Index: lra-constraints.c
===================================================================
--- lra-constraints.c	(revision 193755)
+++ lra-constraints.c	(working copy)
@@ -293,7 +293,9 @@ in_class_p (rtx reg, enum reg_class cl,
 	  if (nregs == 1)
 	    return true;
 	  for (j = 0; j < nregs; j++)
-	    if (TEST_HARD_REG_BIT (lra_no_alloc_regs, hard_regno + j))
+	    if (TEST_HARD_REG_BIT (lra_no_alloc_regs, hard_regno + j)
+		|| ! TEST_HARD_REG_BIT (reg_class_contents[common_class],
+					hard_regno + j))
 	      break;
 	  if (j >= nregs)
 	    return true;
Index: testsuite/gcc.target/i386/pr55277.c
===================================================================
--- testsuite/gcc.target/i386/pr55277.c	(revision 0)
+++ testsuite/gcc.target/i386/pr55277.c	(working copy)
@@ -0,0 +1,18 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target ilp32 } */
+/* { dg-options "-O1" } */
+
+int a, c;
+
+void f(long long p)
+{
+  long long b;
+
+  if(b)
+    b = p ? : 0;
+
+  for (; p; p++)
+    p *= a & (c = p *= !a < 2);
+
+  a = b += !(b & 3740917449u);
+}