[PR65637][PATCH][4/5] Fix inner loop phi in expand_omp_for_static_chunk

[Tom de Vries <Tom_deVries@mentor.com>]

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[ was: Re: [PR65637][PATCH][2/3] Fix inner loop phi in 
expand_omp_for_static_chunk ]

On 15/04/15 15:17, Tom de Vries wrote:
> On 15-04-15 15:10, Tom de Vries wrote:
>> Hi,
>>
>> This patch series fixes PR65637.
>>

<SNIP>

>
> This patch fixes an libgomp.c/autopar-1.c execution failure.
>
> For autopar-1.c, the original loop has a loop phi:
> ...
> # s.5_20 = PHI <s.5_12(4), 0.0(20)>
> ...
>
> After expand_omp_for_static_chunk, there's an inner and an outer loop.
> The outer
> loop phi is:
> ...
> # s.5_11 = PHI <0.0(15), s.5_12(21)>
> ...
>
> and the inner loop phi is:
> ...
> # s.5_20 = PHI <s.5_12(4), 0.0(20)>
> ...
>
> The inner loop phi should not have 0.0 as argument, but the result of
> the outer
> loop phi, like this:
> ...
> # s.5_20 = PHI <s.5_12(4), s.5_11(20)>
> ...
>
> This patch fixes the inner loop phi, and allows the autopar-1.c
> execution test
> to pass.
>

This updated patch includes a test-case. It also handles simple latches.

OK for trunk?

Thanks,
- Tom



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Fix inner loop phi in expand_omp_for_static_chunk

2015-08-31  Tom de Vries  <tom@codesourcery.com>

	PR tree-optimization/65637
	* omp-low.c (find_phi_with_arg_on_edge): New function.
	(expand_omp_for_static_chunk): Fix inner loop phi.

	* testsuite/libgomp.c/autopar-1-chunk-size.c: New test.
---
 gcc/ChangeLog                                      |  6 +++
 gcc/omp-low.c                                      | 30 ++++++++++++++-
 libgomp/testsuite/libgomp.c/autopar-1-chunk-size.c | 44 ++++++++++++++++++++++
 3 files changed, 79 insertions(+), 1 deletion(-)
 create mode 100644 libgomp/testsuite/libgomp.c/autopar-1-chunk-size.c

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 5a273ba..a14564c 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,6 +1,12 @@
 2015-05-18  Tom de Vries  <tom@codesourcery.com>
 
 	PR tree-optimization/65637
+	* omp-low.c (find_phi_with_arg_on_edge): New function.
+	(expand_omp_for_static_chunk): Fix inner loop phi.
+
+2015-05-18  Tom de Vries  <tom@codesourcery.com>
+
+	PR tree-optimization/65637
 	* omp-low.c (expand_omp_for_static_chunk): Fix gcc_assert for the case
 	that head is NULL.
 
diff --git a/gcc/omp-low.c b/gcc/omp-low.c
index 4e732ae..e2be7c7 100644
--- a/gcc/omp-low.c
+++ b/gcc/omp-low.c
@@ -6885,6 +6885,22 @@ expand_omp_for_static_nochunk (struct omp_region *region,
     }
 }
 
+static gphi *
+find_phi_with_arg_on_edge (tree arg, edge e)
+{
+  basic_block bb = e->dest;
+
+  for (gphi_iterator gpi = gsi_start_phis (bb);
+       !gsi_end_p (gpi);
+       gsi_next (&gpi))
+    {
+      gphi *phi = gpi.phi ();
+      if (PHI_ARG_DEF_FROM_EDGE (phi, e) == arg)
+	return phi;
+    }
+
+  return NULL;
+}
 
 /* A subroutine of expand_omp_for.  Generate code for a parallel
    loop with static schedule and a specified chunk size.  Given
@@ -7324,7 +7340,19 @@ expand_omp_for_static_chunk (struct omp_region *region,
 	    t = vextra;
 	  add_phi_arg (nphi, t, ene, locus);
 	  locus = redirect_edge_var_map_location (vm);
-	  add_phi_arg (nphi, redirect_edge_var_map_def (vm), re, locus);
+	  tree back_arg = redirect_edge_var_map_def (vm);
+	  add_phi_arg (nphi, back_arg, re, locus);
+	  edge ce = find_edge (cont_bb, body_bb);
+	  if (ce == NULL)
+	    {
+	      ce = BRANCH_EDGE (cont_bb);
+	      gcc_assert (single_succ (ce->dest) == body_bb);
+	      ce = single_succ_edge (ce->dest);
+	    }
+	  gphi *inner_loop_phi = find_phi_with_arg_on_edge (back_arg, ce);
+	  gcc_assert (inner_loop_phi != NULL);
+	  add_phi_arg (inner_loop_phi, gimple_phi_result (nphi),
+		       find_edge (seq_start_bb, body_bb), locus);
 	}
       gcc_assert (gsi_end_p (psi) && (head == NULL || i == head->length ()));
       redirect_edge_var_map_clear (re);
diff --git a/libgomp/testsuite/libgomp.c/autopar-1-chunk-size.c b/libgomp/testsuite/libgomp.c/autopar-1-chunk-size.c
new file mode 100644
index 0000000..5a36474
--- /dev/null
+++ b/libgomp/testsuite/libgomp.c/autopar-1-chunk-size.c
@@ -0,0 +1,44 @@
+/* { dg-do run } */
+/* { dg-additional-options "-ftree-parallelize-loops=4 -ffast-math --param parloops-chunk-size=100" } */
+
+extern void abort (void);
+
+double d[1024], e[1024];
+int f[1024], g[1024];
+
+double __attribute__((noinline))
+foo (void)
+{
+  double s = 0.0;
+  int i;
+  for (i = 0; i < 1024; i++)
+    s += d[i] - e[i];
+  return s;
+}
+
+int __attribute__((noinline))
+bar (void)
+{
+  int s = 0, i;
+  for (i = 0; i < 1024; i++)
+    s += f[i] - g[i];
+  return s;
+}
+
+int
+main (void)
+{
+  int i;
+  for (i = 0; i < 1024; i++)
+    {
+      d[i] = i * 2;
+      e[i] = i;
+      f[i] = i * 2;
+      g[i] = i;
+    }
+  if (foo () != 1023 * 1024 / 2)
+    abort ();
+  if (bar () != 1023 * 1024 / 2)
+    abort ();
+  return 0;
+}
-- 
1.9.1