complex-lowering: Better handling of PAREN_EXPR [PR68855]

When PAREN_EXPR tree code was added in r0-85884-gdedd42d511b6e4,
a simplified handling was added to complex lowering. Which means
we would get:
```
  _9 = COMPLEX_EXPR <_15, _14>;
  _11 = ((_9));
  _19 = REALPART_EXPR <_11>;
  _20 = IMAGPART_EXPR <_11>;
```

In many cases instead of just simply:
```
  _19 = ((_15));
  _20 = ((_14));
```

So this adds full support for PAREN_EXPR to complex lowering.
It is handled very similar as NEGATE_EXPR; except creating PAREN_EXPR
instead of NEGATE_EXPR for the real/imag parts. This allows for
more optimizations including vectorization, especially with
-ffast-math.
gfortran.dg/vect/pr68855.f90 is an example where this could show up.
It also shows up in SPEC CPU 2006's 465.tonto; though I have not done
any benchmarking there.

Bootstrapped and tested on x86_64-linux-gnu with no regressions.

gcc/ChangeLog:

	PR tree-optimization/68855
	* tree-complex.cc (init_dont_simulate_again): Handle PAREN_EXPR
	like NEGATE_EXPR.
	(complex_propagate::visit_stmt): Likewise.
	(expand_complex_move): Don't handle PAREN_EXPR.
	(expand_complex_paren): New function.
	(expand_complex_operations_1): Handle PAREN_EXPR like
	NEGATE_EXPR. And call expand_complex_paren for PAREN_EXPR.

gcc/testsuite/ChangeLog:

	* gcc.dg/vect/pr68855.c: New test.
	* gfortran.dg/vect/pr68855.f90: New test.

Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>

3 files changed, 60 insertions, 2 deletions

diff --git a/gcc/testsuite/gcc.dg/vect/pr68855.c b/gcc/testsuite/gcc.dg/vect/pr68855.c
new file mode 100644
index 0000000..68a3a1c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/pr68855.c
@@ -0,0 +1,17 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target vect_float } */
+
+/* { dg-final { scan-tree-dump "LOOP VECTORIZED" "vect" } } */
+
+/* PAREN_EXPR should not cause the vectorization of complex float add to be missed. */
+void foo(_Complex float *a, int n)
+{
+  for(int i = 0; i < n; i++)
+  {
+    _Complex float t;
+    t = a[i];
+    t += 6.0;
+    t = __builtin_assoc_barrier(t);
+    a[i] = t;
+  }
+}
diff --git a/gcc/testsuite/gfortran.dg/vect/pr68855.f90 b/gcc/testsuite/gfortran.dg/vect/pr68855.f90
new file mode 100644
index 0000000..90d444c
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/vect/pr68855.f90
@@ -0,0 +1,16 @@
+! { dg-do compile }
+! { dg-require-effective-target vect_float }
+
+! { dg-final { scan-tree-dump "LOOP VECTORIZED" "vect" } }
+! PAREN_EXPR should not cause the vectorization of complex float add to be missed.
+
+subroutine foo(a,n)
+
+  complex (kind(1.0)) :: a(*)
+  integer :: i,n
+
+  do i=1,n
+     a(i)=(a(i)+(6.0,1.0))
+  enddo
+  
+end subroutine foo
diff --git a/gcc/tree-complex.cc b/gcc/tree-complex.cc
index 8779139..8a879ac 100644
--- a/gcc/tree-complex.cc
+++ b/gcc/tree-complex.cc
@@ -281,6 +281,7 @@ init_dont_simulate_again (void)
 
 	      case NEGATE_EXPR:
 	      case CONJ_EXPR:
+	      case PAREN_EXPR:
 		if (TREE_CODE (TREE_TYPE (op0)) == COMPLEX_TYPE)
 		  saw_a_complex_op = true;
 		break;
@@ -391,6 +392,7 @@ complex_propagate::visit_stmt (gimple *stmt, edge *taken_edge_p ATTRIBUTE_UNUSED
       break;
 
     case NEGATE_EXPR:
+    case PAREN_EXPR:
     case CONJ_EXPR:
       new_l = find_lattice_value (gimple_assign_rhs1 (stmt));
       break;
@@ -852,8 +854,7 @@ expand_complex_move (gimple_stmt_iterator *gsi, tree type)
 	  update_complex_components_on_edge (e, lhs, r, i);
 	}
       else if (is_gimple_call (stmt)
-	       || gimple_has_side_effects (stmt)
-	       || gimple_assign_rhs_code (stmt) == PAREN_EXPR)
+	       || gimple_has_side_effects (stmt))
 	{
 	  r = build1 (REALPART_EXPR, inner_type, lhs);
 	  i = build1 (IMAGPART_EXPR, inner_type, lhs);
@@ -1545,6 +1546,25 @@ expand_complex_negation (gimple_stmt_iterator *gsi, tree inner_type,
   update_complex_assignment (gsi, rr, ri);
 }
 
+/* Expand complex paren to scalars:
+	((a)) = ((ar)) + i((ai))
+*/
+
+static void
+expand_complex_paren (gimple_stmt_iterator *gsi, tree inner_type,
+		      tree ar, tree ai)
+{
+  tree rr, ri;
+  gimple_seq stmts = NULL;
+  location_t loc = gimple_location (gsi_stmt (*gsi));
+
+  rr = gimple_build (&stmts, loc, PAREN_EXPR, inner_type, ar);
+  ri = gimple_build (&stmts, loc, PAREN_EXPR, inner_type, ai);
+
+  gsi_insert_seq_before (gsi, stmts, GSI_SAME_STMT);
+  update_complex_assignment (gsi, rr, ri);
+}
+
 /* Expand complex conjugate to scalars:
 	~a = (ar) + i(-ai)
 */
@@ -1697,6 +1717,7 @@ expand_complex_operations_1 (gimple_stmt_iterator *gsi)
     case ROUND_DIV_EXPR:
     case RDIV_EXPR:
     case NEGATE_EXPR:
+    case PAREN_EXPR:
     case CONJ_EXPR:
       if (TREE_CODE (type) != COMPLEX_TYPE)
 	return;
@@ -1815,6 +1836,10 @@ expand_complex_operations_1 (gimple_stmt_iterator *gsi)
       expand_complex_comparison (gsi, ar, ai, br, bi, code);
       break;
 
+    case PAREN_EXPR:
+      expand_complex_paren (gsi, inner_type, ar, ai);
+      break;
+
     default:
       gcc_unreachable ();
     }