diff --git a/gcc/optabs.cc b/gcc/optabs.cc
index 2486e1489609..3d8fa3abdfea 100644
--- a/gcc/optabs.cc
+++ b/gcc/optabs.cc
@@ -4398,12 +4398,14 @@ prepare_cmp_insn (rtx x, rtx y, enum rtx_code comparison, rtx size,
   /* If we are optimizing, force expensive constants into a register.  */
   if (CONSTANT_P (x) && optimize
       && (rtx_cost (x, mode, COMPARE, 0, optimize_insn_for_speed_p ())
-          > COSTS_N_INSNS (1)))
+          > COSTS_N_INSNS (1))
+      && can_create_pseudo_p ())
     x = force_reg (mode, x);
 
   if (CONSTANT_P (y) && optimize
       && (rtx_cost (y, mode, COMPARE, 1, optimize_insn_for_speed_p ())
-          > COSTS_N_INSNS (1)))
+          > COSTS_N_INSNS (1))
+      && can_create_pseudo_p ())
     y = force_reg (mode, y);
 
   /* Don't let both operands fail to indicate the mode.  */
@@ -4472,6 +4474,8 @@ prepare_cmp_insn (rtx x, rtx y, enum rtx_code comparison, rtx size,
      compare and branch in different basic blocks.  */
   if (cfun->can_throw_non_call_exceptions)
     {
+      if (!can_create_pseudo_p () && (may_trap_p (x) || may_trap_p (y)))
+	goto fail;
       if (may_trap_p (x))
 	x = copy_to_reg (x);
       if (may_trap_p (y))
diff --git a/gcc/testsuite/gcc.dg/pr102478.c b/gcc/testsuite/gcc.dg/pr102478.c
new file mode 100644
index 000000000000..43bc49b584df
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr102478.c
@@ -0,0 +1,29 @@
+/* PR rtl-optimization/102478 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fno-if-conversion -Wno-div-by-zero" } */
+
+unsigned a, b, c;
+
+void
+foo (void)
+{
+  c |= __builtin_expect (65535 / a, 0) && 0 / 0;
+  b = 0;
+}
+
+void
+bar (void)
+{
+  if (a <= 65535)
+    __builtin_trap ();
+  b = 0;
+}
+
+void
+baz (void)
+{
+  if (a > 65535)
+    b = 0;
+  else
+    __builtin_trap ();
+}