From a56cd371a2c497e4323756f8b8a08a0bba059bf2 Mon Sep 17 00:00:00 2001
From: Christian Hagedorn <chagedorn@openjdk.org>
Date: Mon, 3 Mar 2025 09:29:11 +0000
Subject: [PATCH] 8349584: Improve compiler processing

Reviewed-by: rhalade, ahgross, epeter, thartmann
---
 src/hotspot/share/opto/phaseX.cpp  | 52 ++++++++++++++++++++++++++++++
 src/hotspot/share/opto/phaseX.hpp  |  2 ++
 src/hotspot/share/opto/subnode.cpp |  8 +++--
 3 files changed, 60 insertions(+), 2 deletions(-)

diff --git a/src/hotspot/share/opto/phaseX.cpp b/src/hotspot/share/opto/phaseX.cpp
index f3435fa2b61..edddd1797b1 100644
--- a/src/hotspot/share/opto/phaseX.cpp
+++ b/src/hotspot/share/opto/phaseX.cpp
@@ -2851,6 +2851,7 @@ void PhaseCCP::push_more_uses(Unique_Node_List& worklist, Node* parent, const No
   push_and(worklist, parent, use);
   push_cast_ii(worklist, parent, use);
   push_opaque_zero_trip_guard(worklist, use);
+  push_bool_with_cmpu_and_mask(worklist, use);
 }
 
 
@@ -2897,6 +2898,57 @@ void PhaseCCP::push_cmpu(Unique_Node_List& worklist, const Node* use) const {
   }
 }
 
+// Look for the following shape, which can be optimized by BoolNode::Value_cmpu_and_mask() (i.e. corresponds to case
+// (1b): "(m & x) <u (m + 1))".
+// If any of the inputs on the level (%%) change, we need to revisit Bool because we could have prematurely found that
+// the Bool is constant (i.e. case (1b) can be applied) which could become invalid with new type information during CCP.
+//
+//  m    x  m    1  (%%)
+//   \  /    \  /
+//   AndI    AddI
+//      \    /
+//       CmpU
+//        |
+//       Bool
+//
+void PhaseCCP::push_bool_with_cmpu_and_mask(Unique_Node_List& worklist, const Node* use) const {
+  uint use_op = use->Opcode();
+  if (use_op != Op_AndI && (use_op != Op_AddI || use->in(2)->find_int_con(0) != 1)) {
+    // Not "m & x" or "m + 1"
+    return;
+  }
+  for (DUIterator_Fast imax, i = use->fast_outs(imax); i < imax; i++) {
+    Node* cmpu = use->fast_out(i);
+    if (cmpu->Opcode() == Op_CmpU) {
+      push_bool_matching_case1b(worklist, cmpu);
+    }
+  }
+}
+
+// Push any Bool below 'cmpu' that matches case (1b) of BoolNode::Value_cmpu_and_mask().
+void PhaseCCP::push_bool_matching_case1b(Unique_Node_List& worklist, const Node* cmpu) const {
+  assert(cmpu->Opcode() == Op_CmpU, "must be");
+  for (DUIterator_Fast imax, i = cmpu->fast_outs(imax); i < imax; i++) {
+    Node* bol = cmpu->fast_out(i);
+    if (!bol->is_Bool() || bol->as_Bool()->_test._test != BoolTest::lt) {
+      // Not a Bool with "<u"
+      continue;
+    }
+    Node* andI = cmpu->in(1);
+    Node* addI = cmpu->in(2);
+    if (andI->Opcode() != Op_AndI || addI->Opcode() != Op_AddI || addI->in(2)->find_int_con(0) != 1) {
+      // Not "m & x" and "m + 1"
+      continue;
+    }
+
+    Node* m = addI->in(1);
+    if (m == andI->in(1) || m == andI->in(2)) {
+      // Is "m" shared? Matched (1b) and thus we revisit Bool.
+      push_if_not_bottom_type(worklist, bol);
+    }
+  }
+}
+
 // If n is used in a counted loop exit condition, then the type of the counted loop's Phi depends on the type of 'n'.
 // Seem PhiNode::Value().
 void PhaseCCP::push_counted_loop_phi(Unique_Node_List& worklist, Node* parent, const Node* use) {
diff --git a/src/hotspot/share/opto/phaseX.hpp b/src/hotspot/share/opto/phaseX.hpp
index 648e911e783..aeba5e8662d 100644
--- a/src/hotspot/share/opto/phaseX.hpp
+++ b/src/hotspot/share/opto/phaseX.hpp
@@ -638,6 +638,8 @@ class PhaseCCP : public PhaseIterGVN {
   void push_and(Unique_Node_List& worklist, const Node* parent, const Node* use) const;
   void push_cast_ii(Unique_Node_List& worklist, const Node* parent, const Node* use) const;
   void push_opaque_zero_trip_guard(Unique_Node_List& worklist, const Node* use) const;
+  void push_bool_with_cmpu_and_mask(Unique_Node_List& worklist, const Node* use) const;
+  void push_bool_matching_case1b(Unique_Node_List& worklist, const Node* cmpu) const;
 
  public:
   PhaseCCP( PhaseIterGVN *igvn ); // Compute conditional constants
diff --git a/src/hotspot/share/opto/subnode.cpp b/src/hotspot/share/opto/subnode.cpp
index cc3c9f3bc96..43461075cff 100644
--- a/src/hotspot/share/opto/subnode.cpp
+++ b/src/hotspot/share/opto/subnode.cpp
@@ -1880,7 +1880,7 @@ const Type* BoolNode::Value_cmpu_and_mask(PhaseValues* phase) const {
         // (1b) "(x & m) <u m + 1" and "(m & x) <u m + 1", cmp2 = m + 1
         Node* rhs_m = cmp2->in(1);
         const TypeInt* rhs_m_type = phase->type(rhs_m)->isa_int();
-        if (rhs_m_type->_lo > -1 || rhs_m_type->_hi < -1) {
+        if (rhs_m_type != nullptr && (rhs_m_type->_lo > -1 || rhs_m_type->_hi < -1)) {
           // Exclude any case where m == -1 is possible.
           m = rhs_m;
         }
@@ -1898,12 +1898,16 @@ const Type* BoolNode::Value_cmpu_and_mask(PhaseValues* phase) const {
 // Simplify a Bool (convert condition codes to boolean (1 or 0)) node,
 // based on local information.   If the input is constant, do it.
 const Type* BoolNode::Value(PhaseGVN* phase) const {
+  const Type* input_type = phase->type(in(1));
+  if (input_type == Type::TOP) {
+    return Type::TOP;
+  }
   const Type* t = Value_cmpu_and_mask(phase);
   if (t != nullptr) {
     return t;
   }
 
-  return _test.cc2logical( phase->type( in(1) ) );
+  return _test.cc2logical(input_type);
 }
 
 #ifndef PRODUCT