[Patch combine] Don't create ZERO_EXTEND from subregs unless we have a scalar int...

gcc/

	* combine.c (simplify_set): Do not transform subregs to zero_extends
	if the destination is not a scalar int mode.

From-SVN: r255945

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index d364df4dd45fdbed02226b2ec48291ef23d4ed49..c6dc455f319b7b2e39e9d244c3ec2c0699b6aebb 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2017-12-21  James Greenhalgh  <james.greenhalgh@arm.com>
+
+       * combine.c (simplify_set): Do not transform subregs to zero_extends
+       if the destination is not a scalar int mode.
+
 2017-12-21  Eric Botcazou  <ebotcazou@adacore.com>
 
        PR c++/82872

diff --git a/gcc/combine.c b/gcc/combine.c
index e78a71380374f7fdb93466c0fff17aad306f7a59..31e6a4f68254fab551300252688a52d8c3dcaaa4 100644 (file)
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -6967,12 +6967,13 @@ simplify_set (rtx x)
   /* If we have (set FOO (subreg:M (mem:N BAR) 0)) with M wider than N, this
      would require a paradoxical subreg.  Replace the subreg with a
      zero_extend to avoid the reload that would otherwise be required.
-     Don't do this for vector modes, as the transformation is incorrect.  */
+     Don't do this unless we have a scalar integer mode, otherwise the
+     transformation is incorrect.  */
 
   enum rtx_code extend_op;
   if (paradoxical_subreg_p (src)
       && MEM_P (SUBREG_REG (src))
-      && !VECTOR_MODE_P (GET_MODE (src))
+      && SCALAR_INT_MODE_P (GET_MODE (src))
       && (extend_op = load_extend_op (GET_MODE (SUBREG_REG (src)))) != UNKNOWN)
     {
       SUBST (SET_SRC (x),