Support WebAssembly target platforms wasm{32,64}-wasip1 (#466)

Note this doesn't differ much from wasm{32,64}-unknown-unknown targets,
except for different sysroot setup. For whatever reason clang expects
slightly differently located libs.

Author: piob-io

platforms/BUILD.bazel

@@ -61,3 +61,19 @@ platform(
         "@platforms//cpu:wasm64",
     ],
 )
+
+platform(
+    name = "wasip1-wasm32",
+    constraint_values = [
+        "@platforms//os:wasi",
+        "@platforms//cpu:wasm32",
+    ],
+)
+
+platform(
+    name = "wasip1-wasm64",
+    constraint_values = [
+        "@platforms//os:wasi",
+        "@platforms//cpu:wasm64",
+    ],
+)

tests/MODULE.bazel

@@ -189,7 +189,7 @@ llvm.toolchain(
 )
 use_repo(llvm, "llvm_toolchain_linux_exec")
 
-# Toolchain example for WebAssembly.
+# Toolchain example for WebAssembly wasm* targets.
 llvm.toolchain(
     name = "llvm_toolchain_wasm",
     libclang_rt = {
@@ -220,6 +220,31 @@ use_repo(llvm, "llvm_toolchain_wasm")
 
 register_toolchains("@llvm_toolchain_wasm//:all")
 
+# Toolchain example for WebAssembly wasm*-wasi* targets.
+llvm.toolchain(
+    name = "llvm_toolchain_wasm_wasi",
+    libclang_rt = {
+        "@libclang_rt_wasm32//:libclang_rt.builtins-wasm32.a": "wasm32-unknown-wasip1/libclang_rt.builtins.a",
+    },
+    # WebAssembly tests use a separate (newer) version of LLVM to exercise
+    # support for experimental features such as wasm64.
+    llvm_versions = {
+        # The most recent LLVM as of 2024-10-17
+        "": "19.1.0",
+    },
+    stdlib = {
+        "wasip1-wasm32": "libc",
+    },
+)
+llvm.sysroot(
+    name = "llvm_toolchain_wasm_wasi",
+    label = "@wasi_sdk_sysroots//wasm32-wasip1",
+    targets = ["wasip1-wasm32"],
+)
+use_repo(llvm, "llvm_toolchain_wasm_wasi")
+
+register_toolchains("@llvm_toolchain_wasm_wasi//:all")
+
 wasi_sdk_sysroots = use_repo_rule("//wasm:wasi_sdk.bzl", "wasi_sdk_sysroots")
 
 wasi_sdk_sysroots(name = "wasi_sdk_sysroots")

tests/WORKSPACE

@@ -156,7 +156,7 @@ llvm_toolchain(
     urls = {"": ["https://github.com/llvm/llvm-project/releases/download/llvmorg-17.0.6/clang+llvm-17.0.6-x86_64-linux-gnu-ubuntu-22.04.tar.xz"]},
 )
 
-# Toolchain example for WebAssembly.
+# Toolchain example for WebAssembly wasm* targets.
 llvm_toolchain(
     name = "llvm_toolchain_wasm",
     libclang_rt = {
@@ -185,6 +185,33 @@ load(
 
 llvm_register_toolchains_wasm()
 
+# Toolchain example for WebAssembly wasm*-wasi* targets.
+llvm_toolchain(
+    name = "llvm_toolchain_wasm_wasi",
+    libclang_rt = {
+        "@libclang_rt_wasm32//:libclang_rt.builtins-wasm32.a": "wasm32-unknown-wasip1/libclang_rt.builtins.a",
+    },
+    # WebAssembly tests use a separate (newer) version of LLVM to exercise
+    # support for experimental features such as wasm64.
+    llvm_versions = {
+        # The most recent LLVM as of 2024-10-17
+        "": "19.1.0",
+    },
+    stdlib = {
+        "wasip1-wasm32": "libc",
+    },
+    sysroot = {
+        "wasip1-wasm32": "@wasi_sdk_sysroots//wasm32-wasip1",
+    },
+)
+
+load(
+    "@llvm_toolchain_wasm_wasi//:toolchains.bzl",
+    llvm_register_toolchains_wasm_wasi = "llvm_register_toolchains",
+)
+
+llvm_register_toolchains_wasm_wasi()
+
 load("//wasm:wasi_sdk.bzl", "libclang_rt_wasm32", "wasi_sdk_sysroots")
 
 libclang_rt_wasm32(name = "libclang_rt_wasm32")

tests/wasm/BUILD.bazel

@@ -8,6 +8,7 @@ build_test(
         ":wasm32_strlen",
         ":wasm32_strlen_nolibc",
         ":wasm64_strlen_nolibc",
+        ":wasm32_wasip1_strlen",
     ],
 )
 
@@ -42,3 +43,16 @@ transition_binary_to_platform(
     bin = ":wasm_strlen_nolibc",
     platform = "@toolchains_llvm//platforms:wasm64",
 )
+
+cc_binary(
+    name = "wasm_strlen_wasi",
+    srcs = ["wasm_strlen_wasi.c"],
+    linkopts = ["-Wl,--no-entry"],
+    tags = ["manual"],
+)
+
+transition_binary_to_platform(
+    name = "wasm32_wasip1_strlen",
+    bin = ":wasm_strlen_wasi",
+    platform = "@toolchains_llvm//platforms:wasip1-wasm32",
+)

tests/wasm/wasi_sdk.bzl

@@ -30,9 +30,14 @@ def _wasi_sdk_sysroots(ctx):
             name = repr(abi),
         ))
         ctx.execute(["mv", "include/" + abi, "%s/include" % (abi,)])
-        ctx.execute(["mv", "lib/" + abi, "%s/lib" % (abi,)])
         ctx.execute(["mv", "share/" + abi, "%s/share" % (abi,)])
 
+        # This is needed for wasm*-unknown-unknown targets
+        ctx.execute(["cp", "-R", "lib/" + abi, "%s/lib" % (abi,)])
+
+        # This is needed for wasm*-wasip1 targets
+        ctx.execute(["mv", "lib/" + abi, "%s/lib/%s" % (abi, abi)])
+
 wasi_sdk_sysroots = repository_rule(_wasi_sdk_sysroots)
 
 def _libclang_rt_wasm32(ctx):

tests/wasm/wasm_strlen_wasi.c

@@ -0,0 +1,13 @@
+#include <stdint.h>
+#include <stdio.h>
+#include <string.h>
+
+uint32_t wasm_strlen(char *s) {
+	return strlen(s);
+}
+
+int main() {
+	char *s = "Hello world!";
+	printf("strlen(\"%s\") = %d\n", s, wasm_strlen(s));
+	return 0;
+}

toolchain/cc_toolchain_config.bzl

@@ -105,6 +105,22 @@ def cc_toolchain_config(
             "unknown",
             "unknown",
         ),
+        "wasip1-wasm32": (
+            "clang-wasm32",
+            "wasm32",
+            "unknown",
+            "clang",
+            "unknown",
+            "unknown",
+        ),
+        "wasip1-wasm64": (
+            "clang-wasm64",
+            "wasm64",
+            "unknown",
+            "clang",
+            "unknown",
+            "unknown",
+        ),
     }[target_os_arch_key]
 
     # Unfiltered compiler flags; these are placed at the end of the command

toolchain/internal/common.bzl

@@ -19,6 +19,8 @@ SUPPORTED_TARGETS = [
     ("darwin", "aarch64"),
     ("none", "wasm32"),
     ("none", "wasm64"),
+    ("wasip1", "wasm32"),
+    ("wasip1", "wasm64"),
 ]
 
 # Map of tool name to its symlinked name in the tools directory.
@@ -132,7 +134,7 @@ def os_from_rctx(rctx):
 
 def os_bzl(os):
     # Return the OS string as used in bazel platform constraints.
-    return {"darwin": "osx", "linux": "linux", "none": "none"}[os]
+    return {"darwin": "osx", "linux": "linux", "none": "none", "wasip1": "wasi"}[os]
 
 def arch(rctx):
     arch = rctx.attr.exec_arch

toolchain/internal/configure.bzl

@@ -324,6 +324,8 @@ def _cc_toolchain_str(
         "linux-x86_64": "x86_64-unknown-linux-gnu",
         "wasm32": "wasm32-unknown-unknown",
         "wasm64": "wasm64-unknown-unknown",
+        "wasip1-wasm32": "wasm32-wasip1",
+        "wasip1-wasm64": "wasm64-wasip1",
     }[target_pair]
     cxx_builtin_include_directories = [
         toolchain_path_prefix + "include/c++/v1",
@@ -350,7 +352,7 @@ def _cc_toolchain_str(
             _join(sysroot_prefix, "/usr/include"),
             _join(sysroot_prefix, "/System/Library/Frameworks"),
         ])
-    elif target_os == "none":
+    elif target_os == "none" or target_os == "wasip1":
         if sysroot_prefix:
             cxx_builtin_include_directories.extend([
                 _join(sysroot_prefix, "/include"),