From: Bin Cheng <bin.cheng@linux.alibaba.com>
Date: Wed, 13 May 2020 03:37:47 +0000 (+0800)
Subject: Add missing unit dependence vector in data dependence analysis
X-Git-Tag: misc/first-auto-changelog~277
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=f6e1a4cd83190746b6544917f7526fa480ca5f18;p=thirdparty%2Fgcc.git

Add missing unit dependence vector in data dependence analysis

Current data dependence analysis misses unit distant vector if DRs in
DDR have the same invariant access functions.  This adds the vector as
the constant access function case.

2020-05-13  Bin Cheng  <bin.cheng@linux.alibaba.com>
PR tree-optimization/94969

gcc/
    * tree-data-dependence.c (constant_access_functions): Rename to...
    (invariant_access_functions): ...this.  Add parameter.  Check for
    invariant access function, rather than constant.
    (build_classic_dist_vector): Call above function.
    * tree-loop-distribution.c (pg_add_dependence_edges): Add comment.

gcc/testsuite/
    * gcc.dg/tree-ssa/pr94969.c: New test.
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index a7c8adecb9d1..4234a72432c6 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,12 @@
+2020-05-13  Bin Cheng  <bin.cheng@linux.alibaba.com>
+
+	PR tree-optimization/94969
+	* tree-data-dependence.c (constant_access_functions): Rename to...
+	(invariant_access_functions): ...this.  Add parameter.  Check for
+	invariant access function, rather than constant.
+	(build_classic_dist_vector): Call above function.
+	* tree-loop-distribution.c (pg_add_dependence_edges): Add comment.
+
 2020-05-13  Hongtao Liu  <hongtao.liu@intel.com>
 
 	PR target/94118
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 9ad48bad0317..5a4215bbe46e 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2020-05-13  Bin Cheng  <bin.cheng@linux.alibaba.com>
+
+	PR tree-optimization/94969
+	* gcc.dg/tree-ssa/pr94969.c: New test.
+
 2020-05-12  Craig Blackmore  <craig.blackmore@embecosm.com>
 
 	* gcc.target/riscv/shorten-memrefs-1.c: New test.
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr94969.c b/gcc/testsuite/gcc.dg/tree-ssa/pr94969.c
new file mode 100644
index 000000000000..056b015f97c5
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr94969.c
@@ -0,0 +1,28 @@
+/* PR tree-optimization/52267 */
+/* { dg-do run } */
+/* { dg-options "-O3 -fdump-tree-ldist-details" } */
+
+int a = 0, b = 0, c = 0;
+struct S {
+  signed m : 7;
+  signed e : 2;
+};
+struct S f[2] = {{0, 0}, {0, 0}};
+struct S g = {0, 0};
+
+void __attribute__((noinline))
+k()
+{
+  for (; c <= 1; c++) {
+    f[b] = g;
+    f[b].e ^= 1;
+  }
+}
+int main()
+{
+  k();
+  if (f[b].e != 1)
+    __builtin_abort ();
+}
+
+/* { dg-final { scan-tree-dump-not "ldist" "Loop 1 distributed: split to 3 loops"} } */
diff --git a/gcc/tree-data-ref.c b/gcc/tree-data-ref.c
index 851225e11717..5505ba467785 100644
--- a/gcc/tree-data-ref.c
+++ b/gcc/tree-data-ref.c
@@ -4821,17 +4821,19 @@ build_classic_dist_vector_1 (struct data_dependence_relation *ddr,
   return true;
 }
 
-/* Return true when the DDR contains only constant access functions.  */
+/* Return true when the DDR contains only invariant access functions wrto. loop
+   number LNUM.  */
 
 static bool
-constant_access_functions (const struct data_dependence_relation *ddr)
+invariant_access_functions (const struct data_dependence_relation *ddr,
+			    int lnum)
 {
   unsigned i;
   subscript *sub;
 
   FOR_EACH_VEC_ELT (DDR_SUBSCRIPTS (ddr), i, sub)
-    if (!evolution_function_is_constant_p (SUB_ACCESS_FN (sub, 0))
-	|| !evolution_function_is_constant_p (SUB_ACCESS_FN (sub, 1)))
+    if (!evolution_function_is_invariant_p (SUB_ACCESS_FN (sub, 0), lnum)
+	|| !evolution_function_is_invariant_p (SUB_ACCESS_FN (sub, 1), lnum))
       return false;
 
   return true;
@@ -5030,7 +5032,7 @@ build_classic_dist_vector (struct data_dependence_relation *ddr,
       dist_v = lambda_vector_new (DDR_NB_LOOPS (ddr));
       save_dist_v (ddr, dist_v);
 
-      if (constant_access_functions (ddr))
+      if (invariant_access_functions (ddr, loop_nest->num))
 	add_distance_for_zero_overlaps (ddr);
 
       if (DDR_NB_LOOPS (ddr) > 1)
diff --git a/gcc/tree-loop-distribution.c b/gcc/tree-loop-distribution.c
index 444232153328..b122c3964a09 100644
--- a/gcc/tree-loop-distribution.c
+++ b/gcc/tree-loop-distribution.c
@@ -2080,7 +2080,8 @@ loop_distribution::pg_add_dependence_edges (struct graph *rdg, int dir,
 		this_dir = -this_dir;
 
 	      /* Known dependences can still be unordered througout the
-		 iteration space, see gcc.dg/tree-ssa/ldist-16.c.  */
+		 iteration space, see gcc.dg/tree-ssa/ldist-16.c and
+		 gcc.dg/tree-ssa/pr94969.c.  */
 	      if (DDR_NUM_DIST_VECTS (ddr) != 1)
 		this_dir = 2;
 	      /* If the overlap is exact preserve stmt order.  */