8283699: Improve the peephole mechanism of hotspot

Reviewed-by: kvn, dlong

Author: Quan Anh Mai

src/hotspot/cpu/x86/peephole_x86_64.cpp

@@ -0,0 +1,145 @@
+/*
+ * Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+#include "precompiled.hpp"
+
+#ifdef COMPILER2
+
+#include "peephole_x86_64.hpp"
+
+// This function transforms the shapes
+// mov d, s1; add d, s2 into
+// lea d, [s1 + s2]     and
+// mov d, s1; shl d, s2 into
+// lea d, [s1 << s2]    with s2 = 1, 2, 3
+bool lea_coalesce_helper(Block* block, int block_index, PhaseCFG* cfg_, PhaseRegAlloc* ra_,
+                         MachNode* (*new_root)(), uint inst0_rule, bool imm) {
+  MachNode* inst0 = block->get_node(block_index)->as_Mach();
+  assert(inst0->rule() == inst0_rule, "sanity");
+
+  OptoReg::Name dst = ra_->get_reg_first(inst0);
+  MachNode* inst1 = nullptr;
+  OptoReg::Name src1 = OptoReg::Bad;
+
+  if (inst0->in(1)->is_MachSpillCopy()) {
+    OptoReg::Name in = ra_->get_reg_first(inst0->in(1)->in(1));
+    if (OptoReg::is_reg(in) && OptoReg::as_VMReg(in)->is_Register()) {
+      inst1 = inst0->in(1)->as_Mach();
+      src1 = in;
+    }
+  }
+  if (inst1 == nullptr) {
+    return false;
+  }
+  assert(dst != src1, "");
+
+  // Only coalesce if inst1 is immediately followed by inst0
+  // Can be improved for more general cases
+  if (block_index < 1 || block->get_node(block_index - 1) != inst1) {
+    return false;
+  }
+  int inst1_index = block_index - 1;
+  Node* inst2;
+  if (imm) {
+    inst2 = nullptr;
+  } else {
+    inst2 = inst0->in(2);
+    if (inst2 == inst1) {
+      inst2 = inst2->in(1);
+    }
+  }
+
+  // See VM_Version::supports_fast_3op_lea()
+  if (!imm) {
+    Register rsrc1 = OptoReg::as_VMReg(src1)->as_Register();
+    Register rsrc2 = OptoReg::as_VMReg(ra_->get_reg_first(inst2))->as_Register();
+    if ((rsrc1 == rbp || rsrc1 == r13) && (rsrc2 == rbp || rsrc2 == r13)) {
+      return false;
+    }
+  }
+
+  // Go down the block to find the output proj node (the flag output) of inst0
+  int proj_index = -1;
+  Node* proj = nullptr;
+  for (uint pos = block_index + 1; pos < block->number_of_nodes(); pos++) {
+    Node* curr = block->get_node(pos);
+    if (curr->is_MachProj() && curr->in(0) == inst0) {
+      proj_index = pos;
+      proj = curr;
+      break;
+    }
+  }
+  assert(proj != nullptr, "");
+  // If some node uses the flag, cannot remove
+  if (proj->outcnt() > 0) {
+    return false;
+  }
+
+  MachNode* root = new_root();
+  // Assign register for the newly allocated node
+  ra_->set_oop(root, ra_->is_oop(inst0));
+  ra_->set_pair(root->_idx, ra_->get_reg_second(inst0), ra_->get_reg_first(inst0));
+
+  // Set input and output for the node
+  root->add_req(inst0->in(0));
+  root->add_req(inst1->in(1));
+  // No input for constant after matching
+  if (!imm) {
+    root->add_req(inst2);
+  }
+  inst0->replace_by(root);
+  proj->set_req(0, inst0);
+
+  // Initialize the operand array
+  root->_opnds[0] = inst0->_opnds[0]->clone();
+  root->_opnds[1] = inst0->_opnds[1]->clone();
+  root->_opnds[2] = inst0->_opnds[2]->clone();
+
+  // Modify the block
+  inst0->set_removed();
+  inst1->set_removed();
+  block->remove_node(proj_index);
+  block->remove_node(block_index);
+  block->remove_node(inst1_index);
+  block->insert_node(root, block_index - 1);
+
+  // Modify the CFG
+  cfg_->map_node_to_block(inst0, nullptr);
+  cfg_->map_node_to_block(inst1, nullptr);
+  cfg_->map_node_to_block(proj, nullptr);
+  cfg_->map_node_to_block(root, block);
+
+  return true;
+}
+
+bool Peephole::lea_coalesce_reg(Block* block, int block_index, PhaseCFG* cfg_, PhaseRegAlloc* ra_,
+                                MachNode* (*new_root)(), uint inst0_rule) {
+  return lea_coalesce_helper(block, block_index, cfg_, ra_, new_root, inst0_rule, false);
+}
+
+bool Peephole::lea_coalesce_imm(Block* block, int block_index, PhaseCFG* cfg_, PhaseRegAlloc* ra_,
+                                MachNode* (*new_root)(), uint inst0_rule) {
+  return lea_coalesce_helper(block, block_index, cfg_, ra_, new_root, inst0_rule, true);
+}
+
+#endif // COMPILER2

src/hotspot/cpu/x86/peephole_x86_64.hpp

@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#ifndef CPU_X86_PEEPHOLE_X86_64_HPP
+#define CPU_X86_PEEPHOLE_X86_64_HPP
+
+#include "opto/machnode.hpp"
+#include "opto/regalloc.hpp"
+
+class Peephole {
+public:
+  static bool lea_coalesce_reg(Block* block, int block_index, PhaseCFG* cfg_, PhaseRegAlloc* ra_,
+                               MachNode* (*new_root)(), uint inst0_rule);
+  static bool lea_coalesce_imm(Block* block, int block_index, PhaseCFG* cfg_, PhaseRegAlloc* ra_,
+                               MachNode* (*new_root)(), uint inst0_rule);
+};
+
+#endif // CPU_X86_PEEPHOLE_X86_64_HPP

src/hotspot/cpu/x86/x86_32.ad

@@ -657,8 +657,8 @@ void MachEpilogNode::format( PhaseRegAlloc *ra_, outputStream* st ) const {
   }
   st->print_cr("POPL   EBP"); st->print("\t");
   if (do_polling() && C->is_method_compilation()) {
-    st->print("CMPL     rsp, poll_offset[thread]  \n\t"
-              "JA       #safepoint_stub\t"
+    st->print("CMPL    rsp, poll_offset[thread]  \n\t"
+              "JA      #safepoint_stub\t"
               "# Safepoint: poll for GC");
   }
 }