[libc][stdfix] Implement idivfx functions in LLVM libc (llvm#133005)

This PR implements the following 8 functions along with the tests.

```c++
int idivr(fract, fract);
long int idivlr(long fract, long fract);
int idivk(accum, accum);
long int idivlk(long accum, long accum);

unsigned int idivur(unsigned fract, unsigned fract);
unsigned long int idivulr(unsigned long fract, unsigned long fract);
unsigned int idivuk(unsigned accum, unsigned accum);
unsigned long int idivulk(unsigned long accum, unsigned long accum);
```

ref: https://www.iso.org/standard/51126.html

Fixes llvm#129125

---------

Signed-off-by: krishna2803 <kpandey81930@gmail.com>

Author: krishna2803

libc/config/baremetal/arm/entrypoints.txt

@@ -820,6 +820,14 @@ if(LIBC_COMPILER_HAS_FIXED_POINT)
     libc.src.stdfix.countlsuhk
     libc.src.stdfix.countlsuk
     libc.src.stdfix.countlsulk
+    libc.src.stdfix.idivr
+    libc.src.stdfix.idivlr
+    libc.src.stdfix.idivk
+    libc.src.stdfix.idivlk
+    libc.src.stdfix.idivur
+    libc.src.stdfix.idivulr
+    libc.src.stdfix.idivuk
+    libc.src.stdfix.idivulk
   )
 endif()
 

libc/config/baremetal/riscv/entrypoints.txt

@@ -820,6 +820,14 @@ if(LIBC_COMPILER_HAS_FIXED_POINT)
     libc.src.stdfix.countlsuhk
     libc.src.stdfix.countlsuk
     libc.src.stdfix.countlsulk
+    libc.src.stdfix.idivr
+    libc.src.stdfix.idivlr
+    libc.src.stdfix.idivk
+    libc.src.stdfix.idivlk
+    libc.src.stdfix.idivur
+    libc.src.stdfix.idivulr
+    libc.src.stdfix.idivuk
+    libc.src.stdfix.idivulk
   )
 endif()
 

libc/config/linux/riscv/entrypoints.txt

@@ -775,6 +775,14 @@ if(LIBC_COMPILER_HAS_FIXED_POINT)
     libc.src.stdfix.countlsuhk
     libc.src.stdfix.countlsuk
     libc.src.stdfix.countlsulk
+    libc.src.stdfix.idivr
+    libc.src.stdfix.idivlr
+    libc.src.stdfix.idivk
+    libc.src.stdfix.idivulk
+    libc.src.stdfix.idivur
+    libc.src.stdfix.idivulr
+    libc.src.stdfix.idivuk
+    libc.src.stdfix.idivulk
   )
 endif()
 

libc/config/linux/x86_64/entrypoints.txt

@@ -920,6 +920,14 @@ if(LIBC_COMPILER_HAS_FIXED_POINT)
     libc.src.stdfix.countlsuhk
     libc.src.stdfix.countlsuk
     libc.src.stdfix.countlsulk
+    libc.src.stdfix.idivr
+    libc.src.stdfix.idivlr
+    libc.src.stdfix.idivk
+    libc.src.stdfix.idivlk
+    libc.src.stdfix.idivur
+    libc.src.stdfix.idivulr
+    libc.src.stdfix.idivuk
+    libc.src.stdfix.idivulk
   )
 endif()
 

libc/docs/headers/stdfix.rst

@@ -77,7 +77,7 @@ The following functions are included in the ISO/IEC TR 18037:2008 standard.
 +---------------+----------------+-------------+---------------+------------+----------------+-------------+----------------+-------------+---------------+------------+----------------+-------------+
 | divi\*        |                |             |               |            |                |             |                |             |               |            |                |             |
 +---------------+----------------+-------------+---------------+------------+----------------+-------------+----------------+-------------+---------------+------------+----------------+-------------+
-| idiv\*        |                |             |               |            |                |             |                |             |               |            |                |             |
+| idiv\*        | |check|        | |check|     | |check|       | |check|    | |check|        | |check|     | |check|        | |check|     | |check|       | |check|    | |check|        | |check|     |
 +---------------+----------------+-------------+---------------+------------+----------------+-------------+----------------+-------------+---------------+------------+----------------+-------------+
 | muli          |                |             |               |            |                |             |                |             |               |            |                |             |
 +---------------+----------------+-------------+---------------+------------+----------------+-------------+----------------+-------------+---------------+------------+----------------+-------------+

libc/include/stdfix.yaml

@@ -238,6 +238,70 @@ functions:
     arguments:
       - type: unsigned long accum
     guard: LIBC_COMPILER_HAS_FIXED_POINT
+  - name: idivr
+    standards:
+      - stdc_ext
+    return_type: int
+    arguments:
+      - type: fract
+      - type: fract
+    guard: LIBC_COMPILER_HAS_FIXED_POINT
+  - name: idivlr
+    standards:
+      - stdc_ext
+    return_type: long int
+    arguments:
+      - type: long fract
+      - type: long fract
+    guard: LIBC_COMPILER_HAS_FIXED_POINT
+  - name: idivk
+    standards:
+      - stdc_ext
+    return_type: int
+    arguments:
+      - type: accum
+      - type: accum
+    guard: LIBC_COMPILER_HAS_FIXED_POINT
+  - name: idivlk
+    standards:
+      - stdc_ext
+    return_type: long int
+    arguments:
+      - type: long accum
+      - type: long accum
+    guard: LIBC_COMPILER_HAS_FIXED_POINT
+  - name: idivur
+    standards:
+      - stdc_ext
+    return_type: unsigned int
+    arguments:
+      - type: unsigned fract
+      - type: unsigned fract
+    guard: LIBC_COMPILER_HAS_FIXED_POINT
+  - name: idivulr
+    standards:
+      - stdc_ext
+    return_type: unsigned long int
+    arguments:
+      - type: unsigned long fract
+      - type: unsigned long fract
+    guard: LIBC_COMPILER_HAS_FIXED_POINT
+  - name: idivuk
+    standards:
+      - stdc_ext
+    return_type: unsigned int
+    arguments:
+      - type: unsigned accum
+      - type: unsigned accum
+    guard: LIBC_COMPILER_HAS_FIXED_POINT
+  - name: idivulk
+    standards:
+      - stdc_ext
+    return_type: unsigned long int
+    arguments:
+      - type: unsigned long accum
+      - type: unsigned long accum
+    guard: LIBC_COMPILER_HAS_FIXED_POINT
   - name: roundhk
     standards:
       - stdc_ext

libc/src/__support/fixed_point/CMakeLists.txt

@@ -16,6 +16,7 @@ add_header_library(
     .fx_rep
     libc.include.llvm-libc-macros.stdfix_macros
     libc.src.__support.macros.attributes
+    libc.src.__support.macros.null_check
     libc.src.__support.macros.optimization
     libc.src.__support.CPP.type_traits
     libc.src.__support.CPP.bit

libc/src/__support/fixed_point/fx_bits.h

@@ -15,6 +15,7 @@
 #include "src/__support/CPP/type_traits.h"
 #include "src/__support/macros/attributes.h"   // LIBC_INLINE
 #include "src/__support/macros/config.h"       // LIBC_NAMESPACE_DECL
+#include "src/__support/macros/null_check.h"   // LIBC_CRASH_ON_VALUE
 #include "src/__support/macros/optimization.h" // LIBC_UNLIKELY
 #include "src/__support/math_extras.h"
 
@@ -201,6 +202,28 @@ bitsfx(T f) {
   return cpp::bit_cast<XType, T>(f);
 }
 
+// divide the two fixed-point types and return an integer result
+template <typename T, typename XType>
+LIBC_INLINE constexpr cpp::enable_if_t<cpp::is_fixed_point_v<T>, XType>
+idiv(T x, T y) {
+  using FXBits = FXBits<T>;
+  using FXRep = FXRep<T>;
+  using CompType = typename FXRep::CompType;
+
+  // If the value of the second operand of the / operator is zero, the
+  // behavior is undefined. Ref: ISO/IEC TR 18037:2008(E) p.g. 16
+  LIBC_CRASH_ON_VALUE(y, FXRep::ZERO());
+
+  CompType x_comp = static_cast<CompType>(FXBits(x).get_bits());
+  CompType y_comp = static_cast<CompType>(FXBits(y).get_bits());
+
+  // If an integer result of one of these functions overflows, the behavior is
+  // undefined. Ref: ISO/IEC TR 18037:2008(E) p.g. 16
+  CompType result = x_comp / y_comp;
+
+  return static_cast<XType>(result);
+}
+
 } // namespace fixed_point
 } // namespace LIBC_NAMESPACE_DECL
 

libc/src/__support/macros/null_check.h

@@ -19,10 +19,19 @@
     if (LIBC_UNLIKELY((ptr) == nullptr))                                       \
       __builtin_trap();                                                        \
   } while (0)
+#define LIBC_CRASH_ON_VALUE(var, value)                                        \
+  do {                                                                         \
+    if (LIBC_UNLIKELY((var) == (value)))                                       \
+      __builtin_trap();                                                        \
+  } while (0)
+
 #else
 #define LIBC_CRASH_ON_NULLPTR(ptr)                                             \
   do {                                                                         \
   } while (0)
+#define LIBC_CRASH_ON_VALUE(var, value)                                        \
+  do {                                                                         \
+  } while (0)
 #endif
 
 #endif // LLVM_LIBC_SRC___SUPPORT_MACROS_NULL_CHECK_H

libc/src/stdfix/CMakeLists.txt

@@ -75,6 +75,20 @@ foreach(suffix IN ITEMS hr r lr hk k lk uhr ur ulr uhk uk ulk)
   )
 endforeach()
 
+foreach(suffix IN ITEMS r lr k lk ur ulr uk ulk)
+  add_entrypoint_object(
+    idiv${suffix}
+    HDRS
+      idiv${suffix}.h
+    SRCS
+      idiv${suffix}.cpp
+    COMPILE_OPTIONS
+      ${libc_opt_high_flag}
+    DEPENDS
+      libc.src.__support.fixed_point.fx_bits
+  )
+endforeach()
+
 add_entrypoint_object(
   uhksqrtus
   HDRS

libc/src/stdfix/idivk.cpp

@@ -0,0 +1,21 @@
+//===-- Implementation of idivk 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 "idivk.h"
+#include "include/llvm-libc-macros/stdfix-macros.h" // accum
+#include "src/__support/common.h"                   // LLVM_LIBC_FUNCTION
+#include "src/__support/fixed_point/fx_bits.h"      // fixed_point
+#include "src/__support/macros/config.h"            // LIBC_NAMESPACE_DECL
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(int, idivk, (accum x, accum y)) {
+  return fixed_point::idiv<accum, int>(x, y);
+}
+
+} // namespace LIBC_NAMESPACE_DECL

libc/src/stdfix/idivk.h

@@ -0,0 +1,21 @@
+//===-- Implementation header for idivk ------------------------*- 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_IDIVK_H
+#define LLVM_LIBC_SRC_STDFIX_IDIVK_H
+
+#include "include/llvm-libc-macros/stdfix-macros.h" // accum
+#include "src/__support/macros/config.h"            // LIBC_NAMESPACE_DECL
+
+namespace LIBC_NAMESPACE_DECL {
+
+int idivk(accum x, accum y);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_STDFIX_IDIVK_H

libc/src/stdfix/idivlk.cpp

@@ -0,0 +1,21 @@
+//===-- Implementation of idivlk 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 "idivlk.h"
+#include "include/llvm-libc-macros/stdfix-macros.h" // long accum
+#include "src/__support/common.h"                   // LLVM_LIBC_FUNCTION
+#include "src/__support/fixed_point/fx_bits.h"      // fixed_point
+#include "src/__support/macros/config.h"            // LIBC_NAMESPACE_DECL
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(long int, idivlk, (long accum x, long accum y)) {
+  return fixed_point::idiv<long accum, long int>(x, y);
+}
+
+} // namespace LIBC_NAMESPACE_DECL

libc/src/stdfix/idivlk.h

@@ -0,0 +1,21 @@
+//===-- Implementation header for idivlk -----------------------*- 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_IDIVLK_H
+#define LLVM_LIBC_SRC_STDFIX_IDIVLK_H
+
+#include "include/llvm-libc-macros/stdfix-macros.h" // long accum
+#include "src/__support/macros/config.h"            // LIBC_NAMESPACE_DECL
+
+namespace LIBC_NAMESPACE_DECL {
+
+long int idivlk(long accum x, long accum y);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_STDFIX_IDIVLK_H

libc/src/stdfix/idivlr.cpp

@@ -0,0 +1,21 @@
+//===-- Implementation of idivlr 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 "idivlr.h"
+#include "include/llvm-libc-macros/stdfix-macros.h" // long fract
+#include "src/__support/common.h"                   // LLVM_LIBC_FUNCTION
+#include "src/__support/fixed_point/fx_bits.h"      // fixed_point
+#include "src/__support/macros/config.h"            // LIBC_NAMESPACE_DECL
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(long int, idivlr, (long fract x, long fract y)) {
+  return fixed_point::idiv<long fract, long int>(x, y);
+}
+
+} // namespace LIBC_NAMESPACE_DECL

libc/src/stdfix/idivlr.h

@@ -0,0 +1,21 @@
+//===-- Implementation header for idivlr -----------------------*- 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_IDIVLR_H
+#define LLVM_LIBC_SRC_STDFIX_IDIVLR_H
+
+#include "include/llvm-libc-macros/stdfix-macros.h" // long fract
+#include "src/__support/macros/config.h"            // LIBC_NAMESPACE_DECL
+
+namespace LIBC_NAMESPACE_DECL {
+
+long int idivlr(long fract x, long fract y);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_STDFIX_IDIVLR_H

libc/src/stdfix/idivr.cpp

@@ -0,0 +1,21 @@
+//===-- Implementation of idivr 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 "idivr.h"
+#include "include/llvm-libc-macros/stdfix-macros.h" // fract
+#include "src/__support/common.h"                   // LLVM_LIBC_FUNCTION
+#include "src/__support/fixed_point/fx_bits.h"      // fixed_point
+#include "src/__support/macros/config.h"            // LIBC_NAMESPACE_DECL
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(int, idivr, (fract x, fract y)) {
+  return fixed_point::idiv<fract, int>(x, y);
+}
+
+} // namespace LIBC_NAMESPACE_DECL