From bf2905726eab2409da70af57a6f787823f0a2f06 Mon Sep 17 00:00:00 2001
From: Leszek Swirski <leszeks@google.com>
Date: Fri, 12 Apr 2024 15:29:09 +0200
Subject: [PATCH] build: disable ICF for mksnapshot
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Refs: https://chromium-review.googlesource.com/c/v8/v8/+/5447267
Co-authored-by: Michaël Zasso <targos@protonmail.com>
---
 node.gyp                 |  6 ++++++
 tools/v8_gypfiles/v8.gyp | 18 ++++++++++++++++++
 unofficial.gni           | 19 ++++++++++++++++++-
 3 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/node.gyp b/node.gyp
index 484d3ff0329..b97b5fc008a 100644
--- a/node.gyp
+++ b/node.gyp
@@ -1294,6 +1294,12 @@
         'tools/snapshot/node_mksnapshot.cc',
       ],
 
+      'msvs_settings': {
+        'VCLinkerTool': {
+          'EnableCOMDATFolding': '1', # /OPT:NOICF
+        },
+      },
+
       'conditions': [
         ['node_write_snapshot_as_array_literals=="true"', {
           'defines': [ 'NODE_MKSNAPSHOT_USE_ARRAY_LITERALS=1' ],
diff --git a/tools/v8_gypfiles/v8.gyp b/tools/v8_gypfiles/v8.gyp
index 1e2b3645132..4e1c2e76855 100644
--- a/tools/v8_gypfiles/v8.gyp
+++ b/tools/v8_gypfiles/v8.gyp
@@ -1692,6 +1692,24 @@
       'sources': [
         '<!@pymod_do_main(GN-scraper "<(V8_ROOT)/BUILD.gn"  "\\"mksnapshot.*?sources = ")',
       ],
+      'configurations': {
+        # We have to repeat the settings for each configuration because toochain.gypi
+        # defines the default EnableCOMDATFolding value in the configurations dicts.
+        'Debug': {
+          'msvs_settings': {
+            'VCLinkerTool': {
+              'EnableCOMDATFolding': '1', # /OPT:NOICF
+            },
+          },
+        },
+        'Release': {
+          'msvs_settings': {
+            'VCLinkerTool': {
+              'EnableCOMDATFolding': '1', # /OPT:NOICF
+            },
+          },
+        },
+      },
       'conditions': [
         ['want_separate_host_toolset', {
           'toolsets': ['host'],
diff --git a/unofficial.gni b/unofficial.gni
index 027805104fc..6244454c178 100644
--- a/unofficial.gni
+++ b/unofficial.gni
@@ -235,13 +235,30 @@ template("node_gn_build") {
   if (node_use_node_snapshot) {
     if (current_toolchain == v8_snapshot_toolchain) {
       executable("node_mksnapshot") {
-        configs += [ ":node_internal_config" ]
+        configs += [ ":node_internal_config", ":disable_icf" ]
         sources = [
           "src/node_snapshot_stub.cc",
           "tools/snapshot/node_mksnapshot.cc",
         ]
         deps = [ ":libnode" ]
       }
+
+      # This config disables a link time optimization "ICF", which may merge
+      # different functions into one if the function signature and body of them are
+      # identical.
+      #
+      # ICF breaks 1:1 mappings of the external references for V8 snapshot, so we
+      # disable it while taking a V8 snapshot.
+      config("disable_icf") {
+        visibility = [ ":*" ]  # Only targets in this file can depend on this.
+        if (is_win) {
+          ldflags = [ "/OPT:NOICF" ]  # link.exe, but also lld-link.exe.
+        } else if (is_apple && !use_lld) {
+          ldflags = [ "-Wl,-no_deduplicate" ]  # ld64.
+        } else if (use_gold || use_lld) {
+          ldflags = [ "-Wl,--icf=none" ]
+        }
+      }
     }
 
     action("run_node_mksnapshot") {