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[bazel] Fix and update emscripten_toolchain #1060

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4dd6bef
[bazel] Use `.bazelrc`
jrandolf Jun 17, 2022
391abf4
[bazel] Use `@bazel_tools//src/conditions`
jrandolf Jun 17, 2022
03cec6f
[bazel] Make `link_wrapper` robust
jrandolf Jun 17, 2022
a3905d7
[bazel] Fix and update `emscripten_toolchain`
jrandolf Jun 17, 2022
0f4c1c9
Revert "[bazel] Make `link_wrapper` robust"
jrandolf Jun 17, 2022
b950a5f
[bazel] Format `link_wrapper.py`
jrandolf Jun 17, 2022
d95cbbb
[bazel] Fix tests
jrandolf Jun 17, 2022
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2 changes: 2 additions & 0 deletions bazel/.bazelrc
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Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
build:wasm --incompatible_enable_cc_toolchain_resolution
build:wasm --platforms='@emsdk//:cpu_wasm32'
54 changes: 18 additions & 36 deletions bazel/BUILD
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Original file line number Diff line number Diff line change
@@ -1,34 +1,16 @@
package(default_visibility = ["//visibility:public"])

config_setting(
name = "linux",
platform(
name = "cpu_wasm32",
constraint_values = [
"@platforms//os:linux",
"@platforms//cpu:x86_64",
"@platforms//cpu:wasm32",
],
)

config_setting(
name = "macos",
platform(
name = "cpu_wasm64",
constraint_values = [
"@platforms//os:macos",
"@platforms//cpu:x86_64",
],
)

config_setting(
name = "macos_arm64",
constraint_values = [
"@platforms//os:macos",
"@platforms//cpu:arm64",
],
)

config_setting(
name = "windows",
constraint_values = [
"@platforms//os:windows",
"@platforms//cpu:x86_64",
"@platforms//cpu:wasm64",
],
)

Expand All @@ -37,32 +19,32 @@ filegroup(name = "empty")
alias(
name = "compiler_files",
actual = select({
":linux": "@emscripten_bin_linux//:compiler_files",
":macos": "@emscripten_bin_mac//:compiler_files",
":macos_arm64": "@emscripten_bin_mac_arm64//:compiler_files",
":windows": "@emscripten_bin_win//:compiler_files",
"@bazel_tools//src/conditions:linux_x86_64": "@emscripten_bin_linux//:compiler_files",
"@bazel_tools//src/conditions:darwin_x86_64": "@emscripten_bin_mac//:compiler_files",
"@bazel_tools//src/conditions:darwin_arm64": "@emscripten_bin_mac_arm64//:compiler_files",
"@bazel_tools//src/conditions:windows": "@emscripten_bin_win//:compiler_files",
"//conditions:default": ":empty",
}),
)

alias(
name = "linker_files",
actual = select({
":linux": "@emscripten_bin_linux//:linker_files",
":macos": "@emscripten_bin_mac//:linker_files",
":macos_arm64": "@emscripten_bin_mac_arm64//:linker_files",
":windows": "@emscripten_bin_win//:linker_files",
"@bazel_tools//src/conditions:linux_x86_64": "@emscripten_bin_linux//:linker_files",
"@bazel_tools//src/conditions:darwin_x86_64": "@emscripten_bin_mac//:linker_files",
"@bazel_tools//src/conditions:darwin_arm64": "@emscripten_bin_mac_arm64//:linker_files",
"@bazel_tools//src/conditions:windows": "@emscripten_bin_win//:linker_files",
"//conditions:default": ":empty",
}),
)

alias(
name = "ar_files",
actual = select({
":linux": "@emscripten_bin_linux//:ar_files",
":macos": "@emscripten_bin_mac//:ar_files",
":macos_arm64": "@emscripten_bin_mac_arm64//:ar_files",
":windows": "@emscripten_bin_win//:ar_files",
"@bazel_tools//src/conditions:linux_x86_64": "@emscripten_bin_linux//:ar_files",
"@bazel_tools//src/conditions:darwin_x86_64": "@emscripten_bin_mac//:ar_files",
"@bazel_tools//src/conditions:darwin_arm64": "@emscripten_bin_mac_arm64//:ar_files",
"@bazel_tools//src/conditions:windows": "@emscripten_bin_win//:ar_files",
"//conditions:default": ":empty",
}),
)
18 changes: 3 additions & 15 deletions bazel/README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,9 @@ emsdk_deps()

load("@emsdk//:emscripten_deps.bzl", emsdk_emscripten_deps = "emscripten_deps")
emsdk_emscripten_deps(emscripten_version = "2.0.31")

load("@emsdk//:toolchains.bzl", "emsdk_register_toolchains")
emsdk_register_toolchains()
```
The SHA1 hash in the above `strip_prefix` and `url` parameters correspond to the git revision of
[emsdk 2.0.31](https://github.com/emscripten-core/emsdk/releases/tag/2.0.31). To get access to
Expand All @@ -26,7 +29,6 @@ parameter of `emsdk_emscripten_deps()`. Supported versions are listed in `revisi

## Building

### Using wasm_cc_binary (preferred)
First, write a new rule wrapping your `cc_binary`.

```
Expand Down Expand Up @@ -54,17 +56,3 @@ and all of its dependencies, and does not require amending `.bazelrc`. This
is the preferred way, since it also unpacks the resulting tarball.

See `test_external/` for an example using [embind](https://emscripten.org/docs/porting/connecting_cpp_and_javascript/embind.html).

### Using --config=wasm
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does --config=wasm no longer work?

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In an ideal world, --config=wasm32 and --config=wasm64 are both allowed, and --config=wasm just points to --config=wasm32 for backwards compatibility.

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@jrandolf jrandolf Jul 5, 2022 •
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I'm not sure what you mean by "backwards-compatibility". If we update the config here, it doesn't imply it propagates to the user. In particular, this only affects developers of this repo, not external users.


Put the following lines into your `.bazelrc`:
```
build:wasm --crosstool_top=@emsdk//emscripten_toolchain:everything
build:wasm --cpu=wasm
build:wasm --host_crosstool_top=@bazel_tools//tools/cpp:toolchain
```

Simply pass `--config=wasm` when building a normal `cc_binary`. The result of
this build will be a tar archive containing any files produced by emscripten.
See the [Bazel documentation](https://docs.bazel.build/versions/main/tutorial/cc-toolchain-config.html)
for more details
4 changes: 4 additions & 0 deletions bazel/WORKSPACE
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Expand Up @@ -7,3 +7,7 @@ deps()
load(":emscripten_deps.bzl", "emscripten_deps")

emscripten_deps()

load(":toolchains.bzl", "emsdk_register_toolchains")

emsdk_register_toolchains()
5 changes: 0 additions & 5 deletions bazel/bazelrc
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This file was deleted.

84 changes: 63 additions & 21 deletions bazel/emscripten_toolchain/BUILD.bazel
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
load(":crosstool.bzl", "emscripten_cc_toolchain_config_rule")
load(":crosstool.bzl", "emscripten_cc_toolchain_config")

package(default_visibility = ["//visibility:public"])

Expand All @@ -7,44 +7,53 @@ package(default_visibility = ["//visibility:public"])
# https://github.com/bazelbuild/rules_nodejs/issues/3375
node_files = "@nodejs_host//:node_files" if existing_rule("@nodejs_host//:node_files") else "@nodejs//:node_files"

filegroup(
name = "all_files",
srcs = [
":ar_files",
":compiler_files",
":linker_files",
],
)

filegroup(
name = "common_files",
srcs = [
"emscripten_config",
"env.sh",
"env.bat",
"env.sh",
node_files,
],
)

filegroup(
name = "compiler_files",
srcs = [
"emcc.sh",
"emcc.bat",
"@emsdk//:compiler_files",
"emcc.sh",
":common_files",
"@emsdk//:compiler_files",
],
)

filegroup(
name = "linker_files",
srcs = [
"emcc_link.sh",
"emcc_link.bat",
"emcc_link.sh",
"link_wrapper.py",
"@emsdk//:linker_files",
":common_files",
"@emsdk//:linker_files",
],
)

filegroup(
name = "ar_files",
srcs = [
"emar.sh",
"emar.bat",
"@emsdk//:ar_files",
"emar.sh",
":common_files",
"@emsdk//:ar_files",
],
)

Expand All @@ -53,9 +62,9 @@ filegroup(name = "empty")
# dlmalloc.bc is implictly added by the emscripten toolchain
cc_library(name = "malloc")

emscripten_cc_toolchain_config_rule(
name = "wasm",
cpu = "wasm",
emscripten_cc_toolchain_config(
name = "wasm32_cc_toolchain_config",
cpu = "wasm32",
em_config = "emscripten_config",
emscripten_binaries = "@emsdk//:compiler_files",
script_extension = select({
Expand All @@ -64,26 +73,59 @@ emscripten_cc_toolchain_config_rule(
}),
)

emscripten_cc_toolchain_config(
name = "wasm64_cc_toolchain_config",
cpu = "wasm64",
em_config = "emscripten_config",
emscripten_binaries = "@emsdk//:compiler_files",
script_extension = select({
"@bazel_tools//src/conditions:host_windows": "bat",
"//conditions:default": "sh",
}),
)

cc_toolchain(
name = "wasm32_cc_toolchain",
all_files = ":all_files",
ar_files = ":ar_files",
compiler_files = ":compiler_files",
dwp_files = ":empty",
linker_files = ":linker_files",
objcopy_files = ":empty",
strip_files = ":empty",
toolchain_config = ":wasm32_cc_toolchain_config",
toolchain_identifier = "emscripten-wasm",
)

cc_toolchain(
name = "cc-compiler-wasm",
all_files = ":empty",
name = "wasm64_cc_toolchain",
all_files = ":all_files",
ar_files = ":ar_files",
as_files = ":empty",
compiler_files = ":compiler_files",
dwp_files = ":empty",
linker_files = ":linker_files",
objcopy_files = ":empty",
strip_files = ":empty",
toolchain_config = "wasm",
toolchain_config = ":wasm64_cc_toolchain_config",
toolchain_identifier = "emscripten-wasm",
)

cc_toolchain_suite(
name = "everything",
toolchains = {
"wasm": ":cc-compiler-wasm",
"wasm|emscripten": ":cc-compiler-wasm",
},
toolchain(
name = "cc_wasm32_toolchain",
target_compatible_with = [
"@platforms//cpu:wasm32",
],
toolchain = ":wasm32_cc_toolchain",
toolchain_type = "@bazel_tools//tools/cpp:toolchain_type",
)

toolchain(
name = "cc_wasm64_toolchain",
target_compatible_with = [
"@platforms//cpu:wasm64",
],
toolchain = ":wasm64_cc_toolchain",
toolchain_type = "@bazel_tools//tools/cpp:toolchain_type",
)

py_binary(
Expand Down
28 changes: 11 additions & 17 deletions bazel/emscripten_toolchain/crosstool.bzl
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Expand Up @@ -54,22 +54,18 @@ CROSSTOOL_DEFAULT_WARNINGS = [
"-Wall",
]

def _impl(ctx):
def _emscripten_cc_toolchain_config(ctx):
target_cpu = ctx.attr.cpu
toolchain_identifier = "emscripten-" + target_cpu
target_system_name = target_cpu + "-unknown-emscripten"

host_system_name = "i686-unknown-linux-gnu"

target_libc = "musl/js"

abi_version = "emscripten_syscalls"

compiler = "emscripten"
abi_libc_version = "default"

cc_target_os = "emscripten"

emscripten_dir = ctx.attr.emscripten_binaries.label.workspace_root

builtin_sysroot = emscripten_dir + "/emscripten/cache/sysroot"
Expand Down Expand Up @@ -150,8 +146,9 @@ def _impl(ctx):
flag_sets = [
flag_set(
flag_groups = [
flag_group(flags = ["rcsD"]),
flag_group(
flags = ["rcsD", "%{output_execpath}"],
flags = ["%{output_execpath}"],
expand_if_available = "output_execpath",
),
],
Expand Down Expand Up @@ -323,11 +320,11 @@ def _impl(ctx):
implies = ["crosstool_cpu_" + target_cpu],
),
feature(
name = "crosstool_cpu_asmjs",
name = "crosstool_cpu_wasm64",
provides = ["variant:crosstool_cpu"],
),
feature(
name = "crosstool_cpu_wasm",
name = "crosstool_cpu_wasm32",
provides = ["variant:crosstool_cpu"],
),

Expand Down Expand Up @@ -409,7 +406,6 @@ def _impl(ctx):
feature(name = "emcc_debug_link"),
feature(
name = "llvm_backend",
requires = [feature_set(features = ["crosstool_cpu_wasm"])],
enabled = True,
),

Expand Down Expand Up @@ -523,8 +519,8 @@ def _impl(ctx):
# Emscripten-specific settings:
flag_set(
actions = all_compile_actions + all_link_actions,
flags = ["-s", "WASM=0"],
features = ["crosstool_cpu_asmjs"],
flags = ["-s", "MEMORY64=1"],
features = ["crosstool_cpu_wasm64"],
),
flag_set(
actions = all_compile_actions +
Expand Down Expand Up @@ -1087,7 +1083,6 @@ def _impl(ctx):
artifact_name_patterns = artifact_name_patterns,
cxx_builtin_include_directories = cxx_builtin_include_directories,
toolchain_identifier = toolchain_identifier,
host_system_name = host_system_name,
target_system_name = target_system_name,
target_cpu = target_cpu,
target_libc = target_libc,
Expand All @@ -1097,15 +1092,14 @@ def _impl(ctx):
tool_paths = tool_paths,
make_variables = make_variables,
builtin_sysroot = builtin_sysroot,
cc_target_os = cc_target_os,
)

emscripten_cc_toolchain_config_rule = rule(
implementation = _impl,
emscripten_cc_toolchain_config = rule(
implementation = _emscripten_cc_toolchain_config,
attrs = {
"cpu": attr.string(mandatory = True, values = ["asmjs", "wasm"]),
"cpu": attr.string(mandatory = True, values = ["wasm32", "wasm64"]),
"em_config": attr.label(mandatory = True, allow_single_file = True),
"emscripten_binaries": attr.label(mandatory = True),
"emscripten_binaries": attr.label(mandatory = True, cfg = "exec"),
"script_extension": attr.string(mandatory = True, values = ["sh", "bat"]),
},
provides = [CcToolchainConfigInfo],
Expand Down
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