gcc/

	Backport from trunk r232819.
	2016-01-26  Jakub Jelinek  <jakub@redhat.com>

	PR target/69442
	* combine.c (combine_instructions): For REG_EQUAL note with
	SET_DEST being ZERO_EXTRACT, also temporarily set SET_DEST
	to the underlying register.
	* doc/rtl.texi (REG_EQUAL): Document the behavior of
	REG_EQUAL/REG_EQUIV notes if SET_DEST is ZERO_EXTRACT.

	gcc/testsuite/
	Backport from trunk r232819.
	2016-01-26  Jakub Jelinek  <jakub@redhat.com>

	PR target/69442
	* gcc.dg/pr69442.c: New test.

Change-Id: I532abd16f2b2f21167b45d704f9901326d33d8dc

3 files changed, 37 insertions, 7 deletions

diff --git a/gcc/combine.c b/gcc/combine.c
index f117015bb72..c00d82b8ef5 100644
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -1494,15 +1494,21 @@ combine_instructions (rtx_insn *f, unsigned int nregs)
 		  && ! unmentioned_reg_p (note, SET_SRC (set))
 		  && (GET_MODE (note) == VOIDmode
 		      ? SCALAR_INT_MODE_P (GET_MODE (SET_DEST (set)))
-		      : GET_MODE (SET_DEST (set)) == GET_MODE (note)))
+		      : (GET_MODE (SET_DEST (set)) == GET_MODE (note)
+			 && (GET_CODE (SET_DEST (set)) != ZERO_EXTRACT
+			     || (GET_MODE (XEXP (SET_DEST (set), 0))
+				 == GET_MODE (note))))))
 		{
 		  /* Temporarily replace the set's source with the
 		     contents of the REG_EQUAL note.  The insn will
 		     be deleted or recognized by try_combine.  */
-		  rtx orig = SET_SRC (set);
+		  rtx orig_src = SET_SRC (set);
+		  rtx orig_dest = SET_DEST (set);
+		  if (GET_CODE (SET_DEST (set)) == ZERO_EXTRACT)
+		    SET_DEST (set) = XEXP (SET_DEST (set), 0);
 		  SET_SRC (set) = note;
 		  i2mod = temp;
-		  i2mod_old_rhs = copy_rtx (orig);
+		  i2mod_old_rhs = copy_rtx (orig_src);
 		  i2mod_new_rhs = copy_rtx (note);
 		  next = try_combine (insn, i2mod, NULL, NULL,
 				      &new_direct_jump_p,
@@ -1513,7 +1519,8 @@ combine_instructions (rtx_insn *f, unsigned int nregs)
 		      statistics_counter_event (cfun, "insn-with-note combine", 1);
 		      goto retry;
 		    }
-		  SET_SRC (set) = orig;
+		  SET_SRC (set) = orig_src;
+		  SET_DEST (set) = orig_dest;
 		}
 	    }
 
diff --git a/gcc/doc/rtl.texi b/gcc/doc/rtl.texi
index 141c957c99f..1c1fc9dc9a2 100644
--- a/gcc/doc/rtl.texi
+++ b/gcc/doc/rtl.texi
@@ -3915,9 +3915,9 @@ indicates that that register will be equal to @var{op} at run time; the
 scope of this equivalence differs between the two types of notes.  The
 value which the insn explicitly copies into the register may look
 different from @var{op}, but they will be equal at run time.  If the
-output of the single @code{set} is a @code{strict_low_part} expression,
-the note refers to the register that is contained in @code{SUBREG_REG}
-of the @code{subreg} expression.
+output of the single @code{set} is a @code{strict_low_part} or
+@code{zero_extract} expression, the note refers to the register that
+is contained in its first operand.
 
 For @code{REG_EQUIV}, the register is equivalent to @var{op} throughout
 the entire function, and could validly be replaced in all its
diff --git a/gcc/testsuite/gcc.dg/pr69442.c b/gcc/testsuite/gcc.dg/pr69442.c
new file mode 100644
index 00000000000..ee75f92951a
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr69442.c
@@ -0,0 +1,23 @@
+/* PR target/69442 */
+/* { dg-do run } */
+/* { dg-options "-Og" } */
+
+unsigned long long __attribute__ ((noinline, noclone))
+foo (unsigned int x, unsigned long long y)
+{
+  x |= 0xffff;
+  y -= 0xffULL;
+  y %= 0xffff0000ffffffe7ULL;
+  return x + y;
+}
+
+int
+main ()
+{
+  if (sizeof (unsigned long long) * __CHAR_BIT__ != 64)
+    return 0;
+
+  if (foo (0, 0) != 0xffff0000ff19ULL)
+    __builtin_abort ();
+  return 0;
+}