From 85c9f0018ac5b671973b916a85692cec2a0c6d3d Mon Sep 17 00:00:00 2001
From: bmeurer <bmeurer@chromium.org>
Date: Wed, 29 Jun 2016 01:17:21 -0700
Subject: [PATCH] [turbofan] Run representation selection without the Typer
 decorator.

It's not safe to magically compute types during representation
selection, so better disable the Typer decorator before we start
to do the representation/truncation analysis. This will also allow
us to move to a world where we can run representation selection
concurrently eventually.

R=jarin@chromium.org

Review-Url: https://codereview.chromium.org/2103363004
Cr-Commit-Position: refs/heads/master@{#37367}
---
 src/compiler/pipeline.cc            | 10 +++++----
 src/compiler/simplified-lowering.cc | 32 ++++++++++++++---------------
 2 files changed, 22 insertions(+), 20 deletions(-)

diff --git a/src/compiler/pipeline.cc b/src/compiler/pipeline.cc
index d592000911..73d484ba19 100644
--- a/src/compiler/pipeline.cc
+++ b/src/compiler/pipeline.cc
@@ -1444,12 +1444,14 @@ bool PipelineImpl::CreateGraph() {
       Run<EscapeAnalysisPhase>();
       RunPrintAndVerify("Escape Analysed");
     }
-
-    // Select representations.
-    Run<RepresentationSelectionPhase>();
-    RunPrintAndVerify("Representations selected", true);
   }
 
+  // Select representations. This has to run w/o the Typer decorator, because
+  // we cannot compute meaningful types anyways, and the computed types might
+  // even conflict with the representation/truncation logic.
+  Run<RepresentationSelectionPhase>();
+  RunPrintAndVerify("Representations selected", true);
+
 #ifdef DEBUG
   // From now on it is invalid to look at types on the nodes, because:
   //
diff --git a/src/compiler/simplified-lowering.cc b/src/compiler/simplified-lowering.cc
index 1905c75107..b36b777224 100644
--- a/src/compiler/simplified-lowering.cc
+++ b/src/compiler/simplified-lowering.cc
@@ -671,6 +671,11 @@ class RepresentationSelector {
 
   Type* GetUpperBound(Node* node) { return NodeProperties::GetType(node); }
 
+  bool InputCannotBe(Node* node, Type* type) {
+    DCHECK_EQ(1, node->op()->ValueInputCount());
+    return !GetUpperBound(node->InputAt(0))->Maybe(type);
+  }
+
   bool InputIs(Node* node, Type* type) {
     DCHECK_EQ(1, node->op()->ValueInputCount());
     return GetUpperBound(node->InputAt(0))->Is(type);
@@ -1703,11 +1708,11 @@ class RepresentationSelector {
         return;
       }
       case IrOpcode::kCheckTaggedPointer: {
-        VisitUnop(node, UseInfo::AnyTagged(), MachineRepresentation::kTagged);
-        if (lower()) {
-          if (InputIs(node, Type::TaggedPointer())) {
-            DeferReplacement(node, node->InputAt(0));
-          }
+        if (InputCannotBe(node, Type::SignedSmall())) {
+          VisitUnop(node, UseInfo::AnyTagged(), MachineRepresentation::kTagged);
+          if (lower()) DeferReplacement(node, node->InputAt(0));
+        } else {
+          VisitUnop(node, UseInfo::AnyTagged(), MachineRepresentation::kTagged);
         }
         return;
       }
@@ -1719,11 +1724,6 @@ class RepresentationSelector {
           if (lower()) DeferReplacement(node, node->InputAt(0));
         } else {
           VisitUnop(node, UseInfo::AnyTagged(), MachineRepresentation::kTagged);
-          if (lower()) {
-            if (InputIs(node, Type::TaggedSigned())) {
-              DeferReplacement(node, node->InputAt(0));
-            }
-          }
         }
         return;
       }
@@ -1743,15 +1743,15 @@ class RepresentationSelector {
       }
       case IrOpcode::kStoreField: {
         FieldAccess access = FieldAccessOf(node->op());
+        WriteBarrierKind write_barrier_kind = WriteBarrierKindFor(
+            access.base_is_tagged, access.machine_type.representation(),
+            access.offset, access.type, node->InputAt(1));
         ProcessInput(node, 0, UseInfoForBasePointer(access));
         ProcessInput(node, 1, TruncatingUseInfoFromRepresentation(
                                   access.machine_type.representation()));
         ProcessRemainingInputs(node, 2);
         SetOutput(node, MachineRepresentation::kNone);
         if (lower()) {
-          WriteBarrierKind write_barrier_kind = WriteBarrierKindFor(
-              access.base_is_tagged, access.machine_type.representation(),
-              access.offset, access.type, node->InputAt(1));
           if (write_barrier_kind < access.write_barrier_kind) {
             access.write_barrier_kind = write_barrier_kind;
             NodeProperties::ChangeOp(
@@ -1816,6 +1816,9 @@ class RepresentationSelector {
       }
       case IrOpcode::kStoreElement: {
         ElementAccess access = ElementAccessOf(node->op());
+        WriteBarrierKind write_barrier_kind = WriteBarrierKindFor(
+            access.base_is_tagged, access.machine_type.representation(),
+            access.type, node->InputAt(2));
         ProcessInput(node, 0, UseInfoForBasePointer(access));  // base
         ProcessInput(node, 1, UseInfo::TruncatingWord32());    // index
         ProcessInput(node, 2,
@@ -1824,9 +1827,6 @@ class RepresentationSelector {
         ProcessRemainingInputs(node, 3);
         SetOutput(node, MachineRepresentation::kNone);
         if (lower()) {
-          WriteBarrierKind write_barrier_kind = WriteBarrierKindFor(
-              access.base_is_tagged, access.machine_type.representation(),
-              access.type, node->InputAt(2));
           if (write_barrier_kind < access.write_barrier_kind) {
             access.write_barrier_kind = write_barrier_kind;
             NodeProperties::ChangeOp(