From: Jakub Jelinek <jakub@redhat.com>
Date: Mon, 25 Jun 2018 17:36:14 +0000 (+0200)
Subject: backport: re PR debug/84875 (ICE in maybe_record_trace_start, at dwarf2cfi.c:2348... 
X-Git-Tag: releases/gcc-6.5.0~203
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ced17f2e8080a4254cfeadd84b16e3eb0ce353c8;p=thirdparty%2Fgcc.git

backport: re PR debug/84875 (ICE in maybe_record_trace_start, at dwarf2cfi.c:2348 on s390x)

	Backported from mainline
	2018-03-20  Jakub Jelinek  <jakub@redhat.com>

	PR debug/84875
	* dce.c (delete_unmarked_insns): Don't remove frame related noop moves
	holding REG_CFA_RESTORE notes, instead turn them into a USE.

	* gcc.dg/pr84875.c: New test.

From-SVN: r262081
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 321c20592f1e..b3ffed6b477e 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -3,6 +3,10 @@
 	Backported from mainline
 	2018-03-20  Jakub Jelinek  <jakub@redhat.com>
 
+	PR debug/84875
+	* dce.c (delete_unmarked_insns): Don't remove frame related noop moves
+	holding REG_CFA_RESTORE notes, instead turn them into a USE.
+
 	PR c/84953
 	* builtins.c (fold_builtin_strpbrk): For strpbrk(x, "") use type
 	instead of TREE_TYPE (s1) for the return value.
diff --git a/gcc/dce.c b/gcc/dce.c
index ea3fb00d433f..1526a78dc1b7 100644
--- a/gcc/dce.c
+++ b/gcc/dce.c
@@ -558,9 +558,19 @@ delete_unmarked_insns (void)
     FOR_BB_INSNS_REVERSE_SAFE (bb, insn, next)
       if (NONDEBUG_INSN_P (insn))
 	{
+	  rtx turn_into_use = NULL_RTX;
+
 	  /* Always delete no-op moves.  */
 	  if (noop_move_p (insn))
-	    ;
+	    {
+	      if (RTX_FRAME_RELATED_P (insn))
+		turn_into_use
+		  = find_reg_note (insn, REG_CFA_RESTORE, NULL);
+	      if (turn_into_use && REG_P (XEXP (turn_into_use, 0)))
+		turn_into_use = XEXP (turn_into_use, 0);
+	      else
+		turn_into_use = NULL_RTX;
+	    }
 
 	  /* Otherwise rely only on the DCE algorithm.  */
 	  else if (marked_insn_p (insn))
@@ -600,8 +610,19 @@ delete_unmarked_insns (void)
 	  if (CALL_P (insn))
 	    must_clean = true;
 
-	  /* Now delete the insn.  */
-	  delete_insn_and_edges (insn);
+	  if (turn_into_use)
+	    {
+	      /* Don't remove frame related noop moves if they cary
+		 REG_CFA_RESTORE note, while we don't need to emit any code,
+		 we need it to emit the CFI restore note.  */
+	      PATTERN (insn)
+		= gen_rtx_USE (GET_MODE (turn_into_use), turn_into_use);
+	      INSN_CODE (insn) = -1;
+	      df_insn_rescan (insn);
+	    }
+	  else
+	    /* Now delete the insn.  */
+	    delete_insn_and_edges (insn);
 	}
 
   /* Deleted a pure or const call.  */
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 658c662ff16c..f7f3f492e67f 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -3,6 +3,9 @@
 	Backported from mainline
 	2018-03-20  Jakub Jelinek  <jakub@redhat.com>
 
+	PR debug/84875
+	* gcc.dg/pr84875.c: New test.
+
 	PR c/84953
 	* gcc.dg/pr84953.c: New test.
 
diff --git a/gcc/testsuite/gcc.dg/pr84875.c b/gcc/testsuite/gcc.dg/pr84875.c
new file mode 100644
index 000000000000..257176de205c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr84875.c
@@ -0,0 +1,28 @@
+/* PR debug/84875 */
+/* { dg-do compile } */
+/* { dg-options "-Os" } */
+/* { dg-additional-options "-fpie" { target pie } } */
+/* { dg-additional-options "-march=z196" { target s390*-*-* } } */
+
+static long *a[100];
+static int b[100];
+long *c;
+int d;
+void foo (long *);
+
+void
+bar ()
+{
+  long *g = c;
+  g--;
+  d = *g;
+  if (d)
+    if (b[d] < 8)
+      {
+	*(void **)g = a[d];
+	a[d] = g;
+	b[d]++;
+	return;
+      }
+  foo (g);
+}