RISC-V: Use li and rori to load constants.

gcc/ChangeLog:

	* config/riscv/riscv.c (riscv_build_integer_1): Build integer
	with rotate.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/zbb-li-rotr.c: New.

diff --git a/gcc/config/riscv/riscv.c b/gcc/config/riscv/riscv.c
index cb93e3fb88a4ab1ee763a94811b7b8be9f4c31e6..3ed34f234e555f4f9bba8dfcf8e6b8f6f53558bf 100644 (file)
--- a/gcc/config/riscv/riscv.c
+++ b/gcc/config/riscv/riscv.c
@@ -462,6 +462,47 @@ riscv_build_integer_1 (struct riscv_integer_op codes[RISCV_MAX_INTEGER_OPS],
        }
     }
 
+  if (cost > 2 && TARGET_64BIT && TARGET_ZBB)
+    {
+      int leading_ones = clz_hwi (~value);
+      int trailing_ones = ctz_hwi (~value);
+
+      /* If all bits are one except a few that are zero, and the zero bits
+        are within a range of 11 bits, and at least one of the upper 32-bits
+        is a zero, then we can generate a constant by loading a small
+        negative constant and rotating.  */
+      if (leading_ones < 32
+         && ((64 - leading_ones - trailing_ones) < 12))
+       {
+         codes[0].code = UNKNOWN;
+         /* The sign-bit might be zero, so just rotate to be safe.  */
+         codes[0].value = (((unsigned HOST_WIDE_INT) value >> trailing_ones)
+                           | (value << (64 - trailing_ones)));
+         codes[1].code = ROTATERT;
+         codes[1].value = 64 - trailing_ones;
+         cost = 2;
+       }
+      /* Handle the case where the 11 bit range of zero bits wraps around.  */
+      else
+       {
+         int upper_trailing_ones = ctz_hwi (~value >> 32);
+         int lower_leading_ones = clz_hwi (~value << 32);
+
+         if (upper_trailing_ones < 32 && lower_leading_ones < 32
+             && ((64 - upper_trailing_ones - lower_leading_ones) < 12))
+           {
+             codes[0].code = UNKNOWN;
+             /* The sign-bit might be zero, so just rotate to be safe.  */
+             codes[0].value = ((value << (32 - upper_trailing_ones))
+                               | ((unsigned HOST_WIDE_INT) value
+                                  >> (32 + upper_trailing_ones)));
+             codes[1].code = ROTATERT;
+             codes[1].value = 32 - upper_trailing_ones;
+             cost = 2;
+           }
+       }
+    }
+
   gcc_assert (cost <= RISCV_MAX_INTEGER_OPS);
   return cost;
 }

diff --git a/gcc/testsuite/gcc.target/riscv/zbb-li-rotr.c b/gcc/testsuite/gcc.target/riscv/zbb-li-rotr.c
new file mode 100644 (file)
index 0000000..03254ed
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/zbb-li-rotr.c
@@ -0,0 +1,35 @@
+/* { dg-do compile } */
+/* { dg-options "-march=rv64gc_zbb -mabi=lp64 -O2" } */
+
+long
+li_rori (void)
+{
+  return 0xffff77ffffffffffL;
+}
+
+long
+li_rori_2 (void)
+{
+  return 0x77ffffffffffffffL;
+}
+
+long
+li_rori_3 (void)
+{
+  return 0xfffffffeefffffffL;
+}
+
+long
+li_rori_4 (void)
+{
+  return 0x5ffffffffffffff5L;
+}
+
+long
+li_rori_5 (void)
+{
+  return 0xaffffffffffffffaL;
+}
+
+
+/* { dg-final { scan-assembler-times "rori\t" 5 } } */