[PowerPC] Add the support for __builtin_setrnd() in clang

Summary:
PowerPC64/PowerPC64le supports the builtin function __builtin_setrnd to set the floating point rounding mode. This function will use the least significant two bits of integer argument to set the floating point rounding mode.
double __builtin_setrnd(int mode);
The effective values for mode are:
0 - round to nearest
1 - round to zero
2 - round to +infinity
3 - round to -infinity
Note that the mode argument will modulo 4, so if the int argument is greater than 3, it will only use the least significant two bits of the mode. Namely, builtin_setrnd(102)) is equal to builtin_setrnd(2).

Reviewed By: jsji

Differential Revision: https://reviews.llvm.org/D59403

llvm-svn: 357242

diff --git a/clang/docs/LanguageExtensions.rst b/clang/docs/LanguageExtensions.rst
index d4c40b2..d79d412 100644 (file)
--- a/clang/docs/LanguageExtensions.rst
+++ b/clang/docs/LanguageExtensions.rst
@@ -2376,6 +2376,78 @@ Which compiles to (on X86-32):
           movl    %gs:(%eax), %eax
           ret
 
+PowerPC Language Extensions
+------------------------------
+
+Set the Floating Point Rounding Mode
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+PowerPC64/PowerPC64le supports the builtin function ``__builtin_setrnd`` to set
+the floating point rounding mode. This function will use the least significant
+two bits of integer argument to set the floating point rounding mode.
+
+.. code-block:: c++
+
+  double __builtin_setrnd(int mode);
+
+The effective values for mode are:
+
+    - 0 - round to nearest
+    - 1 - round to zero
+    - 2 - round to +infinity
+    - 3 - round to -infinity
+
+Note that the mode argument will modulo 4, so if the int argument is greater 
+than 3, it will only use the least significant two bits of the mode. 
+Namely, ``__builtin_setrnd(102))`` is equal to ``__builtin_setrnd(2)``.
+
+PowerPC Language Extensions
+------------------------------
+
+Set the Floating Point Rounding Mode
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+PowerPC64/PowerPC64le supports the builtin function ``__builtin_setrnd`` to set
+the floating point rounding mode. This function will use the least significant
+two bits of integer argument to set the floating point rounding mode.
+
+.. code-block:: c++
+
+  double __builtin_setrnd(int mode);
+
+The effective values for mode are:
+
+    - 0 - round to nearest
+    - 1 - round to zero
+    - 2 - round to +infinity
+    - 3 - round to -infinity
+
+Note that the mode argument will modulo 4, so if the integer argument is greater
+than 3, it will only use the least significant two bits of the mode. 
+Namely, ``__builtin_setrnd(102))`` is equal to ``__builtin_setrnd(2)``.
+
+PowerPC Language Extensions
+------------------------------
+
+Set the Floating Point Rounding Mode
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+PowerPC64/PowerPC64le supports the builtin function ``__builtin_setrnd`` to set
+the floating point rounding mode. This function will use the least significant
+two bits of integer argument to set the floating point rounding mode.
+
+.. code-block:: c++
+
+  double __builtin_setrnd(int mode);
+
+The effective values for mode are:
+
+    - 0 - round to nearest
+    - 1 - round to zero
+    - 2 - round to +infinity
+    - 3 - round to -infinity
+
+Note that the mode argument will modulo 4, so if the integer argument is greater
+than 3, it will only use the least significant two bits of the mode. 
+Namely, ``__builtin_setrnd(102))`` is equal to ``__builtin_setrnd(2)``.
+
 Extensions for Static Analysis
 ==============================
 

diff --git a/clang/include/clang/Basic/BuiltinsPPC.def b/clang/include/clang/Basic/BuiltinsPPC.def
index e55fa04..9292458 100644 (file)
--- a/clang/include/clang/Basic/BuiltinsPPC.def
+++ b/clang/include/clang/Basic/BuiltinsPPC.def
@@ -475,6 +475,9 @@ BUILTIN(__builtin_bpermd, "SLLiSLLiSLLi", "")
 BUILTIN(__builtin_unpack_vector_int128, "ULLiV1LLLii", "")
 BUILTIN(__builtin_pack_vector_int128, "V1LLLiULLiULLi", "")
 
+// Set the floating point rounding mode
+BUILTIN(__builtin_setrnd, "di", "")
+
 // FIXME: Obviously incomplete.
 
 #undef BUILTIN

diff --git a/clang/test/CodeGen/builtins-ppc.c b/clang/test/CodeGen/builtins-ppc.c
index 1f17787..1ff1b81 100644 (file)
--- a/clang/test/CodeGen/builtins-ppc.c
+++ b/clang/test/CodeGen/builtins-ppc.c
@@ -14,3 +14,16 @@ long long test_builtin_ppc_get_timebase() {
   return __builtin_ppc_get_timebase();
 }
 
+void test_builtin_ppc_setrnd() {
+  volatile double res;
+  volatile int x = 100;
+  
+  // CHECK: call double @llvm.ppc.setrnd(i32 2)
+  res = __builtin_setrnd(2);
+
+  // CHECK: call double @llvm.ppc.setrnd(i32 100)
+  res = __builtin_setrnd(100);
+
+  // CHECK: call double @llvm.ppc.setrnd(i32 %2)
+  res = __builtin_setrnd(x);
+}