[cfe-commits] r105631 - in /cfe/trunk: include/clang/Basic/DiagnosticSemaKinds.td lib/Sema/SemaExpr.cpp test/Sema/compare.c test/Sema/ext_vector_comparisons.c test/Sema/self-comparison.c test/SemaCXX/overloaded-operator.cpp test/SemaCXX/warn-self-comparisons.cpp
Douglas Gregor
dgregor at apple.com
Tue Jun 8 12:50:35 PDT 2010
Author: dgregor
Date: Tue Jun 8 14:50:34 2010
New Revision: 105631
URL: http://llvm.org/viewvc/llvm-project?rev=105631&view=rev
Log:
Warn about comparisons between arrays and improve self-comparison
warnings, from Troy Straszheim! Fixes PR6163.
Added:
cfe/trunk/test/Sema/ext_vector_comparisons.c (with props)
cfe/trunk/test/SemaCXX/warn-self-comparisons.cpp (with props)
Modified:
cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
cfe/trunk/lib/Sema/SemaExpr.cpp
cfe/trunk/test/Sema/compare.c
cfe/trunk/test/Sema/self-comparison.c
cfe/trunk/test/SemaCXX/overloaded-operator.cpp
Modified: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td?rev=105631&r1=105630&r2=105631&view=diff
==============================================================================
--- cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td (original)
+++ cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td Tue Jun 8 14:50:34 2010
@@ -2917,8 +2917,10 @@
// For non-floating point, expressions of the form x == x or x != x
// should result in a warning, since these always evaluate to a constant.
-def warn_selfcomparison : Warning<
- "self-comparison always results in a constant value">;
+// Array comparisons have similar warnings
+def warn_comparison_always : Warning<
+ "%select{self-|array }0comparison always evaluates to %select{false|true|a constant}1">;
+
def warn_stringcompare : Warning<
"result of comparison against %select{a string literal|@encode}0 is "
"unspecified (use strncmp instead)">;
Modified: cfe/trunk/lib/Sema/SemaExpr.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaExpr.cpp?rev=105631&r1=105630&r2=105631&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaExpr.cpp (original)
+++ cfe/trunk/lib/Sema/SemaExpr.cpp Tue Jun 8 14:50:34 2010
@@ -5292,13 +5292,6 @@
if (lex->getType()->isVectorType() || rex->getType()->isVectorType())
return CheckVectorCompareOperands(lex, rex, Loc, isRelational);
- // C99 6.5.8p3 / C99 6.5.9p4
- if (lex->getType()->isArithmeticType() && rex->getType()->isArithmeticType())
- UsualArithmeticConversions(lex, rex);
- else {
- UsualUnaryConversions(lex);
- UsualUnaryConversions(rex);
- }
QualType lType = lex->getType();
QualType rType = rex->getType();
@@ -5312,10 +5305,36 @@
Expr *LHSStripped = lex->IgnoreParens();
Expr *RHSStripped = rex->IgnoreParens();
if (DeclRefExpr* DRL = dyn_cast<DeclRefExpr>(LHSStripped))
- if (DeclRefExpr* DRR = dyn_cast<DeclRefExpr>(RHSStripped))
+ if (DeclRefExpr* DRR = dyn_cast<DeclRefExpr>(RHSStripped)) {
if (DRL->getDecl() == DRR->getDecl() &&
- !isa<EnumConstantDecl>(DRL->getDecl()))
- DiagRuntimeBehavior(Loc, PDiag(diag::warn_selfcomparison));
+ !isa<EnumConstantDecl>(DRL->getDecl())) {
+ DiagRuntimeBehavior(Loc, PDiag(diag::warn_comparison_always)
+ << 0 // self-
+ << (Opc == BinaryOperator::EQ
+ || Opc == BinaryOperator::LE
+ || Opc == BinaryOperator::GE));
+ } else if (lType->isArrayType() && rType->isArrayType() &&
+ !DRL->getDecl()->getType()->isReferenceType() &&
+ !DRR->getDecl()->getType()->isReferenceType()) {
+ // what is it always going to eval to?
+ char always_evals_to;
+ switch(Opc) {
+ case BinaryOperator::EQ: // e.g. array1 == array2
+ always_evals_to = 0; // false
+ break;
+ case BinaryOperator::NE: // e.g. array1 != array2
+ always_evals_to = 1; // true
+ break;
+ default:
+ // best we can say is 'a constant'
+ always_evals_to = 2; // e.g. array1 <= array2
+ break;
+ }
+ DiagRuntimeBehavior(Loc, PDiag(diag::warn_comparison_always)
+ << 1 // array
+ << always_evals_to);
+ }
+ }
if (isa<CastExpr>(LHSStripped))
LHSStripped = LHSStripped->IgnoreParenCasts();
@@ -5358,6 +5377,17 @@
}
}
+ // C99 6.5.8p3 / C99 6.5.9p4
+ if (lex->getType()->isArithmeticType() && rex->getType()->isArithmeticType())
+ UsualArithmeticConversions(lex, rex);
+ else {
+ UsualUnaryConversions(lex);
+ UsualUnaryConversions(rex);
+ }
+
+ lType = lex->getType();
+ rType = rex->getType();
+
// The result of comparisons is 'bool' in C++, 'int' in C.
QualType ResultTy = getLangOptions().CPlusPlus ? Context.BoolTy:Context.IntTy;
@@ -5632,7 +5662,11 @@
if (DeclRefExpr* DRL = dyn_cast<DeclRefExpr>(lex->IgnoreParens()))
if (DeclRefExpr* DRR = dyn_cast<DeclRefExpr>(rex->IgnoreParens()))
if (DRL->getDecl() == DRR->getDecl())
- DiagRuntimeBehavior(Loc, PDiag(diag::warn_selfcomparison));
+ DiagRuntimeBehavior(Loc,
+ PDiag(diag::warn_comparison_always)
+ << 0 // self-
+ << 2 // "a constant"
+ );
}
// Check for comparisons of floating point operands using != and ==.
Modified: cfe/trunk/test/Sema/compare.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/compare.c?rev=105631&r1=105630&r2=105631&view=diff
==============================================================================
--- cfe/trunk/test/Sema/compare.c (original)
+++ cfe/trunk/test/Sema/compare.c Tue Jun 8 14:50:34 2010
@@ -3,7 +3,7 @@
int test(char *C) { // nothing here should warn.
return C != ((void*)0);
return C != (void*)0;
- return C != 0;
+ return C != 0;
return C != 1; // expected-warning {{comparison between pointer and integer ('char *' and 'int')}}
}
@@ -218,7 +218,7 @@
int function_pointers(int (*a)(int), int (*b)(int), void (*c)(int)) {
return a > b; // expected-warning {{ordered comparison of function pointers}}
- return function_pointers > function_pointers; // expected-warning {{ordered comparison of function pointers}}
+ return function_pointers > function_pointers; // expected-warning {{self-comparison always evaluates to false}} expected-warning{{ordered comparison of function pointers}}
return a > c; // expected-warning {{comparison of distinct pointer types}}
return a == (void *) 0;
return a == (void *) 1; // expected-warning {{equality comparison between function pointer and void pointer}}
@@ -229,6 +229,7 @@
return foo == (void*) 1;
}
+
int test1(int i) {
enum en { zero };
return i > zero;
Added: cfe/trunk/test/Sema/ext_vector_comparisons.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/ext_vector_comparisons.c?rev=105631&view=auto
==============================================================================
--- cfe/trunk/test/Sema/ext_vector_comparisons.c (added)
+++ cfe/trunk/test/Sema/ext_vector_comparisons.c Tue Jun 8 14:50:34 2010
@@ -0,0 +1,30 @@
+// RUN: %clang_cc1 -fsyntax-only -verify -Wno-unreachable-code %s
+
+typedef __attribute__(( ext_vector_type(4) )) int int4;
+
+static int4 test1() {
+ int4 vec, rv;
+
+ // comparisons to self...
+ return vec == vec; // expected-warning{{self-comparison always evaluates to a constant}}
+ return vec != vec; // expected-warning{{self-comparison always evaluates to a constant}}
+ return vec < vec; // expected-warning{{self-comparison always evaluates to a constant}}
+ return vec <= vec; // expected-warning{{self-comparison always evaluates to a constant}}
+ return vec > vec; // expected-warning{{self-comparison always evaluates to a constant}}
+ return vec >= vec; // expected-warning{{self-comparison always evaluates to a constant}}
+}
+
+
+typedef __attribute__(( ext_vector_type(4) )) float float4;
+
+static int4 test2() {
+ float4 vec, rv;
+
+ // comparisons to self. no warning, they're floats
+ return vec == vec; // no-warning
+ return vec != vec; // no-warning
+ return vec < vec; // no-warning
+ return vec <= vec; // no-warning
+ return vec > vec; // no-warning
+ return vec >= vec; // no-warning
+}
Propchange: cfe/trunk/test/Sema/ext_vector_comparisons.c
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Modified: cfe/trunk/test/Sema/self-comparison.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/self-comparison.c?rev=105631&r1=105630&r2=105631&view=diff
==============================================================================
--- cfe/trunk/test/Sema/self-comparison.c (original)
+++ cfe/trunk/test/Sema/self-comparison.c Tue Jun 8 14:50:34 2010
@@ -1,11 +1,21 @@
// RUN: %clang_cc1 -fsyntax-only -verify %s
int foo(int x) {
- return x == x; // expected-warning {{self-comparison always results}}
+ return x == x; // expected-warning {{self-comparison always evaluates to true}}
}
int foo2(int x) {
- return (x) != (((x))); // expected-warning {{self-comparison always results}}
+ return (x) != (((x))); // expected-warning {{self-comparison always evaluates to false}}
+}
+
+void foo3(short s, short t) {
+ if (s == s) {} // expected-warning {{self-comparison always evaluates to true}}
+ if (s == t) {} // no-warning
+}
+
+void foo4(void* v, void* w) {
+ if (v == v) {} // expected-warning {{self-comparison always evaluates to true}}
+ if (v == w) {} // no-warning
}
int qux(int x) {
@@ -36,3 +46,34 @@
int compare_sizeof(int x) {
return sizeof(x == x); // no-warning
}
+
+int array_comparisons() {
+ int array1[2];
+ int array2[2];
+
+ //
+ // compare same array
+ //
+ return array1 == array1; // expected-warning{{self-comparison always evaluates to true}}
+ return array1 != array1; // expected-warning{{self-comparison always evaluates to false}}
+ return array1 < array1; // expected-warning{{self-comparison always evaluates to false}}
+ return array1 <= array1; // expected-warning{{self-comparison always evaluates to true}}
+ return array1 > array1; // expected-warning{{self-comparison always evaluates to false}}
+ return array1 >= array1; // expected-warning{{self-comparison always evaluates to true}}
+
+ //
+ // compare differrent arrays
+ //
+ return array1 == array2; // expected-warning{{array comparison always evaluates to false}}
+ return array1 != array2; // expected-warning{{array comparison always evaluates to true}}
+
+ //
+ // we don't know what these are going to be
+ //
+ return array1 < array2; // expected-warning{{array comparison always evaluates to a constant}}
+ return array1 <= array2; // expected-warning{{array comparison always evaluates to a constant}}
+ return array1 > array2; // expected-warning{{array comparison always evaluates to a constant}}
+ return array1 >= array2; // expected-warning{{array comparison always evaluates to a constant}}
+
+}
+
Modified: cfe/trunk/test/SemaCXX/overloaded-operator.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/overloaded-operator.cpp?rev=105631&r1=105630&r2=105631&view=diff
==============================================================================
--- cfe/trunk/test/SemaCXX/overloaded-operator.cpp (original)
+++ cfe/trunk/test/SemaCXX/overloaded-operator.cpp Tue Jun 8 14:50:34 2010
@@ -49,6 +49,13 @@
}
};
+// we shouldn't see warnings about self-comparison,
+// this is a member function, we dunno what it'll do
+bool i(B b)
+{
+ return b == b;
+}
+
enum Enum1 { };
enum Enum2 { };
Added: cfe/trunk/test/SemaCXX/warn-self-comparisons.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/warn-self-comparisons.cpp?rev=105631&view=auto
==============================================================================
--- cfe/trunk/test/SemaCXX/warn-self-comparisons.cpp (added)
+++ cfe/trunk/test/SemaCXX/warn-self-comparisons.cpp Tue Jun 8 14:50:34 2010
@@ -0,0 +1,5 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s
+
+void f(int (&array1)[2], int (&array2)[2]) {
+ if (array1 == array2) { } // no warning
+}
Propchange: cfe/trunk/test/SemaCXX/warn-self-comparisons.cpp
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