For checking for floating point comparison using == or !=, we now suppress

errors for cases such as "x == x".

Added test case to test this feature.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@43447 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 17 insertions, 3 deletions

diff --git a/Sema/SemaExpr.cpp b/Sema/SemaExpr.cpp
index 36112e6488..59cff7cc7d 100644
--- a/Sema/SemaExpr.cpp
+++ b/Sema/SemaExpr.cpp
@@ -1208,9 +1208,19 @@ inline QualType Sema::CheckCompareOperands( // C99 6.5.8
     if (lType->isRealType() && rType->isRealType())
       return Context.IntTy;
   } else {
-    if (lType->isFloatingType() && rType->isFloatingType()) 
-      Diag(loc, diag::warn_floatingpoint_eq);
-
+    if (lType->isFloatingType() && rType->isFloatingType()) {
+      // Special case: check for x == x (which is OK).
+      bool EmitWarning = true;
+      
+      if (DeclRefExpr* DRL = dyn_cast<DeclRefExpr>(lex))
+        if (DeclRefExpr* DRR = dyn_cast<DeclRefExpr>(rex))
+          if (DRL->getDecl() == DRR->getDecl())
+            EmitWarning = false;
+      
+      if (EmitWarning)
+        Diag(loc, diag::warn_floatingpoint_eq);
+    }
+    
     if (lType->isArithmeticType() && rType->isArithmeticType())
       return Context.IntTy;
   }
diff --git a/test/Sema/floating-point-compare.c b/test/Sema/floating-point-compare.c
index 6adc228345..62388915a2 100644
--- a/test/Sema/floating-point-compare.c
+++ b/test/Sema/floating-point-compare.c
@@ -7,3 +7,7 @@ int foo(float x, float y) {
 int bar(float x, float y) {
   return x != y; // expected-warning {{comparing floating point with ==}}
 }
+
+int qux(float x) {
+  return x == x; // no-warning
+}