Re: [PATCH GCC][3/7]Don't skip renaming PHIs in loop nest with only one inner loop

[Bin.Cheng]

On Mon, Oct 9, 2017 at 2:33 PM, Richard Biener
<richard.guent...@gmail.com> wrote:
> On Thu, Oct 5, 2017 at 3:16 PM, Bin Cheng <bin.ch...@arm.com> wrote:
>> Hi,
>> Function rename_variables_in_bb skips renaming PHI nodes in loop nest if the
>> outer loop has only one inner loop.  This breaks loop nest distribution when
>> inner loop has PHI node initialized from outer loop's variable.  
>> Unfortunately,
>> I lost the original C code illustrating the issue.  Now it is only triggered
>> in building spec2006/416.gamess with loop nest distribution, but I failed to
>> reduce a test from it.
>
> Bah, can you re-try isolating a testcase?
Hi Richard,
Right, I managed a simple test with help of creduce.  Given the
simplicity of the test,
I assume previous approval still holds for this updated patch and will
apply it later.

Thanks,
bin

2017-10-10  Bin Cheng  <bin.ch...@arm.com>

    * tree-vect-loop-manip.c (rename_variables_in_bb): Rename PHI nodes
    when copying loop nest with only one inner loop.

2017-10-10  Bin Cheng  <bin.ch...@arm.com>

    * gcc.dg/tree-ssa/ldist-34.c: New test.

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ldist-34.c 
b/gcc/testsuite/gcc.dg/tree-ssa/ldist-34.c
new file mode 100644
index 0000000..3d68a85
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/ldist-34.c
@@ -0,0 +1,15 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -ftree-loop-distribution" } */
+
+#define X (3.0)
+int b, c;
+double a[30000];
+int foo () {
+  for (int i = 0; i < 100; ++i) {
+    for (int j = 0; j < c; ++j)
+      if (b)
+        a[0] = b;
+    a[i * 100] = a[1] = X;
+  }
+  return 0;
+}
diff --git a/gcc/tree-vect-loop-manip.c b/gcc/tree-vect-loop-manip.c
index 2c724a2..9fd65a7 100644
--- a/gcc/tree-vect-loop-manip.c
+++ b/gcc/tree-vect-loop-manip.c
@@ -117,8 +117,6 @@ rename_variables_in_bb (basic_block bb, bool 
rename_from_outer_loop)
                      || single_pred (e->src) != outer_loop->header)
                    continue;
                }
-             else
-               continue;
            }
        }
       for (gphi_iterator gsi = gsi_start_phis (bb); !gsi_end_p (gsi);