Add LOOP_VINFO_MAX_VECT_FACTOR

Epilogue vectorisation uses the vectorisation factor of the main loop
as the maximum vectorisation factor allowed for correctness.  That makes
sense as a conservatively correct value, since the chosen vectorisation
factor will be strictly less than that anyway.  However, once the VF
itself becomes variable, it's easier to carry across the original
maximum VF instead.

2017-09-14  Richard Sandiford  <richard.sandiford@linaro.org>
	    Alan Hayward  <alan.hayward@arm.com>
	    David Sherwood  <david.sherwood@arm.com>

gcc/
	* tree-vectorizer.h (_loop_vec_info): Add max_vectorization_factor.
	(LOOP_VINFO_MAX_VECT_FACTOR): New macro.
	(LOOP_VINFO_ORIG_VECT_FACTOR): Replace with...
	(LOOP_VINFO_ORIG_MAX_VECT_FACTOR): ...this new macro.
	* tree-vect-data-refs.c (vect_analyze_data_ref_dependences): Update
	accordingly.
	* tree-vect-loop.c (_loop_vec_info::_loop_vec_info): Initialize
	max_vectorization_factor.
	(vect_analyze_loop_2): Set LOOP_VINFO_MAX_VECT_FACTOR.

Co-Authored-By: Alan Hayward <alan.hayward@arm.com>
Co-Authored-By: David Sherwood <david.sherwood@arm.com>
From-SVN: r252766

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index c3ab19aa7da67a1ddb2418add9db87417980e1cc..31c9d0afb2b25806fa06340476ac554dfc428a73 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,17 @@
+2017-09-14  Richard Sandiford  <richard.sandiford@linaro.org>
+           Alan Hayward  <alan.hayward@arm.com>
+           David Sherwood  <david.sherwood@arm.com>
+
+       * tree-vectorizer.h (_loop_vec_info): Add max_vectorization_factor.
+       (LOOP_VINFO_MAX_VECT_FACTOR): New macro.
+       (LOOP_VINFO_ORIG_VECT_FACTOR): Replace with...
+       (LOOP_VINFO_ORIG_MAX_VECT_FACTOR): ...this new macro.
+       * tree-vect-data-refs.c (vect_analyze_data_ref_dependences): Update
+       accordingly.
+       * tree-vect-loop.c (_loop_vec_info::_loop_vec_info): Initialize
+       max_vectorization_factor.
+       (vect_analyze_loop_2): Set LOOP_VINFO_MAX_VECT_FACTOR.
+
 2017-09-14  Richard Sandiford  <richard.sandiford@linaro.org>
            Alan Hayward  <alan.hayward@arm.com>
            David Sherwood  <david.sherwood@arm.com>

diff --git a/gcc/tree-vect-data-refs.c b/gcc/tree-vect-data-refs.c
index a6969791bb2e181ca5aa6920dc756bc82479c0db..c409dc71a49ec6e55fcf6199304aec3017c7afb3 100644 (file)
--- a/gcc/tree-vect-data-refs.c
+++ b/gcc/tree-vect-data-refs.c
@@ -509,7 +509,7 @@ vect_analyze_data_ref_dependences (loop_vec_info loop_vinfo, int *max_vf)
      was applied to original loop.  Therefore we may just get max_vf
      using VF of original loop.  */
   if (LOOP_VINFO_EPILOGUE_P (loop_vinfo))
-    *max_vf = LOOP_VINFO_ORIG_VECT_FACTOR (loop_vinfo);
+    *max_vf = LOOP_VINFO_ORIG_MAX_VECT_FACTOR (loop_vinfo);
   else
     FOR_EACH_VEC_ELT (LOOP_VINFO_DDRS (loop_vinfo), i, ddr)
       if (vect_analyze_data_ref_dependence (ddr, loop_vinfo, max_vf))

diff --git a/gcc/tree-vect-loop.c b/gcc/tree-vect-loop.c
index f0eafc58504e546a35a3e46c8a3d55a2f7fa8339..80eb4f1fda9734935f87cd7610a63861c1d21430 100644 (file)
--- a/gcc/tree-vect-loop.c
+++ b/gcc/tree-vect-loop.c
@@ -1111,6 +1111,7 @@ _loop_vec_info::_loop_vec_info (struct loop *loop_in)
     num_iters_assumptions (NULL_TREE),
     th (0),
     vectorization_factor (0),
+    max_vectorization_factor (0),
     unaligned_dr (NULL),
     peeling_for_alignment (0),
     ptr_mask (0),
@@ -1920,6 +1921,7 @@ vect_analyze_loop_2 (loop_vec_info loop_vinfo, bool &fatal)
                             "bad data dependence.\n");
       return false;
     }
+  LOOP_VINFO_MAX_VECT_FACTOR (loop_vinfo) = max_vf;
 
   ok = vect_determine_vectorization_factor (loop_vinfo);
   if (!ok)

diff --git a/gcc/tree-vectorizer.h b/gcc/tree-vectorizer.h
index 3807f60680f165be0770105a949d542bf4423232..57152ee08b14405c145fa5a5f98dcd54e4ee2535 100644 (file)
--- a/gcc/tree-vectorizer.h
+++ b/gcc/tree-vectorizer.h
@@ -241,6 +241,10 @@ typedef struct _loop_vec_info : public vec_info {
   /* Unrolling factor  */
   int vectorization_factor;
 
+  /* Maximum runtime vectorization factor, or MAX_VECTORIZATION_FACTOR
+     if there is no particular limit.  */
+  unsigned HOST_WIDE_INT max_vectorization_factor;
+
   /* Unknown DRs according to which loop was peeled.  */
   struct data_reference *unaligned_dr;
 
@@ -355,6 +359,7 @@ typedef struct _loop_vec_info : public vec_info {
 #define LOOP_VINFO_COST_MODEL_THRESHOLD(L) (L)->th
 #define LOOP_VINFO_VECTORIZABLE_P(L)       (L)->vectorizable
 #define LOOP_VINFO_VECT_FACTOR(L)          (L)->vectorization_factor
+#define LOOP_VINFO_MAX_VECT_FACTOR(L)      (L)->max_vectorization_factor
 #define LOOP_VINFO_PTR_MASK(L)             (L)->ptr_mask
 #define LOOP_VINFO_LOOP_NEST(L)            (L)->loop_nest
 #define LOOP_VINFO_DATAREFS(L)             (L)->datarefs
@@ -400,8 +405,8 @@ typedef struct _loop_vec_info : public vec_info {
 #define LOOP_VINFO_EPILOGUE_P(L) \
   (LOOP_VINFO_ORIG_LOOP_INFO (L) != NULL)
 
-#define LOOP_VINFO_ORIG_VECT_FACTOR(L) \
-  (LOOP_VINFO_VECT_FACTOR (LOOP_VINFO_ORIG_LOOP_INFO (L)))
+#define LOOP_VINFO_ORIG_MAX_VECT_FACTOR(L) \
+  (LOOP_VINFO_MAX_VECT_FACTOR (LOOP_VINFO_ORIG_LOOP_INFO (L)))
 
 static inline loop_vec_info
 loop_vec_info_for_loop (struct loop *loop)