[Fixed Point Arithmetic] Fixed Point Addition Constant Expression Evaluation
This patch includes logic for constant expression evaluation of fixed point additions.
Differential Revision: https://reviews.llvm.org/D55868
llvm-svn: 351593
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index 6fced96..de99436 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -44,6 +44,7 @@
#include "clang/AST/StmtVisitor.h"
#include "clang/AST/TypeLoc.h"
#include "clang/Basic/Builtins.h"
+#include "clang/Basic/FixedPoint.h"
#include "clang/Basic/TargetInfo.h"
#include "llvm/Support/SaveAndRestore.h"
#include "llvm/Support/raw_ostream.h"
@@ -613,6 +614,15 @@
}
return *this;
}
+
+ OptionalDiagnostic &operator<<(const APFixedPoint &FX) {
+ if (Diag) {
+ SmallVector<char, 32> Buffer;
+ FX.toString(Buffer);
+ *Diag << StringRef(Buffer.data(), Buffer.size());
+ }
+ return *this;
+ }
};
/// A cleanup, and a flag indicating whether it is lifetime-extended.
@@ -1613,6 +1623,14 @@
EvalInfo &Info);
static bool EvaluateAsRValue(EvalInfo &Info, const Expr *E, APValue &Result);
+/// Evaluate an integer or fixed point expression into an APResult.
+static bool EvaluateFixedPointOrInteger(const Expr *E, APFixedPoint &Result,
+ EvalInfo &Info);
+
+/// Evaluate only a fixed point expression into an APResult.
+static bool EvaluateFixedPoint(const Expr *E, APFixedPoint &Result,
+ EvalInfo &Info);
+
//===----------------------------------------------------------------------===//
// Misc utilities
//===----------------------------------------------------------------------===//
@@ -7493,53 +7511,27 @@
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);
+ return Success(
+ APFixedPoint(I, Info.Ctx.getFixedPointSemantics(E->getType())), E);
}
- 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);
+ return Success(
+ APFixedPoint(Value, Info.Ctx.getFixedPointSemantics(E->getType())), E);
}
bool Success(const APValue &V, const Expr *E) {
- if (V.isLValue() || V.isAddrLabelDiff()) {
- Result = V;
- return true;
- }
- return Success(V.getInt(), E);
+ return Success(V.getFixedPoint(), E);
}
- bool ZeroInitialization(const Expr *E) { return Success(0, E); }
+ bool Success(const APFixedPoint &V, const Expr *E) {
+ assert(E->getType()->isFixedPointType() && "Invalid evaluation result.");
+ assert(V.getWidth() == Info.Ctx.getIntWidth(E->getType()) &&
+ "Invalid evaluation result.");
+ Result = APValue(V);
+ return true;
+ }
//===--------------------------------------------------------------------===//
// Visitor Methods
@@ -7549,7 +7541,9 @@
return Success(E->getValue(), E);
}
+ bool VisitCastExpr(const CastExpr *E);
bool VisitUnaryOperator(const UnaryOperator *E);
+ bool VisitBinaryOperator(const BinaryOperator *E);
};
} // end anonymous namespace
@@ -7581,6 +7575,36 @@
return true;
}
+static bool EvaluateFixedPoint(const Expr *E, APFixedPoint &Result,
+ EvalInfo &Info) {
+ if (E->getType()->isFixedPointType()) {
+ APValue Val;
+ if (!FixedPointExprEvaluator(Info, Val).Visit(E))
+ return false;
+ if (!Val.isFixedPoint())
+ return false;
+
+ Result = Val.getFixedPoint();
+ return true;
+ }
+ return false;
+}
+
+static bool EvaluateFixedPointOrInteger(const Expr *E, APFixedPoint &Result,
+ EvalInfo &Info) {
+ if (E->getType()->isIntegerType()) {
+ auto FXSema = Info.Ctx.getFixedPointSemantics(E->getType());
+ APSInt Val;
+ if (!EvaluateInteger(E, Val, Info))
+ return false;
+ Result = APFixedPoint(Val, FXSema);
+ return true;
+ } else if (E->getType()->isFixedPointType()) {
+ return EvaluateFixedPoint(E, Result, Info);
+ }
+ return false;
+}
+
/// Check whether the given declaration can be directly converted to an integral
/// rvalue. If not, no diagnostic is produced; there are other things we can
/// try.
@@ -9781,7 +9805,7 @@
APValue Val;
if (!Evaluate(Val, Info, SubExpr))
return false;
- return Success(Val.getInt().getBoolValue(), E);
+ return Success(Val.getFixedPoint().getBoolValue(), E);
}
case CK_IntegralCast: {
@@ -9901,16 +9925,13 @@
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);
- Info.CCEDiag(E, diag::note_constexpr_overflow) << S << E->getType();
- if (Info.noteUndefinedBehavior()) return false;
- }
- return Success(-Value, E);
+ if (!Result.isFixedPoint())
+ return Error(E);
+ bool Overflowed;
+ APFixedPoint Negated = Result.getFixedPoint().negate(&Overflowed);
+ if (Overflowed && !HandleOverflow(Info, E, Negated, E->getType()))
+ return false;
+ return Success(Negated, E);
}
case UO_LNot: {
bool bres;
@@ -9921,6 +9942,61 @@
}
}
+bool FixedPointExprEvaluator::VisitCastExpr(const CastExpr *E) {
+ const Expr *SubExpr = E->getSubExpr();
+ QualType DestType = E->getType();
+ assert(DestType->isFixedPointType() &&
+ "Expected destination type to be a fixed point type");
+ auto DestFXSema = Info.Ctx.getFixedPointSemantics(DestType);
+
+ switch (E->getCastKind()) {
+ case CK_FixedPointCast: {
+ APFixedPoint Src(Info.Ctx.getFixedPointSemantics(SubExpr->getType()));
+ if (!EvaluateFixedPoint(SubExpr, Src, Info))
+ return false;
+ bool Overflowed;
+ APFixedPoint Result = Src.convert(DestFXSema, &Overflowed);
+ if (Overflowed && !HandleOverflow(Info, E, Result, DestType))
+ return false;
+ return Success(Result, E);
+ }
+ case CK_NoOp:
+ case CK_LValueToRValue:
+ return ExprEvaluatorBaseTy::VisitCastExpr(E);
+ default:
+ return Error(E);
+ }
+}
+
+bool FixedPointExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
+ const Expr *LHS = E->getLHS();
+ const Expr *RHS = E->getRHS();
+ FixedPointSemantics ResultFXSema =
+ Info.Ctx.getFixedPointSemantics(E->getType());
+
+ APFixedPoint LHSFX(Info.Ctx.getFixedPointSemantics(LHS->getType()));
+ if (!EvaluateFixedPointOrInteger(LHS, LHSFX, Info))
+ return false;
+ APFixedPoint RHSFX(Info.Ctx.getFixedPointSemantics(RHS->getType()));
+ if (!EvaluateFixedPointOrInteger(RHS, RHSFX, Info))
+ return false;
+
+ switch (E->getOpcode()) {
+ case BO_Add: {
+ bool AddOverflow, ConversionOverflow;
+ APFixedPoint Result = LHSFX.add(RHSFX, &AddOverflow)
+ .convert(ResultFXSema, &ConversionOverflow);
+ if ((AddOverflow || ConversionOverflow) &&
+ !HandleOverflow(Info, E, Result, E->getType()))
+ return false;
+ return Success(Result, E);
+ }
+ default:
+ return false;
+ }
+ llvm_unreachable("Should've exited before this");
+}
+
//===----------------------------------------------------------------------===//
// Float Evaluation
//===----------------------------------------------------------------------===//
@@ -10932,6 +11008,23 @@
return true;
}
+static bool EvaluateAsFixedPoint(const Expr *E, Expr::EvalResult &ExprResult,
+ const ASTContext &Ctx,
+ Expr::SideEffectsKind AllowSideEffects,
+ EvalInfo &Info) {
+ if (!E->getType()->isFixedPointType())
+ return false;
+
+ if (!::EvaluateAsRValue(E, ExprResult, Ctx, Info))
+ return false;
+
+ if (!ExprResult.Val.isFixedPoint() ||
+ hasUnacceptableSideEffect(ExprResult, AllowSideEffects))
+ return false;
+
+ return true;
+}
+
/// EvaluateAsRValue - Return true if this is a constant which we can fold using
/// any crazy technique (that has nothing to do with language standards) that
/// we want to. If this function returns true, it returns the folded constant
@@ -10957,6 +11050,12 @@
return ::EvaluateAsInt(this, Result, Ctx, AllowSideEffects, Info);
}
+bool Expr::EvaluateAsFixedPoint(EvalResult &Result, const ASTContext &Ctx,
+ SideEffectsKind AllowSideEffects) const {
+ EvalInfo Info(Ctx, Result, EvalInfo::EM_IgnoreSideEffects);
+ return ::EvaluateAsFixedPoint(this, Result, Ctx, AllowSideEffects, Info);
+}
+
bool Expr::EvaluateAsFloat(APFloat &Result, const ASTContext &Ctx,
SideEffectsKind AllowSideEffects) const {
if (!getType()->isRealFloatingType())