Change compound assignment operators to keep track of both the promoted 
LHS type and the computation result type; this encodes information into 
the AST which is otherwise non-obvious.  Fix Sema to always come up with the 
right answer for both of these types.  Fix IRGen and the analyzer to 
account for these changes.  This fixes PR2601.  The approach is inspired 
by PR2601 comment 2.

Note that this changes real *= complex in CodeGen from a silent 
miscompilation to an explicit error.

I'm not really sure that the analyzer changes are correct, or how to 
test them... someone more familiar with the analyzer should check those 
changes.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@67889 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index 8b646e9..0a77c21 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -174,10 +174,10 @@
 /// GCC.
 QualType Sema::UsualArithmeticConversions(Expr *&lhsExpr, Expr *&rhsExpr,
                                           bool isCompAssign) {
-  if (!isCompAssign) {
+  if (!isCompAssign)
     UsualUnaryConversions(lhsExpr);
-    UsualUnaryConversions(rhsExpr);
-  }
+
+  UsualUnaryConversions(rhsExpr);
 
   // For conversion purposes, we ignore any qualifiers. 
   // For example, "const float" and "float" are equivalent.
@@ -196,10 +196,9 @@
     return lhs;
 
   QualType destType = UsualArithmeticConversionsType(lhs, rhs);
-  if (!isCompAssign) {
+  if (!isCompAssign)
     ImpCastExprToType(lhsExpr, destType);
-    ImpCastExprToType(rhsExpr, destType);
-  }
+  ImpCastExprToType(rhsExpr, destType);
   return destType;
 }
 
@@ -3147,16 +3146,22 @@
 }
 
 inline QualType Sema::CheckAdditionOperands( // C99 6.5.6
-  Expr *&lex, Expr *&rex, SourceLocation Loc, bool isCompAssign)
+  Expr *&lex, Expr *&rex, SourceLocation Loc, QualType* CompLHSTy)
 {
-  if (lex->getType()->isVectorType() || rex->getType()->isVectorType())
-    return CheckVectorOperands(Loc, lex, rex);
+  if (lex->getType()->isVectorType() || rex->getType()->isVectorType()) {
+    QualType compType = CheckVectorOperands(Loc, lex, rex);
+    if (CompLHSTy) *CompLHSTy = compType;
+    return compType;
+  }
 
-  QualType compType = UsualArithmeticConversions(lex, rex, isCompAssign);
+  QualType compType = UsualArithmeticConversions(lex, rex, CompLHSTy);
 
   // handle the common case first (both operands are arithmetic).
-  if (lex->getType()->isArithmeticType() && rex->getType()->isArithmeticType())
+  if (lex->getType()->isArithmeticType() &&
+      rex->getType()->isArithmeticType()) {
+    if (CompLHSTy) *CompLHSTy = compType;
     return compType;
+  }
 
   // Put any potential pointer into PExp
   Expr* PExp = lex, *IExp = rex;
@@ -3193,6 +3198,12 @@
                                      lex->getType()))
         return QualType();
 
+      if (CompLHSTy) {
+        QualType LHSTy = lex->getType();
+        if (LHSTy->isPromotableIntegerType())
+          LHSTy = Context.IntTy;
+        *CompLHSTy = LHSTy;
+      }
       return PExp->getType();
     }
   }
@@ -3202,17 +3213,22 @@
 
 // C99 6.5.6
 QualType Sema::CheckSubtractionOperands(Expr *&lex, Expr *&rex,
-                                        SourceLocation Loc, bool isCompAssign) {
-  if (lex->getType()->isVectorType() || rex->getType()->isVectorType())
-    return CheckVectorOperands(Loc, lex, rex);
+                                        SourceLocation Loc, QualType* CompLHSTy) {
+  if (lex->getType()->isVectorType() || rex->getType()->isVectorType()) {
+    QualType compType = CheckVectorOperands(Loc, lex, rex);
+    if (CompLHSTy) *CompLHSTy = compType;
+    return compType;
+  }
 
-  QualType compType = UsualArithmeticConversions(lex, rex, isCompAssign);
+  QualType compType = UsualArithmeticConversions(lex, rex, CompLHSTy);
 
   // Enforce type constraints: C99 6.5.6p3.
 
   // Handle the common case first (both operands are arithmetic).
-  if (lex->getType()->isArithmeticType() && rex->getType()->isArithmeticType())
+  if (lex->getType()->isArithmeticType() && rex->getType()->isArithmeticType()) {
+    if (CompLHSTy) *CompLHSTy = compType;
     return compType;
+  }
 
   // Either ptr - int   or   ptr - ptr.
   if (const PointerType *LHSPTy = lex->getType()->getAsPointerType()) {
@@ -3258,6 +3274,7 @@
           << ComplainAboutFunc->getType() 
           << ComplainAboutFunc->getSourceRange();
 
+      if (CompLHSTy) *CompLHSTy = lex->getType();
       return lex->getType();
     }
 
@@ -3310,7 +3327,8 @@
         Diag(Loc, diag::ext_gnu_ptr_func_arith)
           << ComplainAboutFunc->getType() 
           << ComplainAboutFunc->getSourceRange();
-        
+
+      if (CompLHSTy) *CompLHSTy = lex->getType();
       return Context.getPointerDiffType();
     }
   }
@@ -3327,12 +3345,18 @@
 
   // Shifts don't perform usual arithmetic conversions, they just do integer
   // promotions on each operand. C99 6.5.7p3
+  QualType LHSTy;
+  if (lex->getType()->isPromotableIntegerType())
+    LHSTy = Context.IntTy;
+  else
+    LHSTy = lex->getType();
   if (!isCompAssign)
-    UsualUnaryConversions(lex);
+    ImpCastExprToType(lex, LHSTy);
+
   UsualUnaryConversions(rex);
 
   // "The type of the result is that of the promoted left operand."
-  return lex->getType();
+  return LHSTy;
 }
 
 // C99 6.5.8
@@ -4049,9 +4073,11 @@
 Action::OwningExprResult Sema::CreateBuiltinBinOp(SourceLocation OpLoc,
                                                   unsigned Op,
                                                   Expr *lhs, Expr *rhs) {
-  QualType ResultTy;  // Result type of the binary operator.
-  QualType CompTy;    // Computation type for compound assignments (e.g. '+=')
+  QualType ResultTy;     // Result type of the binary operator.
   BinaryOperator::Opcode Opc = (BinaryOperator::Opcode)Op;
+  // The following two variables are used for compound assignment operators
+  QualType CompLHSTy;    // Type of LHS after promotions for computation
+  QualType CompResultTy; // Type of computation result
 
   switch (Opc) {
   case BinaryOperator::Assign:
@@ -4100,37 +4126,41 @@
     break;
   case BinaryOperator::MulAssign:
   case BinaryOperator::DivAssign:
-    CompTy = CheckMultiplyDivideOperands(lhs, rhs, OpLoc, true);
-    if (!CompTy.isNull())
-      ResultTy = CheckAssignmentOperands(lhs, rhs, OpLoc, CompTy);
+    CompResultTy = CheckMultiplyDivideOperands(lhs, rhs, OpLoc, true);
+    CompLHSTy = CompResultTy;
+    if (!CompResultTy.isNull())
+      ResultTy = CheckAssignmentOperands(lhs, rhs, OpLoc, CompResultTy);
     break;
   case BinaryOperator::RemAssign:
-    CompTy = CheckRemainderOperands(lhs, rhs, OpLoc, true);
-    if (!CompTy.isNull())
-      ResultTy = CheckAssignmentOperands(lhs, rhs, OpLoc, CompTy);
+    CompResultTy = CheckRemainderOperands(lhs, rhs, OpLoc, true);
+    CompLHSTy = CompResultTy;
+    if (!CompResultTy.isNull())
+      ResultTy = CheckAssignmentOperands(lhs, rhs, OpLoc, CompResultTy);
     break;
   case BinaryOperator::AddAssign:
-    CompTy = CheckAdditionOperands(lhs, rhs, OpLoc, true);
-    if (!CompTy.isNull())
-      ResultTy = CheckAssignmentOperands(lhs, rhs, OpLoc, CompTy);
+    CompResultTy = CheckAdditionOperands(lhs, rhs, OpLoc, &CompLHSTy);
+    if (!CompResultTy.isNull())
+      ResultTy = CheckAssignmentOperands(lhs, rhs, OpLoc, CompResultTy);
     break;
   case BinaryOperator::SubAssign:
-    CompTy = CheckSubtractionOperands(lhs, rhs, OpLoc, true);
-    if (!CompTy.isNull())
-      ResultTy = CheckAssignmentOperands(lhs, rhs, OpLoc, CompTy);
+    CompResultTy = CheckSubtractionOperands(lhs, rhs, OpLoc, &CompLHSTy);
+    if (!CompResultTy.isNull())
+      ResultTy = CheckAssignmentOperands(lhs, rhs, OpLoc, CompResultTy);
     break;
   case BinaryOperator::ShlAssign:
   case BinaryOperator::ShrAssign:
-    CompTy = CheckShiftOperands(lhs, rhs, OpLoc, true);
-    if (!CompTy.isNull())
-      ResultTy = CheckAssignmentOperands(lhs, rhs, OpLoc, CompTy);
+    CompResultTy = CheckShiftOperands(lhs, rhs, OpLoc, true);
+    CompLHSTy = CompResultTy;
+    if (!CompResultTy.isNull())
+      ResultTy = CheckAssignmentOperands(lhs, rhs, OpLoc, CompResultTy);
     break;
   case BinaryOperator::AndAssign:
   case BinaryOperator::XorAssign:
   case BinaryOperator::OrAssign:
-    CompTy = CheckBitwiseOperands(lhs, rhs, OpLoc, true);
-    if (!CompTy.isNull())
-      ResultTy = CheckAssignmentOperands(lhs, rhs, OpLoc, CompTy);
+    CompResultTy = CheckBitwiseOperands(lhs, rhs, OpLoc, true);
+    CompLHSTy = CompResultTy;
+    if (!CompResultTy.isNull())
+      ResultTy = CheckAssignmentOperands(lhs, rhs, OpLoc, CompResultTy);
     break;
   case BinaryOperator::Comma:
     ResultTy = CheckCommaOperands(lhs, rhs, OpLoc);
@@ -4138,11 +4168,12 @@
   }
   if (ResultTy.isNull())
     return ExprError();
-  if (CompTy.isNull())
+  if (CompResultTy.isNull())
     return Owned(new (Context) BinaryOperator(lhs, rhs, Opc, ResultTy, OpLoc));
   else
     return Owned(new (Context) CompoundAssignOperator(lhs, rhs, Opc, ResultTy,
-                                                      CompTy, OpLoc));
+                                                      CompLHSTy, CompResultTy,
+                                                      OpLoc));
 }
 
 // Binary Operators.  'Tok' is the token for the operator.