Fix liveness analysis in lra for spilled-into hard regs

2017-12-12  Tom de Vries  <tom@codesourcery.com>

	PR rtl-optimization/83327
	* lra-int.h (hard_regs_spilled_into): Declare.
	* lra.c (hard_regs_spilled_into): Define.
	(init_reg_info): Init hard_regs_spilled_into.
	* lra-spills.c (assign_spill_hard_regs): Update hard_regs_spilled_into.
	* lra-lives.c (make_hard_regno_born, make_hard_regno_dead)
	(process_bb_lives): Handle hard_regs_spilled_into.
	(lra_create_live_ranges_1): Before doing liveness propagation, clear
	regs in all_hard_regs_bitmap if set in hard_regs_spilled_into.

---
 gcc/lra-int.h    |  2 ++
 gcc/lra-lives.c  | 28 ++++++++++++++++++++++++++--
 gcc/lra-spills.c |  2 ++
 gcc/lra.c        |  3 +++
 4 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/gcc/lra-int.h b/gcc/lra-int.h
index 5a519b0..064961a 100644
--- a/gcc/lra-int.h
+++ b/gcc/lra-int.h
@@ -122,6 +122,8 @@ struct lra_reg
 /* References to the common info about each register.  */
 extern struct lra_reg *lra_reg_info;
 
+extern HARD_REG_SET hard_regs_spilled_into;
+
 /* Static info about each insn operand (common for all insns with the
    same ICODE).	 Warning: if the structure definition is changed, the
    initializer for debug_operand_data in lra.c should be changed
diff --git a/gcc/lra-lives.c b/gcc/lra-lives.c
index 03dfec2..85da626 100644
--- a/gcc/lra-lives.c
+++ b/gcc/lra-lives.c
@@ -245,7 +245,7 @@ make_hard_regno_born (int regno, bool check_pic_pseudo_p ATTRIBUTE_UNUSED)
 	|| i != REGNO (pic_offset_table_rtx))
 #endif
       SET_HARD_REG_BIT (lra_reg_info[i].conflict_hard_regs, regno);
-  if (fixed_regs[regno])
+  if (fixed_regs[regno] || TEST_HARD_REG_BIT (hard_regs_spilled_into, regno))
     bitmap_set_bit (bb_gen_pseudos, regno);
 }
 
@@ -259,7 +259,7 @@ make_hard_regno_dead (int regno)
     return;
   sparseset_set_bit (start_dying, regno);
   CLEAR_HARD_REG_BIT (hard_regs_live, regno);
-  if (fixed_regs[regno])
+  if (fixed_regs[regno] || TEST_HARD_REG_BIT (hard_regs_spilled_into, regno))
     {
       bitmap_clear_bit (bb_gen_pseudos, regno);
       bitmap_set_bit (bb_killed_pseudos, regno);
@@ -1051,6 +1051,25 @@ process_bb_lives (basic_block bb, int &curr_point, bool dead_insn_p)
 	check_pseudos_live_through_calls (j, last_call_used_reg_set);
     }
 
+  for (i = 0; i < FIRST_PSEUDO_REGISTER; ++i)
+    {
+      if (!TEST_HARD_REG_BIT (hard_regs_live, i))
+	continue;
+
+      if (!TEST_HARD_REG_BIT (hard_regs_spilled_into, i))
+	continue;
+
+      if (bitmap_bit_p (df_get_live_in (bb), i))
+	continue;
+
+      live_change_p = true;
+      if (lra_dump_file)
+	fprintf (lra_dump_file,
+		 "  hard reg r%d is added to live at bb%d start\n", i,
+		 bb->index);
+      bitmap_set_bit (df_get_live_in (bb), i);
+    }
+
   if (need_curr_point_incr)
     next_program_point (curr_point, freq);
 
@@ -1320,6 +1339,11 @@ lra_create_live_ranges_1 (bool all_p, bool dead_insn_p)
 	}
       /* As we did not change CFG since LRA start we can use
 	 DF-infrastructure solver to solve live data flow problem.  */
+      for (int i = 0; i < FIRST_PSEUDO_REGISTER; ++i)
+	{
+	  if (TEST_HARD_REG_BIT (hard_regs_spilled_into, i))
+	    bitmap_clear_bit (&all_hard_regs_bitmap, i);
+	}
       df_simple_dataflow
 	(DF_BACKWARD, NULL, live_con_fun_0, live_con_fun_n,
 	 live_trans_fun, &all_blocks,
diff --git a/gcc/lra-spills.c b/gcc/lra-spills.c
index af11b3d..ab13b21 100644
--- a/gcc/lra-spills.c
+++ b/gcc/lra-spills.c
@@ -291,6 +291,8 @@ assign_spill_hard_regs (int *pseudo_regnos, int n)
 	}
       if (lra_dump_file != NULL)
 	fprintf (lra_dump_file, "  Spill r%d into hr%d\n", regno, hard_regno);
+      add_to_hard_reg_set (&hard_regs_spilled_into,
+			   lra_reg_info[regno].biggest_mode, hard_regno);
       /* Update reserved_hard_regs.  */
       for (r = lra_reg_info[regno].live_ranges; r != NULL; r = r->next)
 	for (p = r->start; p <= r->finish; p++)
diff --git a/gcc/lra.c b/gcc/lra.c
index fec2383..047e64f 100644
--- a/gcc/lra.c
+++ b/gcc/lra.c
@@ -1270,6 +1270,8 @@ static int reg_info_size;
 /* Common info about each register.  */
 struct lra_reg *lra_reg_info;
 
+HARD_REG_SET hard_regs_spilled_into;
+
 /* Last register value.	 */
 static int last_reg_value;
 
@@ -1319,6 +1321,7 @@ init_reg_info (void)
   for (i = 0; i < reg_info_size; i++)
     initialize_lra_reg_info_element (i);
   copy_vec.truncate (0);
+  CLEAR_HARD_REG_SET (hard_regs_spilled_into);
 }