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checkTooBigBitwiseShift: bitshift overflow when lhs is signed

This commit is contained in:
Daniel Marjamäki 2017-09-19 09:08:44 +02:00
parent 0cf551351b
commit be0ad20a04
2 changed files with 13 additions and 12 deletions
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3
lib/checktype.cpp
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@ -82,6 +82,9 @@ void CheckType::checkTooBigBitwiseShift()
else else
continue; continue;
if (lhstype->sign == ValueType::Sign::SIGNED)
--lhsbits;
// Get biggest rhs value. preferably a value which doesn't have 'condition'. // Get biggest rhs value. preferably a value which doesn't have 'condition'.
const ValueFlow::Value *value = tok->astOperand2()->getValueGE(lhsbits, _settings); const ValueFlow::Value *value = tok->astOperand2()->getValueGE(lhsbits, _settings);
if (value && _settings->isEnabled(value, false)) if (value && _settings->isEnabled(value, false))

22
test/testtype.cpp
View File

@ -65,11 +65,14 @@ private:
Settings settings; Settings settings;
settings.platform(Settings::Unix32); settings.platform(Settings::Unix32);
check("int foo(int x) {\n" check("int foo(unsigned int x) {\n"
" return x << 32;\n" " return x << 32;\n"
"}",&settings); "}",&settings);
ASSERT_EQUALS("[test.cpp:2]: (error) Shifting 32-bit value by 32 bits is undefined behaviour\n", errout.str()); ASSERT_EQUALS("[test.cpp:2]: (error) Shifting 32-bit value by 32 bits is undefined behaviour\n", errout.str());
check("x = (short)x << 31;",&settings);
ASSERT_EQUALS("[test.cpp:1]: (error) Shifting 31-bit value by 31 bits is undefined behaviour\n", errout.str());
check("int foo(int x) {\n" check("int foo(int x) {\n"
" return x << 2;\n" " return x << 2;\n"
"}",&settings); "}",&settings);
@ -87,16 +90,16 @@ private:
ASSERT_EQUALS("", errout.str()); ASSERT_EQUALS("", errout.str());
// Ticket #6793 // Ticket #6793
check("template<int I> int foo(int x) { return x << I; }\n" check("template<unsigned int I> int foo(unsigned int x) { return x << I; }\n"
"const int f = foo<31>(0);\n" "const unsigned int f = foo<31>(0);\n"
"const int g = foo<100>(0);\n" "const unsigned int g = foo<100>(0);\n"
"template<int I> int hoo(int x) { return x << 32; }\n" "template<unsigned int I> int hoo(unsigned int x) { return x << 32; }\n"
"const int h = hoo<100>(0);", &settings); "const unsigned int h = hoo<100>(0);", &settings);
ASSERT_EQUALS("[test.cpp:4]: (error) Shifting 32-bit value by 32 bits is undefined behaviour\n" ASSERT_EQUALS("[test.cpp:4]: (error) Shifting 32-bit value by 32 bits is undefined behaviour\n"
"[test.cpp:1]: (error) Shifting 32-bit value by 100 bits is undefined behaviour\n", errout.str()); "[test.cpp:1]: (error) Shifting 32-bit value by 100 bits is undefined behaviour\n", errout.str());
// #7266: C++, shift in macro // #7266: C++, shift in macro
check("void f(int x) {\n" check("void f(unsigned int x) {\n"
" UINFO(x << 1234);\n" " UINFO(x << 1234);\n"
"}"); "}");
ASSERT_EQUALS("", errout.str()); ASSERT_EQUALS("", errout.str());
@ -136,11 +139,6 @@ private:
" return 123456U * x;\n" " return 123456U * x;\n"
"}",&settings); "}",&settings);
ASSERT_EQUALS("", errout.str()); ASSERT_EQUALS("", errout.str());
check("int foo() {\n"
" x = 1 << 31;\n" // this is technically integer overflow but it's common code
"}", &settings, "test.c");
ASSERT_EQUALS("", errout.str());
} }
void signConversion() { void signConversion() {