[libc] Add hardware implementations of ceil and ceilf for aarch64.

[sivachandra]

Summary

This change also introduces a new source layout for adding machine
specific and generic implementations. To keep the scope of this change
small, this new pattern is only applied for ceil, ceilf and ceill.
Follow up changes will switch all math functions in to the new pattern.

[lntue]

Do we need to remove ceil(f|l).(h|cpp) in src/math folder?

[sivachandra]

Move generic implementations of ceil* functions to the generic directory.

[sivachandra]

In D95850#2536456, @lntue wrote:

Do we need to remove ceil(f|l).(h|cpp) in src/math folder?

Hopefully I got it right this time. I have removed the .cpp files but kept the .h files.

libc/src/math/CMakeLists.txt

+add_subdirectory(generic)
+if(EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/${LIBC_TARGET_MACHINE})
+  add_subdirectory(${LIBC_TARGET_MACHINE})
+endif()
+
+function(add_math_entrypoint_object name)
+  # We prefer machine specific implementation if available. Hence we check
+  # that first and retrun early if we are able to add an alias target for the
+  # machine specific implementation.
+  get_fq_target_name("${LIBC_TARGET_MACHINE}.${name}" fq_machine_specific_target_name)
+  if(TARGET ${fq_machine_specific_target_name})
+    add_entrypoint_object(
+      ${name}
+      ALIAS
+      DEPENDS
+        .${LIBC_TARGET_MACHINE}.${name}
+    )
+    return()
+  endif()
+
+  get_fq_target_name("generic.${name}" fq_generic_target_name)
+  if(TARGET ${fq_generic_target_name})
+    add_entrypoint_object(
+      ${name}
+      ALIAS
+      DEPENDS
+        .generic.${name}
+    )
+    return()
+  endif()
+
+  message(FATAL_ERROR "No machine specific or generic implementation found for ${name}.")
+endfunction()
+
+add_math_entrypoint_object(ceil)
+add_math_entrypoint_object(ceilf)
+add_math_entrypoint_object(ceill)
+
 add_object_library(
   math_utils
   SRCS
     math_utils.cpp
   HDRS
     math_utils.h
   DEPENDS
     libc.include.errno
HDRS
     truncl.h
   DEPENDS
     libc.utils.FPUtil.fputil
   COMPILE_OPTIONS
     -O2
 )
 
 add_entrypoint_object(
-  ceil
-  SRCS
-    ceil.cpp
-  HDRS
-    ceil.h
-  DEPENDS
-    libc.utils.FPUtil.fputil
-  COMPILE_OPTIONS
-    -O2
-)
-
-add_entrypoint_object(
-  ceilf
-  SRCS
-    ceilf.cpp
-  HDRS
-    ceilf.h
-  DEPENDS
-    libc.utils.FPUtil.fputil
-  COMPILE_OPTIONS
-    -O2
-)
-
-add_entrypoint_object(
-  ceill
-  SRCS
-    ceill.cpp
-  HDRS
-    ceill.h
-  DEPENDS
-    libc.utils.FPUtil.fputil
-  COMPILE_OPTIONS
-    -O2
-)
-
-add_entrypoint_object(
   floor
   SRCS
     floor.cpp
   HDRS
     floor.h
   DEPENDS
     libc.utils.FPUtil.fputil
   COMPILE_OPTIONS

libc/src/math/aarch64/CMakeLists.txt

+add_entrypoint_object(
+  ceil
+  SRCS
+    ceil.cpp
+  HDRS
+    ../ceil.h
+  COMPILE_OPTIONS
+    -O2
+)
+
+add_entrypoint_object(
+  ceilf
+  SRCS
+    ceilf.cpp
+  HDRS
+    ../ceilf.h
+  COMPILE_OPTIONS
+    -O2
+)

libc/src/math/aarch64/ceil.cpp

-//===-- Implementation of ceil function -----------------------------------===//
+//===-- Implementation of the ceil function for aarch64 -------------------===//
 //
 // 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 "src/math/ceil.h"
 #include "src/__support/common.h"
-#include "utils/FPUtil/NearestIntegerOperations.h"
 
 namespace __llvm_libc {
 
-LLVM_LIBC_FUNCTION(double, ceil, (double x)) { return fputil::ceil(x); }
+LLVM_LIBC_FUNCTION(double, ceil, (double x)) {
+  double y;
+  __asm__ __volatile__("ldr d0, %1\n"
+                       "frintp d0, d0\n"
+                       "str d0, %0\n"
+                       : "=m"(y)
+                       : "m"(x)
+                       : "d0");
+  return y;
+}
 
 } // namespace __llvm_libc

libc/src/math/aarch64/ceilf.cpp

-//===-- Implementation of ceilf function ----------------------------------===//
+//===-- Implementation of the ceilf function for aarch64 ------------------===//
 //
 // 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 "src/math/ceilf.h"
 #include "src/__support/common.h"
-#include "utils/FPUtil/NearestIntegerOperations.h"
 
 namespace __llvm_libc {
 
-LLVM_LIBC_FUNCTION(float, ceilf, (float x)) { return fputil::ceil(x); }
+LLVM_LIBC_FUNCTION(float, ceilf, (float x)) {
+  float y;
+  __asm__ __volatile__("ldr s0, %1\n"
+                       "frintp s0, s0\n"
+                       "str s0, %0\n"
+                       : "=m"(y)
+                       : "m"(x)
+                       : "s0");
+  return y;
+}
 
 } // namespace __llvm_libc

libc/src/math/generic/CMakeLists.txt

+add_entrypoint_object(
+  ceil
+  SRCS
+    ceil.cpp
+  HDRS
+    ../ceil.h
+  DEPENDS
+    libc.utils.FPUtil.fputil
+  COMPILE_OPTIONS
+    -O2
+)
+
+add_entrypoint_object(
+  ceilf
+  SRCS
+    ceilf.cpp
+  HDRS
+    ../ceilf.h
+  DEPENDS
+    libc.utils.FPUtil.fputil
+  COMPILE_OPTIONS
+    -O2
+)
+
+add_entrypoint_object(
+  ceill
+  SRCS
+    ceill.cpp
+  HDRS
+    ../ceill.h
+  DEPENDS
+    libc.utils.FPUtil.fputil
+  COMPILE_OPTIONS
+    -O2
+)

libc/test/src/math/CMakeLists.txt

SUITE
     libc_math_unittests
   SRCS
     fmaf_test.cpp
   DEPENDS
     libc.include.math
     libc.src.math.fmaf
     libc.utils.FPUtil.fputil
 )
+
+add_subdirectory(generic)

libc/test/src/math/generic/CMakeLists.txt

+add_fp_unittest(
+  ceil_test
+  NEED_MPFR
+  SUITE
+    libc_math_unittests
+  SRCS
+    ../ceil_test.cpp
+  DEPENDS
+    libc.include.math
+    libc.src.math.generic.ceil
+    libc.utils.FPUtil.fputil
+)
+
+add_fp_unittest(
+  ceilf_test
+  NEED_MPFR
+  SUITE
+    libc_math_unittests
+  SRCS
+    ../ceilf_test.cpp
+  DEPENDS
+    libc.include.math
+    libc.src.math.generic.ceilf
+    libc.utils.FPUtil.fputil
+)
+
+add_fp_unittest(
+  ceill_test
+  NEED_MPFR
+  SUITE
+    libc_math_unittests
+  SRCS
+    ../ceill_test.cpp
+  DEPENDS
+    libc.include.math
+    libc.src.math.generic.ceill
+    libc.utils.FPUtil.fputil
+)
+