[libc-commits] [libc] [libc][stdfix] Add integer square root with fixed point output functions. (PR #83959)
via libc-commits
libc-commits at lists.llvm.org
Tue Mar 5 16:17:22 PST 2024
https://github.com/lntue updated https://github.com/llvm/llvm-project/pull/83959
>From 8f74d732db924f828ea9c2f4968f4c90573e2f97 Mon Sep 17 00:00:00 2001
From: Tue Ly <lntue at google.com>
Date: Tue, 5 Mar 2024 00:18:47 -0500
Subject: [PATCH 1/3] [libc][stdfix] Add integer square root with fixed point
output functions.
---
libc/config/baremetal/arm/entrypoints.txt | 2 +
libc/config/baremetal/riscv/entrypoints.txt | 2 +
libc/config/linux/x86_64/entrypoints.txt | 2 +
libc/spec/stdc_ext.td | 3 +
libc/src/__support/fixed_point/CMakeLists.txt | 1 +
libc/src/__support/fixed_point/fx_rep.h | 24 ++
libc/src/__support/fixed_point/sqrt.h | 207 ++++++++++++++----
libc/src/stdfix/CMakeLists.txt | 26 +++
libc/src/stdfix/uhksqrtus.cpp | 23 ++
libc/src/stdfix/uhksqrtus.h | 20 ++
libc/src/stdfix/uksqrtui.cpp | 23 ++
libc/src/stdfix/uksqrtui.h | 20 ++
libc/test/src/stdfix/CMakeLists.txt | 40 ++++
libc/test/src/stdfix/ISqrtTest.h | 66 ++++++
libc/test/src/stdfix/uhksqrtus_test.cpp | 20 ++
libc/test/src/stdfix/uksqrtui_test.cpp | 20 ++
16 files changed, 460 insertions(+), 39 deletions(-)
create mode 100644 libc/src/stdfix/uhksqrtus.cpp
create mode 100644 libc/src/stdfix/uhksqrtus.h
create mode 100644 libc/src/stdfix/uksqrtui.cpp
create mode 100644 libc/src/stdfix/uksqrtui.h
create mode 100644 libc/test/src/stdfix/ISqrtTest.h
create mode 100644 libc/test/src/stdfix/uhksqrtus_test.cpp
create mode 100644 libc/test/src/stdfix/uksqrtui_test.cpp
diff --git a/libc/config/baremetal/arm/entrypoints.txt b/libc/config/baremetal/arm/entrypoints.txt
index c9887b6e855a6d..99796ad5edf5d5 100644
--- a/libc/config/baremetal/arm/entrypoints.txt
+++ b/libc/config/baremetal/arm/entrypoints.txt
@@ -306,6 +306,8 @@ if(LIBC_COMPILER_HAS_FIXED_POINT)
libc.src.stdfix.sqrtur
# libc.src.stdfix.sqrtulk
libc.src.stdfix.sqrtulr
+ libc.src.stdfix.uhksqrtus
+ libc.src.stdfix.uksqrtui
)
endif()
diff --git a/libc/config/baremetal/riscv/entrypoints.txt b/libc/config/baremetal/riscv/entrypoints.txt
index c9887b6e855a6d..99796ad5edf5d5 100644
--- a/libc/config/baremetal/riscv/entrypoints.txt
+++ b/libc/config/baremetal/riscv/entrypoints.txt
@@ -306,6 +306,8 @@ if(LIBC_COMPILER_HAS_FIXED_POINT)
libc.src.stdfix.sqrtur
# libc.src.stdfix.sqrtulk
libc.src.stdfix.sqrtulr
+ libc.src.stdfix.uhksqrtus
+ libc.src.stdfix.uksqrtui
)
endif()
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index bc10512d942fa7..4ae2f7fc69ca20 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -490,6 +490,8 @@ if(LIBC_COMPILER_HAS_FIXED_POINT)
libc.src.stdfix.sqrtur
# libc.src.stdfix.sqrtulk
libc.src.stdfix.sqrtulr
+ libc.src.stdfix.uhksqrtus
+ libc.src.stdfix.uksqrtui
)
endif()
diff --git a/libc/spec/stdc_ext.td b/libc/spec/stdc_ext.td
index be1e6d4ba2fcdc..4e433e222ce47c 100644
--- a/libc/spec/stdc_ext.td
+++ b/libc/spec/stdc_ext.td
@@ -55,6 +55,9 @@ def StdcExt : StandardSpec<"stdc_ext"> {
GuardedFunctionSpec<"sqrtuhk", RetValSpec<UnsignedShortAccumType>, [ArgSpec<UnsignedShortAccumType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
GuardedFunctionSpec<"sqrtuk", RetValSpec<UnsignedAccumType>, [ArgSpec<UnsignedAccumType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
GuardedFunctionSpec<"sqrtulk", RetValSpec<UnsignedLongAccumType>, [ArgSpec<UnsignedLongAccumType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
+
+ GuardedFunctionSpec<"uhksqrtus", RetValSpec<UnsignedShortAccumType>, [ArgSpec<UnsignedShortType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
+ GuardedFunctionSpec<"uksqrtui", RetValSpec<UnsignedAccumType>, [ArgSpec<UnsignedIntType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
]
>;
diff --git a/libc/src/__support/fixed_point/CMakeLists.txt b/libc/src/__support/fixed_point/CMakeLists.txt
index 0ed118f2408849..3b744081765e4f 100644
--- a/libc/src/__support/fixed_point/CMakeLists.txt
+++ b/libc/src/__support/fixed_point/CMakeLists.txt
@@ -32,5 +32,6 @@ add_header_library(
libc.src.__support.macros.attributes
libc.src.__support.macros.optimization
libc.src.__support.CPP.bit
+ libc.src.__support.CPP.limits
libc.src.__support.CPP.type_traits
)
diff --git a/libc/src/__support/fixed_point/fx_rep.h b/libc/src/__support/fixed_point/fx_rep.h
index f8593a93684cbc..042cd2b20714c6 100644
--- a/libc/src/__support/fixed_point/fx_rep.h
+++ b/libc/src/__support/fixed_point/fx_rep.h
@@ -48,6 +48,8 @@ template <> struct FXRep<short fract> {
LIBC_INLINE static constexpr Type MAX() { return SFRACT_MIN; }
LIBC_INLINE static constexpr Type ZERO() { return 0.0HR; }
LIBC_INLINE static constexpr Type EPS() { return SFRACT_EPSILON; }
+ LIBC_INLINE static constexpr Type ONE_HALF() { return 0.5HR; }
+ LIBC_INLINE static constexpr Type ONE_FOURTH() { return 0.25HR; }
using StorageType = typename internal::Storage<TOTAL_LEN>::Type;
using CompType = cpp::make_signed_t<StorageType>;
@@ -66,6 +68,8 @@ template <> struct FXRep<unsigned short fract> {
LIBC_INLINE static constexpr Type MAX() { return USFRACT_MIN; }
LIBC_INLINE static constexpr Type ZERO() { return 0.0UHR; }
LIBC_INLINE static constexpr Type EPS() { return USFRACT_EPSILON; }
+ LIBC_INLINE static constexpr Type ONE_HALF() { return 0.5UHR; }
+ LIBC_INLINE static constexpr Type ONE_FOURTH() { return 0.25UHR; }
using StorageType = typename internal::Storage<TOTAL_LEN>::Type;
using CompType = cpp::make_unsigned_t<StorageType>;
@@ -84,6 +88,8 @@ template <> struct FXRep<fract> {
LIBC_INLINE static constexpr Type MAX() { return FRACT_MIN; }
LIBC_INLINE static constexpr Type ZERO() { return 0.0R; }
LIBC_INLINE static constexpr Type EPS() { return FRACT_EPSILON; }
+ LIBC_INLINE static constexpr Type ONE_HALF() { return 0.5R; }
+ LIBC_INLINE static constexpr Type ONE_FOURTH() { return 0.25R; }
using StorageType = typename internal::Storage<TOTAL_LEN>::Type;
using CompType = cpp::make_signed_t<StorageType>;
@@ -102,6 +108,8 @@ template <> struct FXRep<unsigned fract> {
LIBC_INLINE static constexpr Type MAX() { return UFRACT_MIN; }
LIBC_INLINE static constexpr Type ZERO() { return 0.0UR; }
LIBC_INLINE static constexpr Type EPS() { return UFRACT_EPSILON; }
+ LIBC_INLINE static constexpr Type ONE_HALF() { return 0.5UR; }
+ LIBC_INLINE static constexpr Type ONE_FOURTH() { return 0.25UR; }
using StorageType = typename internal::Storage<TOTAL_LEN>::Type;
using CompType = cpp::make_unsigned_t<StorageType>;
@@ -120,6 +128,8 @@ template <> struct FXRep<long fract> {
LIBC_INLINE static constexpr Type MAX() { return LFRACT_MIN; }
LIBC_INLINE static constexpr Type ZERO() { return 0.0LR; }
LIBC_INLINE static constexpr Type EPS() { return LFRACT_EPSILON; }
+ LIBC_INLINE static constexpr Type ONE_HALF() { return 0.5LR; }
+ LIBC_INLINE static constexpr Type ONE_FOURTH() { return 0.25LR; }
using StorageType = typename internal::Storage<TOTAL_LEN>::Type;
using CompType = cpp::make_signed_t<StorageType>;
@@ -138,6 +148,8 @@ template <> struct FXRep<unsigned long fract> {
LIBC_INLINE static constexpr Type MAX() { return ULFRACT_MIN; }
LIBC_INLINE static constexpr Type ZERO() { return 0.0ULR; }
LIBC_INLINE static constexpr Type EPS() { return ULFRACT_EPSILON; }
+ LIBC_INLINE static constexpr Type ONE_HALF() { return 0.5ULR; }
+ LIBC_INLINE static constexpr Type ONE_FOURTH() { return 0.25ULR; }
using StorageType = typename internal::Storage<TOTAL_LEN>::Type;
using CompType = cpp::make_unsigned_t<StorageType>;
@@ -156,6 +168,8 @@ template <> struct FXRep<short accum> {
LIBC_INLINE static constexpr Type MAX() { return SACCUM_MIN; }
LIBC_INLINE static constexpr Type ZERO() { return 0.0HK; }
LIBC_INLINE static constexpr Type EPS() { return SACCUM_EPSILON; }
+ LIBC_INLINE static constexpr Type ONE_HALF() { return 0.5HK; }
+ LIBC_INLINE static constexpr Type ONE_FOURTH() { return 0.25HK; }
using StorageType = typename internal::Storage<TOTAL_LEN>::Type;
using CompType = cpp::make_signed_t<StorageType>;
@@ -174,6 +188,8 @@ template <> struct FXRep<unsigned short accum> {
LIBC_INLINE static constexpr Type MAX() { return USACCUM_MIN; }
LIBC_INLINE static constexpr Type ZERO() { return 0.0UHK; }
LIBC_INLINE static constexpr Type EPS() { return USACCUM_EPSILON; }
+ LIBC_INLINE static constexpr Type ONE_HALF() { return 0.5UHK; }
+ LIBC_INLINE static constexpr Type ONE_FOURTH() { return 0.25UHK; }
using StorageType = typename internal::Storage<TOTAL_LEN>::Type;
using CompType = cpp::make_unsigned_t<StorageType>;
@@ -192,6 +208,8 @@ template <> struct FXRep<accum> {
LIBC_INLINE static constexpr Type MAX() { return ACCUM_MIN; }
LIBC_INLINE static constexpr Type ZERO() { return 0.0K; }
LIBC_INLINE static constexpr Type EPS() { return ACCUM_EPSILON; }
+ LIBC_INLINE static constexpr Type ONE_HALF() { return 0.5K; }
+ LIBC_INLINE static constexpr Type ONE_FOURTH() { return 0.25K; }
using StorageType = typename internal::Storage<TOTAL_LEN>::Type;
using CompType = cpp::make_signed_t<StorageType>;
@@ -210,6 +228,8 @@ template <> struct FXRep<unsigned accum> {
LIBC_INLINE static constexpr Type MAX() { return UACCUM_MIN; }
LIBC_INLINE static constexpr Type ZERO() { return 0.0UK; }
LIBC_INLINE static constexpr Type EPS() { return UACCUM_EPSILON; }
+ LIBC_INLINE static constexpr Type ONE_HALF() { return 0.5UK; }
+ LIBC_INLINE static constexpr Type ONE_FOURTH() { return 0.25UK; }
using StorageType = typename internal::Storage<TOTAL_LEN>::Type;
using CompType = cpp::make_unsigned_t<StorageType>;
@@ -228,6 +248,8 @@ template <> struct FXRep<long accum> {
LIBC_INLINE static constexpr Type MAX() { return LACCUM_MIN; }
LIBC_INLINE static constexpr Type ZERO() { return 0.0LK; }
LIBC_INLINE static constexpr Type EPS() { return LACCUM_EPSILON; }
+ LIBC_INLINE static constexpr Type ONE_HALF() { return 0.5LK; }
+ LIBC_INLINE static constexpr Type ONE_FOURTH() { return 0.25LK; }
using StorageType = typename internal::Storage<TOTAL_LEN>::Type;
using CompType = cpp::make_signed_t<StorageType>;
@@ -246,6 +268,8 @@ template <> struct FXRep<unsigned long accum> {
LIBC_INLINE static constexpr Type MAX() { return ULACCUM_MIN; }
LIBC_INLINE static constexpr Type ZERO() { return 0.0ULK; }
LIBC_INLINE static constexpr Type EPS() { return ULACCUM_EPSILON; }
+ LIBC_INLINE static constexpr Type ONE_HALF() { return 0.5ULK; }
+ LIBC_INLINE static constexpr Type ONE_FOURTH() { return 0.25ULK; }
using StorageType = typename internal::Storage<TOTAL_LEN>::Type;
using CompType = cpp::make_unsigned_t<StorageType>;
diff --git a/libc/src/__support/fixed_point/sqrt.h b/libc/src/__support/fixed_point/sqrt.h
index d8df294b18a1a8..4ec016ceab0028 100644
--- a/libc/src/__support/fixed_point/sqrt.h
+++ b/libc/src/__support/fixed_point/sqrt.h
@@ -11,6 +11,7 @@
#include "include/llvm-libc-macros/stdfix-macros.h"
#include "src/__support/CPP/bit.h"
+#include "src/__support/CPP/limits.h" // CHAR_BIT
#include "src/__support/CPP/type_traits.h"
#include "src/__support/macros/attributes.h" // LIBC_INLINE
#include "src/__support/macros/optimization.h" // LIBC_UNLIKELY
@@ -28,16 +29,73 @@ template <typename T> struct SqrtConfig;
template <> struct SqrtConfig<unsigned short fract> {
using Type = unsigned short fract;
static constexpr int EXTRA_STEPS = 0;
+
+ // Linear approximation for the initial values, with errors bounded by:
+ // max(1.5 * 2^-11, eps)
+ // Generated with Sollya:
+ // > for i from 4 to 15 do {
+ // P = fpminimax(sqrt(x), 1, [|8, 8|], [i * 2^-4, (i + 1)*2^-4],
+ // fixed, absolute);
+ // print("{", coeff(P, 1), "uhr,", coeff(P, 0), "uhr},");
+ // };
+ static constexpr Type FIRST_APPROX[12][2] = {
+ {0x1.e8p-1uhr, 0x1.0cp-2uhr}, {0x1.bap-1uhr, 0x1.28p-2uhr},
+ {0x1.94p-1uhr, 0x1.44p-2uhr}, {0x1.74p-1uhr, 0x1.6p-2uhr},
+ {0x1.6p-1uhr, 0x1.74p-2uhr}, {0x1.4ep-1uhr, 0x1.88p-2uhr},
+ {0x1.3ep-1uhr, 0x1.9cp-2uhr}, {0x1.32p-1uhr, 0x1.acp-2uhr},
+ {0x1.22p-1uhr, 0x1.c4p-2uhr}, {0x1.18p-1uhr, 0x1.d4p-2uhr},
+ {0x1.08p-1uhr, 0x1.fp-2uhr}, {0x1.04p-1uhr, 0x1.f8p-2uhr},
+ };
};
template <> struct SqrtConfig<unsigned fract> {
using Type = unsigned fract;
static constexpr int EXTRA_STEPS = 1;
+
+ // Linear approximation for the initial values, with errors bounded by:
+ // max(1.5 * 2^-11, eps)
+ // Generated with Sollya:
+ // > for i from 4 to 15 do {
+ // P = fpminimax(sqrt(x), 1, [|16, 16|], [i * 2^-4, (i + 1)*2^-4],
+ // fixed, absolute);
+ // print("{", coeff(P, 1), "ur,", coeff(P, 0), "ur},");
+ // };
+ static constexpr Type FIRST_APPROX[12][2] = {
+ {0x1.e378p-1ur, 0x1.0ebp-2ur}, {0x1.b512p-1ur, 0x1.2b94p-2ur},
+ {0x1.91fp-1ur, 0x1.45dcp-2ur}, {0x1.7622p-1ur, 0x1.5e24p-2ur},
+ {0x1.5f5ap-1ur, 0x1.74e4p-2ur}, {0x1.4c58p-1ur, 0x1.8a4p-2ur},
+ {0x1.3c1ep-1ur, 0x1.9e84p-2ur}, {0x1.2e0cp-1ur, 0x1.b1d8p-2ur},
+ {0x1.21aap-1ur, 0x1.c468p-2ur}, {0x1.16bap-1ur, 0x1.d62cp-2ur},
+ {0x1.0cfp-1ur, 0x1.e74cp-2ur}, {0x1.0418p-1ur, 0x1.f7ep-2ur},
+ };
};
template <> struct SqrtConfig<unsigned long fract> {
using Type = unsigned long fract;
static constexpr int EXTRA_STEPS = 2;
+
+ // Linear approximation for the initial values, with errors bounded by:
+ // max(1.5 * 2^-11, eps)
+ // Generated with Sollya:
+ // > for i from 4 to 15 do {
+ // P = fpminimax(sqrt(x), 1, [|32, 32|], [i * 2^-4, (i + 1)*2^-4],
+ // fixed, absolute);
+ // print("{", coeff(P, 1), "ulr,", coeff(P, 0), "ulr},");
+ // };
+ static constexpr Type FIRST_APPROX[12][2] = {
+ {0x1.e3779b98p-1ulr, 0x1.0eaff788p-2ulr},
+ {0x1.b5167872p-1ulr, 0x1.2b908ad4p-2ulr},
+ {0x1.91f195cap-1ulr, 0x1.45da800cp-2ulr},
+ {0x1.761ebcb4p-1ulr, 0x1.5e27004cp-2ulr},
+ {0x1.5f619986p-1ulr, 0x1.74db933cp-2ulr},
+ {0x1.4c583adep-1ulr, 0x1.8a3fbfccp-2ulr},
+ {0x1.3c1a591cp-1ulr, 0x1.9e88373cp-2ulr},
+ {0x1.2e08545ap-1ulr, 0x1.b1dd2534p-2ulr},
+ {0x1.21b05c0ap-1ulr, 0x1.c45e023p-2ulr},
+ {0x1.16becd02p-1ulr, 0x1.d624031p-2ulr},
+ {0x1.0cf49fep-1ulr, 0x1.e743b844p-2ulr},
+ {0x1.04214e9cp-1ulr, 0x1.f7ce2c3cp-2ulr},
+ };
};
template <>
@@ -46,46 +104,38 @@ struct SqrtConfig<unsigned short accum> : SqrtConfig<unsigned fract> {};
template <>
struct SqrtConfig<unsigned accum> : SqrtConfig<unsigned long fract> {};
-// TODO: unsigned long accum type is 64-bit, and will need 64-bit fract type.
-// Probably we will use DyadicFloat<64> for intermediate computations instead.
-
-// Linear approximation for the initial values, with errors bounded by:
-// max(1.5 * 2^-11, eps)
-// Generated with Sollya:
-// > for i from 4 to 15 do {
-// P = fpminimax(sqrt(x), 1, [|8, 8|], [i * 2^-4, (i + 1)*2^-4],
-// fixed, absolute);
-// print("{", coeff(P, 1), "uhr,", coeff(P, 0), "uhr},");
-// };
-static constexpr unsigned short fract SQRT_FIRST_APPROX[12][2] = {
- {0x1.e8p-1uhr, 0x1.0cp-2uhr}, {0x1.bap-1uhr, 0x1.28p-2uhr},
- {0x1.94p-1uhr, 0x1.44p-2uhr}, {0x1.74p-1uhr, 0x1.6p-2uhr},
- {0x1.6p-1uhr, 0x1.74p-2uhr}, {0x1.4ep-1uhr, 0x1.88p-2uhr},
- {0x1.3ep-1uhr, 0x1.9cp-2uhr}, {0x1.32p-1uhr, 0x1.acp-2uhr},
- {0x1.22p-1uhr, 0x1.c4p-2uhr}, {0x1.18p-1uhr, 0x1.d4p-2uhr},
- {0x1.08p-1uhr, 0x1.fp-2uhr}, {0x1.04p-1uhr, 0x1.f8p-2uhr},
+// Integer square root
+template <> struct SqrtConfig<unsigned short> {
+ using OutType = unsigned short accum;
+ using FracType = unsigned fract;
+ // For fast-but-less-accurate version
+ using FastFracType = unsigned short fract;
+ using HalfType = unsigned char;
};
-} // namespace internal
+template <> struct SqrtConfig<unsigned int> {
+ using OutType = unsigned accum;
+ using FracType = unsigned long fract;
+ // For fast-but-less-accurate version
+ using FastFracType = unsigned fract;
+ using HalfType = unsigned short;
+};
-template <typename T>
-LIBC_INLINE constexpr cpp::enable_if_t<cpp::is_fixed_point_v<T>, T> sqrt(T x) {
- using BitType = typename FXRep<T>::StorageType;
- BitType x_bit = cpp::bit_cast<BitType>(x);
+// TODO: unsigned long accum type is 64-bit, and will need 64-bit fract type.
+// Probably we will use DyadicFloat<64> for intermediate computations instead.
- if (LIBC_UNLIKELY(x_bit == 0))
- return FXRep<T>::ZERO();
+} // namespace internal
- int leading_zeros = cpp::countl_zero(x_bit);
- constexpr int STORAGE_LENGTH = sizeof(BitType) * CHAR_BIT;
- constexpr int EXP_ADJUSTMENT = STORAGE_LENGTH - FXRep<T>::FRACTION_LEN - 1;
- // x_exp is the real exponent of the leading bit of x.
- int x_exp = EXP_ADJUSTMENT - leading_zeros;
- int shift = EXP_ADJUSTMENT - 1 - (x_exp & (~1));
- // Normalize.
- x_bit <<= shift;
- using FracType = typename internal::SqrtConfig<T>::Type;
- FracType x_frac = cpp::bit_cast<FracType>(x_bit);
+// Core computation for sqrt with normalized inputs (0.25 <= x < 1).
+template <typename Config>
+LIBC_INLINE constexpr typename Config::Type
+sqrt_core(typename Config::Type x_frac) {
+ using FracType = typename Config::Type;
+ using FXRep = FXRep<FracType>;
+ using StorageType = typename FXRep::StorageType;
+ // Exact case:
+ if (x_frac == FXRep::ONE_FOURTH())
+ return FXRep::ONE_HALF();
// Use use Newton method to approximate sqrt(a):
// x_{n + 1} = 1/2 (x_n + a / x_n)
@@ -96,9 +146,10 @@ LIBC_INLINE constexpr cpp::enable_if_t<cpp::is_fixed_point_v<T>, T> sqrt(T x) {
// are between 0b0100 and 0b1111. Hence the lookup table only needs 12
// entries, and we can get the index by subtracting the leading 4 bits of
// x_frac by 4 = 0b0100.
- int index = (x_bit >> (STORAGE_LENGTH - 4)) - 4;
- FracType a = static_cast<FracType>(internal::SQRT_FIRST_APPROX[index][0]);
- FracType b = static_cast<FracType>(internal::SQRT_FIRST_APPROX[index][1]);
+ StorageType x_bit = cpp::bit_cast<StorageType>(x_frac);
+ int index = (static_cast<int>(x_bit >> (FXRep::TOTAL_LEN - 4))) - 4;
+ FracType a = Config::FIRST_APPROX[index][0];
+ FracType b = Config::FIRST_APPROX[index][1];
// Initial approximation step.
// Estimated error bounds: | r - sqrt(x_frac) | < max(1.5 * 2^-11, eps).
@@ -112,9 +163,34 @@ LIBC_INLINE constexpr cpp::enable_if_t<cpp::is_fixed_point_v<T>, T> sqrt(T x) {
// Blanchard, J. D. and Chamberland, M., "Newton's Method Without Division",
// The American Mathematical Monthly (2023).
// https://chamberland.math.grinnell.edu/papers/newton.pdf
- for (int i = 0; i < internal::SqrtConfig<T>::EXTRA_STEPS; ++i)
+ for (int i = 0; i < Config::EXTRA_STEPS; ++i)
r = (r >> 1) + (x_frac >> 1) / r;
+ return r;
+}
+
+template <typename T>
+LIBC_INLINE constexpr cpp::enable_if_t<cpp::is_fixed_point_v<T>, T> sqrt(T x) {
+ using BitType = typename FXRep<T>::StorageType;
+ BitType x_bit = cpp::bit_cast<BitType>(x);
+
+ if (LIBC_UNLIKELY(x_bit == 0))
+ return FXRep<T>::ZERO();
+
+ int leading_zeros = cpp::countl_zero(x_bit);
+ constexpr int STORAGE_LENGTH = sizeof(BitType) * CHAR_BIT;
+ constexpr int EXP_ADJUSTMENT = STORAGE_LENGTH - FXRep<T>::FRACTION_LEN - 1;
+ // x_exp is the real exponent of the leading bit of x.
+ int x_exp = EXP_ADJUSTMENT - leading_zeros;
+ int shift = EXP_ADJUSTMENT - 1 - (x_exp & (~1));
+ // Normalize.
+ x_bit <<= shift;
+ using FracType = typename internal::SqrtConfig<T>::Type;
+ FracType x_frac = cpp::bit_cast<FracType>(x_bit);
+
+ // Compute sqrt(x_frac) using Newton-method.
+ FracType r = sqrt_core<internal::SqrtConfig<T>>(x_frac);
+
// Re-scaling
r >>= EXP_ADJUSTMENT - (x_exp >> 1);
@@ -122,6 +198,59 @@ LIBC_INLINE constexpr cpp::enable_if_t<cpp::is_fixed_point_v<T>, T> sqrt(T x) {
return cpp::bit_cast<T>(r);
}
+// Integer square root - Accurate version:
+// Absolute errors < 2^(-fraction length).
+template <typename T>
+LIBC_INLINE constexpr typename internal::SqrtConfig<T>::OutType isqrt(T x) {
+ using OutType = typename internal::SqrtConfig<T>::OutType;
+ using FracType = typename internal::SqrtConfig<T>::FracType;
+
+ if (x == 0)
+ return FXRep<OutType>::ZERO();
+
+ // Normalize the leading bits to the first two bits.
+ // Shift and then Bit cast x to x_frac gives us:
+ // x = 2^(FRACTION_LEN + 1 - shift) * x_frac;
+ int leading_zeros = cpp::countl_zero(x);
+ int shift = ((leading_zeros >> 1) << 1);
+ x <<= shift;
+ // Convert to frac type and compute square root.
+ FracType x_frac = cpp::bit_cast<FracType>(x);
+ FracType r = sqrt_core<internal::SqrtConfig<FracType>>(x_frac);
+ // To rescale back to the OutType (Accum)
+ r >>= (shift >> 1);
+
+ return cpp::bit_cast<OutType>(r);
+}
+
+// Integer square root - Fast but less accurate version:
+// Relative errors < 2^(-fraction length).
+template <typename T>
+LIBC_INLINE constexpr typename internal::SqrtConfig<T>::OutType
+isqrt_fast(T x) {
+ using OutType = typename internal::SqrtConfig<T>::OutType;
+ using FracType = typename internal::SqrtConfig<T>::FastFracType;
+ using StorageType = typename FXRep<FracType>::StorageType;
+
+ if (x == 0)
+ return FXRep<OutType>::ZERO();
+
+ // Normalize the leading bits to the first two bits.
+ // Shift and then Bit cast x to x_frac gives us:
+ // x = 2^(FRACTION_LEN + 1 - shift) * x_frac;
+ int leading_zeros = cpp::countl_zero(x);
+ int shift = (leading_zeros & (~1));
+ x <<= shift;
+ // Convert to frac type and compute square root.
+ FracType x_frac = cpp::bit_cast<FracType>(
+ static_cast<StorageType>(x >> FXRep<FracType>::FRACTION_LEN));
+ OutType r =
+ static_cast<OutType>(sqrt_core<internal::SqrtConfig<FracType>>(x_frac));
+ // To rescale back to the OutType (Accum)
+ r <<= (FXRep<OutType>::INTEGRAL_LEN - (shift >> 1));
+ return cpp::bit_cast<OutType>(r);
+}
+
} // namespace LIBC_NAMESPACE::fixed_point
#endif // LIBC_COMPILER_HAS_FIXED_POINT
diff --git a/libc/src/stdfix/CMakeLists.txt b/libc/src/stdfix/CMakeLists.txt
index cb2134fe33cf9c..a5c37183fbbb7c 100644
--- a/libc/src/stdfix/CMakeLists.txt
+++ b/libc/src/stdfix/CMakeLists.txt
@@ -46,3 +46,29 @@ foreach(suffix IN ITEMS hr r lr hk k lk uhr ur ulr uhk uk ulk)
libc.src.__support.fixed_point.fx_bits
)
endforeach()
+
+add_entrypoint_object(
+ uhksqrtus
+ HDRS
+ uhksqrtus.h
+ SRCS
+ uhksqrtus.cpp
+ COMPILE_OPTIONS
+ -O3
+ -ffixed-point
+ DEPENDS
+ libc.src.__support.fixed_point.sqrt
+)
+
+add_entrypoint_object(
+ uksqrtui
+ HDRS
+ uksqrtui.h
+ SRCS
+ uksqrtui.cpp
+ COMPILE_OPTIONS
+ -O3
+ -ffixed-point
+ DEPENDS
+ libc.src.__support.fixed_point.sqrt
+)
diff --git a/libc/src/stdfix/uhksqrtus.cpp b/libc/src/stdfix/uhksqrtus.cpp
new file mode 100644
index 00000000000000..335750ae902b28
--- /dev/null
+++ b/libc/src/stdfix/uhksqrtus.cpp
@@ -0,0 +1,23 @@
+//===-- Implementation of uhksqrtus function ------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "uhksqrtus.h"
+#include "src/__support/common.h"
+#include "src/__support/fixed_point/sqrt.h"
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(unsigned short accum, uhksqrtus, (unsigned short x)) {
+#ifdef LIBC_FAST_MATH
+ return fixed_point::isqrt_fast(x);
+#else
+ return fixed_point::isqrt(x);
+#endif
+}
+
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/stdfix/uhksqrtus.h b/libc/src/stdfix/uhksqrtus.h
new file mode 100644
index 00000000000000..c24846a8003037
--- /dev/null
+++ b/libc/src/stdfix/uhksqrtus.h
@@ -0,0 +1,20 @@
+//===-- Implementation header for uhksqrtus ---------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_STDFIX_UHKSQRTUS_H
+#define LLVM_LIBC_SRC_STDFIX_UHKSQRTUS_H
+
+#include "include/llvm-libc-macros/stdfix-macros.h"
+
+namespace LIBC_NAMESPACE {
+
+unsigned short accum uhksqrtus(unsigned short x);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_STDFIX_UHKSQRTUS_H
diff --git a/libc/src/stdfix/uksqrtui.cpp b/libc/src/stdfix/uksqrtui.cpp
new file mode 100644
index 00000000000000..ee1ae1335027a2
--- /dev/null
+++ b/libc/src/stdfix/uksqrtui.cpp
@@ -0,0 +1,23 @@
+//===-- Implementation of uksqrtui function -------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "uksqrtui.h"
+#include "src/__support/common.h"
+#include "src/__support/fixed_point/sqrt.h"
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(unsigned accum, uksqrtui, (unsigned int x)) {
+#ifdef LIBC_FAST_MATH
+ return fixed_point::isqrt_fast(x);
+#else
+ return fixed_point::isqrt(x);
+#endif
+}
+
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/stdfix/uksqrtui.h b/libc/src/stdfix/uksqrtui.h
new file mode 100644
index 00000000000000..cd4ff41ea100a7
--- /dev/null
+++ b/libc/src/stdfix/uksqrtui.h
@@ -0,0 +1,20 @@
+//===-- Implementation header for uksqrtui ----------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_STDFIX_UKSQRTUI_H
+#define LLVM_LIBC_SRC_STDFIX_UKSQRTUI_H
+
+#include "include/llvm-libc-macros/stdfix-macros.h"
+
+namespace LIBC_NAMESPACE {
+
+unsigned accum uksqrtui(unsigned int x);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_STDFIX_UKSQRTUI_H
diff --git a/libc/test/src/stdfix/CMakeLists.txt b/libc/test/src/stdfix/CMakeLists.txt
index 4140b5b29f3b3c..49e904a62771c1 100644
--- a/libc/test/src/stdfix/CMakeLists.txt
+++ b/libc/test/src/stdfix/CMakeLists.txt
@@ -61,3 +61,43 @@ foreach(suffix IN ITEMS hr r lr hk k lk uhr ur ulr uhk uk ulk)
libc.src.__support.fixed_point.fx_bits
)
endforeach()
+
+add_libc_test(
+ uhksqrtus_test
+ SUITE
+ libc-stdfix-tests
+ HDRS
+ ISqrtTest.h
+ SRCS
+ uhksqrtus_test.cpp
+ COMPILE_OPTIONS
+ -O3
+ -ffixed-point
+ DEPENDS
+ libc.src.stdfix.uhksqrtus
+ libc.src.__support.CPP.bit
+ libc.src.__support.fixed_point.fx_rep
+ libc.src.__support.fixed_point.sqrt
+ libc.src.__support.FPUtil.basic_operations
+ libc.src.__support.FPUtil.sqrt
+)
+
+add_libc_test(
+ uksqrtui_test
+ SUITE
+ libc-stdfix-tests
+ HDRS
+ ISqrtTest.h
+ SRCS
+ uksqrtui_test.cpp
+ COMPILE_OPTIONS
+ -O3
+ -ffixed-point
+ DEPENDS
+ libc.src.stdfix.uksqrtui
+ libc.src.__support.CPP.bit
+ libc.src.__support.fixed_point.fx_rep
+ libc.src.__support.fixed_point.sqrt
+ libc.src.__support.FPUtil.basic_operations
+ libc.src.__support.FPUtil.sqrt
+)
diff --git a/libc/test/src/stdfix/ISqrtTest.h b/libc/test/src/stdfix/ISqrtTest.h
new file mode 100644
index 00000000000000..bed57ba1ec6fdc
--- /dev/null
+++ b/libc/test/src/stdfix/ISqrtTest.h
@@ -0,0 +1,66 @@
+//===-- Utility class to test integer sqrt ----------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "test/UnitTest/FPMatcher.h"
+#include "test/UnitTest/Test.h"
+
+#include "src/__support/CPP/bit.h"
+#include "src/__support/FPUtil/BasicOperations.h"
+#include "src/__support/FPUtil/sqrt.h"
+#include "src/__support/fixed_point/fx_rep.h"
+#include "src/__support/fixed_point/sqrt.h"
+
+template <typename T> class ISqrtTest : public LIBC_NAMESPACE::testing::Test {
+
+ using OutType =
+ typename LIBC_NAMESPACE::fixed_point::internal::SqrtConfig<T>::OutType;
+ using FXRep = LIBC_NAMESPACE::fixed_point::FXRep<OutType>;
+ static constexpr OutType zero = FXRep::ZERO();
+ static constexpr OutType one = static_cast<OutType>(1);
+ static constexpr OutType eps = FXRep::EPS();
+
+public:
+ typedef OutType (*SqrtFunc)(T);
+
+ void testSpecialNumbers(SqrtFunc func) {
+ EXPECT_EQ(zero, func(T(0)));
+
+ EXPECT_EQ(one, func(T(1)));
+ EXPECT_EQ(static_cast<OutType>(2.0), func(T(4)));
+ EXPECT_EQ(static_cast<OutType>(3.0), func(T(9)));
+ EXPECT_EQ(static_cast<OutType>(16.0), func(T(256)));
+
+ constexpr int COUNT = 255;
+ constexpr double ERR = 3.0 * static_cast<double>(eps);
+ double x_d = 0.0;
+ T x = 0;
+ for (int i = 0; i < COUNT; ++i) {
+ x_d += 1.0;
+ ++x;
+ double y_d = static_cast<double>(func(x));
+ double result = LIBC_NAMESPACE::fputil::sqrt(x_d);
+ double errors = LIBC_NAMESPACE::fputil::abs((y_d / result) - 1.0);
+ if (errors > ERR) {
+ // Print out the failure input and output.
+ EXPECT_EQ(x, T(0));
+ EXPECT_EQ(func(x), zero);
+ EXPECT_FP_EQ(result, 0.0);
+ EXPECT_FP_EQ(errors, 0.0);
+ EXPECT_FP_EQ(ERR, 0.0);
+ }
+ ASSERT_TRUE(errors <= ERR);
+ }
+ }
+};
+
+#define LIST_ISQRT_TESTS(Name, T, func) \
+ using LlvmLibcISqrt##Name##Test = ISqrtTest<T>; \
+ TEST_F(LlvmLibcISqrt##Name##Test, SpecialNumbers) { \
+ testSpecialNumbers(&func); \
+ } \
+ static_assert(true, "Require semicolon.")
diff --git a/libc/test/src/stdfix/uhksqrtus_test.cpp b/libc/test/src/stdfix/uhksqrtus_test.cpp
new file mode 100644
index 00000000000000..a33297413980de
--- /dev/null
+++ b/libc/test/src/stdfix/uhksqrtus_test.cpp
@@ -0,0 +1,20 @@
+//===-- Unittests for uhksqrtus -------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "ISqrtTest.h"
+
+#include "src/__support/fixed_point/sqrt.h"
+#include "src/stdfix/uhksqrtus.h"
+
+unsigned short accum uhksqrtus_fast(unsigned short x) {
+ return LIBC_NAMESPACE::fixed_point::isqrt_fast(x);
+}
+
+LIST_ISQRT_TESTS(US, unsigned short, LIBC_NAMESPACE::uhksqrtus);
+
+LIST_ISQRT_TESTS(USFast, unsigned short, uhksqrtus_fast);
diff --git a/libc/test/src/stdfix/uksqrtui_test.cpp b/libc/test/src/stdfix/uksqrtui_test.cpp
new file mode 100644
index 00000000000000..0f4c057099daaf
--- /dev/null
+++ b/libc/test/src/stdfix/uksqrtui_test.cpp
@@ -0,0 +1,20 @@
+//===-- Unittests for uksqrtui --------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "ISqrtTest.h"
+
+#include "src/__support/fixed_point/sqrt.h"
+#include "src/stdfix/uksqrtui.h"
+
+unsigned accum uksqrtui_fast(unsigned int x) {
+ return LIBC_NAMESPACE::fixed_point::isqrt_fast(x);
+}
+
+LIST_ISQRT_TESTS(UI, unsigned int, LIBC_NAMESPACE::uksqrtui);
+
+LIST_ISQRT_TESTS(UIFast, unsigned int, uksqrtui_fast);
>From e70925362ac52e66f2cee09a8ed5d7dca75d4805 Mon Sep 17 00:00:00 2001
From: Tue Ly <lntue at google.com>
Date: Tue, 5 Mar 2024 15:42:11 -0500
Subject: [PATCH 2/3] Address comments.
---
libc/config/baremetal/api.td | 1 +
libc/config/linux/api.td | 2 +-
libc/docs/math/stdfix.rst | 21 +++++++++++++++++----
libc/spec/llvm_libc_ext.td | 24 ++++++++++++++++++++++--
libc/spec/stdc_ext.td | 11 -----------
libc/test/src/stdfix/ISqrtTest.h | 4 ++--
6 files changed, 43 insertions(+), 20 deletions(-)
diff --git a/libc/config/baremetal/api.td b/libc/config/baremetal/api.td
index a132d8308122f7..008eb45386f242 100644
--- a/libc/config/baremetal/api.td
+++ b/libc/config/baremetal/api.td
@@ -2,6 +2,7 @@ include "config/public_api.td"
include "spec/stdc.td"
include "spec/stdc_ext.td"
+include "spec/llvm_libc_ext.td"
def AssertMacro : MacroDef<"assert"> {
let Defn = [{
diff --git a/libc/config/linux/api.td b/libc/config/linux/api.td
index 5a1d7642f1aebe..526fd03f94f6a5 100644
--- a/libc/config/linux/api.td
+++ b/libc/config/linux/api.td
@@ -5,8 +5,8 @@ include "spec/posix.td"
include "spec/linux.td"
include "spec/gnu_ext.td"
include "spec/bsd_ext.td"
-include "spec/llvm_libc_ext.td"
include "spec/stdc_ext.td"
+include "spec/llvm_libc_ext.td"
def AssertMacro : MacroDef<"assert"> {
let Defn = [{
diff --git a/libc/docs/math/stdfix.rst b/libc/docs/math/stdfix.rst
index 79f499e61f121c..b55d10cfec3dbf 100644
--- a/libc/docs/math/stdfix.rst
+++ b/libc/docs/math/stdfix.rst
@@ -4,14 +4,19 @@ StdFix Functions
.. include:: ../check.rst
-Standards
----------
+Standards and Goals
+-------------------
- stdfix.h is specified in the `ISO/IEC TR 18037:2008 <https://www.iso.org/standard/51126.html>`_,
C extensions to support embedded processors .
- Its `specifications <https://standards.iso.org/ittf/PubliclyAvailableStandards/c051126_ISO_IEC_TR_18037_2008.zip>`_.
+- Our goal is to implement a complete set of math functions for fixed point
+ types, most of them are currently not included in the ISO/IEC TR
+ 18037:2008 standard. Our math functions for fixed point types are modeled
+ after the C99/C23 math functions for floating point types.
+
---------------
Source location
---------------
@@ -53,6 +58,8 @@ Predefined Macros
Fixed-point Arithmetics
=======================
+The following functions are included in the ISO/IEC TR 18037:2008 standard.
+
+---------------+------------------------------------------------------------------------------------------+------------------------------------------------------------------------------------------+
| Function Name | _Fract (r) | _Accum (k) |
| +------------------------------+----------------------------+------------------------------+------------------------------+----------------------------+------------------------------+
@@ -78,8 +85,6 @@ Fixed-point Arithmetics
+---------------+----------------+-------------+---------------+------------+----------------+-------------+----------------+-------------+---------------+------------+----------------+-------------+
| round | |check| | |check| | |check| | |check| | |check| | |check| | |check| | |check| | |check| | |check| | |check| | |check| |
+---------------+----------------+-------------+---------------+------------+----------------+-------------+----------------+-------------+---------------+------------+----------------+-------------+
-| sqrt | |check| | | |check| | | |check| | | |check| | | |check| | | | |
-+---------------+----------------+-------------+---------------+------------+----------------+-------------+----------------+-------------+---------------+------------+----------------+-------------+
================== =========
Type Generic Macro Available
@@ -93,6 +98,9 @@ roundfx
Higher math functions
=====================
+The following math functions are modeled after C99/C23 math functions for
+floating point types.
+
+---------------+------------------------------------------------------------------------------------------+------------------------------------------------------------------------------------------+
| Function Name | _Fract (r) | _Accum (k) |
| +------------------------------+----------------------------+------------------------------+------------------------------+----------------------------+------------------------------+
@@ -108,6 +116,8 @@ Higher math functions
+---------------+----------------+-------------+---------------+------------+----------------+-------------+----------------+-------------+---------------+------------+----------------+-------------+
| sin | | | | | | | | | | | | |
+---------------+----------------+-------------+---------------+------------+----------------+-------------+----------------+-------------+---------------+------------+----------------+-------------+
+| sqrt | |check| | | |check| | | |check| | | |check| | | |check| | | | |
++---------------+----------------+-------------+---------------+------------+----------------+-------------+----------------+-------------+---------------+------------+----------------+-------------+
| tan | | | | | | | | | | | | |
+---------------+----------------+-------------+---------------+------------+----------------+-------------+----------------+-------------+---------------+------------+----------------+-------------+
@@ -115,6 +125,9 @@ Higher math functions
Conversion Functions
====================
+The following conversion functions are included in the ISO/IEC TR 18037:2008
+standard.
+
+---------------+------------------------------------------------------------------------------------------+------------------------------------------------------------------------------------------+
| Function Name | _Fract (r) | _Accum (k) |
| +------------------------------+----------------------------+------------------------------+------------------------------+----------------------------+------------------------------+
diff --git a/libc/spec/llvm_libc_ext.td b/libc/spec/llvm_libc_ext.td
index 2fd0c5f78fb8a7..274284ed5705e8 100644
--- a/libc/spec/llvm_libc_ext.td
+++ b/libc/spec/llvm_libc_ext.td
@@ -51,9 +51,29 @@ def LLVMLibcExt : StandardSpec<"llvm_libc_ext"> {
]
>;
+ HeaderSpec StdFix = HeaderSpec<
+ "stdfix.h",
+ [], // macros
+ [], // types
+ [], // enums
+ [ // functions
+ GuardedFunctionSpec<"sqrtuhr", RetValSpec<UnsignedShortFractType>, [ArgSpec<UnsignedShortFractType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
+ GuardedFunctionSpec<"sqrtur", RetValSpec<UnsignedFractType>, [ArgSpec<UnsignedFractType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
+ GuardedFunctionSpec<"sqrtulr", RetValSpec<UnsignedLongFractType>, [ArgSpec<UnsignedLongFractType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
+
+ GuardedFunctionSpec<"sqrtuhk", RetValSpec<UnsignedShortAccumType>, [ArgSpec<UnsignedShortAccumType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
+ GuardedFunctionSpec<"sqrtuk", RetValSpec<UnsignedAccumType>, [ArgSpec<UnsignedAccumType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
+ GuardedFunctionSpec<"sqrtulk", RetValSpec<UnsignedLongAccumType>, [ArgSpec<UnsignedLongAccumType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
+
+ GuardedFunctionSpec<"uhksqrtus", RetValSpec<UnsignedShortAccumType>, [ArgSpec<UnsignedShortType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
+ GuardedFunctionSpec<"uksqrtui", RetValSpec<UnsignedAccumType>, [ArgSpec<UnsignedIntType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
+ ]
+ >;
+
let Headers = [
- Strings,
- Sched,
Assert,
+ Sched,
+ Stdfix,
+ Strings,
];
}
diff --git a/libc/spec/stdc_ext.td b/libc/spec/stdc_ext.td
index 4e433e222ce47c..6620142146c471 100644
--- a/libc/spec/stdc_ext.td
+++ b/libc/spec/stdc_ext.td
@@ -47,17 +47,6 @@ def StdcExt : StandardSpec<"stdc_ext"> {
GuardedFunctionSpec<"rounduhk", RetValSpec<UnsignedShortAccumType>, [ArgSpec<UnsignedShortAccumType>, ArgSpec<IntType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
GuardedFunctionSpec<"rounduk", RetValSpec<UnsignedAccumType>, [ArgSpec<UnsignedAccumType>, ArgSpec<IntType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
GuardedFunctionSpec<"roundulk", RetValSpec<UnsignedLongAccumType>, [ArgSpec<UnsignedLongAccumType>, ArgSpec<IntType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
-
- GuardedFunctionSpec<"sqrtuhr", RetValSpec<UnsignedShortFractType>, [ArgSpec<UnsignedShortFractType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
- GuardedFunctionSpec<"sqrtur", RetValSpec<UnsignedFractType>, [ArgSpec<UnsignedFractType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
- GuardedFunctionSpec<"sqrtulr", RetValSpec<UnsignedLongFractType>, [ArgSpec<UnsignedLongFractType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
-
- GuardedFunctionSpec<"sqrtuhk", RetValSpec<UnsignedShortAccumType>, [ArgSpec<UnsignedShortAccumType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
- GuardedFunctionSpec<"sqrtuk", RetValSpec<UnsignedAccumType>, [ArgSpec<UnsignedAccumType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
- GuardedFunctionSpec<"sqrtulk", RetValSpec<UnsignedLongAccumType>, [ArgSpec<UnsignedLongAccumType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
-
- GuardedFunctionSpec<"uhksqrtus", RetValSpec<UnsignedShortAccumType>, [ArgSpec<UnsignedShortType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
- GuardedFunctionSpec<"uksqrtui", RetValSpec<UnsignedAccumType>, [ArgSpec<UnsignedIntType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
]
>;
diff --git a/libc/test/src/stdfix/ISqrtTest.h b/libc/test/src/stdfix/ISqrtTest.h
index bed57ba1ec6fdc..9b963883b6c2c7 100644
--- a/libc/test/src/stdfix/ISqrtTest.h
+++ b/libc/test/src/stdfix/ISqrtTest.h
@@ -32,11 +32,11 @@ template <typename T> class ISqrtTest : public LIBC_NAMESPACE::testing::Test {
EXPECT_EQ(one, func(T(1)));
EXPECT_EQ(static_cast<OutType>(2.0), func(T(4)));
- EXPECT_EQ(static_cast<OutType>(3.0), func(T(9)));
+ EXPECT_EQ(static_cast<OutType>(4.0), func(T(16)));
EXPECT_EQ(static_cast<OutType>(16.0), func(T(256)));
constexpr int COUNT = 255;
- constexpr double ERR = 3.0 * static_cast<double>(eps);
+ constexpr double ERR = 2.0 * static_cast<double>(eps);
double x_d = 0.0;
T x = 0;
for (int i = 0; i < COUNT; ++i) {
>From 0c2da530820872533c38167959e404c6d3c233e9 Mon Sep 17 00:00:00 2001
From: Tue Ly <lntue at google.com>
Date: Tue, 5 Mar 2024 19:16:52 -0500
Subject: [PATCH 3/3] Remove redundant -ffixed-point flags.
---
libc/src/stdfix/CMakeLists.txt | 5 -----
libc/test/src/stdfix/CMakeLists.txt | 5 -----
2 files changed, 10 deletions(-)
diff --git a/libc/src/stdfix/CMakeLists.txt b/libc/src/stdfix/CMakeLists.txt
index a5c37183fbbb7c..3a1cb66b7abcaf 100644
--- a/libc/src/stdfix/CMakeLists.txt
+++ b/libc/src/stdfix/CMakeLists.txt
@@ -11,7 +11,6 @@ foreach(suffix IN ITEMS hr r lr hk k lk)
abs${suffix}.cpp
COMPILE_OPTIONS
-O3
- -ffixed-point
DEPENDS
libc.src.__support.fixed_point.fx_bits
)
@@ -26,7 +25,6 @@ foreach(suffix IN ITEMS uhr ur ulr uhk uk)
sqrt${suffix}.cpp
COMPILE_OPTIONS
-O3
- -ffixed-point
DEPENDS
libc.src.__support.fixed_point.sqrt
)
@@ -41,7 +39,6 @@ foreach(suffix IN ITEMS hr r lr hk k lk uhr ur ulr uhk uk ulk)
round${suffix}.cpp
COMPILE_OPTIONS
-O3
- -ffixed-point
DEPENDS
libc.src.__support.fixed_point.fx_bits
)
@@ -55,7 +52,6 @@ add_entrypoint_object(
uhksqrtus.cpp
COMPILE_OPTIONS
-O3
- -ffixed-point
DEPENDS
libc.src.__support.fixed_point.sqrt
)
@@ -68,7 +64,6 @@ add_entrypoint_object(
uksqrtui.cpp
COMPILE_OPTIONS
-O3
- -ffixed-point
DEPENDS
libc.src.__support.fixed_point.sqrt
)
diff --git a/libc/test/src/stdfix/CMakeLists.txt b/libc/test/src/stdfix/CMakeLists.txt
index 49e904a62771c1..d3e122884eb40e 100644
--- a/libc/test/src/stdfix/CMakeLists.txt
+++ b/libc/test/src/stdfix/CMakeLists.txt
@@ -15,7 +15,6 @@ foreach(suffix IN ITEMS hr r lr hk k lk)
abs${suffix}_test.cpp
COMPILE_OPTIONS
-O3
- -ffixed-point
DEPENDS
libc.src.stdfix.abs${suffix}
libc.src.__support.fixed_point.fx_bits
@@ -33,7 +32,6 @@ foreach(suffix IN ITEMS uhr ur ulr uhk uk)
sqrt${suffix}_test.cpp
COMPILE_OPTIONS
-O3
- -ffixed-point
DEPENDS
libc.src.stdfix.sqrt${suffix}
libc.src.__support.CPP.bit
@@ -55,7 +53,6 @@ foreach(suffix IN ITEMS hr r lr hk k lk uhr ur ulr uhk uk ulk)
round${suffix}_test.cpp
COMPILE_OPTIONS
-O3
- -ffixed-point
DEPENDS
libc.src.stdfix.round${suffix}
libc.src.__support.fixed_point.fx_bits
@@ -72,7 +69,6 @@ add_libc_test(
uhksqrtus_test.cpp
COMPILE_OPTIONS
-O3
- -ffixed-point
DEPENDS
libc.src.stdfix.uhksqrtus
libc.src.__support.CPP.bit
@@ -92,7 +88,6 @@ add_libc_test(
uksqrtui_test.cpp
COMPILE_OPTIONS
-O3
- -ffixed-point
DEPENDS
libc.src.stdfix.uksqrtui
libc.src.__support.CPP.bit
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