add support for riscv64+musl

MODULE.bazel

@@ -53,6 +53,10 @@ register_toolchains(
     "@zig_sdk//libc_aware/toolchain:linux_arm64_gnu.2.28",
     "@zig_sdk//libc_aware/toolchain:linux_arm64_musl",
 
+    # riscv64 toolchains for libc-aware platforms:
+    "@zig_sdk//libc_aware/toolchain:linux_riscv64_gnu.2.28",
+    "@zig_sdk//libc_aware/toolchain:linux_riscv64_musl",
+
     # wasm/wasi toolchains
     "@zig_sdk//toolchain:wasip1_wasm",
     "@zig_sdk//toolchain:none_wasm",

README.md

@@ -517,6 +517,7 @@ This repository is used on the following (host) platforms:
 
 - `linux_amd64`, a.k.a. `x86_64`.
 - `linux_arm64`, a.k.a. `AArch64`.
+- `linux_riscv64`.
 - `darwin_amd64`, the 64-bit post-PowerPC models.
 - `darwin_arm64`, the M1.
 - `windows_amd64`, a.k.a. `x64`.

test/glibc_hacks/BUILD

@@ -21,5 +21,7 @@ cc_binary(
         ("linux_amd64_musl", "//libc_aware/platform:linux_amd64_musl"),
         ("linux_amd64_gnu.2.28", "//libc_aware/platform:linux_amd64_gnu.2.28"),
         ("linux_arm64_musl", "//libc_aware/platform:linux_arm64_musl"),
+        ("linux_riscv64_musl", "//libc_aware/platform:linux_riscv64_musl"),
+        ("linux_riscv64_gnu.2.28", "//libc_aware/platform:linux_riscv64_gnu.2.28"),
     ]
 ]

toolchain/defs.bzl

@@ -22,6 +22,7 @@ _DEFAULT_INCLUDE_DIRECTORIES = [
 
 _HOST_PLATFORM_EXT = {
     "linux-aarch64": "tar.xz",
+    "linux-riscv64": "tar.xz",
     "linux-x86_64": "tar.xz",
     "macos-aarch64": "tar.xz",
     "macos-x86_64": "tar.xz",
@@ -32,6 +33,7 @@ _HOST_PLATFORM_EXT = {
 # map bazel's host_platform to zig's -target= and -mcpu=
 _TARGET_MCPU = {
     "linux-aarch64": ("aarch64-linux-musl", "baseline"),
+    "linux-riscv64": ("riscv64-linux-musl", "baseline"),
     "linux-x86_64": ("x86_64-linux-musl", "baseline"),
     "macos-aarch64": ("aarch64-macos-none", "apple_a14"),
     "macos-x86_64": ("x86_64-macos-none", "baseline"),

toolchain/ext.bzl

@@ -8,7 +8,7 @@ _exec_platform = tag_class(
             mandatory = True,
         ),
         "arch": attr.string(
-            values = ["amd64", "arm64"],
+            values = ["amd64", "arm64", "riscv64"],
             mandatory = True,
         ),
     },

toolchain/platform/defs.bzl

@@ -1,4 +1,4 @@
-load("@hermetic_cc_toolchain//toolchain/private:defs.bzl", "LIBCS")
+load("@hermetic_cc_toolchain//toolchain/private:defs.bzl", "LIBCS", "RISCV64_LIBCS")
 
 _CPUS = (("x86_64", "amd64"), ("aarch64", "arm64"))
 _OS = {
@@ -18,6 +18,9 @@ def declare_platforms():
     declare_platform("wasm", "wasm32", "wasi", "wasip1")
     declare_platform("wasm", "wasm32", "none", "none")
 
+    # gocpu and zigcpu are both riscv64, so this declares a single linux_riscv64 platform.
+    declare_platform("riscv64", "riscv64", "linux", "linux")
+
 def declare_libc_aware_platforms():
     # create @zig_sdk//{os}_{arch}_platform entries with zig and go conventions
     # with libc specified
@@ -32,18 +35,34 @@ def declare_libc_aware_platforms():
                 extra_constraints = ["//libc:{}".format(libc)],
             )
 
+    for libc in RISCV64_LIBCS:
+        declare_platform(
+            "riscv64",
+            "riscv64",
+            "linux",
+            "linux",
+            suffix = "_{}".format(libc),
+            extra_constraints = ["//libc:{}".format(libc)],
+        )
+
 def declare_platform(gocpu, zigcpu, bzlos, os, suffix = "", extra_constraints = []):
     constraint_values = [
         "@platforms//os:{}".format(bzlos),
         "@platforms//cpu:{}".format(zigcpu),
     ] + extra_constraints
 
-    native.platform(
-        name = "{os}_{zigcpu}{suffix}".format(os = os, zigcpu = zigcpu, suffix = suffix),
-        constraint_values = constraint_values,
-    )
+    zig_name = "{os}_{zigcpu}{suffix}".format(os = os, zigcpu = zigcpu, suffix = suffix)
+    go_name = "{os}_{gocpu}{suffix}".format(os = os, gocpu = gocpu, suffix = suffix)
 
     native.platform(
-        name = "{os}_{gocpu}{suffix}".format(os = os, gocpu = gocpu, suffix = suffix),
+        name = zig_name,
         constraint_values = constraint_values,
     )
+
+    # amd64/arm64 use different Go and Zig arch names, so both aliases exist.
+    # riscv64 uses the same name in both, and a second platform() would collide.
+    if go_name != zig_name:
+        native.platform(
+            name = go_name,
+            constraint_values = constraint_values,
+        )

toolchain/private/defs.bzl

@@ -37,6 +37,11 @@ _INCLUDE_TAIL = [
 
 LIBCS = ["musl"] + ["gnu.{}".format(glibc) for glibc in _GLIBCS]
 
+# RISC-V was added to glibc in 2.27. Zig 0.15.2 rejects older versions
+# (lib/std/zig/target.zig: riscv64 linux gnu glibc_min = 2.27).
+_RISCV64_GLIBCS = _GLIBCS[_GLIBCS.index("2.27"):]
+RISCV64_LIBCS = ["musl"] + ["gnu.{}".format(glibc) for glibc in _RISCV64_GLIBCS]
+
 def zig_tool_path(os):
     if os == "windows":
         return _ZIG_TOOL_PATH + ".exe"
@@ -51,6 +56,9 @@ def target_structs():
         ret.append(_target_linux_musl(gocpu, zigcpu))
         for glibc in _GLIBCS:
             ret.append(_target_linux_gnu(gocpu, zigcpu, glibc))
+    ret.append(_target_linux_musl("riscv64", "riscv64"))
+    for glibc in _RISCV64_GLIBCS:
+        ret.append(_target_linux_gnu("riscv64", "riscv64", glibc))
     ret.append(_target_wasm())
     ret.append(_target_wasm_no_wasi())
     return ret
@@ -160,8 +168,9 @@ def _target_linux_gnu(gocpu, zigcpu, glibc_version):
                    # x86-linux-gnu dir. x86_64-linux-any never existed and is
                    # likewise covered by x86-linux-any.
                    (["libc/include/x86-linux-gnu", "libc/include/x86-linux-any"] if zigcpu == "x86_64" else [
-                       "libc/include/{}-linux-gnu".format(zigcpu),
-                       "libc/include/{}-linux-any".format(zigcpu),
+                       # Zig names the RISC-V glibc headers riscv-linux-gnu, not riscv64-linux-gnu.
+                       "libc/include/riscv-linux-gnu" if zigcpu == "riscv64" else "libc/include/{}-linux-gnu".format(zigcpu),
+                       "libc/include/riscv-linux-any" if zigcpu == "riscv64" else "libc/include/{}-linux-any".format(zigcpu),
                    ]) + [
             "libc/include/any-linux-any",
         ] + _INCLUDE_TAIL,
@@ -195,7 +204,9 @@ def _target_linux_musl(gocpu, zigcpu):
                    ] +
                    # x86_64-linux-any is x86_64-linux and x86-linux combined.
                    (["libc/include/x86-linux-any"] if zigcpu == "x86_64" else []) +
-                   (["libc/include/{}-linux-any".format(zigcpu)] if zigcpu != "x86_64" else []) + [
+                   # Zig names the RISC-V asm headers riscv-linux-any, not riscv64-linux-any.
+                   (["libc/include/riscv-linux-any"] if zigcpu == "riscv64" else []) +
+                   (["libc/include/{}-linux-any".format(zigcpu)] if zigcpu not in ("x86_64", "riscv64") else []) + [
             "libc/include/any-linux-any",
         ] + _INCLUDE_TAIL,
         linkopts = [],

toolchain/private/zig_sdk.bzl

@@ -2,6 +2,7 @@ VERSION = "0.15.2"
 
 HOST_PLATFORM_SHA256 = {
     "linux-aarch64": "958ed7d1e00d0ea76590d27666efbf7a932281b3d7ba0c6b01b0ff26498f667f",
+    "linux-riscv64": "493512bdca485be3c6a9b0f69dcb4cbe4587f3af8e1be282fdd827108ba39930",
     "linux-x86_64": "02aa270f183da276e5b5920b1dac44a63f1a49e55050ebde3aecc9eb82f93239",
     "macos-aarch64": "3cc2bab367e185cdfb27501c4b30b1b0653c28d9f73df8dc91488e66ece5fa6b",
     "macos-x86_64": "375b6909fc1495d16fc2c7db9538f707456bfc3373b14ee83fdd3e22b3d43f7f",

toolchain/zig-wrapper.zig

@@ -378,7 +378,7 @@ fn getRunMode(self_exe: []const u8, self_base_noexe: []const u8) error{BadParent
     var it = mem.splitScalar(u8, triple, '-');
 
     const arch = it.next() orelse return error.BadParent;
-    if (mem.indexOf(u8, "aarch64,x86_64,wasm32", arch) == null)
+    if (mem.indexOf(u8, "aarch64,x86_64,wasm32,riscv64", arch) == null)
         return error.BadParent;
 
     const got_os = it.next() orelse return error.BadParent;