[Fixed Point Arithmetic] Fixed Point Precision Bits and Fixed Point Literals

This diff includes the logic for setting the precision bits for each primary fixed point type in the target info and logic for initializing a fixed point literal.

Fixed point literals are declared using the suffixes

```
hr: short _Fract
uhr: unsigned short _Fract
r: _Fract
ur: unsigned _Fract
lr: long _Fract
ulr: unsigned long _Fract
hk: short _Accum
uhk: unsigned short _Accum
k: _Accum
uk: unsigned _Accum
```
Errors are also thrown for illegal literal values

```
unsigned short _Accum u_short_accum = 256.0uhk;   // expected-error{{the integral part of this literal is too large for this unsigned _Accum type}}
```

Differential Revision: https://reviews.llvm.org/D46915

llvm-svn: 335148

1 files changed, 101 insertions, 0 deletions

diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index 2079f901ed3..c700da635b7 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -7220,6 +7220,73 @@ public:
 
   // FIXME: Missing: array subscript of vector, member of vector
 };
+
+class FixedPointExprEvaluator
+    : public ExprEvaluatorBase<FixedPointExprEvaluator> {
+  APValue &Result;
+
+ public:
+  FixedPointExprEvaluator(EvalInfo &info, APValue &result)
+      : ExprEvaluatorBaseTy(info), Result(result) {}
+
+  bool Success(const llvm::APSInt &SI, const Expr *E, APValue &Result) {
+    assert(E->getType()->isFixedPointType() && "Invalid evaluation result.");
+    assert(SI.isSigned() == E->getType()->isSignedFixedPointType() &&
+           "Invalid evaluation result.");
+    assert(SI.getBitWidth() == Info.Ctx.getIntWidth(E->getType()) &&
+           "Invalid evaluation result.");
+    Result = APValue(SI);
+    return true;
+  }
+  bool Success(const llvm::APSInt &SI, const Expr *E) {
+    return Success(SI, E, Result);
+  }
+
+  bool Success(const llvm::APInt &I, const Expr *E, APValue &Result) {
+    assert(E->getType()->isFixedPointType() && "Invalid evaluation result.");
+    assert(I.getBitWidth() == Info.Ctx.getIntWidth(E->getType()) &&
+           "Invalid evaluation result.");
+    Result = APValue(APSInt(I));
+    Result.getInt().setIsUnsigned(E->getType()->isUnsignedFixedPointType());
+    return true;
+  }
+  bool Success(const llvm::APInt &I, const Expr *E) {
+    return Success(I, E, Result);
+  }
+
+  bool Success(uint64_t Value, const Expr *E, APValue &Result) {
+    assert(E->getType()->isFixedPointType() && "Invalid evaluation result.");
+    Result = APValue(Info.Ctx.MakeIntValue(Value, E->getType()));
+    return true;
+  }
+  bool Success(uint64_t Value, const Expr *E) {
+    return Success(Value, E, Result);
+  }
+
+  bool Success(CharUnits Size, const Expr *E) {
+    return Success(Size.getQuantity(), E);
+  }
+
+  bool Success(const APValue &V, const Expr *E) {
+    if (V.isLValue() || V.isAddrLabelDiff()) {
+      Result = V;
+      return true;
+    }
+    return Success(V.getInt(), E);
+  }
+
+  bool ZeroInitialization(const Expr *E) { return Success(0, E); }
+
+  //===--------------------------------------------------------------------===//
+  //                            Visitor Methods
+  //===--------------------------------------------------------------------===//
+
+  bool VisitFixedPointLiteral(const FixedPointLiteral *E) {
+    return Success(E->getValue(), E);
+  }
+
+  bool VisitUnaryOperator(const UnaryOperator *E);
+};
 } // end anonymous namespace
 
 /// EvaluateIntegerOrLValue - Evaluate an rvalue integral-typed expression, and
@@ -9460,6 +9527,37 @@ bool IntExprEvaluator::VisitCXXNoexceptExpr(const CXXNoexceptExpr *E) {
   return Success(E->getValue(), E);
 }
 
+bool FixedPointExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) {
+  switch (E->getOpcode()) {
+    default:
+      // Invalid unary operators
+      return Error(E);
+    case UO_Plus:
+      // The result is just the value.
+      return Visit(E->getSubExpr());
+    case UO_Minus: {
+      if (!Visit(E->getSubExpr())) return false;
+      if (!Result.isInt()) return Error(E);
+      const APSInt &Value = Result.getInt();
+      if (Value.isSigned() && Value.isMinSignedValue() && E->canOverflow()) {
+        SmallString<64> S;
+        FixedPointValueToString(S, Value,
+                                Info.Ctx.getTypeInfo(E->getType()).Width,
+                                /*Radix=*/10);
+        Info.CCEDiag(E, diag::note_constexpr_overflow) << S << E->getType();
+        if (Info.noteUndefinedBehavior()) return false;
+      }
+      return Success(-Value, E);
+    }
+    case UO_LNot: {
+      bool bres;
+      if (!EvaluateAsBooleanCondition(E->getSubExpr(), bres, Info))
+        return false;
+      return Success(!bres, E);
+    }
+  }
+}
+
 //===----------------------------------------------------------------------===//
 // Float Evaluation
 //===----------------------------------------------------------------------===//
@@ -10311,6 +10409,8 @@ static bool Evaluate(APValue &Result, EvalInfo &Info, const Expr *E) {
     if (!EvaluateComplex(E, C, Info))
       return false;
     C.moveInto(Result);
+  } else if (T->isFixedPointType()) {
+    if (!FixedPointExprEvaluator(Info, Result).Visit(E)) return false;
   } else if (T->isMemberPointerType()) {
     MemberPtr P;
     if (!EvaluateMemberPointer(E, P, Info))
@@ -10759,6 +10859,7 @@ static ICEDiag CheckICE(const Expr* E, const ASTContext &Ctx) {
   case Expr::GenericSelectionExprClass:
     return CheckICE(cast<GenericSelectionExpr>(E)->getResultExpr(), Ctx);
   case Expr::IntegerLiteralClass:
+  case Expr::FixedPointLiteralClass:
   case Expr::CharacterLiteralClass:
   case Expr::ObjCBoolLiteralExprClass:
   case Expr::CXXBoolLiteralExprClass: