diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 60bd34758c0..39de837b326 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2020-02-10  Hans-Peter Nilsson  <hp@axis.com>
+
+	Try to generate zero-based comparisons.
+	* config/cris/cris.c (cris_reduce_compare): New function.
+	* config/cris/cris-protos.h  (cris_reduce_compare): Add prototype.
+	* config/cris/cris.md ("cbranch<mode>4", "cbranchdi4", "cstoredi4")
+	(cstore<mode>4"): Apply cris_reduce_compare in expanders.
+
 2020-02-10  Richard Earnshaw  <rearnsha@arm.com>
 
 	PR target/91913
diff --git a/gcc/config/cris/cris-protos.h b/gcc/config/cris/cris-protos.h
index 2105256cc78..6f6d815678a 100644
--- a/gcc/config/cris/cris-protos.h
+++ b/gcc/config/cris/cris-protos.h
@@ -38,6 +38,7 @@ extern bool cris_constant_index_p (const_rtx);
 extern bool cris_base_p (const_rtx, bool);
 extern bool cris_base_or_autoincr_p (const_rtx, bool);
 extern bool cris_bdap_index_p (const_rtx, bool);
+extern void cris_reduce_compare (rtx *, rtx *, rtx *);
 extern bool cris_biap_index_p (const_rtx, bool);
 extern bool cris_legitimate_address_p (machine_mode, rtx, bool);
 extern bool cris_store_multiple_op_p (rtx);
diff --git a/gcc/config/cris/cris.c b/gcc/config/cris/cris.c
index 01388b3d019..91cb63c01e7 100644
--- a/gcc/config/cris/cris.c
+++ b/gcc/config/cris/cris.c
@@ -3053,6 +3053,63 @@ cris_split_movdx (rtx *operands)
   return val;
 }
 
+/* Try to change a comparison against a constant to be against zero, and
+   an unsigned compare against zero to be an equality test.  Beware:
+   only valid for compares of integer-type operands.  Also, note that we
+   don't use operand 0 at the moment.  */
+
+void
+cris_reduce_compare (rtx *relp, rtx *, rtx *op1p)
+{
+  rtx op1 = *op1p;
+  rtx_code code = GET_CODE (*relp);
+
+  /* Code lifted mostly from emit_store_flag_1.  */
+  switch (code)
+    {
+    case LT:
+      if (op1 == const1_rtx)
+	code = LE;
+      break;
+    case LE:
+      if (op1 == constm1_rtx)
+	code = LT;
+      break;
+    case GE:
+      if (op1 == const1_rtx)
+	code = GT;
+      break;
+    case GT:
+      if (op1 == constm1_rtx)
+	code = GE;
+      break;
+    case GEU:
+      if (op1 == const1_rtx)
+	code = NE;
+      break;
+    case LTU:
+      if (op1 == const1_rtx)
+	code = EQ;
+      break;
+    case GTU:
+      if (op1 == const0_rtx)
+	code = NE;
+      break;
+    case LEU:
+      if (op1 == const0_rtx)
+	code = EQ;
+      break;
+    default:
+      break;
+    }
+
+  if (code != GET_CODE (*relp))
+  {
+    *op1p = const0_rtx;
+    PUT_CODE (*relp, code);
+  }
+}
+
 /* The expander for the prologue pattern name.  */
 
 void
diff --git a/gcc/config/cris/cris.md b/gcc/config/cris/cris.md
index b73ea8bb78e..fd8355c23a3 100644
--- a/gcc/config/cris/cris.md
+++ b/gcc/config/cris/cris.md
@@ -3539,7 +3539,7 @@
 		      (label_ref (match_operand 3 "" ""))
 		      (pc)))]
   ""
-  "")
+  "cris_reduce_compare (&operands[0], &operands[1], &operands[2]);")
 
 (define_expand "cbranchdi4"
   [(set (cc0)
@@ -3552,6 +3552,7 @@
 		      (pc)))]
   ""
 {
+  cris_reduce_compare (&operands[0], &operands[1], &operands[2]);
   if (TARGET_V32 && !REG_P (operands[1]))
     operands[1] = force_reg (DImode, operands[1]);
   if (TARGET_V32 && MEM_P (operands[2]))
@@ -3652,6 +3653,7 @@
 	 [(cc0) (const_int 0)]))]
   ""
 {
+  cris_reduce_compare (&operands[1], &operands[2], &operands[3]);
   if (TARGET_V32 && !REG_P (operands[2]))
     operands[2] = force_reg (DImode, operands[2]);
   if (TARGET_V32 && MEM_P (operands[3]))
@@ -3666,7 +3668,7 @@
 	(match_operator:SI 1 "ordered_comparison_operator"
 	 [(cc0) (const_int 0)]))]
   ""
-  "")
+  "cris_reduce_compare (&operands[1], &operands[2], &operands[3]);")
 
 ;; Like bCC, we have to check the overflow bit for
 ;; signed conditions.