Simplify firstGeq - make it not stepwise

ConflictSet.cpp

@@ -1741,32 +1741,17 @@ void addWriteRange(Node *&root, int64_t oldestVersion,
   }
 }
 
-struct FirstGeqStepwise {
+Iterator firstGeq(Node *n, const std::span<const uint8_t> key) {
-  Node *n;
+  auto remaining = key;
-  std::span<const uint8_t> remaining;
+  for (;;) {
-  int cmp;
-
-  enum Phase {
-    Init,
-    // Being in this phase implies that the key matches the search path exactly
-    // up to this point
-    Search,
-    DownLeftSpine
-  };
-  Phase phase;
-
-  FirstGeqStepwise(Node *n, std::span<const uint8_t> remaining)
-      : n(n), remaining(remaining), phase(Init) {}
-
-  // Not being done implies that n is not the firstGeq
-  bool step() {
-    switch (phase) {
-    case Search: {
     if (remaining.size() == 0) {
+      if (n->entryPresent) {
+        return {n, 0};
+      }
       int c = getChildGeq(n, 0);
       assert(c >= 0);
       n = getChildExists(n, c);
-        return downLeftSpine();
+      goto downLeftSpine;
     }
 
     auto *child = getChild(n, remaining[0]);
@@ -1774,10 +1759,10 @@ struct FirstGeqStepwise {
       int c = getChildGeq(n, remaining[0]);
       if (c >= 0) {
         n = getChildExists(n, c);
-          return downLeftSpine();
+        goto downLeftSpine;
       } else {
         n = nextSibling(n);
-          return downLeftSpine();
+        goto downLeftSpine;
       }
     }
 
@@ -1791,59 +1776,34 @@ struct FirstGeqStepwise {
       if (i < commonLen) {
         auto c = n->partialKey[i] <=> remaining[i];
         if (c > 0) {
-            return downLeftSpine();
+          goto downLeftSpine;
         } else {
           n = nextSibling(n);
-            return downLeftSpine();
+          goto downLeftSpine;
         }
       }
       if (commonLen == n->partialKeyLen) {
         // partial key matches
-          remaining =
+        remaining = remaining.subspan(commonLen, remaining.size() - commonLen);
-              remaining.subspan(commonLen, remaining.size() - commonLen);
       } else if (n->partialKeyLen > int(remaining.size())) {
         // n is the first physical node greater than remaining, and there's no
         // eq node
-          return downLeftSpine();
+        goto downLeftSpine;
       }
     }
   }
-      [[fallthrough]];
+downLeftSpine:
-    case Init:
+  if (n == nullptr) {
-      phase = Search;
+    return {nullptr, 1};
-      if (remaining.size() == 0 && n->entryPresent) {
+  }
-        cmp = 0;
+  for (;;) {
-        return true;
+    if (n->entryPresent) {
+      return {n, 1};
     }
-      return false;
-    case DownLeftSpine:
     int c = getChildGeq(n, 0);
     assert(c >= 0);
     n = getChildExists(n, c);
-      if (n->entryPresent) {
-        cmp = 1;
-        return true;
   }
-      return false;
-    }
-    __builtin_unreachable(); // GCOVR_EXCL_LINE
-  }
-
-  bool downLeftSpine() {
-    phase = DownLeftSpine;
-    if (n == nullptr || n->entryPresent) {
-      cmp = 1;
-      return true;
-    }
-    return step();
-  }
-};
-
-Iterator firstGeq(Node *n, const std::span<const uint8_t> key) {
-  FirstGeqStepwise stepwise{n, key};
-  while (!stepwise.step())
-    ;
-  return {stepwise.n, stepwise.cmp};
 }
 
 struct __attribute__((visibility("hidden"))) ConflictSet::Impl {