gcc-9 sra: Cap number of sub-access propagations with a param (PR 93435)

This is non-trivial but rather straightforward backport of
29f23ed79b60949fc60f6fdbbd931bd58090b241 from master.  See
https://gcc.gnu.org/pipermail/gcc-patches/2020-March/542390.html for
more information.

2020-04-02  Martin Jambor  <mjambor@suse.cz>

	PR tree-optimization/93435
	* params.def (PARAM_SRA_MAX_PROPAGATIONS): New parameter.
	* tree-sra.c (propagation_budget): New variable.
	(budget_for_propagation_access): New function.
	(propagate_subaccesses_across_link): Use it.
	(propagate_all_subaccesses): Set up and destroy propagation_budget.
	* doc/invoke.texi (sra-max-propagations): New.

	testsuite/
	* gcc.dg/tree-ssa/pr93435.c: New test.

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 04e297cd4552cb5aa96c25d54e312f54dead87f4..3994227a158e57d6bb4a570cc5f2b076c0362ca8 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,13 @@
+2020-04-02  Martin Jambor  <mjambor@suse.cz>
+
+       PR tree-optimization/93435
+       * params.def (PARAM_SRA_MAX_PROPAGATIONS): New parameter.
+       * tree-sra.c (propagation_budget): New variable.
+       (budget_for_propagation_access): New function.
+       (propagate_subaccesses_across_link): Use it.
+       (propagate_all_subaccesses): Set up and destroy propagation_budget.
+       * doc/invoke.texi (sra-max-propagations): New.
+
 2020-04-03  Martin Liska  <mliska@suse.cz>
 
        Backport from mainline

diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 792b768fceb61d58911a5dd8efc8ae816579118c..b18e9124b4e6e4c7b0854a60e26012cbf0dc8f51 100644 (file)
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -11798,6 +11798,11 @@ speed
 (@option{sra-max-scalarization-size-Ospeed}) or size
 (@option{sra-max-scalarization-size-Osize}) respectively.
 
+@item sra-max-propagations
+The maximum number of artificial accesses that Scalar Replacement of
+Aggregates (SRA) will track, per one local variable, in order to
+facilitate copy propagation.
+
 @item tm-max-aggregate-size
 When making copies of thread-local variables in a transaction, this
 parameter specifies the size in bytes after which variables are

diff --git a/gcc/params.def b/gcc/params.def
index 8e4887e50a2f040bc7926f96be3a97fe37bc2c5a..e23a4530bfa2711ec03d81a76a4cd35211ca630a 100644 (file)
--- a/gcc/params.def
+++ b/gcc/params.def
@@ -1081,6 +1081,13 @@ DEFPARAM (PARAM_SRA_MAX_SCALARIZATION_SIZE_SIZE,
          "considered for scalarization when compiling for size.",
          0, 0, 0)
 
+DEFPARAM (PARAM_SRA_MAX_PROPAGATIONS,
+         "sra-max-propagations",
+         "Maximum number of artificial accesses to enable forward propagation "
+         "that Scalar Replacement of Aggregates will keep for one local "
+         "variable.",
+         32, 0, 0)
+
 DEFPARAM (PARAM_IPA_CP_VALUE_LIST_SIZE,
          "ipa-cp-value-list-size",
          "Maximum size of a list of values associated with each parameter for "

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index da06792dc1860e0516c41071b0041f7deccb9139..a1101ae50b5d8a10848d2f919d41da22fd5f0db3 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2020-04-02  Martin Jambor  <mjambor@suse.cz>
+
+       PR tree-optimization/93435
+       * gcc.dg/tree-ssa/pr93435.c: New test.
+
 2020-04-02  Fritz Reese  <foreese@gcc.gnu.org>
 
        Backport from master.

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr93435.c b/gcc/testsuite/gcc.dg/tree-ssa/pr93435.c
new file mode 100644 (file)
index 0000000..cb8e749
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr93435.c
@@ -0,0 +1,159 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+typedef signed char int8_T;
+typedef int int32_T;
+
+typedef struct {
+  int8_T a;
+} struct0_T;
+
+typedef struct {
+  struct0_T f10[4];
+} struct_T;
+
+typedef struct {
+  struct_T f9[4];
+} b_struct_T;
+
+typedef struct {
+  b_struct_T f8[4];
+} c_struct_T;
+
+typedef struct {
+  c_struct_T f7[4];
+} d_struct_T;
+
+typedef struct {
+  d_struct_T f6[4];
+} e_struct_T;
+
+typedef struct {
+  e_struct_T f5[4];
+} f_struct_T;
+
+typedef struct {
+  f_struct_T f4[4];
+} g_struct_T;
+
+typedef struct {
+  g_struct_T f3[4];
+} h_struct_T;
+
+typedef struct {
+  h_struct_T f2[4];
+} i_struct_T;
+
+typedef struct {
+  i_struct_T f1[4];
+} j_struct_T;
+
+typedef struct {
+  struct {
+    j_struct_T ds21[4];
+    i_struct_T ds20[4];
+    i_struct_T r9;
+  } f0;
+} deep_struct_arraysStackData;
+
+/* Function Definitions */
+void deep_struct_arrays(deep_struct_arraysStackData *SD,
+  int8_T in1, int8_T inCount, int8_T *out1, int8_T *out2, struct0_T out3[4])
+{
+  struct0_T r;
+  struct_T r1;
+  b_struct_T r2;
+  c_struct_T r3;
+  d_struct_T r4;
+  e_struct_T r5;
+  f_struct_T r6;
+  g_struct_T r7;
+  h_struct_T r8;
+  int32_T count;
+  int32_T i;
+
+  /*  Check properties of input in1 */
+  /*  Check properties of input inCount */
+  /*  Copyright 2006 The MathWorks, Inc. */
+  r.a = in1;
+  r1.f10[0] = r;
+  r1.f10[1] = r;
+  r1.f10[2] = r;
+  r1.f10[3] = r;
+  r2.f9[0] = r1;
+  r2.f9[1] = r1;
+  r2.f9[2] = r1;
+  r2.f9[3] = r1;
+  r3.f8[0] = r2;
+  r3.f8[1] = r2;
+  r3.f8[2] = r2;
+  r3.f8[3] = r2;
+  r4.f7[0] = r3;
+  r4.f7[1] = r3;
+  r4.f7[2] = r3;
+  r4.f7[3] = r3;
+  r5.f6[0] = r4;
+  r5.f6[1] = r4;
+  r5.f6[2] = r4;
+  r5.f6[3] = r4;
+  r6.f5[0] = r5;
+  r6.f5[1] = r5;
+  r6.f5[2] = r5;
+  r6.f5[3] = r5;
+  r7.f4[0] = r6;
+  r7.f4[1] = r6;
+  r7.f4[2] = r6;
+  r7.f4[3] = r6;
+  r8.f3[0] = r7;
+  r8.f3[1] = r7;
+  r8.f3[2] = r7;
+  r8.f3[3] = r7;
+  SD->f0.r9.f2[0] = r8;
+  SD->f0.r9.f2[1] = r8;
+  SD->f0.r9.f2[2] = r8;
+  SD->f0.r9.f2[3] = r8;
+  SD->f0.ds20[0] = SD->f0.r9;
+  SD->f0.ds20[3] = SD->f0.r9;
+  count = 0;
+  while (count < inCount) {
+    i = in1 + SD->f0.ds20[0].f2[0].f3[0].f4[0].f5[0].f6[0].f7[0].f8[0].f9[0]
+      .f10[0].a;
+    if (i > 127) {
+      i = 127;
+    } else {
+      if (i < -128) {
+        i = -128;
+      }
+    }
+
+    SD->f0.ds20[0].f2[0].f3[0].f4[0].f5[0].f6[0].f7[0].f8[0].f9[0].f10[0].a =
+      (int8_T)i;
+    i = SD->f0.ds20[3].f2[3].f3[3].f4[3].f5[3].f6[3].f7[3].f8[3].f9[3].f10[3].a
+      + 3;
+    if (i > 127) {
+      i = 127;
+    }
+
+    SD->f0.ds20[3].f2[3].f3[3].f4[3].f5[3].f6[3].f7[3].f8[3].f9[3].f10[3].a =
+      (int8_T)i;
+    count++;
+  }
+
+  if (inCount > 10) {
+    SD->f0.ds21[0].f1[1].f2[2].f3[3].f4[3].f5[3].f6[3].f7[3].f8[3].f9[3].f10[3].
+      a = 14;
+  } else {
+    SD->f0.ds21[0].f1[1].f2[2].f3[3].f4[3].f5[3].f6[3].f7[3].f8[3].f9[3].f10[3].
+      a = 16;
+  }
+
+  *out1 = SD->f0.ds20[0].f2[0].f3[0].f4[0].f5[0].f6[0].f7[0].f8[0].f9[0].f10[0].
+    a;
+  *out2 = SD->f0.ds20[3].f2[3].f3[3].f4[3].f5[3].f6[3].f7[3].f8[3].f9[3].f10[3].
+    a;
+  out3[0] = r;
+  out3[1] = r;
+  out3[2] = r;
+  out3[3] = SD->f0.ds21[0].f1[1].f2[2].f3[3].f4[3].f5[3].f6[3].f7[3].f8[3].f9[3]
+    .f10[3];
+}

diff --git a/gcc/tree-sra.c b/gcc/tree-sra.c
index fd51a3d0323548b35c000f0332f2000bd15f0a8e..0a5c24a183a7240bb073e2ea69398c07dadb4560 100644 (file)
--- a/gcc/tree-sra.c
+++ b/gcc/tree-sra.c
@@ -291,6 +291,9 @@ static object_allocator<assign_link> assign_link_pool ("SRA links");
 /* Base (tree) -> Vector (vec<access_p> *) map.  */
 static hash_map<tree, auto_vec<access_p> > *base_access_vec;
 
+/* Hash to limit creation of artificial accesses */
+static hash_map<tree, unsigned> *propagation_budget;
+
 /* Candidate hash table helpers.  */
 
 struct uid_decl_hasher : nofree_ptr_hash <tree_node>
@@ -2670,6 +2673,32 @@ subtree_mark_written_and_enqueue (struct access *access)
     subtree_mark_written_and_enqueue (child);
 }
 
+/* If there is still budget to create a propagation access for DECL, return
+   true and decrement the budget.  Otherwise return false.  */
+
+static bool
+budget_for_propagation_access (tree decl)
+{
+  unsigned b, *p = propagation_budget->get (decl);
+  if (p)
+    b = *p;
+  else
+    b = PARAM_SRA_MAX_PROPAGATIONS;
+
+  if (b == 0)
+    return false;
+  b--;
+
+  if (b == 0 && dump_file && (dump_flags & TDF_DETAILS))
+    {
+      fprintf (dump_file, "The propagation budget of ");
+      print_generic_expr (dump_file, decl);
+      fprintf (dump_file, " (UID: %u) has been exhausted.\n", DECL_UID (decl));
+    }
+  propagation_budget->put (decl, b);
+  return true;
+}
+
 /* Propagate subaccesses and grp_write flags of RACC across an assignment link
    to LACC.  Enqueue sub-accesses as necessary so that the write flag is
    propagated transitively.  Return true if anything changed.  Additionally, if
@@ -2770,7 +2799,8 @@ propagate_subaccesses_across_link (struct access *lacc, struct access *racc)
          continue;
        }
 
-      if (rchild->grp_unscalarizable_region)
+      if (rchild->grp_unscalarizable_region
+         || !budget_for_propagation_access (lacc->base))
        {
          if (rchild->grp_write && !lacc->grp_write)
            {
@@ -2800,6 +2830,7 @@ propagate_subaccesses_across_link (struct access *lacc, struct access *racc)
 static void
 propagate_all_subaccesses (void)
 {
+  propagation_budget = new hash_map<tree, unsigned>;
   while (work_queue_head)
     {
       struct access *racc = pop_access_from_work_queue ();
@@ -2838,6 +2869,7 @@ propagate_all_subaccesses (void)
            while (lacc);
        }
     }
+  delete propagation_budget;
 }
 
 /* Go through all accesses collected throughout the (intraprocedural) analysis