[clang] 94e8ec6 - [AST] Add fixed-point division constant evaluation.
Bevin Hansson via cfe-commits
cfe-commits at lists.llvm.org
Fri Jun 26 04:42:00 PDT 2020
Author: Bevin Hansson
Date: 2020-06-26T13:38:11+02:00
New Revision: 94e8ec631dda98639930c3fcf6b84148cd58cd59
URL: https://github.com/llvm/llvm-project/commit/94e8ec631dda98639930c3fcf6b84148cd58cd59
DIFF: https://github.com/llvm/llvm-project/commit/94e8ec631dda98639930c3fcf6b84148cd58cd59.diff
LOG: [AST] Add fixed-point division constant evaluation.
Reviewers: rjmccall, leonardchan, bjope
Subscribers: cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D73187
Added:
Modified:
clang/include/clang/Basic/FixedPoint.h
clang/lib/AST/ExprConstant.cpp
clang/lib/Basic/FixedPoint.cpp
clang/test/Frontend/fixed_point_div.c
Removed:
################################################################################
diff --git a/clang/include/clang/Basic/FixedPoint.h b/clang/include/clang/Basic/FixedPoint.h
index 2566169cfd23..8937bccb0edb 100644
--- a/clang/include/clang/Basic/FixedPoint.h
+++ b/clang/include/clang/Basic/FixedPoint.h
@@ -130,6 +130,7 @@ class APFixedPoint {
APFixedPoint add(const APFixedPoint &Other, bool *Overflow = nullptr) const;
APFixedPoint sub(const APFixedPoint &Other, bool *Overflow = nullptr) const;
APFixedPoint mul(const APFixedPoint &Other, bool *Overflow = nullptr) const;
+ APFixedPoint div(const APFixedPoint &Other, bool *Overflow = nullptr) const;
/// Perform a unary negation (-X) on this fixed point type, taking into
/// account saturation if applicable.
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index 35aeb6f8f089..b55499fd5075 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -12948,6 +12948,15 @@ bool FixedPointExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
return false;
return Success(Result, E);
}
+ case BO_Div: {
+ bool AddOverflow, ConversionOverflow;
+ APFixedPoint Result = LHSFX.div(RHSFX, &AddOverflow)
+ .convert(ResultFXSema, &ConversionOverflow);
+ if ((AddOverflow || ConversionOverflow) &&
+ !HandleOverflow(Info, E, Result, E->getType()))
+ return false;
+ return Success(Result, E);
+ }
default:
return false;
}
diff --git a/clang/lib/Basic/FixedPoint.cpp b/clang/lib/Basic/FixedPoint.cpp
index 21fa1c00aa83..e8db43c6fe90 100644
--- a/clang/lib/Basic/FixedPoint.cpp
+++ b/clang/lib/Basic/FixedPoint.cpp
@@ -254,6 +254,61 @@ APFixedPoint APFixedPoint::mul(const APFixedPoint &Other,
CommonFXSema);
}
+APFixedPoint APFixedPoint::div(const APFixedPoint &Other,
+ bool *Overflow) 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();
+ bool Overflowed = false;
+
+ // Widen the LHS and RHS so we can perform a full division.
+ unsigned Wide = CommonFXSema.getWidth() * 2;
+ if (CommonFXSema.isSigned()) {
+ ThisVal = ThisVal.sextOrSelf(Wide);
+ OtherVal = OtherVal.sextOrSelf(Wide);
+ } else {
+ ThisVal = ThisVal.zextOrSelf(Wide);
+ OtherVal = OtherVal.zextOrSelf(Wide);
+ }
+
+ // Upscale to compensate for the loss of precision from division, and
+ // perform the full division.
+ ThisVal = ThisVal.shl(CommonFXSema.getScale());
+ llvm::APSInt Result;
+ if (CommonFXSema.isSigned()) {
+ llvm::APInt Rem;
+ llvm::APInt::sdivrem(ThisVal, OtherVal, Result, Rem);
+ // If the quotient is negative and the remainder is nonzero, round
+ // towards negative infinity by subtracting epsilon from the result.
+ if (Result.isNegative() && !Rem.isNullValue())
+ Result = Result - 1;
+ } else
+ Result = ThisVal.udiv(OtherVal);
+ Result.setIsSigned(CommonFXSema.isSigned());
+
+ // If our result lies outside of the representative range of the common
+ // semantic, we either have overflow or saturation.
+ llvm::APSInt Max = APFixedPoint::getMax(CommonFXSema).getValue()
+ .extOrTrunc(Wide);
+ llvm::APSInt Min = APFixedPoint::getMin(CommonFXSema).getValue()
+ .extOrTrunc(Wide);
+ if (CommonFXSema.isSaturated()) {
+ if (Result < Min)
+ Result = Min;
+ else if (Result > Max)
+ Result = Max;
+ } else
+ Overflowed = Result < Min || Result > Max;
+
+ if (Overflow)
+ *Overflow = Overflowed;
+
+ return APFixedPoint(Result.sextOrTrunc(CommonFXSema.getWidth()),
+ CommonFXSema);
+}
+
void APFixedPoint::toString(llvm::SmallVectorImpl<char> &Str) const {
llvm::APSInt Val = getValue();
unsigned Scale = getScale();
diff --git a/clang/test/Frontend/fixed_point_div.c b/clang/test/Frontend/fixed_point_div.c
index ec17e082558c..28fa5e0e9cbc 100644
--- a/clang/test/Frontend/fixed_point_div.c
+++ b/clang/test/Frontend/fixed_point_div.c
@@ -1,6 +1,70 @@
// RUN: %clang_cc1 -ffixed-point -triple x86_64-unknown-linux-gnu -S -emit-llvm %s -o - | FileCheck %s --check-prefixes=CHECK,SIGNED
// RUN: %clang_cc1 -ffixed-point -triple x86_64-unknown-linux-gnu -fpadding-on-unsigned-fixed-point -S -emit-llvm %s -o - | FileCheck %s --check-prefixes=CHECK,UNSIGNED
+// Division between
diff erent fixed point types
+short _Accum sa_const = 1.0hk / 2.0hk; // CHECK-DAG: @sa_const = {{.*}}global i16 64, align 2
+_Accum a_const = 1.0hk / 2.0k; // CHECK-DAG: @a_const = {{.*}}global i32 16384, align 4
+long _Accum la_const = 1.0hk / 2.0lk; // CHECK-DAG: @la_const = {{.*}}global i64 1073741824, align 8
+short _Accum sa_const2 = 0.5hr / 2.0hk; // CHECK-DAG: @sa_const2 = {{.*}}global i16 32, align 2
+short _Accum sa_const3 = 0.5r / 2.0hk; // CHECK-DAG: @sa_const3 = {{.*}}global i16 32, align 2
+short _Accum sa_const4 = 0.5lr / 2.0hk; // CHECK-DAG: @sa_const4 = {{.*}}global i16 32, align 2
+short _Accum sa_const5 = 2.0hk / 0.5lr; // CHECK-DAG: @sa_const5 = {{.*}}global i16 512, align 2
+
+// Unsigned division
+unsigned short _Accum usa_const = 3.0uhk / 2.0uhk;
+// CHECK-SIGNED-DAG: @usa_const = {{.*}}global i16 192, align 2
+// CHECK-UNSIGNED-DAG: @usa_const = {{.*}}global i16 384, align 2
+
+// Unsigned / signed
+short _Accum sa_const6 = 1.0uhk / 2.0hk;
+// CHECK-DAG: @sa_const6 = {{.*}}global i16 64, align 2
+
+// Division with negative number
+short _Accum sa_const7 = 0.5hr / (-2.0hk);
+// CHECK-DAG: @sa_const7 = {{.*}}global i16 -32, align 2
+
+// Int division
+unsigned short _Accum usa_const2 = 2 / 0.5uhk;
+// CHECK-SIGNED-DAG: @usa_const2 = {{.*}}global i16 512, align 2
+// CHECK-UNSIGNED-DAG: @usa_const2 = {{.*}}global i16 1024, align 2
+short _Accum sa_const8 = 2 / (-0.5hk); // CHECK-DAG: @sa_const8 = {{.*}}global i16 -512, align 2
+short _Accum sa_const9 = 256 / 2.0hk; // CHECK-DAG: @sa_const9 = {{.*}}global i16 16384, align 2
+long _Fract lf_const = 0.5lr / -1; // CHECK-DAG: @lf_const = {{.*}}global i32 -1073741824, align 4
+
+// Saturated division
+_Sat short _Accum sat_sa_const = (_Sat short _Accum)128.0hk / (-0.25hk);
+// CHECK-DAG: @sat_sa_const = {{.*}}global i16 -32768, align 2
+_Sat unsigned short _Accum sat_usa_const = (_Sat unsigned short _Accum)128.0uhk / (0.25uhk);
+// 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 / (-0.0125hr);
+// 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 / -1;
+// CHECK-DAG: @sat_usa_const3 = {{.*}}global i16 0, align 2
+_Sat short _Accum sat_sa_const3 = (_Sat short _Accum)-128.0hk / 128;
+// CHECK-DAG: @sat_sa_const3 = {{.*}}global i16 -128, align 2
+_Sat short _Accum sat_sa_const4 = (_Sat short _Accum)-25.7hk / 0.1lk;
+// CHECK-DAG: @sat_sa_const4 = {{.*}}global i16 -32768, align 2
+
+// Some more cases
+short _Accum sa_const10 = 255.9921875hk / 255.9921875hk;
+// CHECK-DAG: @sa_const10 = {{.*}}global i16 128, align 2
+short _Accum sat_sa_const5 = (_Sat short _Accum)(-255.0hk - 1.0hk) / 0.0078125hk;
+// CHECK-DAG: @sat_sa_const5 = {{.*}}global i16 -32768, align 2
+_Sat short _Accum sat_sa_const6 = (_Sat short _Accum)(-255.0hk - 1.0hk) / -0.0078125hk;
+// CHECK-DAG: @sat_sa_const6 = {{.*}}global i16 32767, align 2
+short _Accum sa_const12 = 255.9921875hk / -1.0hk;
+// CHECK-DAG: @sa_const12 = {{.*}}global i16 -32767, align 2
+_Sat short _Accum sat_sa_const7 = (_Sat short _Accum)(-255.0hk - 1.0hk) / -1.0hk;
+// CHECK-DAG: @sat_sa_const7 = {{.*}}global i16 32767, align 2
+short _Accum sa_const13 = 0.0234375hk / 2.0hk;
+// CHECK-DAG: @sa_const13 = {{.*}}global i16 1, align 2
+short _Accum sa_const14 = -0.0234375hk / 2.0hk;
+// CHECK-DAG: @sa_const14 = {{.*}}global i16 -2, align 2
+
void SignedDivision() {
// CHECK-LABEL: SignedDivision
short _Accum sa;
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