diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index ea434f6e280..e5b4c75f380 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,9 @@
 2017-04-11  Jakub Jelinek  <jakub@redhat.com>
 
+	PR middle-end/80100
+	* simplify-rtx.c (simplify_binary_operation_1) <case IOR>: Perform
+	left shift in unsigned HOST_WIDE_INT type.
+
 	PR rtl-optimization/80385
 	* simplify-rtx.c (simplify_unary_operation_1): Don't transform
 	(not (neg X)) into (plus X -1) for complex or non-integral modes.
diff --git a/gcc/simplify-rtx.c b/gcc/simplify-rtx.c
index 4bbbe2354e3..ce632aeabb8 100644
--- a/gcc/simplify-rtx.c
+++ b/gcc/simplify-rtx.c
@@ -2741,8 +2741,8 @@ simplify_binary_operation_1 (enum rtx_code code, machine_mode mode,
           && CONST_INT_P (XEXP (op0, 1))
           && INTVAL (XEXP (op0, 1)) < HOST_BITS_PER_WIDE_INT)
         {
-          int count = INTVAL (XEXP (op0, 1));
-          HOST_WIDE_INT mask = INTVAL (trueop1) << count;
+	  int count = INTVAL (XEXP (op0, 1));
+	  HOST_WIDE_INT mask = UINTVAL (trueop1) << count;
 
           if (mask >> count == INTVAL (trueop1)
 	      && trunc_int_for_mode (mask, mode) == mask
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index a0182888174..d8597e2b597 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,5 +1,8 @@
 2017-04-11  Jakub Jelinek  <jakub@redhat.com>
 
+	PR middle-end/80100
+	* gcc.dg/pr80100.c: New test.
+
 	PR rtl-optimization/80385
 	* g++.dg/opt/pr80385.C: New test.
 
diff --git a/gcc/testsuite/gcc.dg/pr80100.c b/gcc/testsuite/gcc.dg/pr80100.c
new file mode 100644
index 00000000000..0d462be30aa
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr80100.c
@@ -0,0 +1,9 @@
+/* PR middle-end/80100 */
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+long int
+foo (long int x)
+{
+  return 2L | ((x - 1L) >> (__SIZEOF_LONG__ * __CHAR_BIT__ - 1));
+}