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authortsepez <tsepez@chromium.org>2016-11-02 13:26:50 -0700
committerCommit bot <commit-bot@chromium.org>2016-11-02 13:26:50 -0700
commit66bd67023f747c489d7144aaf4ca6222c686cd26 (patch)
tree218975bef99211cbf0e6e8d6ede1e9db266871d2 /third_party/base/numerics/safe_math_impl.h
parent521b7508dfe8ab93975eeb9f4ef8068012c4dbd8 (diff)
downloadpdfium-66bd67023f747c489d7144aaf4ca6222c686cd26.tar.xz
Take more current safe_math_impl.h from upstream.chromium/2908
Corresponds to version dfd77a987650965071d0fddfbe0b806ce62ba337. Major change is to handle div by 0 without exceptions. Safe shift is not yet present. TBR=thestig@chromium.org TBR=jschuh@chromium.org Review-Url: https://codereview.chromium.org/2473513002
Diffstat (limited to 'third_party/base/numerics/safe_math_impl.h')
-rw-r--r--third_party/base/numerics/safe_math_impl.h96
1 files changed, 61 insertions, 35 deletions
diff --git a/third_party/base/numerics/safe_math_impl.h b/third_party/base/numerics/safe_math_impl.h
index 959b7f1b61..f950f5d517 100644
--- a/third_party/base/numerics/safe_math_impl.h
+++ b/third_party/base/numerics/safe_math_impl.h
@@ -2,8 +2,8 @@
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
-#ifndef PDFIUM_THIRD_PARTY_SAFE_MATH_IMPL_H_
-#define PDFIUM_THIRD_PARTY_SAFE_MATH_IMPL_H_
+#ifndef PDFIUM_THIRD_PARTY_BASE_NUMERICS_SAFE_MATH_IMPL_H_
+#define PDFIUM_THIRD_PARTY_BASE_NUMERICS_SAFE_MATH_IMPL_H_
#include <stddef.h>
#include <stdint.h>
@@ -14,8 +14,8 @@
#include <limits>
#include <type_traits>
-#include "safe_conversions.h"
#include "third_party/base/macros.h"
+#include "third_party/base/numerics/safe_conversions.h"
namespace pdfium {
namespace base {
@@ -95,6 +95,25 @@ struct PositionOfSignBit {
CHAR_BIT * sizeof(Integer) - 1;
};
+// This is used for UnsignedAbs, where we need to support floating-point
+// template instantiations even though we don't actually support the operations.
+// However, there is no corresponding implementation of e.g. CheckedUnsignedAbs,
+// so the float versions will not compile.
+template <typename Numeric,
+ bool IsInteger = std::numeric_limits<Numeric>::is_integer,
+ bool IsFloat = std::numeric_limits<Numeric>::is_iec559>
+struct UnsignedOrFloatForSize;
+
+template <typename Numeric>
+struct UnsignedOrFloatForSize<Numeric, true, false> {
+ typedef typename UnsignedIntegerForSize<Numeric>::type type;
+};
+
+template <typename Numeric>
+struct UnsignedOrFloatForSize<Numeric, false, true> {
+ typedef Numeric type;
+};
+
// Helper templates for integer manipulations.
template <typename T>
@@ -238,6 +257,7 @@ T CheckedDiv(T x,
*validity = RANGE_OVERFLOW;
return std::numeric_limits<T>::min();
}
+
*validity = RANGE_VALID;
return static_cast<T>(x / y);
}
@@ -268,7 +288,7 @@ CheckedNeg(T value, RangeConstraint* validity) {
*validity =
value != std::numeric_limits<T>::min() ? RANGE_VALID : RANGE_OVERFLOW;
// The negation of signed min is min, so catch that one.
- return -value;
+ return static_cast<T>(*validity == RANGE_VALID ? -value : 0);
}
template <typename T>
@@ -279,7 +299,9 @@ CheckedNeg(T value, RangeConstraint* validity) {
// The only legal unsigned negation is zero.
*validity = value ? RANGE_UNDERFLOW : RANGE_VALID;
return static_cast<T>(
- -static_cast<typename SignedIntegerForSize<T>::type>(value));
+ *validity == RANGE_VALID
+ ? -static_cast<typename SignedIntegerForSize<T>::type>(value)
+ : 0);
}
template <typename T>
@@ -289,7 +311,7 @@ typename std::enable_if<std::numeric_limits<T>::is_integer &&
CheckedAbs(T value, RangeConstraint* validity) {
*validity =
value != std::numeric_limits<T>::min() ? RANGE_VALID : RANGE_OVERFLOW;
- return std::abs(value);
+ return static_cast<T>(*validity == RANGE_VALID ? std::abs(value) : 0);
}
template <typename T>
@@ -297,11 +319,31 @@ typename std::enable_if<std::numeric_limits<T>::is_integer &&
!std::numeric_limits<T>::is_signed,
T>::type
CheckedAbs(T value, RangeConstraint* validity) {
- // Absolute value of a positive is just its identiy.
+ // T is unsigned, so |value| must already be positive.
*validity = RANGE_VALID;
return value;
}
+template <typename T>
+typename std::enable_if<std::numeric_limits<T>::is_integer &&
+ std::numeric_limits<T>::is_signed,
+ typename UnsignedIntegerForSize<T>::type>::type
+CheckedUnsignedAbs(T value) {
+ typedef typename UnsignedIntegerForSize<T>::type UnsignedT;
+ return value == std::numeric_limits<T>::min()
+ ? static_cast<UnsignedT>(std::numeric_limits<T>::max()) + 1
+ : static_cast<UnsignedT>(std::abs(value));
+}
+
+template <typename T>
+typename std::enable_if<std::numeric_limits<T>::is_integer &&
+ !std::numeric_limits<T>::is_signed,
+ T>::type
+CheckedUnsignedAbs(T value) {
+ // T is unsigned, so |value| must already be positive.
+ return static_cast<T>(value);
+}
+
// These are the floating point stubs that the compiler needs to see. Only the
// negation operation is ever called.
#define BASE_FLOAT_ARITHMETIC_STUBS(NAME) \
@@ -324,14 +366,14 @@ template <typename T>
typename std::enable_if<std::numeric_limits<T>::is_iec559, T>::type CheckedNeg(
T value,
RangeConstraint*) {
- return -value;
+ return static_cast<T>(-value);
}
template <typename T>
typename std::enable_if<std::numeric_limits<T>::is_iec559, T>::type CheckedAbs(
T value,
RangeConstraint*) {
- return std::abs(value);
+ return static_cast<T>(std::abs(value));
}
// Floats carry around their validity state with them, but integers do not. So,
@@ -361,7 +403,7 @@ template <typename T>
class CheckedNumericState<T, NUMERIC_INTEGER> {
private:
T value_;
- RangeConstraint validity_;
+ RangeConstraint validity_ : CHAR_BIT; // Actually requires only two bits.
public:
template <typename Src, NumericRepresentation type>
@@ -371,11 +413,11 @@ class CheckedNumericState<T, NUMERIC_INTEGER> {
template <typename Src>
CheckedNumericState(Src value, RangeConstraint validity)
- : value_(value),
+ : value_(static_cast<T>(value)),
validity_(GetRangeConstraint(validity |
DstRangeRelationToSrcRange<T>(value))) {
- COMPILE_ASSERT(std::numeric_limits<Src>::is_specialized,
- argument_must_be_numeric);
+ static_assert(std::numeric_limits<Src>::is_specialized,
+ "Argument must be numeric.");
}
// Copy constructor.
@@ -456,27 +498,16 @@ class CheckedNumericState<T, NUMERIC_FLOATING> {
T value() const { return value_; }
};
-// For integers less than 128-bit and floats 32-bit or larger, we can distil
-// C/C++ arithmetic promotions down to two simple rules:
-// 1. The type with the larger maximum exponent always takes precedence.
-// 2. The resulting type must be promoted to at least an int.
-// The following template specializations implement that promotion logic.
-enum ArithmeticPromotionCategory {
- LEFT_PROMOTION,
- RIGHT_PROMOTION,
- DEFAULT_PROMOTION
-};
+// For integers less than 128-bit and floats 32-bit or larger, we have the type
+// with the larger maximum exponent take precedence.
+enum ArithmeticPromotionCategory { LEFT_PROMOTION, RIGHT_PROMOTION };
template <typename Lhs,
typename Rhs = Lhs,
ArithmeticPromotionCategory Promotion =
(MaxExponent<Lhs>::value > MaxExponent<Rhs>::value)
- ? (MaxExponent<Lhs>::value > MaxExponent<int>::value
- ? LEFT_PROMOTION
- : DEFAULT_PROMOTION)
- : (MaxExponent<Rhs>::value > MaxExponent<int>::value
- ? RIGHT_PROMOTION
- : DEFAULT_PROMOTION) >
+ ? LEFT_PROMOTION
+ : RIGHT_PROMOTION>
struct ArithmeticPromotion;
template <typename Lhs, typename Rhs>
@@ -489,11 +520,6 @@ struct ArithmeticPromotion<Lhs, Rhs, RIGHT_PROMOTION> {
typedef Rhs type;
};
-template <typename Lhs, typename Rhs>
-struct ArithmeticPromotion<Lhs, Rhs, DEFAULT_PROMOTION> {
- typedef int type;
-};
-
// We can statically check if operations on the provided types can wrap, so we
// can skip the checked operations if they're not needed. So, for an integer we
// care if the destination type preserves the sign and is twice the width of
@@ -513,4 +539,4 @@ struct IsIntegerArithmeticSafe {
} // namespace base
} // namespace pdfium
-#endif // PDFIUM_THIRD_PARTY_SAFE_MATH_IMPL_H_
+#endif // PDFIUM_THIRD_PARTY_BASE_NUMERICS_SAFE_MATH_IMPL_H_