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| author | Richard Trieu <rtrieu@google.com> | 2019-10-19 00:57:23 +0000 |
|---|---|---|
| committer | Richard Trieu <rtrieu@google.com> | 2019-10-19 00:57:23 +0000 |
| commit | a27ae544f30bfd7dc765b8a6080190d39d893b99 (patch) | |
| tree | 20f6b66320ee0e421f33e6e54eab73db57932762 /test | |
| parent | 7decfe83555385bebac2e4bed35035f3b0f4d666 (diff) | |
| download | clang-a27ae544f30bfd7dc765b8a6080190d39d893b99.tar.gz | |
New tautological warning for bitwise-or with non-zero constant always true.
Taking a value and the bitwise-or it with a non-zero constant will always
result in a non-zero value. In a boolean context, this is always true.
if (x | 0x4) {} // always true, intended '&'
This patch creates a new warning group -Wtautological-bitwise-compare for this
warning. It also moves in the existing tautological bitwise comparisons into
this group. A few other changes were needed to the CFGBuilder so that all bool
contexts would be checked. The warnings in -Wtautological-bitwise-compare will
be off by default due to using the CFG.
Fixes: https://bugs.llvm.org/show_bug.cgi?id=42666
Differential Revision: https://reviews.llvm.org/D66046
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@375318 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'test')
| -rw-r--r-- | test/Sema/warn-bitwise-compare.c | 21 | ||||
| -rw-r--r-- | test/SemaCXX/warn-bitwise-compare.cpp | 12 |
2 files changed, 32 insertions, 1 deletions
diff --git a/test/Sema/warn-bitwise-compare.c b/test/Sema/warn-bitwise-compare.c index 175f8f5367..d08f1bf13f 100644 --- a/test/Sema/warn-bitwise-compare.c +++ b/test/Sema/warn-bitwise-compare.c @@ -1,7 +1,12 @@ -// RUN: %clang_cc1 -fsyntax-only -verify -Wtautological-compare %s +// RUN: %clang_cc1 -fsyntax-only -verify -Wtautological-bitwise-compare %s #define mydefine 2 +enum { + ZERO, + ONE, +}; + void f(int x) { if ((8 & x) == 3) {} // expected-warning {{bitwise comparison always evaluates to false}} if ((x & 8) == 4) {} // expected-warning {{bitwise comparison always evaluates to false}} @@ -13,6 +18,9 @@ void f(int x) { if ((x & 0x15) == 0x13) {} // expected-warning {{bitwise comparison always evaluates to false}} if ((0x23 | x) == 0x155){} // expected-warning {{bitwise comparison always evaluates to false}} + if (!!((8 & x) == 3)) {} // expected-warning {{bitwise comparison always evaluates to false}} + int y = ((8 & x) == 3) ? 1 : 2; // expected-warning {{bitwise comparison always evaluates to false}} + if ((x & 8) == 8) {} if ((x & 8) != 8) {} if ((x | 4) == 4) {} @@ -26,3 +34,14 @@ void f(int x) { if ((x & mydefine) == 8) {} if ((x | mydefine) == 4) {} } + +void g(int x) { + if (x | 5) {} // expected-warning {{bitwise or with non-zero value always evaluates to true}} + if (5 | x) {} // expected-warning {{bitwise or with non-zero value always evaluates to true}} + if (!((x | 5))) {} // expected-warning {{bitwise or with non-zero value always evaluates to true}} + + if (x | -1) {} // expected-warning {{bitwise or with non-zero value always evaluates to true}} + if (x | ONE) {} // expected-warning {{bitwise or with non-zero value always evaluates to true}} + + if (x | ZERO) {} +} diff --git a/test/SemaCXX/warn-bitwise-compare.cpp b/test/SemaCXX/warn-bitwise-compare.cpp new file mode 100644 index 0000000000..894d4c581e --- /dev/null +++ b/test/SemaCXX/warn-bitwise-compare.cpp @@ -0,0 +1,12 @@ +// RUN: %clang_cc1 -fsyntax-only -verify -Wtautological-bitwise-compare %s + +void test(int x) { + bool b1 = (8 & x) == 3; + // expected-warning@-1 {{bitwise comparison always evaluates to false}} + bool b2 = x | 5; + // expected-warning@-1 {{bitwise or with non-zero value always evaluates to true}} + bool b3 = (x | 5); + // expected-warning@-1 {{bitwise or with non-zero value always evaluates to true}} + bool b4 = !!(x | 5); + // expected-warning@-1 {{bitwise or with non-zero value always evaluates to true}} +} |