build: disable ICF for mksnapshot

Refs: https://chromium-review.googlesource.com/c/v8/v8/+/5447267
Co-authored-by: Michaël Zasso <[email protected]>

Author: LeszekSwirski

node.gyp

@@ -1319,6 +1319,11 @@
             'winmm.lib',
             'Ws2_32.lib',
           ],
+          'msbuild_settings': {
+            'Link': {
+              'EnableCOMDATFolding': 'false', # /OPT:NOICF
+            },
+          },
         }],
         # Avoid excessive LTO
         ['enable_lto=="true"', {

tools/v8_gypfiles/v8.gyp

@@ -1700,6 +1700,13 @@
         ['enable_lto=="true"', {
           'ldflags': [ '-fno-lto' ],
         }],
+        ['OS=="win"', {
+          'msbuild_settings': {
+            'Link': {
+              'EnableCOMDATFolding': 'false', # /OPT:NOICF
+            },
+          },
+        }],
       ],
     },  # mksnapshot
     {

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") {