emsdk.patch

diff --git a/bazel/BUILD b/bazel/BUILD
index cb3135c..4d6d92c 100644
--- a/bazel/BUILD
+++ b/bazel/BUILD
@@ -78,6 +78,18 @@ alias(
     }),
 )
 
+alias(
+    name = "dwp_files",
+    actual = select({
+        ":linux": "@emscripten_bin_linux//:dwp_files",
+        ":linux_arm64": "@emscripten_bin_linux_arm64//:dwp_files",
+        ":macos": "@emscripten_bin_mac//:dwp_files",
+        ":macos_arm64": "@emscripten_bin_mac_arm64//:dwp_files",
+        ":windows": "@emscripten_bin_win//:dwp_files",
+        "//conditions:default": ":empty",
+    }),
+)
+
 platform(
     name = "platform_wasm",
     constraint_values = [
diff --git a/bazel/emscripten_deps.bzl b/bazel/emscripten_deps.bzl
index 9d020bd..f466edb 100644
--- a/bazel/emscripten_deps.bzl
+++ b/bazel/emscripten_deps.bzl
@@ -96,6 +96,13 @@ filegroup(
         ],
     ),
 )
+
+filegroup(
+    name = "dwp_files",
+    srcs = [
+        "bin/llvm-dwp{bin_extension}",
+    ],
+)
 """
 
 def emscripten_deps(emscripten_version = "latest"):
@@ -173,38 +180,3 @@ def emscripten_deps(emscripten_version = "latest"):
             build_file_content = BUILD_FILE_CONTENT_TEMPLATE.format(bin_extension = ".exe"),
             type = "zip",
         )
-
-    if "emscripten_npm_linux" not in excludes:
-        npm_translate_lock(
-            name = "emscripten_npm_linux",
-            data = ["@emscripten_bin_linux//:emscripten/package.json"],
-            npm_package_lock = "@emscripten_bin_linux//:emscripten/package-lock.json",
-        )
-
-    if "emscripten_npm_linux_arm64" not in excludes:
-        npm_translate_lock(
-            name = "emscripten_npm_linux_arm64",
-            data = ["@emscripten_bin_linux_arm64//:emscripten/package.json"],
-            npm_package_lock = "@emscripten_bin_linux_arm64//:emscripten/package-lock.json",
-        )
-
-    if "emscripten_npm_mac" not in excludes:
-        npm_translate_lock(
-            name = "emscripten_npm_mac",
-            data = ["@emscripten_bin_mac//:emscripten/package.json"],
-            npm_package_lock = "@emscripten_bin_mac//:emscripten/package-lock.json",
-        )
-
-    if "emscripten_npm_mac_arm64" not in excludes:
-        npm_translate_lock(
-            name = "emscripten_npm_mac",
-            data = ["@emscripten_bin_mac_arm64//:emscripten/package.json"],
-            npm_package_lock = "@emscripten_bin_mac_arm64//:emscripten/package-lock.json",
-        )
-
-    if "emscripten_npm_win" not in excludes:
-        npm_translate_lock(
-            name = "emscripten_npm_win",
-            data = ["@emscripten_bin_win//:emscripten/package.json"],
-            npm_package_lock = "@emscripten_bin_win//:emscripten/package-lock.json",
-        )
diff --git a/bazel/emscripten_toolchain/BUILD.bazel b/bazel/emscripten_toolchain/BUILD.bazel
index a989450..4f1c213 100644
--- a/bazel/emscripten_toolchain/BUILD.bazel
+++ b/bazel/emscripten_toolchain/BUILD.bazel
@@ -1,3 +1,4 @@
+load("@python3_12//:defs.bzl", "py_binary")
 load(":toolchain.bzl", "emscripten_cc_toolchain_config_rule")
 
 package(default_visibility = ["//visibility:public"])
@@ -9,6 +10,7 @@ filegroup(
         "env.sh",
         "env.bat",
         "@nodejs//:node_files",
+        "@python3_12//:files",
     ],
 )
 
@@ -43,12 +45,25 @@ filegroup(
     ],
 )
 
+filegroup(
+    name = "dwp_files",
+    srcs = [
+        "emdwp-emscripten_bin_linux_arm64.sh",
+        "emdwp-emscripten_bin_linux.sh",
+        "emdwp-emscripten_bin_mac_arm64.sh",
+        "emdwp-emscripten_bin_mac.sh",
+        "emdwp-emscripten_bin_win.bat",
+        "@emsdk//:dwp_files",
+    ],
+)
+
 filegroup(
     name = "all_files",
     srcs = [
         ":ar_files",
         ":compiler_files",
         ":linker_files",
+        ":dwp_files",
     ],
 )
 
@@ -63,9 +78,9 @@ emscripten_cc_toolchain_config_rule(
     em_config = "@emscripten_cache//:emscripten_config",
     emscripten_binaries = "@emsdk//:compiler_files",
     nodejs_bin = "@nodejs//:node",
-    script_extension = select({
-        "@bazel_tools//src/conditions:host_windows": "bat",
-        "//conditions:default": "sh",
+    is_windows = select({
+        "@bazel_tools//src/conditions:host_windows": True,
+        "//conditions:default": False,
     }),
 )
 
@@ -75,7 +90,7 @@ cc_toolchain(
     ar_files = ":ar_files",
     as_files = ":empty",
     compiler_files = ":compiler_files",
-    dwp_files = ":empty",
+    dwp_files = ":dwp_files",
     linker_files = ":linker_files",
     objcopy_files = ":empty",
     strip_files = ":empty",
diff --git a/bazel/emscripten_toolchain/dwp.bat b/bazel/emscripten_toolchain/dwp.bat
new file mode 100644
index 0000000..85ed4b5
--- /dev/null
+++ b/bazel/emscripten_toolchain/dwp.bat
@@ -0,0 +1,4 @@
+@echo off
+REM Dummy dwp script for emscripten toolchain
+REM Since wasm doesn't support split debug info, this is a no-op
+exit /b 0
diff --git a/bazel/emscripten_toolchain/dwp.sh b/bazel/emscripten_toolchain/dwp.sh
new file mode 100644
index 0000000..50a1d80
--- /dev/null
+++ b/bazel/emscripten_toolchain/dwp.sh
@@ -0,0 +1,8 @@
+#!/bin/bash
+
+# Dummy dwp script for emscripten toolchain
+# Since wasm doesn't support split debug info, this is a no-op
+# Just echo the command for debugging and exit successfully
+
+echo "DWP called with args: $@" >&2
+exit 0
diff --git a/bazel/emscripten_toolchain/emar.bat b/bazel/emscripten_toolchain/emar.bat
index b8e9125..844c378 100644
--- a/bazel/emscripten_toolchain/emar.bat
+++ b/bazel/emscripten_toolchain/emar.bat
@@ -2,4 +2,4 @@
 
 call external\emsdk\emscripten_toolchain\env.bat
 
-py -3 %EMSCRIPTEN%\emar.py %*
+%EMSDK_PYTHON% %EMSCRIPTEN%\emar.py %*
diff --git a/bazel/emscripten_toolchain/emar.sh b/bazel/emscripten_toolchain/emar.sh
index b4ead6e..d57222f 100755
--- a/bazel/emscripten_toolchain/emar.sh
+++ b/bazel/emscripten_toolchain/emar.sh
@@ -2,4 +2,11 @@
 
 source $(dirname $0)/env.sh
 
-exec python3 $EMSCRIPTEN/emar.py "$@"
+if [[ "$EMSDK_PYTHON" != /* ]]; then
+    EMSDK_PYTHON="$ROOT_DIR/$EMSDK_PYTHON"
+fi
+
+PYBINPATH="$(dirname "${EMSDK_PYTHON}")"
+export PATH=$PYBINPATH:$PATH
+
+exec $EMSDK_PYTHON $EMSCRIPTEN/emar.py "$@"
diff --git a/bazel/emscripten_toolchain/emcc.bat b/bazel/emscripten_toolchain/emcc.bat
index aba66f4..b302736 100644
--- a/bazel/emscripten_toolchain/emcc.bat
+++ b/bazel/emscripten_toolchain/emcc.bat
@@ -2,4 +2,4 @@
 
 call external\emsdk\emscripten_toolchain\env.bat
 
-py -3 %EMSCRIPTEN%\emcc.py %*
+%EMSDK_PYTHON% %EMSCRIPTEN%\emcc.py %*
diff --git a/bazel/emscripten_toolchain/emcc.sh b/bazel/emscripten_toolchain/emcc.sh
index 5fdaf9c..f0f36ab 100755
--- a/bazel/emscripten_toolchain/emcc.sh
+++ b/bazel/emscripten_toolchain/emcc.sh
@@ -1,5 +1,12 @@
-#!/bin/bash
+#!/bin/bash -e
 
 source $(dirname $0)/env.sh
 
-exec python3 $EMSCRIPTEN/emcc.py "$@"
+if [[ "$EMSDK_PYTHON" != /* ]]; then
+    EMSDK_PYTHON="$ROOT_DIR/$EMSDK_PYTHON"
+fi
+
+PYBINPATH="$(dirname "${EMSDK_PYTHON}")"
+export PATH=$PYBINPATH:$PATH
+
+exec $EMSDK_PYTHON $EMSCRIPTEN/emcc.py "$@"
diff --git a/bazel/emscripten_toolchain/emcc_base.sh b/bazel/emscripten_toolchain/emcc_base.sh
new file mode 100755
index 0000000..e9ddd2c
--- /dev/null
+++ b/bazel/emscripten_toolchain/emcc_base.sh
@@ -0,0 +1,7 @@
+#!/bin/bash
+
+source $(dirname $0)/env.sh
+
+PYTHON3="${PYTHON3:-python3}"
+
+exec $PYTHON3 $EMSCRIPTEN/emcc.py "$@"
diff --git a/bazel/emscripten_toolchain/emcc_link.bat b/bazel/emscripten_toolchain/emcc_link.bat
index 8e5a6eb..fef6501 100644
--- a/bazel/emscripten_toolchain/emcc_link.bat
+++ b/bazel/emscripten_toolchain/emcc_link.bat
@@ -2,4 +2,4 @@
 
 call external\emsdk\emscripten_toolchain\env.bat
 
-py -3 external\emsdk\emscripten_toolchain\link_wrapper.py %*
+%EMSDK_PYTHON% external\emsdk\emscripten_toolchain\link_wrapper.py %*
diff --git a/bazel/emscripten_toolchain/emcc_link.sh b/bazel/emscripten_toolchain/emcc_link.sh
index 44f3235..950e529 100755
--- a/bazel/emscripten_toolchain/emcc_link.sh
+++ b/bazel/emscripten_toolchain/emcc_link.sh
@@ -2,4 +2,11 @@
 
 source $(dirname $0)/env.sh
 
-exec python3 $(dirname $0)/link_wrapper.py "$@"
+if [[ "$EMSDK_PYTHON" != /* ]]; then
+    EMSDK_PYTHON="$ROOT_DIR/$EMSDK_PYTHON"
+fi
+
+PYBINPATH="$(dirname "${EMSDK_PYTHON}")"
+export PATH=$PYBINPATH:$PATH
+
+exec $EMSDK_PYTHON $(dirname $0)/link_wrapper.py "$@"
diff --git a/bazel/emscripten_toolchain/emdwp-emscripten_bin_linux.sh b/bazel/emscripten_toolchain/emdwp-emscripten_bin_linux.sh
new file mode 100755
index 0000000..513feee
--- /dev/null
+++ b/bazel/emscripten_toolchain/emdwp-emscripten_bin_linux.sh
@@ -0,0 +1,10 @@
+#!/bin/bash
+#
+#  This script differs in form from emcc.{py,bat}/…, because bazel are limited/bugged in the way of executing dwp tool.
+#  Bazel dwp action configuration does not pass environment variables, so we cannot use them in this script.
+#  For more info, see PR discussion and bazel issue:
+#  - https://github.com/emscripten-core/emsdk/pull/1531#discussion_r1962090650
+#  - https://github.com/bazelbuild/bazel/issues/25336
+#
+
+exec external/emscripten_bin_linux/bin/llvm-dwp "$@"
diff --git a/bazel/emscripten_toolchain/emdwp-emscripten_bin_linux_arm64.sh b/bazel/emscripten_toolchain/emdwp-emscripten_bin_linux_arm64.sh
new file mode 100755
index 0000000..f6f3383
--- /dev/null
+++ b/bazel/emscripten_toolchain/emdwp-emscripten_bin_linux_arm64.sh
@@ -0,0 +1,10 @@
+#!/bin/bash
+#
+#  This script differs in form from emcc.{py,bat}/…, because bazel are limited/bugged in the way of executing dwp tool.
+#  Bazel dwp action configuration does not pass environment variables, so we cannot use them in this script.
+#  For more info, see PR discussion and bazel issue:
+#  - https://github.com/emscripten-core/emsdk/pull/1531#discussion_r1962090650
+#  - https://github.com/bazelbuild/bazel/issues/25336
+#
+
+exec external/emscripten_bin_linux_arm64/bin/llvm-dwp "$@"
diff --git a/bazel/emscripten_toolchain/emdwp-emscripten_bin_mac.sh b/bazel/emscripten_toolchain/emdwp-emscripten_bin_mac.sh
new file mode 100755
index 0000000..0f97690
--- /dev/null
+++ b/bazel/emscripten_toolchain/emdwp-emscripten_bin_mac.sh
@@ -0,0 +1,10 @@
+#!/bin/bash
+#
+#  This script differs in form from emcc.{py,bat}/…, because bazel are limited/bugged in the way of executing dwp tool.
+#  Bazel dwp action configuration does not pass environment variables, so we cannot use them in this script.
+#  For more info, see PR discussion and bazel issue:
+#  - https://github.com/emscripten-core/emsdk/pull/1531#discussion_r1962090650
+#  - https://github.com/bazelbuild/bazel/issues/25336
+#
+
+exec external/emscripten_bin_mac/bin/llvm-dwp "$@"
diff --git a/bazel/emscripten_toolchain/emdwp-emscripten_bin_mac_arm64.sh b/bazel/emscripten_toolchain/emdwp-emscripten_bin_mac_arm64.sh
new file mode 100755
index 0000000..4ae033c
--- /dev/null
+++ b/bazel/emscripten_toolchain/emdwp-emscripten_bin_mac_arm64.sh
@@ -0,0 +1,10 @@
+#!/bin/bash
+#
+#  This script differs in form from emcc.{py,bat}/…, because bazel are limited/bugged in the way of executing dwp tool.
+#  Bazel dwp action configuration does not pass environment variables, so we cannot use them in this script.
+#  For more info, see PR discussion and bazel issue:
+#  - https://github.com/emscripten-core/emsdk/pull/1531#discussion_r1962090650
+#  - https://github.com/bazelbuild/bazel/issues/25336
+#
+
+exec external/emscripten_bin_mac_arm64/bin/llvm-dwp "$@"
diff --git a/bazel/emscripten_toolchain/emdwp-emscripten_bin_win.bat b/bazel/emscripten_toolchain/emdwp-emscripten_bin_win.bat
new file mode 100644
index 0000000..3cb1f2e
--- /dev/null
+++ b/bazel/emscripten_toolchain/emdwp-emscripten_bin_win.bat
@@ -0,0 +1,10 @@
+::
+::  This script differs in form from emcc.{py,bat}/…, because bazel are limited/bugged in the way of executing dwp tool.
+::  Bazel dwp action configuration does not pass environment variables, so we cannot use them in this script.
+::  For more info, see PR discussion and bazel issue:
+::  - https://github.com/emscripten-core/emsdk/pull/1531#discussion_r1962090650
+::  - https://github.com/bazelbuild/bazel/issues/25336
+::
+@ECHO OFF
+
+call external\emscripten_bin_win\bin\llvm-dwp %*
diff --git a/bazel/emscripten_toolchain/link_wrapper.py b/bazel/emscripten_toolchain/link_wrapper.py
index 6a6fe2f..6dcacf8 100644
--- a/bazel/emscripten_toolchain/link_wrapper.py
+++ b/bazel/emscripten_toolchain/link_wrapper.py
@@ -1,4 +1,3 @@
-#!/usr/bin/env python
 """wrapper around emcc link step.
 
 This wrapper currently serves the following purposes.
diff --git a/bazel/emscripten_toolchain/toolchain.bzl b/bazel/emscripten_toolchain/toolchain.bzl
index c8cec07..9559cd1 100644
--- a/bazel/emscripten_toolchain/toolchain.bzl
+++ b/bazel/emscripten_toolchain/toolchain.bzl
@@ -54,6 +54,11 @@ CROSSTOOL_DEFAULT_WARNINGS = [
     "-Wall",
 ]
 
+def _os_path(ctx, path):
+    if ctx.attr.is_windows:
+        path = path.replace("/", "\\")
+    return path
+
 def _impl(ctx):
     target_cpu = ctx.attr.cpu
     toolchain_identifier = "emscripten-" + target_cpu
@@ -72,12 +77,15 @@ def _impl(ctx):
 
     emscripten_dir = ctx.attr.emscripten_binaries.label.workspace_root
     nodejs_path = ctx.file.nodejs_bin.path
+    emscripten_name = ctx.attr.emscripten_binaries.label.workspace_name
 
     builtin_sysroot = emscripten_dir + "/emscripten/cache/sysroot"
 
-    emcc_script = "emcc.%s" % ctx.attr.script_extension
-    emcc_link_script = "emcc_link.%s" % ctx.attr.script_extension
-    emar_script = "emar.%s" % ctx.attr.script_extension
+    script_extension = "bat" if ctx.attr.is_windows else "sh"
+    emcc_script = "emcc.%s" % script_extension
+    emcc_link_script = "emcc_link.%s" % script_extension
+    emar_script = "emar.%s" % script_extension
+    emdwp_script = "emdwp-%s.%s" % (emscripten_name, script_extension)
 
     ################################################################
     # Tools
@@ -99,6 +107,7 @@ def _impl(ctx):
         tool_path(name = "nm", path = "NOT_USED"),
         tool_path(name = "objdump", path = "/bin/false"),
         tool_path(name = "strip", path = "NOT_USED"),
+        tool_path(name = "dwp", path = emdwp_script),
     ]
 
     ################################################################
@@ -460,6 +469,49 @@ def _impl(ctx):
         feature(
             name = "wasm_standalone",
         ),
+        # Support for debug fission. In short, debugging fission should:
+        #   * reduce linking time, RAM usage and disk usage
+        #   * speed up incremental builds
+        #   * speed up debugger work (reduce startup and breakpoint time)
+        # (to use this, follow the --fission=yes flag)
+        # https://developer.chrome.com/blog/faster-wasm-debugging
+        # https://bazel.build/docs/user-manual#fission
+        feature(
+            name = "per_object_debug_info",
+            flag_sets = [
+                flag_set(
+                    actions = [
+                        ACTION_NAMES.c_compile,
+                        ACTION_NAMES.cpp_compile,
+                        ACTION_NAMES.cpp_module_codegen,
+                        ACTION_NAMES.assemble,
+                        ACTION_NAMES.preprocess_assemble,
+                    ],
+                    flag_groups = [
+                        flag_group(
+                            flags = ["-g", "-gsplit-dwarf", "-gdwarf-5", "-gpubnames"],
+                            expand_if_available = "per_object_debug_info_file",
+                        ),
+                    ],
+                ),
+            ],
+            enabled = True,
+        ),
+        feature(
+            name = "fission_support",
+            flag_sets = [
+                flag_set(
+                    actions = all_link_actions,
+                    flag_groups = [
+                        flag_group(
+                            flags = ["-sWASM_BIGINT"], # WASM_BIGINT required to support dwarf-5
+                            expand_if_available = "is_using_fission",
+                        ),
+                    ],
+                ),
+            ],
+            enabled = True,
+        )
     ]
 
     crosstool_default_flag_sets = [
@@ -1046,6 +1098,16 @@ def _impl(ctx):
         ),
     ]
 
+    python_files = ctx.attr._python_interpreter[DefaultInfo].files.to_list()
+    python_bin_path = None
+    for f in python_files:
+        if f.basename == "python3" or f.path.endswith("/bin/python3"):
+            python_bin_path = f.path
+            break
+
+    if not python_bin_path:
+        fail("Could not find python3 binary in " + str(ctx.attr._python_interpreter))
+
     crosstool_default_env_sets = [
         # Globals
         env_set(
@@ -1065,6 +1127,10 @@ def _impl(ctx):
                     key = "NODE_JS_PATH",
                     value = nodejs_path,
                 ),
+                env_entry(
+                    key = "EMSDK_PYTHON",
+                    value = _os_path(ctx, python_bin_path),
+                ),
             ],
         ),
         # Use llvm backend.  Off by default, enabled via --features=llvm_backend
@@ -1140,7 +1206,8 @@ emscripten_cc_toolchain_config_rule = rule(
         "em_config": attr.label(mandatory = True, allow_single_file = True),
         "emscripten_binaries": attr.label(mandatory = True, cfg = "exec"),
         "nodejs_bin": attr.label(mandatory = True, allow_single_file = True),
-        "script_extension": attr.string(mandatory = True, values = ["sh", "bat"]),
+        "is_windows": attr.bool(mandatory = True),
+        "_python_interpreter": attr.label(cfg = "exec", default = Label("@python3_12//:files")),
     },
     provides = [CcToolchainConfigInfo],
 )
diff --git a/bazel/emscripten_toolchain/wasm_binary.py b/bazel/emscripten_toolchain/wasm_binary.py
index d7d6142..0da7f55 100644
--- a/bazel/emscripten_toolchain/wasm_binary.py
+++ b/bazel/emscripten_toolchain/wasm_binary.py
@@ -14,6 +14,7 @@ WebAssembly binary into a larger web application.
 import argparse
 import os
 import tarfile
+import shutil
 
 
 def ensure(f):
@@ -26,11 +27,20 @@ def main():
   parser = argparse.ArgumentParser()
   parser.add_argument('--archive', help='The archive to extract from.')
   parser.add_argument('--outputs', help='Comma separated list of files that should be extracted from the archive. Only the extname has to match a file in the archive.')
+  parser.add_argument('--dwp_file', help='Optional dwp input file, generated when fission flags set.')
   parser.add_argument('--allow_empty_outputs', help='If an output listed in --outputs does not exist, create it anyways.', action='store_true')
   args = parser.parse_args()
 
   args.archive = os.path.normpath(args.archive)
   args.outputs = args.outputs.split(",")
+  args.dwp_file = os.path.normpath(args.dwp_file) if args.dwp_file else None
+
+  if args.dwp_file:
+    for idx, output in enumerate(args.outputs):
+      if output.endswith(".dwp"):  # also update extension 'binary.dwp' to 'binary.wasm.dwp'
+        shutil.copy2(args.dwp_file, output)
+        args.outputs.pop(idx)
+        break
 
   tar = tarfile.open(args.archive)
 
diff --git a/bazel/emscripten_toolchain/wasm_cc_binary.bzl b/bazel/emscripten_toolchain/wasm_cc_binary.bzl
index 6ea4f12..fcc3391 100644
--- a/bazel/emscripten_toolchain/wasm_cc_binary.bzl
+++ b/bazel/emscripten_toolchain/wasm_cc_binary.bzl
@@ -69,6 +69,7 @@ _ALLOW_OUTPUT_EXTNAMES = [
     ".fetch.js",
     ".js.symbols",
     ".wasm.debug.wasm",
+    ".wasm.dwp",
     ".html",
     ".aw.js",
 ]
@@ -107,10 +108,11 @@ _WASM_BINARY_COMMON_ATTRS = {
 }
 
 def _wasm_cc_binary_impl(ctx):
-    args = ctx.actions.args()
     cc_target = ctx.attr.cc_target[0]
+    dwp_file = cc_target[DebugPackageInfo].dwp_file if DebugPackageInfo in cc_target else None
+    outputs = ctx.outputs.outputs
 
-    for output in ctx.outputs.outputs:
+    for output in outputs:
         valid_extname = False
         for allowed_extname in _ALLOW_OUTPUT_EXTNAMES:
             if output.path.endswith(allowed_extname):
@@ -119,28 +121,35 @@ def _wasm_cc_binary_impl(ctx):
         if not valid_extname:
             fail("Invalid output '{}'. Allowed extnames: {}".format(output.basename, ", ".join(_ALLOW_OUTPUT_EXTNAMES)))
 
+    inputs = ctx.files.cc_target
+    args = ctx.actions.args()
     args.add_all("--archive", ctx.files.cc_target)
-    args.add_joined("--outputs", ctx.outputs.outputs, join_with = ",")
+    args.add_joined("--outputs", outputs, join_with = ",")
+
+    if dwp_file:
+        args.add("--dwp_file", dwp_file)
+        inputs = inputs + [dwp_file]
 
     ctx.actions.run(
-        inputs = ctx.files.cc_target,
-        outputs = ctx.outputs.outputs,
+        inputs = inputs,
+        outputs = outputs,
         arguments = [args],
         executable = ctx.executable._wasm_binary_extractor,
     )
 
     return [
         DefaultInfo(
-            files = depset(ctx.outputs.outputs),
+            files = depset(outputs),
             # This is needed since rules like web_test usually have a data
             # dependency on this target.
-            data_runfiles = ctx.runfiles(transitive_files = depset(ctx.outputs.outputs)),
+            data_runfiles = ctx.runfiles(transitive_files = depset(outputs)),
         ),
         OutputGroupInfo(_wasm_tar = cc_target.files),
     ]
 
 def _wasm_cc_binary_legacy_impl(ctx):
     cc_target = ctx.attr.cc_target[0]
+    dwp_file = cc_target[DebugPackageInfo].dwp_file if DebugPackageInfo in cc_target else None
     outputs = [
         ctx.outputs.loader,
         ctx.outputs.wasm,
@@ -151,20 +160,31 @@ def _wasm_cc_binary_legacy_impl(ctx):
         ctx.outputs.data,
         ctx.outputs.symbols,
         ctx.outputs.dwarf,
+        ctx.outputs.dwp,
         ctx.outputs.html,
         ctx.outputs.audio_worklet,
     ]
 
+    inputs = ctx.files.cc_target
     args = ctx.actions.args()
     args.add("--allow_empty_outputs")
     args.add_all("--archive", ctx.files.cc_target)
     args.add_joined("--outputs", outputs, join_with = ",")
 
+    if dwp_file:
+        args.add("--dwp_file", dwp_file)
+        inputs = inputs + [dwp_file]
+
+    py_toolchain = ctx.toolchains["@rules_python//python:toolchain_type"]
+    python_path = py_toolchain.py3_runtime.interpreter.path
+    env = dict(ctx.configuration.default_shell_env)
+    env["PATH"] = "%s:/usr/bin:/bin" % python_path.rpartition("/")[0]
     ctx.actions.run(
-        inputs = ctx.files.cc_target,
+        inputs = inputs + py_toolchain.py3_runtime.files.to_list(),
         outputs = outputs,
-        arguments = [args],
         executable = ctx.executable._wasm_binary_extractor,
+        arguments = [args],
+        env = env,
     )
 
     return [
@@ -202,6 +222,7 @@ def _wasm_binary_legacy_outputs(name, cc_target):
         "data": "{}/{}.data".format(name, basename),
         "symbols": "{}/{}.js.symbols".format(name, basename),
         "dwarf": "{}/{}.wasm.debug.wasm".format(name, basename),
+        "dwp": "{}/{}.wasm.dwp".format(name, basename),
         "html": "{}/{}.html".format(name, basename),
         "audio_worklet": "{}/{}.aw.js".format(name, basename)
     }
@@ -212,6 +233,7 @@ _wasm_cc_binary_legacy = rule(
     implementation = _wasm_cc_binary_legacy_impl,
     attrs = _WASM_BINARY_COMMON_ATTRS,
     outputs = _wasm_binary_legacy_outputs,
+    toolchains = ["@rules_python//python:toolchain_type"],
 )
 
 # Wraps a C++ Blaze target, extracting the appropriate files.