
+ clang_analyzer_eval((a + 2U) < min); // expected-warning{{FALSE}}
+}
+
+void mixedSignedness10(unsigned a) {
+ int min = 0;
+ clang_analyzer_eval(a <= min); // expected-warning{{UNKNOWN}}
+ clang_analyzer_eval((a + 2) <= min); // expected-warning{{UNKNOWN}}
+ clang_analyzer_eval((a + 2U) <= min); // expected-warning{{UNKNOWN}}
+}
+
+void mixedSignedness11(int a) {
+ int min = 0;
+ clang_analyzer_eval(a < min); // expected-warning{{UNKNOWN}}
+ clang_analyzer_eval((a + 2) < min); // expected-warning{{UNKNOWN}}
+ clang_analyzer_eval((a + 2U) < min); // expected-warning{{FALSE}}
+}
+
+void mixedSignedness12(int a) {
+ int min = 0;
+ clang_analyzer_eval(a <= min); // expected-warning{{UNKNOWN}}
+ clang_analyzer_eval((a + 2) <= min); // expected-warning{{UNKNOWN}}
+ clang_analyzer_eval((a + 2U) <= min); // expected-warning{{UNKNOWN}}
+}
+
+void mixedSignedness13(int a) {
+ unsigned max = INT_MAX;
+ clang_analyzer_eval(a < max); // expected-warning{{UNKNOWN}}
+ clang_analyzer_eval((a + 2) < max); // expected-warning{{UNKNOWN}}
+ clang_analyzer_eval((a + 2U) < max); // expected-warning{{UNKNOWN}}
+}
+
+void mixedSignedness14(int a) {
+ unsigned max = INT_MAX;
+ clang_analyzer_eval(a <= max); // expected-warning{{UNKNOWN}}
+ clang_analyzer_eval((a + 2) <= max); // expected-warning{{UNKNOWN}}
+ clang_analyzer_eval((a + 2U) <= max); // expected-warning{{UNKNOWN}}
+}
+
+void mixedSignedness15(int a) {
+ unsigned min = INT_MIN;
+ clang_analyzer_eval(a < min); // expected-warning{{UNKNOWN}}
+ clang_analyzer_eval((a + 2) < min); // expected-warning{{UNKNOWN}}
+ clang_analyzer_eval((a + 2U) < min); // expected-warning{{UNKNOWN}}
+}
+
+void mixedSignedness16(int a) {
+ unsigned min = INT_MIN;
+ clang_analyzer_eval(a <= min); // expected-warning{{UNKNOWN}}
+ clang_analyzer_eval((a + 2) <= min); // expected-warning{{UNKNOWN}}
+ clang_analyzer_eval((a + 2U) <= min); // expected-warning{{UNKNOWN}}
+}
+
+void mixedSignedness17(int a) {
+ unsigned max = INT_MAX;
+ if (a < max)
+ return;
+
+ clang_analyzer_eval(a < 0); // expected-warning{{UNKNOWN}}
+ clang_analyzer_eval(a == 0); // expected-warning{{FALSE}}
+ clang_analyzer_eval(a == INT_MAX); // expected-warning{{UNKNOWN}}
+}
+
+void mixedSignedness18(int a) {
+ if (a >= 0)
+ return;
+
+ clang_analyzer_eval(a < 0); // expected-warning{{TRUE}}
+ clang_analyzer_eval(a == (unsigned)INT_MIN); // expected-warning{{UNKNOWN}}
+ clang_analyzer_eval(a == UINT_MAX); // expected-warning{{UNKNOWN}}
+}
diff --git a/test/Analysis/additive-folding.cpp b/test/Analysis/additive-folding.cpp
index 33f3b9b..c2e5026 100644
--- a/test/Analysis/additive-folding.cpp
+++ b/test/Analysis/additive-folding.cpp
@@ -184,6 +184,18 @@
clang_analyzer_eval(b == uMin && b != sMin); // expected-warning{{FALSE}}
}
+void mixedSignedness2(int a) {
+ if (a != -1)
+ return;
+ clang_analyzer_eval(a == UINT_MAX); // expected-warning{{TRUE}}
+}
+
+void mixedSignedness3(unsigned a) {
+ if (a != UINT_MAX)
+ return;
+ clang_analyzer_eval(a == -1); // expected-warning{{TRUE}}
+}
+
void multiplicativeSanityTest(int x) {
// At one point we were ignoring the *4 completely -- the constraint manager
