[gcc(refs/vendors/redhat/heads/gcc-8-branch)] gcc-8 sra: Cap number of sub-access propagations with a param (PR 93435)

[gcc(refs/vendors/redhat/heads/gcc-8-branch)] gcc-8 sra: Cap number of sub-access propagations with a param (PR 93435)

[Jakub Jelinek]

https://gcc.gnu.org/g:5b74c267b8029a3245d4d12085e757de74bab64f

commit 5b74c267b8029a3245d4d12085e757de74bab64f
Author: Martin Jambor <mjambor@suse.cz>
Date:   Fri Apr 3 22:01:17 2020 +0200

    gcc-8 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.
    
    Bootstrapped and tested on gcc-8 branch.
    
    2020-04-03  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:
---
 gcc/ChangeLog                           |  10 ++
 gcc/doc/invoke.texi                     |   5 +
 gcc/params.def                          |   7 ++
 gcc/testsuite/ChangeLog                 |   5 +
 gcc/testsuite/gcc.dg/tree-ssa/pr93435.c | 159 ++++++++++++++++++++++++++++++++
 gcc/tree-sra.c                          |  34 ++++++-
 6 files changed, 219 insertions(+), 1 deletion(-)

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 662d3d85d10..cb0030e5077 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,13 @@
+2020-04-03  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 83c95892029..c138a0e84ce 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -10907,6 +10907,11 @@ 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 74215f24a4f..e54483c4606 100644
--- a/gcc/params.def
+++ b/gcc/params.def
@@ -1017,6 +1017,13 @@ 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 7b2374572bc..195c4eb41af 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2020-04-03  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
index 00000000000..cb8e7495b15
--- /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 e1ebdfaa225..264e1282c5a 100644
--- 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>
@@ -2665,6 +2668,32 @@ 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
@@ -2765,7 +2794,8 @@ 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)
 	    {
@@ -2795,6 +2825,7 @@ 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 ();
@@ -2833,6 +2864,7 @@ propagate_all_subaccesses (void)
 	    while (lacc);
 	}
     }
+  delete propagation_budget;
 }
 
 /* Go through all accesses collected throughout the (intraprocedural) analysis