From 71b3c7fb7fa7c1eb60070594ccda7f04b5076430 Mon Sep 17 00:00:00 2001
From: Andrew Noyes <andrew@weaselab.dev>
Date: Sat, 12 Oct 2024 23:56:01 -0700
Subject: [PATCH] Stop tracking first iteration

We can tell with other means
---
 ConflictSet.cpp | 34 ++++++++++++++++------------------
 1 file changed, 16 insertions(+), 18 deletions(-)

diff --git a/ConflictSet.cpp b/ConflictSet.cpp
index a828f0c..f589372 100644
--- a/ConflictSet.cpp
+++ b/ConflictSet.cpp
@@ -2507,7 +2507,9 @@ bool checkRangeRightSide(Node *n, std::span<const uint8_t> key, int prefixLen,
     }
   }
 
-  for (bool first = true;; first = false) {
+  Node *commonPrefixNode = n;
+
+  for (;;) {
     Node *child = getChild(n, remaining[0]);
     if (child == nullptr) {
       auto c = getChildGeq(n, remaining[0]);
@@ -2515,7 +2517,7 @@ bool checkRangeRightSide(Node *n, std::span<const uint8_t> key, int prefixLen,
         n = c;
         goto downLeftSpine;
       } else {
-        if (!first && maxVersion(n) > readVersion) {
+        if (n != commonPrefixNode && maxVersion(n) > readVersion) {
           return false;
         }
         goto backtrack;
@@ -2533,11 +2535,12 @@ bool checkRangeRightSide(Node *n, std::span<const uint8_t> key, int prefixLen,
         if (c > 0) {
           goto downLeftSpine;
         } else {
-          if ((!first || i + 1 >= prefixLen) && n->entryPresent &&
-              n->entry.rangeVersion > readVersion) {
+          if ((n->parent != commonPrefixNode || i + 1 >= prefixLen) &&
+              n->entryPresent && n->entry.rangeVersion > readVersion) {
             return false;
           }
-          if ((!first || i + 1 >= prefixLen) && maxVersion(n) > readVersion) {
+          if ((n->parent != commonPrefixNode || i + 1 >= prefixLen) &&
+              maxVersion(n) > readVersion) {
             return false;
           }
           goto backtrack;
@@ -3280,21 +3283,16 @@ static Continuation commonPrefixIterTable[] = {
     common_prefix_iter<Node16>, common_prefix_iter<Node48>,
     common_prefix_iter<Node256>};
 
-template <class NodeT, bool kFirst>
+template <class NodeT>
 PRESERVE_NONE void left_side_iter(CheckJob *, CheckContext *);
 
 PRESERVE_NONE void left_side_down_left_spine(CheckJob *, CheckContext *);
 
 PRESERVE_NONE void done_left_side_iter(CheckJob *, CheckContext *);
 
-static Continuation leftSideIterTable[2][5] = {
-    {left_side_iter<Node0, false>, left_side_iter<Node3, false>,
-     left_side_iter<Node16, false>, left_side_iter<Node48, false>,
-     left_side_iter<Node256, false>},
-    {left_side_iter<Node0, true>, left_side_iter<Node3, true>,
-     left_side_iter<Node16, true>, left_side_iter<Node48, true>,
-     left_side_iter<Node256, true>},
-};
+static Continuation leftSideIterTable[] = {
+    left_side_iter<Node0>, left_side_iter<Node3>, left_side_iter<Node16>,
+    left_side_iter<Node48>, left_side_iter<Node256>};
 
 PRESERVE_NONE void begin(CheckJob *job, CheckContext *context) {
   job->lcp = longestCommonPrefix(job->begin.data(), job->end.data(),
@@ -3435,14 +3433,14 @@ PRESERVE_NONE void done_common_prefix_iter(CheckJob *job,
   }
 
   job->n = child;
-  job->continuation = leftSideIterTable[true][c.getType()];
+  job->continuation = leftSideIterTable[c.getType()];
   __builtin_prefetch(job->n);
   MUSTTAIL return keepGoing(job, context);
 }
 
 // Return true if the max version among all keys that start with key[:prefixLen]
 // that are >= key is <= readVersion
-template <class NodeT, bool kFirst>
+template <class NodeT>
 PRESERVE_NONE void left_side_iter(CheckJob *job, CheckContext *context) {
   assert(NodeT::kType == job->n->getType());
   NodeT *n = static_cast<NodeT *>(job->n);
@@ -3456,7 +3454,7 @@ PRESERVE_NONE void left_side_iter(CheckJob *job, CheckContext *context) {
     if (i < commonLen) {
       auto c = n->partialKey()[i] <=> job->remaining[i];
       if (c > 0) {
-        if constexpr (kFirst) {
+        if (n->parent == job->commonPrefixNode) {
           if (i < job->lcp) {
             job->continuation = left_side_down_left_spine;
             MUSTTAIL return job->continuation(job, context);
@@ -3541,7 +3539,7 @@ PRESERVE_NONE void left_side_iter(CheckJob *job, CheckContext *context) {
   }
 
   job->n = child;
-  job->continuation = leftSideIterTable[false][c.getType()];
+  job->continuation = leftSideIterTable[c.getType()];
   __builtin_prefetch(job->n);
   MUSTTAIL return keepGoing(job, context);
 }