openmp: Add testing checks (whether lhs appears in operands at all) to more trees

This patch adds testing checks (goa_stabilize_expr with NULL pre_p) for more
tree codes, so that we don't gimplify their operands individually unless lhs
appears in them.  Also, so that we don't have exponential compile time complexity
with the added checks, I've added a depth computation, we don't expect lhs
to be found in depth 8 or above as all the atomic forms must have x expression
in specific places in the expressions.

2021-09-14  Jakub Jelinek  <jakub@redhat.com>

	* gimplify.c (goa_stabilize_expr): Add depth argument, propagate
	it to recursive calls, for depth above 7 just gimplify or return.
	Perform a test even for MODIFY_EXPR, ADDR_EXPR, COMPOUND_EXPR with
	__builtin_clear_padding and TARGET_EXPR.
	(gimplify_omp_atomic): Adjust goa_stabilize_expr callers.

diff --git a/gcc/gimplify.c b/gcc/gimplify.c
index 66dfd25ad21379042a2a40c9993844757058a6b0..f680292fd91d2dae84b8ddb270a0ed0afabd363d 100644 (file)
--- a/gcc/gimplify.c
+++ b/gcc/gimplify.c
@@ -13859,10 +13859,10 @@ goa_lhs_expr_p (tree expr, tree addr)
 
 static int
 goa_stabilize_expr (tree *expr_p, gimple_seq *pre_p, tree lhs_addr,
-                   tree lhs_var, tree &target_expr, bool rhs)
+                   tree lhs_var, tree &target_expr, bool rhs, int depth)
 {
   tree expr = *expr_p;
-  int saw_lhs;
+  int saw_lhs = 0;
 
   if (goa_lhs_expr_p (expr, lhs_addr))
     {
@@ -13873,17 +13873,22 @@ goa_stabilize_expr (tree *expr_p, gimple_seq *pre_p, tree lhs_addr,
   if (is_gimple_val (expr))
     return 0;
 
-  saw_lhs = 0;
+  /* Maximum depth of lhs in expression is for the
+     __builtin_clear_padding (...), __builtin_clear_padding (...),
+     __builtin_memcmp (&TARGET_EXPR <lhs, >, ...) == 0 ? ... : lhs;  */
+  if (++depth > 7)
+    goto finish;
+
   switch (TREE_CODE_CLASS (TREE_CODE (expr)))
     {
     case tcc_binary:
     case tcc_comparison:
       saw_lhs |= goa_stabilize_expr (&TREE_OPERAND (expr, 1), pre_p, lhs_addr,
-                                    lhs_var, target_expr, true);
+                                    lhs_var, target_expr, true, depth);
       /* FALLTHRU */
     case tcc_unary:
       saw_lhs |= goa_stabilize_expr (&TREE_OPERAND (expr, 0), pre_p, lhs_addr,
-                                    lhs_var, target_expr, true);
+                                    lhs_var, target_expr, true, depth);
       break;
     case tcc_expression:
       switch (TREE_CODE (expr))
@@ -13895,84 +13900,101 @@ goa_stabilize_expr (tree *expr_p, gimple_seq *pre_p, tree lhs_addr,
        case TRUTH_XOR_EXPR:
        case BIT_INSERT_EXPR:
          saw_lhs |= goa_stabilize_expr (&TREE_OPERAND (expr, 1), pre_p,
-                                        lhs_addr, lhs_var, target_expr, true);
+                                        lhs_addr, lhs_var, target_expr, true,
+                                        depth);
          /* FALLTHRU */
        case TRUTH_NOT_EXPR:
          saw_lhs |= goa_stabilize_expr (&TREE_OPERAND (expr, 0), pre_p,
-                                        lhs_addr, lhs_var, target_expr, true);
+                                        lhs_addr, lhs_var, target_expr, true,
+                                        depth);
          break;
        case MODIFY_EXPR:
+         if (pre_p && !goa_stabilize_expr (expr_p, NULL, lhs_addr, lhs_var,
+                                           target_expr, true, depth))
+           break;
          saw_lhs |= goa_stabilize_expr (&TREE_OPERAND (expr, 1), pre_p,
-                                        lhs_addr, lhs_var, target_expr, true);
+                                        lhs_addr, lhs_var, target_expr, true,
+                                        depth);
+         saw_lhs |= goa_stabilize_expr (&TREE_OPERAND (expr, 0), pre_p,
+                                        lhs_addr, lhs_var, target_expr, false,
+                                        depth);
+         break;
          /* FALLTHRU */
        case ADDR_EXPR:
+         if (pre_p && !goa_stabilize_expr (expr_p, NULL, lhs_addr, lhs_var,
+                                           target_expr, true, depth))
+           break;
          saw_lhs |= goa_stabilize_expr (&TREE_OPERAND (expr, 0), pre_p,
-                                        lhs_addr, lhs_var, target_expr, false);
+                                        lhs_addr, lhs_var, target_expr, false,
+                                        depth);
          break;
        case COMPOUND_EXPR:
-         /* Special-case __builtin_clear_padding call before
-            __builtin_memcmp.  */
-         if (TREE_CODE (TREE_OPERAND (expr, 0)) == CALL_EXPR)
-           {
-             tree fndecl = get_callee_fndecl (TREE_OPERAND (expr, 0));
-             if (fndecl
-                 && fndecl_built_in_p (fndecl, BUILT_IN_CLEAR_PADDING)
-                 && VOID_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 0))))
+         /* Break out any preevaluations from cp_build_modify_expr.  */
+         for (; TREE_CODE (expr) == COMPOUND_EXPR;
+              expr = TREE_OPERAND (expr, 1))
+           {
+             /* Special-case __builtin_clear_padding call before
+                __builtin_memcmp.  */
+             if (TREE_CODE (TREE_OPERAND (expr, 0)) == CALL_EXPR)
                {
-                 saw_lhs = goa_stabilize_expr (&TREE_OPERAND (expr, 0), pre_p,
-                                               lhs_addr, lhs_var,
-                                               target_expr, true);
-                 if (!saw_lhs)
-                   {
-                     expr = TREE_OPERAND (expr, 1);
-                     if (!pre_p)
-                       return goa_stabilize_expr (&expr, pre_p, lhs_addr,
-                                                  lhs_var, target_expr, true);
-                     *expr_p = expr;
-                     return goa_stabilize_expr (expr_p, pre_p, lhs_addr,
-                                                lhs_var, target_expr, true);
-                   }
-                 else
+                 tree fndecl = get_callee_fndecl (TREE_OPERAND (expr, 0));
+                 if (fndecl
+                     && fndecl_built_in_p (fndecl, BUILT_IN_CLEAR_PADDING)
+                     && VOID_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 0)))
+                     && (!pre_p
+                         || goa_stabilize_expr (&TREE_OPERAND (expr, 0), NULL,
+                                                lhs_addr, lhs_var,
+                                                target_expr, true, depth)))
                    {
+                     if (pre_p)
+                       *expr_p = expr;
+                     saw_lhs = goa_stabilize_expr (&TREE_OPERAND (expr, 0),
+                                                   pre_p, lhs_addr, lhs_var,
+                                                   target_expr, true, depth);
                      saw_lhs |= goa_stabilize_expr (&TREE_OPERAND (expr, 1),
                                                     pre_p, lhs_addr, lhs_var,
-                                                    target_expr, rhs);
-                     break;
+                                                    target_expr, rhs, depth);
+                     return saw_lhs;
                    }
                }
+
+             if (pre_p)
+               gimplify_stmt (&TREE_OPERAND (expr, 0), pre_p);
            }
-         /* Break out any preevaluations from cp_build_modify_expr.  */
-         for (; TREE_CODE (expr) == COMPOUND_EXPR;
-              expr = TREE_OPERAND (expr, 1))
-           if (pre_p)
-             gimplify_stmt (&TREE_OPERAND (expr, 0), pre_p);
          if (!pre_p)
            return goa_stabilize_expr (&expr, pre_p, lhs_addr, lhs_var,
-                                      target_expr, rhs);
+                                      target_expr, rhs, depth);
          *expr_p = expr;
          return goa_stabilize_expr (expr_p, pre_p, lhs_addr, lhs_var,
-                                    target_expr, rhs);
+                                    target_expr, rhs, depth);
        case COND_EXPR:
          if (!goa_stabilize_expr (&TREE_OPERAND (expr, 0), NULL, lhs_addr,
-                                  lhs_var, target_expr, true))
+                                  lhs_var, target_expr, true, depth))
            break;
          saw_lhs |= goa_stabilize_expr (&TREE_OPERAND (expr, 0), pre_p,
-                                        lhs_addr, lhs_var, target_expr, true);
+                                        lhs_addr, lhs_var, target_expr, true,
+                                        depth);
          saw_lhs |= goa_stabilize_expr (&TREE_OPERAND (expr, 1), pre_p,
-                                        lhs_addr, lhs_var, target_expr, true);
+                                        lhs_addr, lhs_var, target_expr, true,
+                                        depth);
          saw_lhs |= goa_stabilize_expr (&TREE_OPERAND (expr, 2), pre_p,
-                                        lhs_addr, lhs_var, target_expr, true);
+                                        lhs_addr, lhs_var, target_expr, true,
+                                        depth);
          break;
        case TARGET_EXPR:
          if (TARGET_EXPR_INITIAL (expr))
            {
+             if (pre_p && !goa_stabilize_expr (expr_p, NULL, lhs_addr,
+                                               lhs_var, target_expr, true,
+                                               depth))
+               break;
              if (expr == target_expr)
                saw_lhs = 1;
              else
                {
                  saw_lhs = goa_stabilize_expr (&TARGET_EXPR_INITIAL (expr),
                                                pre_p, lhs_addr, lhs_var,
-                                               target_expr, true);
+                                               target_expr, true, depth);
                  if (saw_lhs && target_expr == NULL_TREE && pre_p)
                    target_expr = expr;
                }
@@ -13986,7 +14008,8 @@ goa_stabilize_expr (tree *expr_p, gimple_seq *pre_p, tree lhs_addr,
       if (TREE_CODE (expr) == BIT_FIELD_REF
          || TREE_CODE (expr) == VIEW_CONVERT_EXPR)
        saw_lhs |= goa_stabilize_expr (&TREE_OPERAND (expr, 0), pre_p,
-                                      lhs_addr, lhs_var, target_expr, true);
+                                      lhs_addr, lhs_var, target_expr, true,
+                                      depth);
       break;
     case tcc_vl_exp:
       if (TREE_CODE (expr) == CALL_EXPR)
@@ -13999,24 +14022,24 @@ goa_stabilize_expr (tree *expr_p, gimple_seq *pre_p, tree lhs_addr,
                for (int i = 0; i < nargs; i++)
                  saw_lhs |= goa_stabilize_expr (&CALL_EXPR_ARG (expr, i),
                                                 pre_p, lhs_addr, lhs_var,
-                                                target_expr, true);
+                                                target_expr, true, depth);
              }
-         if (saw_lhs == 0 && VOID_TYPE_P (TREE_TYPE (expr)))
-           {
-             if (pre_p)
-               gimplify_stmt (&expr, pre_p);
-             return 0;
-           }
        }
       break;
     default:
       break;
     }
 
+ finish:
   if (saw_lhs == 0 && pre_p)
     {
       enum gimplify_status gs;
-      if (rhs)
+      if (TREE_CODE (expr) == CALL_EXPR && VOID_TYPE_P (TREE_TYPE (expr)))
+       {
+         gimplify_stmt (&expr, pre_p);
+         return saw_lhs;
+       }
+      else if (rhs)
        gs = gimplify_expr (expr_p, pre_p, NULL, is_gimple_val, fb_rvalue);
       else
        gs = gimplify_expr (expr_p, pre_p, NULL, is_gimple_lvalue, fb_lvalue);
@@ -14044,7 +14067,7 @@ gimplify_omp_atomic (tree *expr_p, gimple_seq *pre_p)
   tmp_load = create_tmp_reg (type);
   if (rhs
       && goa_stabilize_expr (&rhs, pre_p, addr, tmp_load, target_expr,
-                            true) < 0)
+                            true, 0) < 0)
     return GS_ERROR;
 
   if (gimplify_expr (&addr, pre_p, NULL, is_gimple_val, fb_rvalue)