[PATCH 3/4] rs6000: build constant via li/lis;rldicl/rldicr

[Jiufu Guo <guojiufu@linux.ibm.com>]

Hi,

This patch checks if a constant is possible left/right cleaned on a rotated
value from a negative value of "li/lis".  If so, we can build the constant
through "li/lis ; rldicl/rldicr".

Bootstrap and regtest pass on ppc64{,le}.
Is this ok for trunk?

BR,
Jeff (Jiufu)

gcc/ChangeLog:

	* config/rs6000/rs6000.cc (can_be_built_by_li_lis_and_rldicl): New
	function.
	(can_be_built_by_li_lis_and_rldicr): New function.
	(rs6000_emit_set_long_const): Call can_be_built_by_li_lis_and_rldicr and
	can_be_built_by_li_lis_and_rldicl.

gcc/testsuite/ChangeLog:

	* gcc.target/powerpc/const-build.c: Add more tests.
---
 gcc/config/rs6000/rs6000.cc                   | 61 ++++++++++++++++++-
 .../gcc.target/powerpc/const-build.c          | 44 +++++++++++++
 2 files changed, 104 insertions(+), 1 deletion(-)

diff --git a/gcc/config/rs6000/rs6000.cc b/gcc/config/rs6000/rs6000.cc
index 03cd9d5e952..2a3fa733b45 100644
--- a/gcc/config/rs6000/rs6000.cc
+++ b/gcc/config/rs6000/rs6000.cc
@@ -10332,6 +10332,61 @@ can_be_built_by_li_lis_and_rotldi (HOST_WIDE_INT c, int *shift,
   return false;
 }
 
+/* Check if value C can be built by 2 instructions: one is 'li or lis',
+   another is rldicl.
+
+   If so, *SHIFT is set to the shift operand of rldicl, and *MASK is set to
+   the mask operand of rldicl, and return true.
+   Return false otherwise.  */
+
+static bool
+can_be_built_by_li_lis_and_rldicl (HOST_WIDE_INT c, int *shift,
+				   HOST_WIDE_INT *mask)
+{
+  /* Leading zeros may be cleaned by rldicl with a mask.  Change leading zeros
+     to ones and then recheck it.  */
+  int lz = clz_hwi (c);
+  HOST_WIDE_INT unmask_c
+    = c | (HOST_WIDE_INT_M1U << (HOST_BITS_PER_WIDE_INT - lz));
+  int n;
+  if (can_be_rotated_to_negative_li (unmask_c, &n)
+      || can_be_rotated_to_negative_lis (unmask_c, &n))
+    {
+      *mask = HOST_WIDE_INT_M1U >> lz;
+      *shift = n == 0 ? 0 : HOST_BITS_PER_WIDE_INT - n;
+      return true;
+    }
+
+  return false;
+}
+
+/* Check if value C can be built by 2 instructions: one is 'li or lis',
+   another is rldicr.
+
+   If so, *SHIFT is set to the shift operand of rldicr, and *MASK is set to
+   the mask operand of rldicr, and return true.
+   Return false otherwise.  */
+
+static bool
+can_be_built_by_li_lis_and_rldicr (HOST_WIDE_INT c, int *shift,
+				   HOST_WIDE_INT *mask)
+{
+  /* Tailing zeros may be cleaned by rldicr with a mask.  Change tailing zeros
+     to ones and then recheck it.  */
+  int tz = ctz_hwi (c);
+  HOST_WIDE_INT unmask_c = c | ((HOST_WIDE_INT_1U << tz) - 1);
+  int n;
+  if (can_be_rotated_to_negative_li (unmask_c, &n)
+      || can_be_rotated_to_negative_lis (unmask_c, &n))
+    {
+      *mask = HOST_WIDE_INT_M1U << tz;
+      *shift = HOST_BITS_PER_WIDE_INT - n;
+      return true;
+    }
+
+  return false;
+}
+
 /* Subroutine of rs6000_emit_set_const, handling PowerPC64 DImode.
    Output insns to set DEST equal to the constant C as a series of
    lis, ori and shl instructions.  */
@@ -10378,7 +10433,9 @@ rs6000_emit_set_long_const (rtx dest, HOST_WIDE_INT c)
       emit_move_insn (dest, gen_rtx_XOR (DImode, temp,
 					 GEN_INT ((ud2 ^ 0xffff) << 16)));
     }
-  else if (can_be_built_by_li_lis_and_rotldi (c, &shift, &mask))
+  else if (can_be_built_by_li_lis_and_rotldi (c, &shift, &mask)
+	   || can_be_built_by_li_lis_and_rldicl (c, &shift, &mask)
+	   || can_be_built_by_li_lis_and_rldicr (c, &shift, &mask))
     {
       temp = !can_create_pseudo_p () ? dest : gen_reg_rtx (DImode);
       unsigned HOST_WIDE_INT imm = (c | ~mask);
@@ -10387,6 +10444,8 @@ rs6000_emit_set_long_const (rtx dest, HOST_WIDE_INT c)
       emit_move_insn (temp, GEN_INT (imm));
       if (shift != 0)
 	temp = gen_rtx_ROTATE (DImode, temp, GEN_INT (shift));
+      if (mask != HOST_WIDE_INT_M1)
+	temp = gen_rtx_AND (DImode, temp, GEN_INT (mask));
       emit_move_insn (dest, temp);
     }
   else if (ud3 == 0 && ud4 == 0)
diff --git a/gcc/testsuite/gcc.target/powerpc/const-build.c b/gcc/testsuite/gcc.target/powerpc/const-build.c
index c38a1dd91f2..8c209921d41 100644
--- a/gcc/testsuite/gcc.target/powerpc/const-build.c
+++ b/gcc/testsuite/gcc.target/powerpc/const-build.c
@@ -46,6 +46,42 @@ lis_rotldi_6 (void)
   return 0x5310000ffffffff8LL;
 }
 
+long long NOIPA
+li_rldicl_7 (void)
+{
+  return 0x3ffffffa1LL;
+}
+
+long long NOIPA
+li_rldicl_8 (void)
+{
+  return 0xff8531ffffffffLL;
+}
+
+long long NOIPA
+lis_rldicl_9 (void)
+{
+  return 0x00ff85310000ffffLL;
+}
+
+long long NOIPA
+li_rldicr_10 (void)
+{
+  return 0xffff8531fff00000LL;
+}
+
+long long NOIPA
+li_rldicr_11 (void)
+{
+  return 0x21fffffffff00000LL;
+}
+
+long long NOIPA
+lis_rldicr_12 (void)
+{
+  return 0x5310000ffffffff0LL;
+}
+
 struct fun arr[] = {
   {li_rotldi_1, 0x7531000000000LL},
   {li_rotldi_2, 0x2100000000000064LL},
@@ -53,9 +89,17 @@ struct fun arr[] = {
   {li_rotldi_4, 0x21ffffffffffff94LL},
   {lis_rotldi_5, 0xffff85310000ffffLL},
   {lis_rotldi_6, 0x5310000ffffffff8LL},
+  {li_rldicl_7, 0x3ffffffa1LL},
+  {li_rldicl_8, 0xff8531ffffffffLL},
+  {lis_rldicl_9, 0x00ff85310000ffffLL},
+  {li_rldicr_10, 0xffff8531fff00000LL},
+  {li_rldicr_11, 0x21fffffffff00000LL},
+  {lis_rldicr_12, 0x5310000ffffffff0LL},
 };
 
 /* { dg-final { scan-assembler-times {\mrotldi\M} 6 } } */
+/* { dg-final { scan-assembler-times {\mrldicl\M} 3 } } */
+/* { dg-final { scan-assembler-times {\mrldicr\M} 3 } } */
 
 int
 main ()
-- 
2.39.1