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* [PATCH] Fix x86_64 ICE with -fpie -mcmodel=large (PR target/81766)
@ 2017-09-01 11:42 Jakub Jelinek
  2017-09-01 16:22 ` Uros Bizjak
  0 siblings, 1 reply; 2+ messages in thread
From: Jakub Jelinek @ 2017-09-01 11:42 UTC (permalink / raw)
  To: Uros Bizjak; +Cc: gcc-patches

Hi!

As mentioned in the PR, ix86_init_pic_reg for -mcmodel=large PIC creates
invalid RTL.  Shrink wrapping managed to work around it by unconditionally
running find_many_sub_basic_blocks that has been invoked even when the
prologue or split prologue actually didn't contain anything, but that isn't
done anymore.

The problem is that we add a label into the sequence that we then insert on
the single succ edge after ENTRY; but this insertion inserts the label after
the NOTE_INSN_BLOCK_BEG, which is invalid, because labels should precede
that.

Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux, ok for
trunk?

2017-09-01  Jakub Jelinek  <jakub@redhat.com>

	PR target/81766
	* config/i386/i386.c (ix86_init_large_pic_reg): Return label instead of void.
	(ix86_init_pic_reg): Remember label from ix86_init_large_pic_reg, if non-NULL
	and preceded by NOTE_INSN_BASIC_BLOCK, swap the note and label.

	* gcc.target/i386/pr81766.c: New test.

--- gcc/config/i386/i386.c.jj	2017-08-07 18:50:10.000000000 +0200
+++ gcc/config/i386/i386.c	2017-08-08 16:01:41.917136120 +0200
@@ -8829,7 +8829,7 @@ ix86_use_pseudo_pic_reg (void)
 
 /* Initialize large model PIC register.  */
 
-static void
+static rtx_code_label *
 ix86_init_large_pic_reg (unsigned int tmp_regno)
 {
   rtx_code_label *label;
@@ -8846,6 +8846,7 @@ ix86_init_large_pic_reg (unsigned int tm
   emit_insn (gen_set_got_offset_rex64 (tmp_reg, label));
   emit_insn (ix86_gen_add3 (pic_offset_table_rtx,
 			    pic_offset_table_rtx, tmp_reg));
+  return label;
 }
 
 /* Create and initialize PIC register if required.  */
@@ -8854,6 +8855,7 @@ ix86_init_pic_reg (void)
 {
   edge entry_edge;
   rtx_insn *seq;
+  rtx_code_label *label = NULL;
 
   if (!ix86_use_pseudo_pic_reg ())
     return;
@@ -8863,7 +8865,7 @@ ix86_init_pic_reg (void)
   if (TARGET_64BIT)
     {
       if (ix86_cmodel == CM_LARGE_PIC)
-	ix86_init_large_pic_reg (R11_REG);
+	label = ix86_init_large_pic_reg (R11_REG);
       else
 	emit_insn (gen_set_got_rex64 (pic_offset_table_rtx));
     }
@@ -8887,6 +8889,22 @@ ix86_init_pic_reg (void)
   entry_edge = single_succ_edge (ENTRY_BLOCK_PTR_FOR_FN (cfun));
   insert_insn_on_edge (seq, entry_edge);
   commit_one_edge_insertion (entry_edge);
+
+  if (label)
+    {
+      basic_block bb = BLOCK_FOR_INSN (label);
+      rtx_insn *bb_note = PREV_INSN (label);
+      /* If the note preceding the label starts a basic block, and the
+	 label is a member of the same basic block, interchange the two.  */
+      if (bb_note != NULL_RTX
+	  && NOTE_INSN_BASIC_BLOCK_P (bb_note)
+	  && bb != NULL
+	  && bb == BLOCK_FOR_INSN (bb_note))
+	{
+	  reorder_insns_nobb (bb_note, bb_note, label);
+	  BB_HEAD (bb) = label;
+	}
+    }
 }
 
 /* Initialize a variable CUM of type CUMULATIVE_ARGS
--- gcc/testsuite/gcc.target/i386/pr81766.c.jj	2017-08-08 16:10:04.299459808 +0200
+++ gcc/testsuite/gcc.target/i386/pr81766.c	2017-08-08 16:09:28.000000000 +0200
@@ -0,0 +1,9 @@
+/* PR target/81766 */
+/* { dg-do compile { target { pie && lp64 } } } */
+/* { dg-options "-O2 -fpie -mcmodel=large" } */
+
+int
+main ()
+{
+  return 0;
+}

	Jakub

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2017-09-01 11:42 [PATCH] Fix x86_64 ICE with -fpie -mcmodel=large (PR target/81766) Jakub Jelinek
2017-09-01 16:22 ` Uros Bizjak

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