Add a target calls hook: TARGET_PUSH_ARGUMENT

1. Replace PUSH_ARGS with a target calls hook, TARGET_PUSH_ARGUMENT, which
takes an integer argument.  When it returns true, push instructions will
be used to pass outgoing arguments.  If the argument is nonzero, it is
the number of bytes to push and indicates the PUSH instruction usage is
optional so that the backend can decide if PUSH instructions should be
generated.  Otherwise, the argument is zero.
2. Implement x86 target hook which returns false when the number of bytes
to push is no less than 16 (8 for 32-bit targets) if vector load and store
can be used.
3. Remove target PUSH_ARGS definitions which return 0 as it is the same
as the default.
4. Define TARGET_PUSH_ARGUMENT of cr16 and m32c to always return true.

gcc/

	PR target/100704
	* calls.c (expand_call): Replace PUSH_ARGS with
	targetm.calls.push_argument (0).
	(emit_library_call_value_1): Likewise.
	* defaults.h (PUSH_ARGS): Removed.
	(PUSH_ARGS_REVERSED): Replace PUSH_ARGS with
	targetm.calls.push_argument (0).
	* expr.c (block_move_libcall_safe_for_call_parm): Likewise.
	(emit_push_insn): Pass the number bytes to push to
	targetm.calls.push_argument and pass 0 if ARGS_ADDR is 0.
	* hooks.c (hook_bool_uint_true): New.
	* hooks.h (hook_bool_uint_true): Likewise.
	* rtlanal.c (nonzero_bits1): Replace PUSH_ARGS with
	targetm.calls.push_argument (0).
	* target.def (push_argument): Add a targetm.calls hook.
	* targhooks.c (default_push_argument): New.
	* targhooks.h (default_push_argument): Likewise.
	* config/bpf/bpf.h (PUSH_ARGS): Removed.
	* config/cr16/cr16.c (TARGET_PUSH_ARGUMENT): New.
	* config/cr16/cr16.h (PUSH_ARGS): Removed.
	* config/i386/i386.c (ix86_push_argument): New.
	(TARGET_PUSH_ARGUMENT): Likewise.
	* config/i386/i386.h (PUSH_ARGS): Removed.
	* config/m32c/m32c.c (TARGET_PUSH_ARGUMENT): New.
	* config/m32c/m32c.h (PUSH_ARGS): Removed.
	* config/nios2/nios2.h (PUSH_ARGS): Likewise.
	* config/pru/pru.h (PUSH_ARGS): Likewise.
	* doc/tm.texi.in: Remove PUSH_ARGS documentation.  Add
	TARGET_PUSH_ARGUMENT hook.
	* doc/tm.texi: Regenerated.

gcc/testsuite/

	PR target/100704
	* gcc.target/i386/pr100704-1.c: New test.
	* gcc.target/i386/pr100704-2.c: Likewise.
	* gcc.target/i386/pr100704-3.c: Likewise.

1 files changed, 11 insertions, 3 deletions

diff --git a/gcc/expr.c b/gcc/expr.c
index 231487f..025033c 100644
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -1823,7 +1823,7 @@ block_move_libcall_safe_for_call_parm (void)
   tree fn;
 
   /* If arguments are pushed on the stack, then they're safe.  */
-  if (PUSH_ARGS)
+  if (targetm.calls.push_argument (0))
     return true;
 
   /* If registers go on the stack anyway, any argument is sure to clobber
@@ -4639,11 +4639,19 @@ emit_push_insn (rtx x, machine_mode mode, tree type, rtx size,
       skip = (reg_parm_stack_space == 0) ? 0 : used;
 
 #ifdef PUSH_ROUNDING
+      /* NB: Let the backend known the number of bytes to push and
+	 decide if push insns should be generated.  */
+      unsigned int push_size;
+      if (CONST_INT_P (size))
+	push_size = INTVAL (size);
+      else
+	push_size = 0;
+
       /* Do it with several push insns if that doesn't take lots of insns
 	 and if there is no difficulty with push insns that skip bytes
 	 on the stack for alignment purposes.  */
       if (args_addr == 0
-	  && PUSH_ARGS
+	  && targetm.calls.push_argument (push_size)
 	  && CONST_INT_P (size)
 	  && skip == 0
 	  && MEM_ALIGN (xinner) >= align
@@ -4848,7 +4856,7 @@ emit_push_insn (rtx x, machine_mode mode, tree type, rtx size,
 	anti_adjust_stack (gen_int_mode (extra, Pmode));
 
 #ifdef PUSH_ROUNDING
-      if (args_addr == 0 && PUSH_ARGS)
+      if (args_addr == 0 && targetm.calls.push_argument (0))
 	emit_single_push_insn (mode, x, type);
       else
 #endif