re PR c++/60336 (empty struct value is passed differently in C and C++)

	PR c++/60336
	PR middle-end/67239
	PR target/68355
	* c-decl.c (grokdeclarator): Set DECL_PADDING_P on unnamed bit-fields.

	* class.c (layout_class_type): Set DECL_PADDING_P on padding.
	* decl.c (cxx_init_decl_processing): Set TRANSLATION_UNIT_WARN_EMPTY_P.
	(grokdeclarator): Set DECL_PADDING_P on unnamed bit-fields.

	* lto.c (compare_tree_sccs_1): Compare TYPE_EMPTY_P and DECL_PADDING_P.

	* calls.c (initialize_argument_information): Call
	warn_parameter_passing_abi target hook.
	(store_one_arg): Use 0 for empty record size.  Don't push 0 size
	argument onto stack.
	(must_pass_in_stack_var_size_or_pad): Return false for empty types.
	* common.opt: Update -fabi-version description.
	* config/i386/i386.c (init_cumulative_args): Set cum->warn_empty.
	(ix86_gimplify_va_arg): Call arg_int_size_in_bytes instead of
	int_size_in_bytes.
	(ix86_is_empty_record): New function.
	(ix86_warn_parameter_passing_abi): New function.
	(TARGET_EMPTY_RECORD_P): Redefine.
	(TARGET_WARN_PARAMETER_PASSING_ABI): Redefine.
	* config/i386/i386.h (CUMULATIVE_ARGS): Add warn_empty.
	* doc/tm.texi: Regenerated.
	* doc/tm.texi.in (TARGET_EMPTY_RECORD_P,
	TARGET_WARN_PARAMETER_PASSING_ABI): Add.
	* dwarf2out.c (get_ultimate_context): Move to tree.c.
	* explow.c (hard_function_value): Call arg_int_size_in_bytes
	instead of int_size_in_bytes.
	* expr.c (copy_blkmode_to_reg): Likewise.
	* function.c (aggregate_value_p): Return 0 for empty types.
	(assign_parm_find_entry_rtl): Call warn_parameter_passing_abi target hook.
	(locate_and_pad_parm): Call arg size_in_bytes instead
	size_in_bytes.
	* lto-streamer-out.c (hash_tree): Hash TYPE_EMPTY_P and DECL_PADDING_P.
	* stor-layout.c (finalize_type_size): Set TYPE_EMPTY_P.
	* target.def (empty_record_p, warn_parameter_passing_abi): New target
	hooks.
	* targhooks.c (hook_void_CUMULATIVE_ARGS_tree): New hook.
	(std_gimplify_va_arg_expr): Skip empty records.  Call
	arg_size_in_bytes instead size_in_bytes.
	* targhooks.h (hook_void_CUMULATIVE_ARGS_tree): Declare.
	* tree-core.h (tree_type_common): Add empty_flag.
	(tree_decl_common): Update comments.
	* tree-streamer-in.c (unpack_ts_decl_common_value_fields): Stream
	DECL_PADDING_P.
	(unpack_ts_type_common_value_fields): Stream TYPE_EMPTY_P.
	* tree-streamer-out.c (pack_ts_decl_common_value_fields): Stream
	DECL_PADDING_P.
	(pack_ts_type_common_value_fields): Stream TYPE_EMPTY_P.
	* tree.c (default_is_empty_type): New function.
	(default_is_empty_record): New function.
	(arg_int_size_in_bytes): New function.
	(arg_size_in_bytes): New function.
	(get_ultimate_context): New function.
	* tree.h: Define TYPE_EMPTY_P, DECL_PADDING_P and
	TRANSLATION_UNIT_WARN_EMPTY_P.
	(default_is_empty_record, arg_int_size_in_bytes,
	arg_size_in_bytes, get_ultimate_context): Declare.

	* g++.dg/abi/empty12.C: New test.
	* g++.dg/abi/empty12.h: New test.
	* g++.dg/abi/empty12a.c: New test.
	* g++.dg/abi/empty13.C: New test.
	* g++.dg/abi/empty13.h: New test.
	* g++.dg/abi/empty13a.c: New test.
	* g++.dg/abi/empty14.C: New test.
	* g++.dg/abi/empty14.h: New test.
	* g++.dg/abi/empty14a.c: New test.
	* g++.dg/abi/empty15.C: New test.
	* g++.dg/abi/empty15.h: New test.
	* g++.dg/abi/empty15a.c: New test.
	* g++.dg/abi/empty16.C: New test.
	* g++.dg/abi/empty16.h: New test.
	* g++.dg/abi/empty16a.c: New test.
	* g++.dg/abi/empty17.C: New test.
	* g++.dg/abi/empty17.h: New test.
	* g++.dg/abi/empty17a.c: New test.
	* g++.dg/abi/empty18.C: New test.
	* g++.dg/abi/empty18.h: New test.
	* g++.dg/abi/empty18a.c: New test.
	* g++.dg/abi/empty19.C: New test.
	* g++.dg/abi/empty19.h: New test.
	* g++.dg/abi/empty19a.c: New test.
	* g++.dg/abi/empty20.C: New test.
	* g++.dg/abi/empty21.C: New test.
	* g++.dg/abi/empty22.C: New test.
	* g++.dg/abi/empty22.h: New test.
	* g++.dg/abi/empty22a.c: New test.
	* g++.dg/abi/empty23.C: New test.
	* g++.dg/abi/empty24.C: New test.
	* g++.dg/abi/empty25.C: New test.
	* g++.dg/abi/empty25.h: New test.
	* g++.dg/abi/empty25a.c: New test.
	* g++.dg/abi/empty26.C: New test.
	* g++.dg/abi/empty26.h: New test.
	* g++.dg/abi/empty26a.c: New test.
	* g++.dg/abi/empty27.C: New test.
	* g++.dg/abi/empty28.C: New test.
	* g++.dg/abi/pr60336-1.C: New test.
	* g++.dg/abi/pr60336-10.C: New test.
	* g++.dg/abi/pr60336-11.C: New test.
	* g++.dg/abi/pr60336-12.C: New test.
	* g++.dg/abi/pr60336-2.C: New test.
	* g++.dg/abi/pr60336-3.C: New test.
	* g++.dg/abi/pr60336-4.C: New test.
	* g++.dg/abi/pr60336-5.C: New test.
	* g++.dg/abi/pr60336-6.C: New test.
	* g++.dg/abi/pr60336-7.C: New test.
	* g++.dg/abi/pr60336-8.C: New test.
	* g++.dg/abi/pr60336-9.C: New test.
	* g++.dg/abi/pr68355.C: New test.
	* g++.dg/lto/pr60336_0.C: New test.

Co-Authored-By: H.J. Lu <hongjiu.lu@intel.com>
Co-Authored-By: Jason Merrill <jason@redhat.com>

From-SVN: r255066

1 files changed, 24 insertions, 11 deletions

diff --git a/gcc/calls.c b/gcc/calls.c
index 64f9f50..8ae9899 100644
--- a/gcc/calls.c
+++ b/gcc/calls.c
@@ -2002,6 +2002,8 @@ initialize_argument_information (int num_actuals ATTRIBUTE_UNUSED,
       args[i].unsignedp = unsignedp;
       args[i].mode = mode;
 
+      targetm.calls.warn_parameter_passing_abi (args_so_far, type);
+
       args[i].reg = targetm.calls.function_arg (args_so_far, mode, type,
 						argpos < n_named_args);
 
@@ -5514,7 +5516,11 @@ store_one_arg (struct arg_data *arg, rtx argblock, int flags,
 	 Note that in C the default argument promotions
 	 will prevent such mismatches.  */
 
-      size = GET_MODE_SIZE (arg->mode);
+      if (TYPE_EMPTY_P (TREE_TYPE (pval)))
+	size = 0;
+      else
+	size = GET_MODE_SIZE (arg->mode);
+
       /* Compute how much space the push instruction will push.
 	 On many machines, pushing a byte will advance the stack
 	 pointer by a halfword.  */
@@ -5546,10 +5552,12 @@ store_one_arg (struct arg_data *arg, rtx argblock, int flags,
 
       /* This isn't already where we want it on the stack, so put it there.
 	 This can either be done with push or copy insns.  */
-      if (!emit_push_insn (arg->value, arg->mode, TREE_TYPE (pval), NULL_RTX,
-		      parm_align, partial, reg, used - size, argblock,
-		      ARGS_SIZE_RTX (arg->locate.offset), reg_parm_stack_space,
-		      ARGS_SIZE_RTX (arg->locate.alignment_pad), true))
+      if (used
+	  && !emit_push_insn (arg->value, arg->mode, TREE_TYPE (pval),
+			      NULL_RTX, parm_align, partial, reg, used - size,
+			      argblock, ARGS_SIZE_RTX (arg->locate.offset),
+			      reg_parm_stack_space,
+			      ARGS_SIZE_RTX (arg->locate.alignment_pad), true))
 	sibcall_failure = 1;
 
       /* Unless this is a partially-in-register argument, the argument is now
@@ -5582,9 +5590,9 @@ store_one_arg (struct arg_data *arg, rtx argblock, int flags,
 	  /* PUSH_ROUNDING has no effect on us, because emit_push_insn
 	     for BLKmode is careful to avoid it.  */
 	  excess = (arg->locate.size.constant
-		    - int_size_in_bytes (TREE_TYPE (pval))
+		    - arg_int_size_in_bytes (TREE_TYPE (pval))
 		    + partial);
-	  size_rtx = expand_expr (size_in_bytes (TREE_TYPE (pval)),
+	  size_rtx = expand_expr (arg_size_in_bytes (TREE_TYPE (pval)),
 				  NULL_RTX, TYPE_MODE (sizetype),
 				  EXPAND_NORMAL);
 	}
@@ -5660,10 +5668,12 @@ store_one_arg (struct arg_data *arg, rtx argblock, int flags,
 	    }
 	}
 
-      emit_push_insn (arg->value, arg->mode, TREE_TYPE (pval), size_rtx,
-		      parm_align, partial, reg, excess, argblock,
-		      ARGS_SIZE_RTX (arg->locate.offset), reg_parm_stack_space,
-		      ARGS_SIZE_RTX (arg->locate.alignment_pad), false);
+      if (!CONST_INT_P (size_rtx) || INTVAL (size_rtx) != 0)
+	emit_push_insn (arg->value, arg->mode, TREE_TYPE (pval), size_rtx,
+			parm_align, partial, reg, excess, argblock,
+			ARGS_SIZE_RTX (arg->locate.offset),
+			reg_parm_stack_space,
+			ARGS_SIZE_RTX (arg->locate.alignment_pad), false);
 
       /* Unless this is a partially-in-register argument, the argument is now
 	 in the stack.
@@ -5741,6 +5751,9 @@ must_pass_in_stack_var_size_or_pad (machine_mode mode, const_tree type)
   if (TREE_ADDRESSABLE (type))
     return true;
 
+  if (TYPE_EMPTY_P (type))
+    return false;
+
   /* If the padding and mode of the type is such that a copy into
      a register would put it into the wrong part of the register.  */
   if (mode == BLKmode