i386: Align stack frame if argument is passed on stack

When a function call is removed, it may become a leaf function.  But if
argument may be passed on stack, we need to align the stack frame when
there is no tail call.

Tested on Linux/i686 and Linux/x86-64.

gcc/

	Backport from mainline
	PR target/83330
	* config/i386/i386.c (ix86_function_arg_advance): Set
	outgoing_args_on_stack to true if there are outgoing arguments
	on stack.
	(ix86_function_arg): Likewise.
	(ix86_compute_frame_layout): Align stack frame if argument is
	passed on stack.
	* config/i386/i386.h (machine_function): Add
	outgoing_args_on_stack.

gcc/testsuite/

	Backport from mainline
	PR target/83330
	* gcc.target/i386/pr83330.c: New test.

From-SVN: r256703

gcc/ChangeLog

@@ -1,3 +1,16 @@
+2018-01-15  H.J. Lu  <hongjiu.lu@intel.com>
+
+	Backport from mainline
+	PR target/83330
+	* config/i386/i386.c (ix86_function_arg_advance): Set
+	outgoing_args_on_stack to true if there are outgoing arguments
+	on stack.
+	(ix86_function_arg): Likewise.
+	(ix86_compute_frame_layout): Align stack frame if argument is
+	passed on stack.
+	* config/i386/i386.h (machine_function): Add
+	outgoing_args_on_stack.
+
 2018-01-15  H.J. Lu  <hongjiu.lu@intel.com>
 
 	Backport from mainline

gcc/config/i386/i386.c

@@ -9752,7 +9752,13 @@ ix86_function_arg_advance (cumulative_args_t cum_v, machine_mode mode,
   /* For pointers passed in memory we expect bounds passed in Bounds
      Table.  */
   if (!nregs)
-    cum->bnds_in_bt = chkp_type_bounds_count (type);
+    {
+      /* Track if there are outgoing arguments on stack.  */
+      if (cum->caller)
+	cfun->machine->outgoing_args_on_stack = true;
+
+      cum->bnds_in_bt = chkp_type_bounds_count (type);
+    }
 }
 
 /* Define where to put the arguments to a function.
@@ -10081,6 +10087,10 @@ ix86_function_arg (cumulative_args_t cum_v, machine_mode omode,
   else
     arg = function_arg_32 (cum, mode, omode, type, bytes, words);
 
+  /* Track if there are outgoing arguments on stack.  */
+  if (arg == NULL_RTX && cum->caller)
+    cfun->machine->outgoing_args_on_stack = true;
+
   return arg;
 }
 
@@ -12510,11 +12520,16 @@ ix86_compute_frame_layout (void)
   frame->va_arg_size = ix86_varargs_gpr_size + ix86_varargs_fpr_size;
   offset += frame->va_arg_size;
 
-  /* Align start of frame for local function.  */
+  /* Align start of frame for local function.  When a function call
+     is removed, it may become a leaf function.  But if argument may
+     be passed on stack, we need to align the stack when there is no
+     tail call.  */
   if (stack_realign_fp
       || offset != frame->sse_reg_save_offset
       || size != 0
       || !crtl->is_leaf
+      || (!crtl->tail_call_emit
+	  && cfun->machine->outgoing_args_on_stack)
       || cfun->calls_alloca
       || ix86_current_function_calls_tls_descriptor)
     offset = ROUND_UP (offset, stack_alignment_needed);

gcc/config/i386/i386.h

@@ -2620,6 +2620,9 @@ struct GTY(()) machine_function {
      pass arguments and can be used for indirect sibcall.  */
   BOOL_BITFIELD arg_reg_available : 1;
 
+  /* Nonzero if the function places outgoing arguments on stack.  */
+  BOOL_BITFIELD outgoing_args_on_stack : 1;
+
   /* During prologue/epilogue generation, the current frame state.
      Otherwise, the frame state at the end of the prologue.  */
   struct machine_frame_state fs;

gcc/testsuite/ChangeLog

@@ -1,3 +1,9 @@
+2018-01-15  H.J. Lu  <hongjiu.lu@intel.com>
+
+	Backport from mainline
+	PR target/83330
+	* gcc.target/i386/pr83330.c: New test.
+
 2018-01-14  Jerry DeLisle  <jvdelisle@gcc.gnu.org>
 
 	Backport from trunk

gcc/testsuite/gcc.target/i386/pr83330.c

@@ -0,0 +1,29 @@
+/* { dg-do run { target int128 } } */
+/* { dg-options "-O2 -fno-tree-dce -mno-push-args" } */
+
+typedef unsigned long long u64;
+typedef unsigned __int128 u128;
+
+u64 v;
+u64 g;
+
+u64 __attribute__ ((noinline, noclone))
+bar (u128 d, u64 e, u64 f, u64 g, u128 h)
+{
+  (void)d, (void)e, (void)f, (void)g, (void)h;
+  return 0;
+}
+
+static u64
+foo (void)
+{
+  (void)(v - bar (0, 0, 0, 0, 0));
+  return g;
+}
+
+int
+main (void)
+{
+  (void)foo ();
+  return 0;
+}