--- /dev/null
+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
+
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