gcc/0313-Add-tracer-transformation-for-static-probabilities.patch

From ed300a0b07e608efb756b623263f014c2cebdf08 Mon Sep 17 00:00:00 2001
From: Egorov Ivan WX1280859 <egorov.ivan@huawei-partners.com>
Date: Tue, 26 Nov 2024 14:53:59 +0300
Subject: [PATCH 6/8] Add tracer transformation for static probabilities

---
 gcc/common.opt                         |  4 ++++
 gcc/opts.cc                            |  4 ++++
 gcc/params.opt                         |  8 ++++++++
 gcc/testsuite/gcc.dg/tracer-static-1.c | 28 ++++++++++++++++++++++++++
 gcc/tracer.cc                          | 11 ++++++++++
 5 files changed, 55 insertions(+)
 create mode 100644 gcc/testsuite/gcc.dg/tracer-static-1.c

diff --git a/gcc/common.opt b/gcc/common.opt
index 96888cf1b..db35391c3 100644
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -2990,6 +2990,10 @@ ftracer
 Common Var(flag_tracer) Optimization
 Perform superblock formation via tail duplication.
 
+ftracer-static
+Common Var(flag_tracer_static) Init(0) Optimization
+Perform superblock formation via tail duplication for a given bb size.
+
 ftrampolines
 Common Var(flag_trampolines) Init(0)
 For targets that normally need trampolines for nested functions, always
diff --git a/gcc/opts.cc b/gcc/opts.cc
index 84dd8925a..34b84db8f 100644
--- a/gcc/opts.cc
+++ b/gcc/opts.cc
@@ -3180,6 +3180,10 @@ common_handle_option (struct gcc_options *opts,
       }
       break;
 
+    case OPT_ftracer_static:
+      SET_OPTION_IF_UNSET (opts, opts_set, flag_tracer, true);
+      break;
+
     case OPT_ftree_vectorize:
       /* Automatically sets -ftree-loop-vectorize and
 	 -ftree-slp-vectorize.  Nothing more to do here.  */
diff --git a/gcc/params.opt b/gcc/params.opt
index bb4dc1825..e5472dfc8 100644
--- a/gcc/params.opt
+++ b/gcc/params.opt
@@ -1116,6 +1116,10 @@ The percentage of function, weighted by execution frequency, that must be covere
 Common Joined UInteger Var(param_tracer_max_code_growth) Init(100) Param Optimization
 Maximal code growth caused by tail duplication (in percent).
 
+-param=tracer-max-not-covered-insns-num=
+Common Joined UInteger Var(param_tracer_max_not_covered_insns_num) Init(12) Param Optimization
+Maximal number of instructions in the block, that must not be covered by trace formation.
+
 -param=tracer-min-branch-probability=
 Common Joined UInteger Var(param_tracer_min_branch_probability) Init(50) IntegerRange(0, 100) Param Optimization
 Stop forward growth if the probability of best edge is less than this threshold (in percent). Used when profile feedback is not available.
@@ -1128,6 +1132,10 @@ Stop forward growth if the probability of best edge is less than this threshold
 Common Joined UInteger Var(param_tracer_min_branch_ratio) Init(10) IntegerRange(0, 100) Param Optimization
 Stop reverse growth if the reverse probability of best edge is less than this threshold (in percent).
 
+-param=tracer-min-not-covered-insns-num=
+Common Joined UInteger Var(param_tracer_min_not_covered_insns_num) Init(1) Param Optimization
+Minimal number of instructions in the block, that must not be covered by trace formation.
+
 -param=tree-reassoc-width=
 Common Joined UInteger Var(param_tree_reassoc_width) Param Optimization
 Set the maximum number of instructions executed in parallel in reassociated tree.  If 0, use the target dependent heuristic.
diff --git a/gcc/testsuite/gcc.dg/tracer-static-1.c b/gcc/testsuite/gcc.dg/tracer-static-1.c
new file mode 100644
index 000000000..76c863b48
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tracer-static-1.c
@@ -0,0 +1,28 @@
+/* { dg-do compile } */
+/* { dg-options "-O3 -ftracer-static -fdump-tree-tracer" } */
+
+static __attribute__ ((noinline)) int fib (int n)
+{
+  if (n < 3)
+    return 0;
+
+  long long fib1 = 0, fib2 = 1;
+  long long currentFib = 0;
+
+  for (int i = 3; i <= n; ++i)
+    {
+      currentFib = fib1 + fib2;
+      fib1 = fib2;
+      fib2 = currentFib;
+    }
+
+  return currentFib;
+}
+
+int main (int argc, char** argv)
+{
+  int n = argc;
+  return fib (n);
+}
+
+/* { dg-final { scan-tree-dump-times "BB\\d+ with n = \\d+ will not be covered by tracer formation" 4 "tracer" } } */
\ No newline at end of file
diff --git a/gcc/tracer.cc b/gcc/tracer.cc
index 4d054fe8f..9b1578cd4 100644
--- a/gcc/tracer.cc
+++ b/gcc/tracer.cc
@@ -304,6 +304,17 @@ tail_duplicate (void)
     {
       int n;
       analyze_bb (bb, &n);
+
+    if (flag_tracer_static && n >= param_tracer_min_not_covered_insns_num
+	&& n <= param_tracer_max_not_covered_insns_num)
+      {
+	if (dump_file)
+	  fprintf (dump_file,
+		   "BB%d with n = %d will not be covered by tracer formation\n",
+		   bb->index, n);
+	continue;
+      }
+
       if (!ignore_bb_p (bb))
 	blocks[bb->index] = heap.insert (-bb->count.to_frequency (cfun), bb);
 
-- 
2.33.0