[arm64] Use Abseil's btree_map for unresolved branches

Use Abseil's fast map container for unresolved branches in the
assembler.

Change-Id: I2b7e5d4407bd8e61102634e675dbabe895f65327
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/4720550
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/main@{#91335}

BUILD.bazel

@@ -3996,6 +3996,7 @@ v8_library(
     deps = [
         ":v8_libbase",
         "//external:base_trace_event_common",
+        "//external:absl_btree",
         "//external:absl_flat_hash_map",
         "//external:absl_flat_hash_set",
     ],

DEPS

@@ -340,6 +340,7 @@ include_rules = [
   # https://chromium.googlesource.com/chromium/src/+/main/styleguide/c++/c++11.md
   '+absl/container/flat_hash_map.h',
   '+absl/container/flat_hash_set.h',
+  '+absl/container/btree_map.h',
   '+absl/types/optional.h',
   '+absl/types/variant.h',
   '+absl/status',

WORKSPACE

@@ -44,6 +44,11 @@ bind(
     actual = "@com_google_absl//absl/types:optional"
 )
 
+bind(
+    name = "absl_btree",
+    actual = "@com_google_absl//absl/container:btree"
+)
+
 bind(
     name = "absl_flat_hash_map",
     actual = "@com_google_absl//absl/container:flat_hash_map"

src/codegen/arm64/assembler-arm64.cc

@@ -4709,8 +4709,7 @@ void Assembler::EmitVeneers(bool force_emit, bool need_protection,
         pc_offset -= Instruction::ImmBranchRange(CondBranchType);
       }
       tasks.emplace_back(FarBranchInfo{pc_offset, it->second});
-      auto eraser_it = it++;
-      unresolved_branches_.erase(eraser_it);
+      it = unresolved_branches_.erase(it);
     }
   }
 

src/codegen/arm64/assembler-arm64.h

@@ -9,6 +9,7 @@
 #include <map>
 #include <memory>
 
+#include "absl/container/btree_map.h"
 #include "src/base/optional.h"
 #include "src/codegen/arm64/constants-arm64.h"
 #include "src/codegen/arm64/instructions-arm64.h"
@@ -3350,7 +3351,7 @@ class V8_EXPORT_PRIVATE Assembler : public AssemblerBase {
   // Note that the maximum reachable offset (first member of the pairs) should
   // always be positive but has the same type as the return value for
   // pc_offset() for convenience.
-  std::map<int, Label*> unresolved_branches_;
+  absl::btree_map<int, Label*> unresolved_branches_;
 
   // We generate a veneer for a branch if we reach within this distance of the
   // limit of the range.