leonardchan created this revision.
leonardchan added reviewers: ebevhan, bjope, rjmccall.
leonardchan added a project: clang.
leonardchan added a parent revision: D53738: [Fixed Point Arithmetic] Fixed
Point Addition.
This patch includes logic for constant expression evaluation of fixed point
additions.
Repository:
rC Clang
https://reviews.llvm.org/D55868
Files:
clang/include/clang/Basic/FixedPoint.h
clang/lib/AST/ExprConstant.cpp
clang/lib/Basic/FixedPoint.cpp
clang/test/Frontend/fixed_point_add.c
Index: clang/test/Frontend/fixed_point_add.c
===================================================================
--- clang/test/Frontend/fixed_point_add.c
+++ clang/test/Frontend/fixed_point_add.c
@@ -1,6 +1,49 @@
// RUN: %clang_cc1 -ffixed-point -S -emit-llvm %s -o - | FileCheck %s --check-prefixes=CHECK,SIGNED
// RUN: %clang_cc1 -ffixed-point -fpadding-on-unsigned-fixed-point -S -emit-llvm %s -o - | FileCheck %s --check-prefixes=CHECK,UNSIGNED
+// Addition between different fixed point types
+short _Accum sa_const = 1.0hk + 2.0hk; // CHECK-DAG: @sa_const = {{.*}}global i16 384, align 2
+_Accum a_const = 1.0hk + 2.0k; // CHECK-DAG: @a_const = {{.*}}global i32 98304, align 4
+long _Accum la_const = 1.0hk + 2.0lk; // CHECK-DAG: @la_const = {{.*}}global i64 6442450944, align 8
+short _Accum sa_const2 = 0.5hr + 2.0hk; // CHECK-DAG: @sa_const2 = {{.*}}global i16 320, align 2
+short _Accum sa_const3 = 0.5r + 2.0hk; // CHECK-DAG: @sa_const3 = {{.*}}global i16 320, align 2
+short _Accum sa_const4 = 0.5lr + 2.0hk; // CHECK-DAG: @sa_const4 = {{.*}}global i16 320, align 2
+
+// Unsigned addition
+unsigned short _Accum usa_const = 1.0uhk + 2.0uhk;
+// CHECK-SIGNED-DAG: @usa_const = {{.*}}global i16 768, align 2
+// CHECK-UNSIGNED-DAG: @usa_const = {{.*}}global i16 384, align 2
+
+// Unsigned + signed
+short _Accum sa_const5 = 1.0uhk + 2.0hk;
+// CHECK-DAG: @sa_const5 = {{.*}}global i16 384, align 2
+
+// Addition with negative number
+short _Accum sa_const6 = 0.5hr + (-2.0hk);
+// CHECK-DAG: @sa_const6 = {{.*}}global i16 -192, align 2
+
+// Int addition
+unsigned short _Accum usa_const2 = 2 + 0.5uhk;
+// CHECK-SIGNED-DAG: @usa_const2 = {{.*}}global i16 640, align 2
+// CHECK-UNSIGNED-DAG: @usa_const2 = {{.*}}global i16 320, align 2
+short _Accum sa_const7 = 2 + (-0.5hk); // CHECK-DAG: @sa_const7 = {{.*}}global i16 192, align 2
+short _Accum sa_const8 = 257 + (-2.0hk); // CHECK-DAG: @sa_const8 = {{.*}}global i16 32640, align 2
+long _Fract lf_const = -0.5lr + 1; // CHECK-DAG: @lf_const = {{.*}}global i32 1073741824, align 4
+
+// Saturated addition
+_Sat short _Accum sat_sa_const = (_Sat short _Accum)128.0hk + 128.0hk;
+// CHECK-DAG: @sat_sa_const = {{.*}}global i16 32767, align 2
+_Sat unsigned short _Accum sat_usa_const = (_Sat unsigned short _Accum)128.0uhk + 128.0uhk;
+// CHECK-SIGNED-DAG: @sat_usa_const = {{.*}}global i16 65535, align 2
+// CHECK-UNSIGNED-DAG: @sat_usa_const = {{.*}}global i16 32767, align 2
+_Sat short _Accum sat_sa_const2 = (_Sat short _Accum)128.0hk + 128;
+// CHECK-DAG: @sat_sa_const2 = {{.*}}global i16 32767, align 2
+_Sat unsigned short _Accum sat_usa_const2 = (_Sat unsigned short _Accum)128.0uhk + 128;
+// CHECK-SIGNED-DAG: @sat_usa_const2 = {{.*}}global i16 65535, align 2
+// CHECK-UNSIGNED-DAG: @sat_usa_const2 = {{.*}}global i16 32767, align 2
+_Sat unsigned short _Accum sat_usa_const3 = (_Sat unsigned short _Accum)0.5uhk + (-2);
+// CHECK-DAG: @sat_usa_const3 = {{.*}}global i16 0, align 2
+
void SignedAddition() {
// CHECK-LABEL: SignedAddition
short _Accum sa;
Index: clang/lib/Basic/FixedPoint.cpp
===================================================================
--- clang/lib/Basic/FixedPoint.cpp
+++ clang/lib/Basic/FixedPoint.cpp
@@ -39,7 +39,7 @@
if (!(Masked == Mask || Masked == 0))
NewVal = NewVal.isNegative() ? Mask : ~Mask;
- if (!DstSema.isSigned() && NewVal.isNegative())
+ if (!DstSema.isSigned() && NewVal.isSigned() && NewVal.isNegative())
NewVal = 0;
}
@@ -137,4 +137,21 @@
ResultIsSaturated, ResultHasUnsignedPadding);
}
+APFixedPoint APFixedPoint::add(const APFixedPoint &Other) const {
+ auto CommonFXSema = Sema.getCommonSemantics(Other.getSemantics());
+ APFixedPoint ConvertedThis = convert(CommonFXSema);
+ APFixedPoint ConvertedOther = Other.convert(CommonFXSema);
+ llvm::APSInt ThisVal = ConvertedThis.getValue();
+ llvm::APSInt OtherVal = ConvertedOther.getValue();
+
+ llvm::APInt Result;
+ if (CommonFXSema.isSaturated()) {
+ Result = CommonFXSema.isSigned() ? ThisVal.sadd_sat(OtherVal)
+ : ThisVal.uadd_sat(OtherVal);
+ } else
+ Result = ThisVal + OtherVal;
+
+ return APFixedPoint(Result, CommonFXSema);
+}
+
} // namespace clang
Index: clang/lib/AST/ExprConstant.cpp
===================================================================
--- clang/lib/AST/ExprConstant.cpp
+++ 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"
@@ -1613,6 +1614,10 @@
EvalInfo &Info);
static bool EvaluateAsRValue(EvalInfo &Info, const Expr *E, APValue &Result);
+/// Evaluate an integer or fixed point expression into an APFixedPoint.
+static bool EvaluateFixedPointOrInteger(const Expr *E, APFixedPoint &Result,
+ EvalInfo &Info);
+
//===----------------------------------------------------------------------===//
// Misc utilities
//===----------------------------------------------------------------------===//
@@ -7523,6 +7528,10 @@
return Success(V.getInt(), E);
}
+ bool Success(const APFixedPoint &V, const Expr *E) {
+ return Success(V.getValue(), E);
+ }
+
bool ZeroInitialization(const Expr *E) { return Success(0, E); }
//===--------------------------------------------------------------------===//
@@ -7533,7 +7542,9 @@
return Success(E->getValue(), E);
}
+ bool VisitCastExpr(const CastExpr *E);
bool VisitUnaryOperator(const UnaryOperator *E);
+ bool VisitBinaryOperator(const BinaryOperator *E);
};
} // end anonymous namespace
@@ -7565,6 +7576,28 @@
return true;
}
+static bool EvaluateFixedPointOrInteger(const Expr *E, APFixedPoint &Result,
+ EvalInfo &Info) {
+ auto FXSema = Info.Ctx.getFixedPointSemantics(E->getType());
+ if (E->getType()->isIntegerType()) {
+ APSInt Val;
+ if (!EvaluateInteger(E, Val, Info))
+ return false;
+ Result = APFixedPoint(Val, FXSema);
+ return true;
+ } else if (E->getType()->isFixedPointType()) {
+ APValue Val;
+ if (!FixedPointExprEvaluator(Info, Val).Visit(E))
+ return false;
+ if (!Val.isInt())
+ return false;
+
+ Result = APFixedPoint(Val.getInt(), FXSema);
+ return true;
+ }
+ 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.
@@ -9905,6 +9938,50 @@
}
}
+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;
+ if (!EvaluateFixedPointOrInteger(SubExpr, Src, Info))
+ return false;
+ APFixedPoint Result = Src.convert(DestFXSema);
+ return Success(Result, E);
+ }
+ default:
+ return Error(E);
+ }
+ llvm_unreachable("unknown cast resulting in fixed point value");
+}
+
+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, RHSFX;
+ if (!EvaluateFixedPointOrInteger(LHS, LHSFX, Info))
+ return false;
+ if (!EvaluateFixedPointOrInteger(RHS, RHSFX, Info))
+ return false;
+
+ switch (E->getOpcode()) {
+ case BO_Add: {
+ APFixedPoint Result = LHSFX.add(RHSFX).convert(ResultFXSema);
+ return Success(Result, E);
+ }
+ default:
+ return false;
+ }
+ llvm_unreachable("Should've exited before this");
+}
+
//===----------------------------------------------------------------------===//
// Float Evaluation
//===----------------------------------------------------------------------===//
Index: clang/include/clang/Basic/FixedPoint.h
===================================================================
--- clang/include/clang/Basic/FixedPoint.h
+++ clang/include/clang/Basic/FixedPoint.h
@@ -32,6 +32,7 @@
/// in the value this represents is treaded as padding.
class FixedPointSemantics {
public:
+ FixedPointSemantics() = default;
FixedPointSemantics(unsigned Width, unsigned Scale, bool IsSigned,
bool IsSaturated, bool HasUnsignedPadding)
: Width(Width), Scale(Scale), IsSigned(IsSigned),
@@ -94,6 +95,7 @@
/// native IR support.
class APFixedPoint {
public:
+ APFixedPoint() = default;
APFixedPoint(const llvm::APInt &Val, const FixedPointSemantics &Sema)
: Val(Val, !Sema.isSigned()), Sema(Sema) {
assert(Val.getBitWidth() == Sema.getWidth() &&
@@ -110,13 +112,19 @@
inline bool isSaturated() const { return Sema.isSaturated(); }
inline bool isSigned() const { return Sema.isSigned(); }
inline bool hasPadding() const { return Sema.hasUnsignedPadding(); }
+ FixedPointSemantics getSemantics() const { return Sema; }
// Convert this number to match the semantics provided.
APFixedPoint convert(const FixedPointSemantics &DstSema) const;
+ // Perform binary operations on a fixed point type. The resulting fixed point
+ // value will be in the common, full precision semantics that can represent
+ // the precision and ranges os both input values.
+ APFixedPoint add(const APFixedPoint &Other) const;
+
APFixedPoint shr(unsigned Amt) const {
return APFixedPoint(Val >> Amt, Sema);
- }
+ }
APFixedPoint shl(unsigned Amt) const {
return APFixedPoint(Val << Amt, Sema);
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