2011-09-01  Andrew Stubbs  <ams@codesourcery.com>

	gcc/
	* config/arm/predicates.md (shift_amount_operand): Ensure shift
	amount is positive.

	gcc/testsuite/
	* gcc.dg/pr50193-1.c: New file.

=== modified file 'gcc/config/arm/predicates.md'
--- old/gcc/config/arm/predicates.md	2011-09-05 09:40:19 +0000
+++ new/gcc/config/arm/predicates.md	2011-09-12 11:24:34 +0000
@@ -132,7 +132,8 @@
 (define_predicate "shift_amount_operand"
   (ior (and (match_test "TARGET_ARM")
 	    (match_operand 0 "s_register_operand"))
-       (match_operand 0 "const_int_operand")))
+       (and (match_operand 0 "const_int_operand")
+	    (match_test "INTVAL (op) > 0"))))
 
 (define_predicate "arm_add_operand"
   (ior (match_operand 0 "arm_rhs_operand")

=== added file 'gcc/testsuite/gcc.dg/pr50193-1.c'
--- old/gcc/testsuite/gcc.dg/pr50193-1.c	1970-01-01 00:00:00 +0000
+++ new/gcc/testsuite/gcc.dg/pr50193-1.c	2011-09-01 12:22:14 +0000
@@ -0,0 +1,10 @@
+/* PR 50193: ARM: ICE on a | (b << negative-constant) */
+/* Ensure that the compiler doesn't ICE.  */
+
+/* { dg-options "-O2" } */
+
+int
+foo(int a, int b)
+{
+  return a | (b << -3); /* { dg-warning "left shift count is negative" } */
+}