[wasm] Do float constant folding if the origin is not wasm

src/compiler/machine-operator-reducer.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/machine-operator-reducer.h"
 
 #include "src/base/bits.h"
 #include "src/base/division-by-constant.h"
 #include "src/base/ieee754.h"
 #include "src/codegen.h"
 #include "src/compiler/diamond.h"
 #include "src/compiler/graph.h"
 #include "src/compiler/js-graph.h"
 #include "src/compiler/node-matchers.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
-MachineOperatorReducer::MachineOperatorReducer(JSGraph* jsgraph)
-    : jsgraph_(jsgraph) {}
-
+MachineOperatorReducer::MachineOperatorReducer(JSGraph* jsgraph,
+                                               bool allow_signalling_nan)
+    : jsgraph_(jsgraph), allow_signalling_nan_(allow_signalling_nan) {}
 
 MachineOperatorReducer::~MachineOperatorReducer() {}
 
 
 Node* MachineOperatorReducer::Float32Constant(volatile float value) {
   return graph()->NewNode(common()->Float32Constant(value));
 }
 
 
 Node* MachineOperatorReducer::Float64Constant(volatile double value) {
@@ skipping 276 matching lines @@
       if (m.left().Is(0)) return ReplaceBool(true);            // 0 <= x => true
       if (m.right().Is(kMaxUInt32)) return ReplaceBool(true);  // x <= M => true
       if (m.IsFoldable()) {                                    // K <= K => K
         return ReplaceBool(m.left().Value() <= m.right().Value());
       }
       if (m.LeftEqualsRight()) return ReplaceBool(true);  // x <= x => true
       break;
     }
     case IrOpcode::kFloat32Sub: {
       Float32BinopMatcher m(node);
-      // TODO(ahaas): We could do x - 0.0 = x if we knew that x is not an sNaN.
+      if (allow_signalling_nan_ && m.right().Is(0) &&
+          (copysign(1.0, m.right().Value()) > 0)) {
+        return Replace(m.left().node());  // x - 0 => x
+      }
       if (m.right().IsNaN()) {  // x - NaN => NaN
         // Do some calculation to make a signalling NaN quiet.
         return ReplaceFloat32(m.right().Value() - m.right().Value());
       }
       if (m.left().IsNaN()) {  // NaN - x => NaN
         // Do some calculation to make a signalling NaN quiet.
         return ReplaceFloat32(m.left().Value() - m.left().Value());
       }
       if (m.IsFoldable()) {  // L - R => (L - R)
         return ReplaceFloat32(m.left().Value() - m.right().Value());
@@ skipping 23 matching lines @@
         // Do some calculation to make a signalling NaN quiet.
         return ReplaceFloat64(m.right().Value() - m.right().Value());
       }
       if (m.IsFoldable()) {  // K + K => K
         return ReplaceFloat64(m.left().Value() + m.right().Value());
       }
       break;
     }
     case IrOpcode::kFloat64Sub: {
       Float64BinopMatcher m(node);
-      // TODO(ahaas): We could do x - 0.0 = x if we knew that x is not an sNaN.
+      if (allow_signalling_nan_ && m.right().Is(0) &&
+          (Double(m.right().Value()).Sign() > 0)) {
+        return Replace(m.left().node());  // x - 0 => x
+      }
       if (m.right().IsNaN()) {  // x - NaN => NaN
         // Do some calculation to make a signalling NaN quiet.
         return ReplaceFloat64(m.right().Value() - m.right().Value());
       }
       if (m.left().IsNaN()) {  // NaN - x => NaN
         // Do some calculation to make a signalling NaN quiet.
         return ReplaceFloat64(m.left().Value() - m.left().Value());
       }
       if (m.IsFoldable()) {  // L - R => (L - R)
         return ReplaceFloat64(m.left().Value() - m.right().Value());
@@ skipping 12 matching lines @@
         }
         // -0.0 - R => -R
         node->RemoveInput(0);
         NodeProperties::ChangeOp(node, machine()->Float64Neg());
         return Changed(node);
       }
       break;
     }
     case IrOpcode::kFloat64Mul: {
       Float64BinopMatcher m(node);
-      // TODO(ahaas): We could do x * 1.0 = x if we knew that x is not an sNaN.
+      if (allow_signalling_nan_ && m.right().Is(1))
+        return Replace(m.left().node());  // x * 1.0 => x
       if (m.right().Is(-1)) {  // x * -1.0 => -0.0 - x
         node->ReplaceInput(0, Float64Constant(-0.0));
         node->ReplaceInput(1, m.left().node());
         NodeProperties::ChangeOp(node, machine()->Float64Sub());
         return Changed(node);
       }
       if (m.right().IsNaN()) {                               // x * NaN => NaN
         // Do some calculation to make a signalling NaN quiet.
         return ReplaceFloat64(m.right().Value() - m.right().Value());
       }
       if (m.IsFoldable()) {  // K * K => K
         return ReplaceFloat64(m.left().Value() * m.right().Value());
       }
       if (m.right().Is(2)) {  // x * 2.0 => x + x
         node->ReplaceInput(1, m.left().node());
         NodeProperties::ChangeOp(node, machine()->Float64Add());
         return Changed(node);
       }
       break;
     }
     case IrOpcode::kFloat64Div: {
       Float64BinopMatcher m(node);
+      if (allow_signalling_nan_ && m.right().Is(1))
+        return Replace(m.left().node());  // x / 1.0 => x
       // TODO(ahaas): We could do x / 1.0 = x if we knew that x is not an sNaN.
       if (m.right().IsNaN()) {                               // x / NaN => NaN
         // Do some calculation to make a signalling NaN quiet.
         return ReplaceFloat64(m.right().Value() - m.right().Value());
       }
       if (m.left().IsNaN()) {  // NaN / x => NaN
         // Do some calculation to make a signalling NaN quiet.
         return ReplaceFloat64(m.left().Value() - m.left().Value());
       }
       if (m.IsFoldable()) {  // K / K => K
@@ skipping 985 matching lines @@
 MachineOperatorBuilder* MachineOperatorReducer::machine() const {
   return jsgraph()->machine();
 }
 
 
 Graph* MachineOperatorReducer::graph() const { return jsgraph()->graph(); }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8