package/gcc: fix ICE on xtensa, 6.2, PR target/78118

This fixes gcc build for xtensa configurations with call0 ABI.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/gcc/6.2.0/870-xtensa-Fix-PR-target-78118.patch

@@ -0,0 +1,320 @@
+From 0d2556fa652cc85b3d042e862a38dd07d454175a Mon Sep 17 00:00:00 2001
+From: Max Filippov <jcmvbkbc@gmail.com>
+Date: Wed, 26 Oct 2016 08:02:51 +0000
+Subject: [PATCH 1/2] xtensa: Fix PR target/78118
+
+It started failing after the following commit: 32e90dc6a0cda45 ("PR
+rtl-optimization/61047").
+
+The change that made xtensa backend go ICE looks completely unrelated,
+and indeed, the issue is caused by the side effect of
+compute_frame_size() function call hidden in the
+INITIAL_ELIMINATION_OFFSET macro. This call updates the value of the
+xtensa_current_frame_size static variable, used in "return" instruction
+predicate. Prior to the change the value of xtensa_current_frame_size was
+set to 0 after the end of epilogue generation, which enabled the "return"
+instruction for the CALL0 ABI, but after the change the additional
+INITIAL_ELIMINATION_OFFSET calls make xtensa_current_frame_size non-zero
+and "return" pattern unavailable.
+
+Get rid of the global xtensa_current_frame_size and
+xtensa_callee_save_size variables by moving them into the
+machine_function structure. Implement predicate for the "return" pattern
+as a function. Don't communicate completion of epilogue generation
+through zeroing of xtensa_current_frame_size, add explicit epilogue_done
+variable to the machine_function structure. Don't update stack frame
+layout after the completion of reload.
+
+2016-10-26  Max Filippov  <jcmvbkbc@gmail.com>
+gcc/
+	* config/xtensa/xtensa-protos.h
+	(xtensa_use_return_instruction_p): New prototype.
+	* config/xtensa/xtensa.c (xtensa_current_frame_size,
+	xtensa_callee_save_size): Remove.
+	(struct machine_function): Add new fields: current_frame_size,
+	callee_save_size, frame_laid_out and epilogue_done.
+	(compute_frame_size, xtensa_expand_prologue,
+	xtensa_expand_epilogue): Replace xtensa_callee_save_size with
+	cfun->machine->callee_save_size and xtensa_current_frame_size
+	with cfun->machine->current_frame_size.
+	(compute_frame_size): Update cfun->machine->frame_laid_out and
+	don't update frame layout after reload completion.
+	(xtensa_expand_epilogue): Set cfun->machine->epilogue_done
+	instead of zeroing xtensa_current_frame_size.
+	(xtensa_use_return_instruction_p): New function.
+	* config/xtensa/xtensa.h (xtensa_current_frame_size): Remove
+	declaration.
+	(INITIAL_ELIMINATION_OFFSET): Use return value of
+	compute_frame_size instead of xtensa_current_frame_size value.
+	* config/xtensa/xtensa.md ("return" pattern): Use new predicate
+	function xtensa_use_return_instruction_p instead of inline code.
+
+Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
+---
+Backported from: r241748
+
+ gcc/config/xtensa/xtensa-protos.h |  1 +
+ gcc/config/xtensa/xtensa.c        | 82 ++++++++++++++++++++++++---------------
+ gcc/config/xtensa/xtensa.h        |  6 +--
+ gcc/config/xtensa/xtensa.md       |  2 +-
+ 4 files changed, 55 insertions(+), 36 deletions(-)
+
+diff --git a/gcc/config/xtensa/xtensa-protos.h b/gcc/config/xtensa/xtensa-protos.h
+index f2ca526..873557f 100644
+--- a/gcc/config/xtensa/xtensa-protos.h
++++ b/gcc/config/xtensa/xtensa-protos.h
+@@ -68,6 +68,7 @@ extern rtx xtensa_return_addr (int, rtx);
+ extern void xtensa_setup_frame_addresses (void);
+ extern int xtensa_dbx_register_number (int);
+ extern long compute_frame_size (int);
++extern bool xtensa_use_return_instruction_p (void);
+ extern void xtensa_expand_prologue (void);
+ extern void xtensa_expand_epilogue (void);
+ extern void order_regs_for_local_alloc (void);
+diff --git a/gcc/config/xtensa/xtensa.c b/gcc/config/xtensa/xtensa.c
+index 64d089b..e49f784 100644
+--- a/gcc/config/xtensa/xtensa.c
++++ b/gcc/config/xtensa/xtensa.c
+@@ -78,11 +78,6 @@ enum internal_test
+    can support a given mode.  */
+ char xtensa_hard_regno_mode_ok[(int) MAX_MACHINE_MODE][FIRST_PSEUDO_REGISTER];
+ 
+-/* Current frame size calculated by compute_frame_size.  */
+-unsigned xtensa_current_frame_size;
+-/* Callee-save area size in the current frame calculated by compute_frame_size. */
+-int xtensa_callee_save_size;
+-
+ /* Largest block move to handle in-line.  */
+ #define LARGEST_MOVE_RATIO 15
+ 
+@@ -94,6 +89,13 @@ struct GTY(()) machine_function
+   bool vararg_a7;
+   rtx vararg_a7_copy;
+   rtx_insn *set_frame_ptr_insn;
++  /* Current frame size calculated by compute_frame_size.  */
++  unsigned current_frame_size;
++  /* Callee-save area size in the current frame calculated by
++     compute_frame_size.  */
++  int callee_save_size;
++  bool frame_laid_out;
++  bool epilogue_done;
+ };
+ 
+ /* Vector, indexed by hard register number, which contains 1 for a
+@@ -2628,24 +2630,29 @@ compute_frame_size (int size)
+ {
+   int regno;
+ 
++  if (reload_completed && cfun->machine->frame_laid_out)
++    return cfun->machine->current_frame_size;
++
+   /* Add space for the incoming static chain value.  */
+   if (cfun->static_chain_decl != NULL)
+     size += (1 * UNITS_PER_WORD);
+ 
+-  xtensa_callee_save_size = 0;
++  cfun->machine->callee_save_size = 0;
+   for (regno = 0; regno < FIRST_PSEUDO_REGISTER; ++regno)
+     {
+       if (xtensa_call_save_reg(regno))
+-	xtensa_callee_save_size += UNITS_PER_WORD;
++	cfun->machine->callee_save_size += UNITS_PER_WORD;
+     }
+ 
+-  xtensa_current_frame_size =
++  cfun->machine->current_frame_size =
+     XTENSA_STACK_ALIGN (size
+-			+ xtensa_callee_save_size
++			+ cfun->machine->callee_save_size
+ 			+ crtl->outgoing_args_size
+ 			+ (WINDOW_SIZE * UNITS_PER_WORD));
+-  xtensa_callee_save_size = XTENSA_STACK_ALIGN (xtensa_callee_save_size);
+-  return xtensa_current_frame_size;
++  cfun->machine->callee_save_size =
++    XTENSA_STACK_ALIGN (cfun->machine->callee_save_size);
++  cfun->machine->frame_laid_out = true;
++  return cfun->machine->current_frame_size;
+ }
+ 
+ 
+@@ -2696,6 +2703,7 @@ xtensa_expand_prologue (void)
+     {
+       int regno;
+       HOST_WIDE_INT offset = 0;
++      int callee_save_size = cfun->machine->callee_save_size;
+ 
+       /* -128 is a limit of single addi instruction. */
+       if (total_size > 0 && total_size <= 128)
+@@ -2709,7 +2717,7 @@ xtensa_expand_prologue (void)
+ 	  add_reg_note (insn, REG_FRAME_RELATED_EXPR, note_rtx);
+ 	  offset = total_size - UNITS_PER_WORD;
+ 	}
+-      else if (xtensa_callee_save_size)
++      else if (callee_save_size)
+ 	{
+ 	  /* 1020 is maximal s32i offset, if the frame is bigger than that
+ 	   * we move sp to the end of callee-saved save area, save and then
+@@ -2717,13 +2725,13 @@ xtensa_expand_prologue (void)
+ 	  if (total_size > 1024)
+ 	    {
+ 	      insn = emit_insn (gen_addsi3 (stack_pointer_rtx, stack_pointer_rtx,
+-					    GEN_INT (-xtensa_callee_save_size)));
++					    GEN_INT (-callee_save_size)));
+ 	      RTX_FRAME_RELATED_P (insn) = 1;
+ 	      note_rtx = gen_rtx_SET (stack_pointer_rtx,
+ 				      plus_constant (Pmode, stack_pointer_rtx,
+-						     -xtensa_callee_save_size));
++						     -callee_save_size));
+ 	      add_reg_note (insn, REG_FRAME_RELATED_EXPR, note_rtx);
+-	      offset = xtensa_callee_save_size - UNITS_PER_WORD;
++	      offset = callee_save_size - UNITS_PER_WORD;
+ 	    }
+ 	  else
+ 	    {
+@@ -2759,13 +2767,13 @@ xtensa_expand_prologue (void)
+ 	{
+ 	  rtx tmp_reg = gen_rtx_REG (Pmode, A9_REG);
+ 	  emit_move_insn (tmp_reg, GEN_INT (total_size -
+-					    xtensa_callee_save_size));
++					    callee_save_size));
+ 	  insn = emit_insn (gen_subsi3 (stack_pointer_rtx,
+ 					stack_pointer_rtx, tmp_reg));
+ 	  RTX_FRAME_RELATED_P (insn) = 1;
+ 	  note_rtx = gen_rtx_SET (stack_pointer_rtx,
+ 				  plus_constant (Pmode, stack_pointer_rtx,
+-						 xtensa_callee_save_size -
++						 callee_save_size -
+ 						 total_size));
+ 	  add_reg_note (insn, REG_FRAME_RELATED_EXPR, note_rtx);
+ 	}
+@@ -2833,21 +2841,21 @@ xtensa_expand_epilogue (void)
+       int regno;
+       HOST_WIDE_INT offset;
+ 
+-      if (xtensa_current_frame_size > (frame_pointer_needed ? 127 : 1024))
++      if (cfun->machine->current_frame_size > (frame_pointer_needed ? 127 : 1024))
+ 	{
+ 	  rtx tmp_reg = gen_rtx_REG (Pmode, A9_REG);
+-	  emit_move_insn (tmp_reg, GEN_INT (xtensa_current_frame_size -
+-					    xtensa_callee_save_size));
++	  emit_move_insn (tmp_reg, GEN_INT (cfun->machine->current_frame_size -
++					    cfun->machine->callee_save_size));
+ 	  emit_insn (gen_addsi3 (stack_pointer_rtx, frame_pointer_needed ?
+ 				 hard_frame_pointer_rtx : stack_pointer_rtx,
+ 				 tmp_reg));
+-	  offset = xtensa_callee_save_size - UNITS_PER_WORD;
++	  offset = cfun->machine->callee_save_size - UNITS_PER_WORD;
+ 	}
+       else
+ 	{
+ 	  if (frame_pointer_needed)
+ 	    emit_move_insn (stack_pointer_rtx, hard_frame_pointer_rtx);
+-	  offset = xtensa_current_frame_size - UNITS_PER_WORD;
++	  offset = cfun->machine->current_frame_size - UNITS_PER_WORD;
+ 	}
+ 
+       /* Prevent reordering of saved a0 update and loading it back from
+@@ -2867,16 +2875,16 @@ xtensa_expand_epilogue (void)
+ 	    }
+ 	}
+ 
+-      if (xtensa_current_frame_size > 0)
++      if (cfun->machine->current_frame_size > 0)
+ 	{
+ 	  if (frame_pointer_needed || /* always reachable with addi */
+-	      xtensa_current_frame_size > 1024 ||
+-	      xtensa_current_frame_size <= 127)
++	      cfun->machine->current_frame_size > 1024 ||
++	      cfun->machine->current_frame_size <= 127)
+ 	    {
+-	      if (xtensa_current_frame_size <= 127)
+-		offset = xtensa_current_frame_size;
++	      if (cfun->machine->current_frame_size <= 127)
++		offset = cfun->machine->current_frame_size;
+ 	      else
+-		offset = xtensa_callee_save_size;
++		offset = cfun->machine->callee_save_size;
+ 
+ 	      emit_insn (gen_addsi3 (stack_pointer_rtx,
+ 				     stack_pointer_rtx,
+@@ -2885,7 +2893,8 @@ xtensa_expand_epilogue (void)
+ 	  else
+ 	    {
+ 	      rtx tmp_reg = gen_rtx_REG (Pmode, A9_REG);
+-	      emit_move_insn (tmp_reg, GEN_INT (xtensa_current_frame_size));
++	      emit_move_insn (tmp_reg,
++			      GEN_INT (cfun->machine->current_frame_size));
+ 	      emit_insn (gen_addsi3 (stack_pointer_rtx, stack_pointer_rtx,
+ 				     tmp_reg));
+ 	    }
+@@ -2896,11 +2905,22 @@ xtensa_expand_epilogue (void)
+ 				  stack_pointer_rtx,
+ 				  EH_RETURN_STACKADJ_RTX));
+     }
+-  xtensa_current_frame_size = 0;
+-  xtensa_callee_save_size = 0;
++  cfun->machine->epilogue_done = true;
+   emit_jump_insn (gen_return ());
+ }
+ 
++bool
++xtensa_use_return_instruction_p (void)
++{
++  if (!reload_completed)
++    return false;
++  if (TARGET_WINDOWED_ABI)
++    return true;
++  if (compute_frame_size (get_frame_size ()) == 0)
++    return true;
++  return cfun->machine->epilogue_done;
++}
++
+ void
+ xtensa_set_return_address (rtx address, rtx scratch)
+ {
+diff --git a/gcc/config/xtensa/xtensa.h b/gcc/config/xtensa/xtensa.h
+index 82e9900..58eb1b2 100644
+--- a/gcc/config/xtensa/xtensa.h
++++ b/gcc/config/xtensa/xtensa.h
+@@ -23,8 +23,6 @@ along with GCC; see the file COPYING3.  If not see
+ 
+ /* External variables defined in xtensa.c.  */
+ 
+-extern unsigned xtensa_current_frame_size;
+-
+ /* Macros used in the machine description to select various Xtensa
+    configuration options.  */
+ #ifndef XCHAL_HAVE_MUL32_HIGH
+@@ -477,14 +475,14 @@ enum reg_class
+ /* Specify the initial difference between the specified pair of registers.  */
+ #define INITIAL_ELIMINATION_OFFSET(FROM, TO, OFFSET)			\
+   do {									\
+-    compute_frame_size (get_frame_size ());				\
++    long frame_size = compute_frame_size (get_frame_size ());		\
+     switch (FROM)							\
+       {									\
+       case FRAME_POINTER_REGNUM:					\
+         (OFFSET) = 0;							\
+ 	break;								\
+       case ARG_POINTER_REGNUM:						\
+-        (OFFSET) = xtensa_current_frame_size;				\
++        (OFFSET) = frame_size;						\
+ 	break;								\
+       default:								\
+ 	gcc_unreachable ();						\
+diff --git a/gcc/config/xtensa/xtensa.md b/gcc/config/xtensa/xtensa.md
+index db54a12..fcdb6c8 100644
+--- a/gcc/config/xtensa/xtensa.md
++++ b/gcc/config/xtensa/xtensa.md
+@@ -1663,7 +1663,7 @@
+ (define_insn "return"
+   [(return)
+    (use (reg:SI A0_REG))]
+-  "(TARGET_WINDOWED_ABI || !xtensa_current_frame_size) && reload_completed"
++  "xtensa_use_return_instruction_p ()"
+ {
+   return TARGET_WINDOWED_ABI ?
+       (TARGET_DENSITY ? "retw.n" : "retw") :
+-- 
+2.1.4
+