nvptx: Add suppport for __builtin_nvptx_brev instrinsic.

This patch adds support for (a pair of) bit reversal intrinsics
__builtin_nvptx_brev and __builtin_nvptx_brevll which perform 32-bit
and 64-bit bit reversal (using nvptx's brev instruction) matching
the __brev and __brevll instrinsics provided by NVidia's nvcc compiler.
https://docs.nvidia.com/cuda/cuda-math-api/group__CUDA__MATH__INTRINSIC__INT.html

2023-05-21  Roger Sayle  <roger@nextmovesoftware.com>

gcc/ChangeLog
	* config/nvptx/nvptx.cc (nvptx_expand_brev): Expand target
	builtin for bit reversal using brev instruction.
	(enum nvptx_builtins): Add NVPTX_BUILTIN_BREV and
	NVPTX_BUILTIN_BREVLL.
	(nvptx_init_builtins): Define "brev" and "brevll".
	(nvptx_expand_builtin): Expand NVPTX_BUILTIN_BREV and
	NVPTX_BUILTIN_BREVLL via nvptx_expand_brev function.
	* doc/extend.texi (Nvidia PTX Builtin-in Functions): New
	section, document __builtin_nvptx_brev{,ll}.

gcc/testsuite/ChangeLog
	* gcc.target/nvptx/brev-1.c: New 32-bit test case.
	* gcc.target/nvptx/brev-2.c: Likewise.
	* gcc.target/nvptx/brevll-1.c: New 64-bit test case.
	* gcc.target/nvptx/brevll-2.c: Likewise.

6 files changed, 311 insertions, 0 deletions

diff --git a/gcc/config/nvptx/nvptx.cc b/gcc/config/nvptx/nvptx.cc
index d76c0bb..e3b0304 100644
--- a/gcc/config/nvptx/nvptx.cc
+++ b/gcc/config/nvptx/nvptx.cc
@@ -6047,6 +6047,29 @@ nvptx_expand_shuffle (tree exp, rtx target, machine_mode mode, int ignore)
   return target;
 }
 
+/* Expander for the bit reverse builtins.  */
+
+static rtx
+nvptx_expand_brev (tree exp, rtx target, machine_mode mode, int ignore)
+{
+  if (ignore)
+    return target;
+  
+  rtx arg = expand_expr (CALL_EXPR_ARG (exp, 0),
+			 NULL_RTX, mode, EXPAND_NORMAL);
+  if (!REG_P (arg))
+    arg = copy_to_mode_reg (mode, arg);
+  if (!target)
+    target = gen_reg_rtx (mode);
+  rtx pat;
+  if (mode == SImode)
+    pat = gen_bitrevsi2 (target, arg);
+  else
+    pat = gen_bitrevdi2 (target, arg);
+  emit_insn (pat);
+  return target;
+}
+
 const char *
 nvptx_output_red_partition (rtx dst, rtx offset)
 {
@@ -6164,6 +6187,8 @@ enum nvptx_builtins
   NVPTX_BUILTIN_BAR_RED_AND,
   NVPTX_BUILTIN_BAR_RED_OR,
   NVPTX_BUILTIN_BAR_RED_POPC,
+  NVPTX_BUILTIN_BREV,
+  NVPTX_BUILTIN_BREVLL,
   NVPTX_BUILTIN_MAX
 };
 
@@ -6292,6 +6317,9 @@ nvptx_init_builtins (void)
   DEF (BAR_RED_POPC, "bar_red_popc",
        (UINT, UINT, UINT, UINT, UINT, NULL_TREE));
 
+  DEF (BREV, "brev", (UINT, UINT, NULL_TREE));
+  DEF (BREVLL, "brevll", (LLUINT, LLUINT, NULL_TREE));
+
 #undef DEF
 #undef ST
 #undef UINT
@@ -6339,6 +6367,10 @@ nvptx_expand_builtin (tree exp, rtx target, rtx ARG_UNUSED (subtarget),
     case NVPTX_BUILTIN_BAR_RED_POPC:
       return nvptx_expand_bar_red (exp, target, mode, ignore);
 
+    case NVPTX_BUILTIN_BREV:
+    case NVPTX_BUILTIN_BREVLL:
+      return nvptx_expand_brev (exp, target, mode, ignore);
+
     default: gcc_unreachable ();
     }
 }
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index ed8b9c8..f9d13b4 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -14685,6 +14685,7 @@ instructions, but allow the compiler to schedule those calls.
 * Other MIPS Built-in Functions::
 * MSP430 Built-in Functions::
 * NDS32 Built-in Functions::
+* Nvidia PTX Built-in Functions::
 * Basic PowerPC Built-in Functions::
 * PowerPC AltiVec/VSX Built-in Functions::
 * PowerPC Hardware Transactional Memory Built-in Functions::
@@ -17944,6 +17945,20 @@ Enable global interrupt.
 Disable global interrupt.
 @enddefbuiltin
 
+@node Nvidia PTX Built-in Functions
+@subsection Nvidia PTX Built-in Functions
+
+These built-in functions are available for the Nvidia PTX target:
+
+@defbuiltin{unsigned int __builtin_nvptx_brev (unsigned int @var{x})}
+Reverse the bit order of a 32-bit unsigned integer.
+Disable global interrupt.
+@enddefbuiltin
+
+@defbuiltin{unsigned long long __builtin_nvptx_brevll (unsigned long long @var{x})}
+Reverse the bit order of a 64-bit unsigned integer.
+@enddefbuiltin
+
 @node Basic PowerPC Built-in Functions
 @subsection Basic PowerPC Built-in Functions
 
diff --git a/gcc/testsuite/gcc.target/nvptx/brev-1.c b/gcc/testsuite/gcc.target/nvptx/brev-1.c
new file mode 100644
index 0000000..fbb4fff
--- /dev/null
+++ b/gcc/testsuite/gcc.target/nvptx/brev-1.c
@@ -0,0 +1,8 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+unsigned int foo(unsigned int x)
+{
+  return __builtin_nvptx_brev(x);
+}
+
+/* { dg-final { scan-assembler "brev.b32" } } */
diff --git a/gcc/testsuite/gcc.target/nvptx/brev-2.c b/gcc/testsuite/gcc.target/nvptx/brev-2.c
new file mode 100644
index 0000000..9d0defe
--- /dev/null
+++ b/gcc/testsuite/gcc.target/nvptx/brev-2.c
@@ -0,0 +1,94 @@
+/* { dg-do run } */
+/* { dg-options "-O2" } */
+unsigned int bitreverse32(unsigned int x)
+{
+  return __builtin_nvptx_brev(x);
+}
+
+int main(void)
+{
+  if (bitreverse32(0x00000000) != 0x00000000)
+    __builtin_abort();
+  if (bitreverse32(0xffffffff) != 0xffffffff)
+    __builtin_abort();
+
+  if (bitreverse32(0x00000001) != 0x80000000)
+    __builtin_abort();
+  if (bitreverse32(0x00000002) != 0x40000000)
+    __builtin_abort();
+  if (bitreverse32(0x00000004) != 0x20000000)
+    __builtin_abort();
+  if (bitreverse32(0x00000008) != 0x10000000)
+    __builtin_abort();
+  if (bitreverse32(0x00000010) != 0x08000000)
+    __builtin_abort();
+  if (bitreverse32(0x00000020) != 0x04000000)
+    __builtin_abort();
+  if (bitreverse32(0x00000040) != 0x02000000)
+    __builtin_abort();
+  if (bitreverse32(0x00000080) != 0x01000000)
+    __builtin_abort();
+  if (bitreverse32(0x00000100) != 0x00800000)
+    __builtin_abort();
+  if (bitreverse32(0x00000200) != 0x00400000)
+    __builtin_abort();
+  if (bitreverse32(0x00000400) != 0x00200000)
+    __builtin_abort();
+  if (bitreverse32(0x00000800) != 0x00100000)
+    __builtin_abort();
+  if (bitreverse32(0x00001000) != 0x00080000)
+    __builtin_abort();
+  if (bitreverse32(0x00002000) != 0x00040000)
+    __builtin_abort();
+  if (bitreverse32(0x00004000) != 0x00020000)
+    __builtin_abort();
+  if (bitreverse32(0x00008000) != 0x00010000)
+    __builtin_abort();
+  if (bitreverse32(0x00010000) != 0x00008000)
+    __builtin_abort();
+  if (bitreverse32(0x00020000) != 0x00004000)
+    __builtin_abort();
+  if (bitreverse32(0x00040000) != 0x00002000)
+    __builtin_abort();
+  if (bitreverse32(0x00080000) != 0x00001000)
+    __builtin_abort();
+  if (bitreverse32(0x00100000) != 0x00000800)
+    __builtin_abort();
+  if (bitreverse32(0x00200000) != 0x00000400)
+    __builtin_abort();
+  if (bitreverse32(0x00400000) != 0x00000200)
+    __builtin_abort();
+  if (bitreverse32(0x00800000) != 0x00000100)
+    __builtin_abort();
+  if (bitreverse32(0x01000000) != 0x00000080)
+    __builtin_abort();
+  if (bitreverse32(0x02000000) != 0x00000040)
+    __builtin_abort();
+  if (bitreverse32(0x04000000) != 0x00000020)
+    __builtin_abort();
+  if (bitreverse32(0x08000000) != 0x00000010)
+    __builtin_abort();
+  if (bitreverse32(0x10000000) != 0x00000008)
+    __builtin_abort();
+  if (bitreverse32(0x20000000) != 0x00000004)
+    __builtin_abort();
+  if (bitreverse32(0x40000000) != 0x00000002)
+    __builtin_abort();
+  if (bitreverse32(0x80000000) != 0x00000001)
+    __builtin_abort();
+
+  if (bitreverse32(0x01234567) != 0xe6a2c480)
+    __builtin_abort();
+  if (bitreverse32(0xe6a2c480) != 0x01234567)
+    __builtin_abort();
+  if (bitreverse32(0xdeadbeef) != 0xf77db57b)
+    __builtin_abort();
+  if (bitreverse32(0xf77db57b) != 0xdeadbeef)
+    __builtin_abort();
+  if (bitreverse32(0xcafebabe) != 0x7d5d7f53)
+    __builtin_abort();
+  if (bitreverse32(0x7d5d7f53) != 0xcafebabe)
+    __builtin_abort();
+  return 0;
+}
+
diff --git a/gcc/testsuite/gcc.target/nvptx/brevll-1.c b/gcc/testsuite/gcc.target/nvptx/brevll-1.c
new file mode 100644
index 0000000..7009d5f
--- /dev/null
+++ b/gcc/testsuite/gcc.target/nvptx/brevll-1.c
@@ -0,0 +1,8 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+unsigned long foo(unsigned long x)
+{
+  return __builtin_nvptx_brevll(x);
+}
+
+/* { dg-final { scan-assembler "brev.b64" } } */
diff --git a/gcc/testsuite/gcc.target/nvptx/brevll-2.c b/gcc/testsuite/gcc.target/nvptx/brevll-2.c
new file mode 100644
index 0000000..56054b1
--- /dev/null
+++ b/gcc/testsuite/gcc.target/nvptx/brevll-2.c
@@ -0,0 +1,154 @@
+/* { dg-do run } */
+/* { dg-options "-O2" } */
+unsigned long long bitreverse64(unsigned long long x)
+{
+  return __builtin_nvptx_brevll(x);
+}
+
+int main(void)
+{
+  if (bitreverse64(0x0000000000000000ll) != 0x0000000000000000ll)
+    __builtin_abort();
+  if (bitreverse64(0xffffffffffffffffll) != 0xffffffffffffffffll)
+    __builtin_abort();
+
+  if (bitreverse64(0x0000000000000001ll) != 0x8000000000000000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000000000000002ll) != 0x4000000000000000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000000000000004ll) != 0x2000000000000000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000000000000008ll) != 0x1000000000000000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000000000000010ll) != 0x0800000000000000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000000000000020ll) != 0x0400000000000000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000000000000040ll) != 0x0200000000000000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000000000000080ll) != 0x0100000000000000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000000000000100ll) != 0x0080000000000000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000000000000200ll) != 0x0040000000000000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000000000000400ll) != 0x0020000000000000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000000000000800ll) != 0x0010000000000000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000000000001000ll) != 0x0008000000000000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000000000002000ll) != 0x0004000000000000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000000000004000ll) != 0x0002000000000000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000000000008000ll) != 0x0001000000000000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000000000010000ll) != 0x0000800000000000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000000000020000ll) != 0x0000400000000000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000000000040000ll) != 0x0000200000000000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000000000080000ll) != 0x0000100000000000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000000000100000ll) != 0x0000080000000000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000000000200000ll) != 0x0000040000000000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000000000400000ll) != 0x0000020000000000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000000000800000ll) != 0x0000010000000000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000000001000000ll) != 0x0000008000000000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000000002000000ll) != 0x0000004000000000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000000004000000ll) != 0x0000002000000000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000000008000000ll) != 0x0000001000000000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000000010000000ll) != 0x0000000800000000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000000020000000ll) != 0x0000000400000000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000000040000000ll) != 0x0000000200000000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000000080000000ll) != 0x0000000100000000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000000100000000ll) != 0x0000000080000000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000000200000000ll) != 0x0000000040000000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000000400000000ll) != 0x0000000020000000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000000800000000ll) != 0x0000000010000000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000001000000000ll) != 0x0000000008000000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000002000000000ll) != 0x0000000004000000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000004000000000ll) != 0x0000000002000000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000008000000000ll) != 0x0000000001000000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000010000000000ll) != 0x0000000000800000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000020000000000ll) != 0x0000000000400000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000040000000000ll) != 0x0000000000200000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000080000000000ll) != 0x0000000000100000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000100000000000ll) != 0x0000000000080000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000200000000000ll) != 0x0000000000040000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000400000000000ll) != 0x0000000000020000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0000800000000000ll) != 0x0000000000010000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0001000000000000ll) != 0x0000000000008000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0002000000000000ll) != 0x0000000000004000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0004000000000000ll) != 0x0000000000002000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0008000000000000ll) != 0x0000000000001000ll)
+    __builtin_abort();
+  if (bitreverse64(0x0010000000000000ll) != 0x0000000000000800ll)
+    __builtin_abort();
+  if (bitreverse64(0x0020000000000000ll) != 0x0000000000000400ll)
+    __builtin_abort();
+  if (bitreverse64(0x0040000000000000ll) != 0x0000000000000200ll)
+    __builtin_abort();
+  if (bitreverse64(0x0080000000000000ll) != 0x0000000000000100ll)
+    __builtin_abort();
+  if (bitreverse64(0x0100000000000000ll) != 0x0000000000000080ll)
+    __builtin_abort();
+  if (bitreverse64(0x0200000000000000ll) != 0x0000000000000040ll)
+    __builtin_abort();
+  if (bitreverse64(0x0400000000000000ll) != 0x0000000000000020ll)
+    __builtin_abort();
+  if (bitreverse64(0x0800000000000000ll) != 0x0000000000000010ll)
+    __builtin_abort();
+  if (bitreverse64(0x1000000000000000ll) != 0x0000000000000008ll)
+    __builtin_abort();
+  if (bitreverse64(0x2000000000000000ll) != 0x0000000000000004ll)
+    __builtin_abort();
+  if (bitreverse64(0x4000000000000000ll) != 0x0000000000000002ll)
+    __builtin_abort();
+  if (bitreverse64(0x8000000000000000ll) != 0x0000000000000001ll)
+    __builtin_abort();
+
+  if (bitreverse64(0x0123456789abcdefll) != 0xf7b3d591e6a2c480ll)
+    __builtin_abort();
+  if (bitreverse64(0xf7b3d591e6a2c480ll) != 0x0123456789abcdefll)
+    __builtin_abort();
+  if (bitreverse64(0xdeadbeefcafebabell) != 0x7d5d7f53f77db57bll)
+    __builtin_abort();
+  if (bitreverse64(0x7d5d7f53f77db57bll) != 0xdeadbeefcafebabell)
+    __builtin_abort();
+  return 0;
+}
+