From: Jakub Jelinek <jakub@redhat.com>
Date: Thu, 31 Mar 2016 13:21:43 +0000 (+0200)
Subject: re PR rtl-optimization/70460 (Miscompilation of glibc on i686-linux starting with... 
X-Git-Tag: releases/gcc-4.9.4~247
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=51b334cdd2bdfcc21381e9a05df5d222987c8f1a;p=thirdparty%2Fgcc.git

re PR rtl-optimization/70460 (Miscompilation of glibc on i686-linux starting with r234101)

	PR rtl-optimization/70460
	* ira.c (indirect_jump_optimize): Don't substitute LABEL_REF
	with operand from REG_LABEL_OPERAND, instead substitute
	SET_SRC or REG_EQUAL note content if it is a LABEL_REF.
	Don't do anything for REG_NON_LOCAL_GOTO jumps.

	* gcc.c-torture/execute/pr70460.c: New test.

From-SVN: r234618
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index b0db665b472b..2d2631c82dba 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2016-03-31  Jakub Jelinek  <jakub@redhat.com>
+
+	PR rtl-optimization/70460
+	* ira.c (indirect_jump_optimize): Don't substitute LABEL_REF
+	with operand from REG_LABEL_OPERAND, instead substitute
+	SET_SRC or REG_EQUAL note content if it is a LABEL_REF.
+	Don't do anything for REG_NON_LOCAL_GOTO jumps.
+
 2016-03-31  Alan Modra  <amodra@gmail.com>
 
 	Backport from mainline
diff --git a/gcc/ira.c b/gcc/ira.c
index 2c00990ff283..ca1bf38b9e65 100644
--- a/gcc/ira.c
+++ b/gcc/ira.c
@@ -3937,7 +3937,8 @@ indirect_jump_optimize (void)
   FOR_EACH_BB_REVERSE_FN (bb, cfun)
     {
       rtx insn = BB_END (bb);
-      if (!JUMP_P (insn))
+      if (!JUMP_P (insn)
+	  || find_reg_note (insn, REG_NON_LOCAL_GOTO, NULL_RTX))
 	continue;
 
       rtx x = pc_set (insn);
@@ -3951,19 +3952,18 @@ indirect_jump_optimize (void)
 	  if (!DF_REF_IS_ARTIFICIAL (def))
 	    {
 	      rtx def_insn = DF_REF_INSN (def);
-	      rtx note = find_reg_note (def_insn, REG_LABEL_OPERAND, NULL_RTX);
-
-	      if (note)
+	      rtx lab = NULL_RTX;
+	      rtx set = single_set (def_insn);
+	      if (set && GET_CODE (SET_SRC (set)) == LABEL_REF)
+		lab = SET_SRC (set);
+	      else
 		{
-		  /* Substitute a LABEL_REF to the label given by the
-		     note rather than using SET_SRC of DEF_INSN.
-		     DEF_INSN might be loading the label constant from
-		     a constant pool, which isn't what we want in a
-		     direct branch.  */
-		  rtx lab = gen_rtx_LABEL_REF (Pmode, XEXP (note, 0));
-		  if (validate_replace_rtx (SET_SRC (x), lab, insn))
-		    rebuild_p = true;
+		  rtx eqnote = find_reg_note (def_insn, REG_EQUAL, NULL_RTX);
+		  if (eqnote && GET_CODE (XEXP (eqnote, 0)) == LABEL_REF)
+		    lab = XEXP (eqnote, 0);
 		}
+	      if (lab && validate_replace_rtx (SET_SRC (x), lab, insn))
+		rebuild_p = true;
 	    }
 	}
     }
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 0b6ed07609b0..c440eae34476 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2016-03-31  Jakub Jelinek  <jakub@redhat.com>
+
+	PR rtl-optimization/70460
+	* gcc.c-torture/execute/pr70460.c: New test.
+
 2016-02-29  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
 
 	PR target/69875
diff --git a/gcc/testsuite/gcc.c-torture/execute/pr70460.c b/gcc/testsuite/gcc.c-torture/execute/pr70460.c
new file mode 100644
index 000000000000..bfecea0932e9
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/pr70460.c
@@ -0,0 +1,29 @@
+/* PR rtl-optimization/70460 */
+
+int c;
+
+__attribute__((noinline, noclone)) void
+foo (int x)
+{
+  static int b[] = { &&lab1 - &&lab0, &&lab2 - &&lab0 };
+  void *a = &&lab0 + b[x];
+  goto *a;
+lab1:
+  c += 2;
+lab2:
+  c++;
+lab0:
+  ;
+}
+
+int
+main ()
+{
+  foo (0);
+  if (c != 3)
+    __builtin_abort ();
+  foo (1);
+  if (c != 4)
+    __builtin_abort ();
+  return 0;
+}