aarch64/expr: Use ccmp when the outer expression is used twice [PR100942]

Ccmp is not used if the result of the and/ior is used by both
a GIMPLE_COND and a GIMPLE_ASSIGN. This improves the code generation
here by using ccmp in this case.
Two changes is required, first we need to allow the outer statement's
result be used more than once.
The second change is that during the expansion of the gimple, we need
to try using ccmp. This is needed because we don't use expand the ssa
name of the lhs but rather expand directly from the gimple.

A small note on the ccmp_4.c testcase, we should be able to get slightly
better than with this patch but it is one extra instruction compared to
before.

	PR target/100942

gcc/ChangeLog:

	* ccmp.cc (ccmp_candidate_p): Add outer argument.
	Allow if the outer is true and the lhs is used more
	than once.
	(expand_ccmp_expr): Update call to ccmp_candidate_p.
	* expr.h (expand_expr_real_gassign): Declare.
	* expr.cc (expand_expr_real_gassign): New function, split out from...
	(expand_expr_real_1): ...here.
	* cfgexpand.cc (expand_gimple_stmt_1): Use expand_expr_real_gassign.

gcc/testsuite/ChangeLog:

	* gcc.target/aarch64/ccmp_3.c: New test.
	* gcc.target/aarch64/ccmp_4.c: New test.
	* gcc.target/aarch64/ccmp_5.c: New test.

Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>
Co-Authored-By: Richard Sandiford <richard.sandiford@arm.com>

diff --git a/gcc/ccmp.cc b/gcc/ccmp.cc
index 09d6b5595a41918cf5c5d1f44d15dcb08f886c31..7cb525addf422c1dcd1f6bee412ad8178f2f2b77 100644 (file)
--- a/gcc/ccmp.cc
+++ b/gcc/ccmp.cc
@@ -90,9 +90,10 @@ ccmp_tree_comparison_p (tree t, basic_block bb)
    If all checks OK in expand_ccmp_expr, it emits insns in prep_seq, then
    insns in gen_seq.  */
 
-/* Check whether G is a potential conditional compare candidate.  */
+/* Check whether G is a potential conditional compare candidate; OUTER is true if
+   G is the outer most AND/IOR.  */
 static bool
-ccmp_candidate_p (gimple *g)
+ccmp_candidate_p (gimple *g, bool outer = false)
 {
   tree lhs, op0, op1;
   gimple *gs0, *gs1;
@@ -109,8 +110,9 @@ ccmp_candidate_p (gimple *g)
   lhs = gimple_assign_lhs (g);
   op0 = gimple_assign_rhs1 (g);
   op1 = gimple_assign_rhs2 (g);
-  if ((TREE_CODE (op0) != SSA_NAME) || (TREE_CODE (op1) != SSA_NAME)
-      || !has_single_use (lhs))
+  if ((TREE_CODE (op0) != SSA_NAME) || (TREE_CODE (op1) != SSA_NAME))
+    return false;
+  if (!outer && !has_single_use (lhs))
     return false;
 
   bb = gimple_bb (g);
@@ -284,7 +286,7 @@ expand_ccmp_expr (gimple *g, machine_mode mode)
   rtx_insn *last;
   rtx tmp;
 
-  if (!ccmp_candidate_p (g))
+  if (!ccmp_candidate_p (g, true))
     return NULL_RTX;
 
   last = get_last_insn ();

diff --git a/gcc/cfgexpand.cc b/gcc/cfgexpand.cc
index 767982a63a9ae7d58b53a2d753ed39c7008acaf4..316b8830ec006477d500000a7ae1d6dcfdf7665e 100644 (file)
--- a/gcc/cfgexpand.cc
+++ b/gcc/cfgexpand.cc
@@ -3997,37 +3997,18 @@ expand_gimple_stmt_1 (gimple *stmt)
          {
            rtx target, temp;
            bool nontemporal = gimple_assign_nontemporal_move_p (assign_stmt);
-           struct separate_ops ops;
            bool promoted = false;
 
            target = expand_expr (lhs, NULL_RTX, VOIDmode, EXPAND_WRITE);
            if (GET_CODE (target) == SUBREG && SUBREG_PROMOTED_VAR_P (target))
              promoted = true;
 
-           ops.code = gimple_assign_rhs_code (assign_stmt);
-           ops.type = TREE_TYPE (lhs);
-           switch (get_gimple_rhs_class (ops.code))
-             {
-               case GIMPLE_TERNARY_RHS:
-                 ops.op2 = gimple_assign_rhs3 (assign_stmt);
-                 /* Fallthru */
-               case GIMPLE_BINARY_RHS:
-                 ops.op1 = gimple_assign_rhs2 (assign_stmt);
-                 /* Fallthru */
-               case GIMPLE_UNARY_RHS:
-                 ops.op0 = gimple_assign_rhs1 (assign_stmt);
-                 break;
-               default:
-                 gcc_unreachable ();
-             }
-           ops.location = gimple_location (stmt);
-
-           /* If we want to use a nontemporal store, force the value to
-              register first.  If we store into a promoted register,
-              don't directly expand to target.  */
+          /* If we want to use a nontemporal store, force the value to
+             register first.  If we store into a promoted register,
+             don't directly expand to target.  */
            temp = nontemporal || promoted ? NULL_RTX : target;
-           temp = expand_expr_real_2 (&ops, temp, GET_MODE (target),
-                                      EXPAND_NORMAL);
+           temp = expand_expr_real_gassign (assign_stmt, temp,
+                                            GET_MODE (target), EXPAND_NORMAL);
 
            if (temp == target)
              ;
@@ -4039,7 +4020,7 @@ expand_gimple_stmt_1 (gimple *stmt)
                if (CONSTANT_P (temp) && GET_MODE (temp) == VOIDmode)
                  {
                    temp = convert_modes (GET_MODE (target),
-                                         TYPE_MODE (ops.type),
+                                         TYPE_MODE (TREE_TYPE (lhs)),
                                          temp, unsignedp);
                    temp = convert_modes (GET_MODE (SUBREG_REG (target)),
                                          GET_MODE (target), temp, unsignedp);

diff --git a/gcc/expr.cc b/gcc/expr.cc
index 502518d69c527e46e039cea0ee392477e88be09d..ee822c11dce632bd7901a3ad9f045c4ba108859d 100644 (file)
--- a/gcc/expr.cc
+++ b/gcc/expr.cc
@@ -11038,6 +11038,62 @@ stmt_is_replaceable_p (gimple *stmt)
   return false;
 }
 
+/* A subroutine of expand_expr_real_1.  Expand gimple assignment G,
+   which is known to set an SSA_NAME result.  The other arguments are
+   as for expand_expr_real_1.  */
+
+rtx
+expand_expr_real_gassign (gassign *g, rtx target, machine_mode tmode,
+                         enum expand_modifier modifier, rtx *alt_rtl,
+                         bool inner_reference_p)
+{
+  separate_ops ops;
+  rtx r;
+  location_t saved_loc = curr_insn_location ();
+  auto loc = gimple_location (g);
+  if (loc != UNKNOWN_LOCATION)
+    set_curr_insn_location (loc);
+  tree lhs = gimple_assign_lhs (g);
+  ops.code = gimple_assign_rhs_code (g);
+  ops.type = TREE_TYPE (lhs);
+  switch (get_gimple_rhs_class (ops.code))
+    {
+    case GIMPLE_TERNARY_RHS:
+      ops.op2 = gimple_assign_rhs3 (g);
+      /* Fallthru */
+    case GIMPLE_BINARY_RHS:
+      ops.op1 = gimple_assign_rhs2 (g);
+
+      /* Try to expand conditonal compare.  */
+      if (targetm.gen_ccmp_first)
+       {
+         gcc_checking_assert (targetm.gen_ccmp_next != NULL);
+         r = expand_ccmp_expr (g, TYPE_MODE (ops.type));
+         if (r)
+           break;
+       }
+      /* Fallthru */
+    case GIMPLE_UNARY_RHS:
+      ops.op0 = gimple_assign_rhs1 (g);
+      ops.location = loc;
+      r = expand_expr_real_2 (&ops, target, tmode, modifier);
+      break;
+    case GIMPLE_SINGLE_RHS:
+      {
+       r = expand_expr_real (gimple_assign_rhs1 (g), target,
+                             tmode, modifier, alt_rtl,
+                             inner_reference_p);
+       break;
+      }
+    default:
+      gcc_unreachable ();
+    }
+  set_curr_insn_location (saved_loc);
+  if (REG_P (r) && !REG_EXPR (r))
+    set_reg_attrs_for_decl_rtl (lhs, r);
+  return r;
+}
+
 rtx
 expand_expr_real_1 (tree exp, rtx target, machine_mode tmode,
                    enum expand_modifier modifier, rtx *alt_rtl,
@@ -11201,51 +11257,8 @@ expand_expr_real_1 (tree exp, rtx target, machine_mode tmode,
          && stmt_is_replaceable_p (SSA_NAME_DEF_STMT (exp)))
        g = SSA_NAME_DEF_STMT (exp);
       if (g)
-       {
-         rtx r;
-         location_t saved_loc = curr_insn_location ();
-         loc = gimple_location (g);
-         if (loc != UNKNOWN_LOCATION)
-           set_curr_insn_location (loc);
-         ops.code = gimple_assign_rhs_code (g);
-          switch (get_gimple_rhs_class (ops.code))
-           {
-           case GIMPLE_TERNARY_RHS:
-             ops.op2 = gimple_assign_rhs3 (g);
-             /* Fallthru */
-           case GIMPLE_BINARY_RHS:
-             ops.op1 = gimple_assign_rhs2 (g);
-
-             /* Try to expand conditonal compare.  */
-             if (targetm.gen_ccmp_first)
-               {
-                 gcc_checking_assert (targetm.gen_ccmp_next != NULL);
-                 r = expand_ccmp_expr (g, mode);
-                 if (r)
-                   break;
-               }
-             /* Fallthru */
-           case GIMPLE_UNARY_RHS:
-             ops.op0 = gimple_assign_rhs1 (g);
-             ops.type = TREE_TYPE (gimple_assign_lhs (g));
-             ops.location = loc;
-             r = expand_expr_real_2 (&ops, target, tmode, modifier);
-             break;
-           case GIMPLE_SINGLE_RHS:
-             {
-               r = expand_expr_real (gimple_assign_rhs1 (g), target,
-                                     tmode, modifier, alt_rtl,
-                                     inner_reference_p);
-               break;
-             }
-           default:
-             gcc_unreachable ();
-           }
-         set_curr_insn_location (saved_loc);
-         if (REG_P (r) && !REG_EXPR (r))
-           set_reg_attrs_for_decl_rtl (SSA_NAME_VAR (exp), r);
-         return r;
-       }
+       return expand_expr_real_gassign (as_a<gassign *> (g), target, tmode,
+                                        modifier, alt_rtl, inner_reference_p);
 
       ssa_name = exp;
       decl_rtl = get_rtx_for_ssa_name (ssa_name);

diff --git a/gcc/expr.h b/gcc/expr.h
index f04f40da6ab985cf58fcacfdd86596000b16a82f..64956f630297c3d124c9241834e5cbeacbe2863e 100644 (file)
--- a/gcc/expr.h
+++ b/gcc/expr.h
@@ -302,6 +302,9 @@ extern rtx expand_expr_real_1 (tree, rtx, machine_mode,
                               enum expand_modifier, rtx *, bool);
 extern rtx expand_expr_real_2 (sepops, rtx, machine_mode,
                               enum expand_modifier);
+extern rtx expand_expr_real_gassign (gassign *, rtx, machine_mode,
+                                    enum expand_modifier modifier,
+                                    rtx * = nullptr, bool = false);
 
 /* Generate code for computing expression EXP.
    An rtx for the computed value is returned.  The value is never null.

diff --git a/gcc/testsuite/gcc.target/aarch64/ccmp_3.c b/gcc/testsuite/gcc.target/aarch64/ccmp_3.c
new file mode 100644 (file)
index 0000000..a2b47fb
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/ccmp_3.c
@@ -0,0 +1,20 @@
+/* { dg-options "-O2" } */
+/* PR target/100942 */
+
+void foo(void);
+int f1(int a, int b)
+{
+  int c = a == 0 || b == 0;
+  if (c) foo();
+  return c;
+}
+
+/* We should get one cmp followed by ccmp and one cset. */
+/* { dg-final { scan-assembler "\tccmp\t" } } */
+/* { dg-final { scan-assembler-times "\tcset\t" 1 } } */
+/* { dg-final { scan-assembler-times "\tcmp\t" 1 } } */
+/* And not get 2 cmps and 2 (or more cset) and orr and a cbnz. */
+/* { dg-final { scan-assembler-not "\torr\t" } } */
+/* { dg-final { scan-assembler-not "\tcbnz\t" } } */
+/* { dg-final { scan-assembler-not "\tcbz\t" } } */
+

diff --git a/gcc/testsuite/gcc.target/aarch64/ccmp_4.c b/gcc/testsuite/gcc.target/aarch64/ccmp_4.c
new file mode 100644 (file)
index 0000000..bc0f57a
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/ccmp_4.c
@@ -0,0 +1,35 @@
+/* { dg-options "-O2" } */
+/* PR target/100942 */
+
+void foo(void);
+int f1(int a, int b, int d)
+{
+  int c = a < 8 || b < 9;
+  int e = d < 11 || c;
+  if (e) foo();
+  return c;
+}
+
+/*
+  We really should get:
+        cmp     w0, 7
+        ccmp    w1, 8, 4, gt
+        cset    w0, le
+        ccmp    w2, 10, 4, gt
+        ble     .L11
+
+  But we currently get:
+        cmp     w0, 7
+        ccmp    w1, 8, 4, gt
+        cset    w0, le
+        cmp     w0, 0
+        ccmp    w2, 10, 4, eq
+        ble     .L11
+  The middle cmp is not needed.
+ */
+
+/* We should end up with only one cmp and 2 ccmp and 1 cset but currently we get 2 cmp
+   though. */
+/* { dg-final { scan-assembler-times "\tccmp\t" 2 } } */
+/* { dg-final { scan-assembler-times "\tcset\t" 1 } } */
+/* { dg-final { scan-assembler-times "\tcmp\t" 1 { xfail *-*-* } } } */

diff --git a/gcc/testsuite/gcc.target/aarch64/ccmp_5.c b/gcc/testsuite/gcc.target/aarch64/ccmp_5.c
new file mode 100644 (file)
index 0000000..7e52ae4
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/ccmp_5.c
@@ -0,0 +1,20 @@
+
+/* { dg-options "-O2" } */
+/* PR target/100942 */
+void f1(int a, int b, _Bool *x)
+{
+  x[0] = x[1] = a == 0 || b == 0;
+}
+
+void f2(int a, int b, int *x)
+{
+  x[0] = x[1] = a == 0 || b == 0;
+}
+
+
+/* Both functions should be using ccmp rather than 2 cset/orr.  */
+/* { dg-final { scan-assembler-times "\tccmp\t" 2 } } */
+/* { dg-final { scan-assembler-times "\tcset\t" 2 } } */
+/* { dg-final { scan-assembler-times "\tcmp\t" 2 } } */
+/* { dg-final { scan-assembler-not "\torr\t" } } */
+