expmed.h (canonicalize_comparison): New declaration.

	* expmed.h (canonicalize_comparison): New declaration.
	* expmed.c (canonicalize_comparison, equivalent_cmp_code): New function.
	* expmed.c (emit_store_flag_1): Add call to canonicalize_comparison.
	* optabs.c (prepare_cmp_insn): Likewise.
	* rtl.h (unsigned_condition_p): New function which checks if a
	comparison operator is unsigned.

	* gcc.target/aarch64/imm_choice_comparison.c: New test.

From-SVN: r263591

1 files changed, 93 insertions, 0 deletions

diff --git a/gcc/expmed.c b/gcc/expmed.c
index 101e7b8..be9f0ec 100644
--- a/gcc/expmed.c
+++ b/gcc/expmed.c
@@ -5541,6 +5541,9 @@ emit_store_flag_1 (rtx target, enum rtx_code code, rtx op0, rtx op1,
   if (mode == VOIDmode)
     mode = GET_MODE (op0);
 
+  if (CONST_SCALAR_INT_P (op1))
+    canonicalize_comparison (mode, &code, &op1);
+
   /* For some comparisons with 1 and -1, we can convert this to
      comparisons with zero.  This will often produce more opportunities for
      store-flag insns.  */
@@ -6161,6 +6164,96 @@ emit_store_flag_force (rtx target, enum rtx_code code, rtx op0, rtx op1,
 
   return target;
 }
+
+/* Helper function for canonicalize_cmp_for_target.  Swap between inclusive
+   and exclusive ranges in order to create an equivalent comparison.  See
+   canonicalize_cmp_for_target for the possible cases.  */
+
+static enum rtx_code
+equivalent_cmp_code (enum rtx_code code)
+{
+  switch (code)
+    {
+    case GT:
+      return GE;
+    case GE:
+      return GT;
+    case LT:
+      return LE;
+    case LE:
+      return LT;
+    case GTU:
+      return GEU;
+    case GEU:
+      return GTU;
+    case LTU:
+      return LEU;
+    case LEU:
+      return LTU;
+
+    default:
+      return code;
+    }
+}
+
+/* Choose the more appropiate immediate in scalar integer comparisons.  The
+   purpose of this is to end up with an immediate which can be loaded into a
+   register in fewer moves, if possible.
+
+   For each integer comparison there exists an equivalent choice:
+     i)   a >  b or a >= b + 1
+     ii)  a <= b or a <  b + 1
+     iii) a >= b or a >  b - 1
+     iv)  a <  b or a <= b - 1
+
+   MODE is the mode of the first operand.
+   CODE points to the comparison code.
+   IMM points to the rtx containing the immediate.  *IMM must satisfy
+   CONST_SCALAR_INT_P on entry and continues to satisfy CONST_SCALAR_INT_P
+   on exit.  */
+
+void
+canonicalize_comparison (machine_mode mode, enum rtx_code *code, rtx *imm)
+{
+  if (!SCALAR_INT_MODE_P (mode))
+    return;
+
+  int to_add = 0;
+  enum signop sgn = unsigned_condition_p (*code) ? UNSIGNED : SIGNED;
+
+  /* Extract the immediate value from the rtx.  */
+  wide_int imm_val = rtx_mode_t (*imm, mode);
+
+  if (*code == GT || *code == GTU || *code == LE || *code == LEU)
+    to_add = 1;
+  else if (*code == GE || *code == GEU || *code == LT || *code == LTU)
+    to_add = -1;
+  else
+    return;
+
+  /* Check for overflow/underflow in the case of signed values and
+     wrapping around in the case of unsigned values.  If any occur
+     cancel the optimization.  */
+  wi::overflow_type overflow = wi::OVF_NONE;
+  wide_int imm_modif = wi::add (imm_val, to_add, sgn, &overflow);
+  if (overflow)
+    return;
+
+  rtx reg = gen_rtx_REG (mode, LAST_VIRTUAL_REGISTER + 1);
+  rtx new_imm = immed_wide_int_const (imm_modif, mode);
+
+  rtx_insn *old_rtx = gen_move_insn (reg, *imm);
+  rtx_insn *new_rtx = gen_move_insn (reg, new_imm);
+
+  /* Update the immediate and the code.  */
+  if (insn_cost (old_rtx, true) > insn_cost (new_rtx, true))
+    {
+      *code = equivalent_cmp_code (*code);
+      *imm = new_imm;
+    }
+}
+
+
 
 /* Perform possibly multi-word comparison and conditional jump to LABEL
    if ARG1 OP ARG2 true where ARG1 and ARG2 are of mode MODE.  This is