[PATCH][AAarch64][v3] Add support for TARGET_COMPUTE_FRAME_LAYOUT

[Vlad Lazar <vlad.lazar@arm.com>]

Hi,

The patch adds support for the TARGET_COMPUTE_FRAME_LAYOUT hook on AArch64
and removes unneeded frame layout recalculation.

The removed aarch64_layout_frame calls are unnecessary because the functions in which
they appear will be called during or after the reload pass in which the TARGET_COMPUTE_FRAME_LAYOUT
hook is called. The if statement in aarch64_layout_frame had the purpose of avoiding
the extra work from the calls which have been removed and is now redundant.

Bootstrapped and regtested on aarch64-none-linux-gnu and there are no regressions.

Thanks,
Vlad

gcc/
2018-08-06  Vlad Lazar  <vlad.lazar@arm.com>

	* config/aarch64/aarch64.h (TARGET_COMPUTE_FRAME_LAYOUT): Define.
	* config/aarch64/aarch64.c (aarch64_expand_prologue): Remove aarch64_layout_frame call.
	(aarch64_expand_epilogue): Likewise.
	(aarch64_initial_elimination_offset): Likewise.
	(aarch64_get_separate_components): Likewise.
	(aarch64_use_return_insn_p): Likewise.
	(aarch64_layout_frame): Remove unneeded check.

---

diff --git a/gcc/config/aarch64/aarch64.h b/gcc/config/aarch64/aarch64.h
index 976f9afae54c1c98c22a4d5002d8d94e33b3190a..02aaa333fb57eff918049681173403f004a8a8e3 100644
--- a/gcc/config/aarch64/aarch64.h
+++ b/gcc/config/aarch64/aarch64.h
@@ -478,6 +478,9 @@ extern unsigned aarch64_architecture_version;
  #undef DONT_USE_BUILTIN_SETJMP
  #define DONT_USE_BUILTIN_SETJMP 1
  
+#undef TARGET_COMPUTE_FRAME_LAYOUT
+#define TARGET_COMPUTE_FRAME_LAYOUT aarch64_layout_frame
+
  /* Register in which the structure value is to be returned.  */
  #define AARCH64_STRUCT_VALUE_REGNUM R8_REGNUM
  
diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index b88e7cac27ab76e01b9769563ec9077d2a81bd7b..6a52eecf94011f5a7ee787c1295ca24732af2ff4 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -4021,9 +4021,6 @@ aarch64_layout_frame (void)
    HOST_WIDE_INT offset = 0;
    int regno, last_fp_reg = INVALID_REGNUM;
  
-  if (reload_completed && cfun->machine->frame.laid_out)
-    return;
-
    cfun->machine->frame.emit_frame_chain = aarch64_needs_frame_chain ();
  
  #define SLOT_NOT_REQUIRED (-2)
@@ -4567,8 +4564,6 @@ offset_12bit_unsigned_scaled_p (machine_mode mode, poly_int64 offset)
  static sbitmap
  aarch64_get_separate_components (void)
  {
-  aarch64_layout_frame ();
-
    sbitmap components = sbitmap_alloc (LAST_SAVED_REGNUM + 1);
    bitmap_clear (components);
  
@@ -4592,7 +4587,7 @@ aarch64_get_separate_components (void)
  
    unsigned reg1 = cfun->machine->frame.wb_candidate1;
    unsigned reg2 = cfun->machine->frame.wb_candidate2;
-  /* If aarch64_layout_frame has chosen registers to store/restore with
+  /* If registers have been chosen to be stored/restored with
       writeback don't interfere with them to avoid having to output explicit
       stack adjustment instructions.  */
    if (reg2 != INVALID_REGNUM)
@@ -4850,8 +4845,6 @@ aarch64_add_cfa_expression (rtx_insn *insn, unsigned int reg,
  void
  aarch64_expand_prologue (void)
  {
-  aarch64_layout_frame ();
-
    poly_int64 frame_size = cfun->machine->frame.frame_size;
    poly_int64 initial_adjust = cfun->machine->frame.initial_adjust;
    HOST_WIDE_INT callee_adjust = cfun->machine->frame.callee_adjust;
@@ -4964,8 +4957,6 @@ aarch64_use_return_insn_p (void)
    if (crtl->profile)
      return false;
  
-  aarch64_layout_frame ();
-
    return known_eq (cfun->machine->frame.frame_size, 0);
  }
  
@@ -4977,8 +4968,6 @@ aarch64_use_return_insn_p (void)
  void
  aarch64_expand_epilogue (bool for_sibcall)
  {
-  aarch64_layout_frame ();
-
    poly_int64 initial_adjust = cfun->machine->frame.initial_adjust;
    HOST_WIDE_INT callee_adjust = cfun->machine->frame.callee_adjust;
    poly_int64 final_adjust = cfun->machine->frame.final_adjust;
@@ -7525,8 +7514,6 @@ aarch64_can_eliminate (const int from ATTRIBUTE_UNUSED, const int to)
  poly_int64
  aarch64_initial_elimination_offset (unsigned from, unsigned to)
  {
-  aarch64_layout_frame ();
-
    if (to == HARD_FRAME_POINTER_REGNUM)
      {
        if (from == ARG_POINTER_REGNUM)