commit 7ca1b135babbe3a542c850591e1b0e8736a19f55
Author: Kyrylo Tkachov <kyrylo.tkachov@arm.com>
Date:   Fri Nov 13 15:01:47 2015 +0000

    [RTL-ree] PR rtl-optimization/68194: Restrict copy instruction in presence of conditional moves

diff --git a/gcc/ree.c b/gcc/ree.c
index b8436f2..e91d164 100644
--- a/gcc/ree.c
+++ b/gcc/ree.c
@@ -814,7 +814,30 @@ combine_reaching_defs (ext_cand *cand, const_rtx set_pat, ext_state *state)
 
       rtx tmp_reg = gen_rtx_REG (GET_MODE (SET_DEST (PATTERN (cand->insn))),
 				 REGNO (SET_DEST (*dest_sub_rtx)));
-      if (reg_overlap_mentioned_p (tmp_reg, SET_DEST (PATTERN (cand->insn))))
+
+      /* When transforming:
+	(set (reg1) (expression))
+	 ...
+	(set (reg2) (any_extend (reg1)))
+
+	into
+
+	(set (reg2) (any_extend (expression)))
+	(set (reg1) (reg2))
+	make sure that reg1 from the first set feeds directly into the extend.
+	This may not hold in a situation with an intermediate
+	conditional copy i.e.
+	I1: (set (reg3) (expression))
+	I2: (set (reg1) (cond ? reg3 : reg1))
+	I3: (set (reg2) (any_extend (reg1)))
+
+	where I3 is cand, I1 is def_insn and I2 is a conditional copy.
+	We want to avoid transforming that into:
+	(set (reg2) (any_extend (expression)))
+	(set (reg1) (reg2))
+	(set (reg1) (cond ? reg3 : reg1)).  */
+      if (reg_overlap_mentioned_p (tmp_reg, SET_DEST (PATTERN (cand->insn)))
+	  || !reg_overlap_mentioned_p (tmp_reg, SET_SRC (PATTERN (cand->insn))))
 	return false;
 
       /* The destination register of the extension insn must not be
diff --git a/gcc/testsuite/gcc.c-torture/execute/pr68185.c b/gcc/testsuite/gcc.c-torture/execute/pr68185.c
new file mode 100644
index 0000000..826531b
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/pr68185.c
@@ -0,0 +1,29 @@
+int a, b, d = 1, e, f, o, u, w = 1, z;
+short c, q, t;
+
+int
+main ()
+{
+  char g;
+  for (; d; d--)
+    {
+      while (o)
+	for (; e;)
+	  {
+	    c = b;
+	    int h = o = z;
+	    for (; u;)
+	      for (; a;)
+		;
+	  }
+      if (t < 1)
+	g = w;
+      f = g;
+      g && (q = 1);
+    }
+
+  if (q != 1)
+    __builtin_abort ();
+
+  return 0;
+}
diff --git a/gcc/testsuite/gcc.c-torture/execute/pr68328.c b/gcc/testsuite/gcc.c-torture/execute/pr68328.c
new file mode 100644
index 0000000..edf244b
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/pr68328.c
@@ -0,0 +1,44 @@
+int a, b, c = 1, d = 1, e;
+
+__attribute__ ((noinline, noclone))
+     int foo (void)
+{
+  asm volatile ("":::"memory");
+  return 4195552;
+}
+
+__attribute__ ((noinline, noclone))
+     void bar (int x, int y)
+{
+  asm volatile (""::"g" (x), "g" (y):"memory");
+  if (y == 0)
+    __builtin_abort ();
+}
+
+int
+baz (int x)
+{
+  char g, h;
+  int i, j;
+
+  foo ();
+  for (;;)
+    {
+      if (c)
+	h = d;
+      g = h < x ? h : 0;
+      i = (signed char) ((unsigned char) (g - 120) ^ 1);
+      j = i > 97;
+      if (a - j)
+	bar (0x123456, 0);
+      if (!b)
+	return e;
+    }
+}
+
+int
+main ()
+{
+  baz (2);
+  return 0;
+}