[bazel] Change how tools are pulled from cc_toolchains

Bazel is moving towards deprecating the `tool_path` style of CC
toolchain which allowed executables to be taken using the `*_executable`
parameters. The new method is `cc_common.get_tool_for_action` which
works with both the old and new toolchain style.

This commit changes all usages except for `objdump` which has no
associated action. A future commit will create a custom objdump action
for our toolchain and change this usage then.

The OTBN toolchain actually needs exact tools. Instead of pulling these
from the `cc_toolchain` it makes more sense to access the binaries
directly from our toolchain repo.

Signed-off-by: James Wainwright <james.wainwright@lowrisc.org>

Author: jwnrt

rules/opentitan/static_library.bzl

@@ -7,6 +7,7 @@
 # Inspired by:
 # https://gist.github.com/shareefj/4e314b16148fded3a8ec874e71b07143
 
+load("@rules_cc//cc:action_names.bzl", "CPP_LINK_STATIC_LIBRARY_ACTION_NAME")
 load("@rules_cc//cc:find_cc_toolchain.bzl", "find_cc_toolchain")
 load("@lowrisc_opentitan//rules:rv.bzl", "rv_rule")
 
@@ -15,6 +16,16 @@ def _ot_static_library_impl(ctx):
     output_flags = ctx.actions.declare_file("lib{}.link".format(ctx.attr.name))
 
     cc_toolchain = find_cc_toolchain(ctx)
+    feature_config = cc_common.configure_features(
+        ctx = ctx,
+        cc_toolchain = cc_toolchain,
+        requested_features = ctx.features,
+        unsupported_features = ctx.disabled_features,
+    )
+    archiver = cc_common.get_tool_for_action(
+        feature_configuration = feature_config,
+        action_name = CPP_LINK_STATIC_LIBRARY_ACTION_NAME,
+    )
 
     # Aggregate linker inputs of all dependencies
     lib_sets = []
@@ -42,11 +53,9 @@ def _ot_static_library_impl(ctx):
 
     lib_paths = [lib.path for lib in libs]
 
-    ar_path = cc_toolchain.ar_executable
-
     ctx.actions.run_shell(
         command = "\"{0}\" rcT {1} {2} && echo -e 'create {1}\naddlib {1}\nsave\nend' | \"{0}\" -M".format(
-            ar_path,
+            archiver,
             output_lib.path,
             " ".join(lib_paths),
         ),

rules/opentitan/transform.bzl

@@ -3,6 +3,7 @@
 # SPDX-License-Identifier: Apache-2.0
 
 load("@bazel_skylib//rules:common_settings.bzl", "BuildSettingInfo")
+load("@rules_cc//cc:action_names.bzl", "OBJ_COPY_ACTION_NAME")
 load("@rules_cc//cc:find_cc_toolchain.bzl", "find_cc_toolchain")
 load("@bazel_skylib//lib:paths.bzl", "paths")
 load("@lowrisc_opentitan//rules/opentitan:util.bzl", "get_override")
@@ -21,6 +22,17 @@ def obj_transform(ctx, **kwargs):
       The transformed File.
     """
     cc_toolchain = find_cc_toolchain(ctx)
+    feature_config = cc_common.configure_features(
+        ctx = ctx,
+        cc_toolchain = cc_toolchain,
+        requested_features = ctx.features,
+        unsupported_features = ctx.disabled_features,
+    )
+    objcopy = cc_common.get_tool_for_action(
+        feature_configuration = feature_config,
+        action_name = OBJ_COPY_ACTION_NAME,
+    )
+
     output = kwargs.get("output")
     if not output:
         name = get_override(ctx, "attr.name", kwargs)
@@ -40,7 +52,7 @@ def obj_transform(ctx, **kwargs):
             src.path,
             output.path,
         ],
-        executable = cc_toolchain.objcopy_executable,
+        executable = objcopy,
     )
     return output
 

rules/otbn.bzl

@@ -5,23 +5,13 @@
 load("//rules:rv.bzl", "rv_rule")
 load("@rules_cc//cc:find_cc_toolchain.bzl", "find_cc_toolchain")
 
-def _get_assembler(cc_toolchain):
-    """Find the path to riscv-unknown-elf-as."""
-
-    # Note: the toolchain config doesn"t appear to have a good way to get
-    # access to the assembler.  We should be able to access it via the
-    # the compiler, but I had trouble with //hw/ip/otbn/util/otbn_as.py invoking
-    # the compiler as assembler.
-    return [f for f in cc_toolchain.all_files.to_list() if f.basename.endswith("as")][0]
-
 def _otbn_assemble_sources(ctx, additional_srcs = []):
     """Helper function that, for each source file in the provided context, adds
     an action to the context that invokes the otbn assember (otbn_as.py),
     producing a corresponding object file. Returns a list of all object files
     that will be generated by these actions.
     """
     cc_toolchain = find_cc_toolchain(ctx)
-    assembler = _get_assembler(cc_toolchain)
 
     objs = []
     for src in ctx.files.srcs + additional_srcs:
@@ -33,7 +23,7 @@ def _otbn_assemble_sources(ctx, additional_srcs = []):
                       cc_toolchain.all_files.to_list() +
                       [ctx.executable._otbn_as]),
             env = {
-                "RV32_TOOL_AS": assembler.path,
+                "RV32_TOOL_AS": ctx.executable._riscv32_as.path,
             },
             arguments = ["-o", obj.path, src.path] + ctx.attr.args,
             executable = ctx.executable._otbn_as,
@@ -78,7 +68,6 @@ def _otbn_binary(ctx, additional_srcs = []):
     that other rules can depend on in their `deps`.
     """
     cc_toolchain = find_cc_toolchain(ctx)
-    assembler = _get_assembler(cc_toolchain)
 
     # Run the otbn assembler on source files to produce object (.o) files.
     objs = _otbn_assemble_sources(ctx, additional_srcs)
@@ -100,10 +89,10 @@ def _otbn_binary(ctx, additional_srcs = []):
                   ctx.files._otbn_data +
                   [ctx.executable._wrapper]),
         env = {
-            "RV32_TOOL_AS": assembler.path,
-            "RV32_TOOL_AR": cc_toolchain.ar_executable,
-            "RV32_TOOL_LD": cc_toolchain.ld_executable,
-            "RV32_TOOL_OBJCOPY": cc_toolchain.objcopy_executable,
+            "RV32_TOOL_AS": ctx.executable._riscv32_as.path,
+            "RV32_TOOL_AR": ctx.executable._riscv32_ar.path,
+            "RV32_TOOL_LD": ctx.executable._riscv32_ld.path,
+            "RV32_TOOL_OBJCOPY": ctx.executable._riscv32_objcopy.path,
         },
         arguments = [
             "--app-name={}".format(ctx.attr.name),
@@ -286,8 +275,11 @@ otbn_library = rv_rule(
     attrs = {
         "srcs": attr.label_list(allow_files = True),
         "args": attr.string_list(),
-        "_cc_toolchain": attr.label(
-            default = Label("@bazel_tools//tools/cpp:current_cc_toolchain"),
+        "_riscv32_as": attr.label(
+            default = Label("@lowrisc_rv32imcb_toolchain//:bin/riscv32-unknown-elf-as"),
+            allow_single_file = True,
+            executable = True,
+            cfg = "exec",
         ),
         "_otbn_as": attr.label(
             default = "//hw/ip/otbn/util:otbn_as",
@@ -306,7 +298,30 @@ otbn_binary = rv_rule(
         "srcs": attr.label_list(allow_files = True),
         "deps": attr.label_list(providers = [DefaultInfo]),
         "args": attr.string_list(),
-        "_cc_toolchain": attr.label(default = Label("@bazel_tools//tools/cpp:current_cc_toolchain")),
+        "_riscv32_ar": attr.label(
+            default = Label("@lowrisc_rv32imcb_toolchain//:bin/riscv32-unknown-elf-ar"),
+            allow_single_file = True,
+            executable = True,
+            cfg = "exec",
+        ),
+        "_riscv32_as": attr.label(
+            default = Label("@lowrisc_rv32imcb_toolchain//:bin/riscv32-unknown-elf-as"),
+            allow_single_file = True,
+            executable = True,
+            cfg = "exec",
+        ),
+        "_riscv32_ld": attr.label(
+            default = Label("@lowrisc_rv32imcb_toolchain//:bin/riscv32-unknown-elf-ld"),
+            allow_single_file = True,
+            executable = True,
+            cfg = "exec",
+        ),
+        "_riscv32_objcopy": attr.label(
+            default = Label("@lowrisc_rv32imcb_toolchain//:bin/riscv32-unknown-elf-objcopy"),
+            allow_single_file = True,
+            executable = True,
+            cfg = "exec",
+        ),
         "_otbn_as": attr.label(
             default = "//hw/ip/otbn/util:otbn_as",
             executable = True,

rules/tock.bzl

@@ -5,6 +5,7 @@
 """Rules for assembling Tock binaries.
 """
 
+load("@rules_cc//cc/action_names.bzl", "OBJ_COPY_ACTION_NAME")
 load("@rules_cc//cc:find_cc_toolchain.bzl", "find_cc_toolchain")
 load(
     "//rules:rv.bzl",
@@ -98,6 +99,16 @@ opt_mode = transition(
 
 def _tock_image_impl(ctx):
     cc_toolchain = find_cc_toolchain(ctx)
+    feature_config = cc_common.configure_features(
+        ctx = ctx,
+        cc_toolchain = cc_toolchain,
+        requested_features = ctx.features,
+        unsupported_features = ctx.disabled_features,
+    )
+    objcopy = cc_common.get_tool_for_action(
+        feature_configuration = feature_config,
+        action_name = OBJ_COPY_ACTION_NAME,
+    )
 
     kernel_binary = ctx.actions.declare_file("{}_kernel.bin".format(ctx.attr.name))
     images = [ctx.actions.declare_file("{}0.bin".format(ctx.attr.name))]
@@ -110,7 +121,7 @@ def _tock_image_impl(ctx):
             ctx.file.kernel.path,
             kernel_binary.path,
         ],
-        executable = cc_toolchain.objcopy_executable,
+        executable = objcopy,
     )
 
     ctx.actions.run(

sw/device/silicon_creator/imm_rom_ext/utils.bzl

@@ -2,11 +2,23 @@
 # Licensed under the Apache License, Version 2.0, see LICENSE for details.
 # SPDX-License-Identifier: Apache-2.0
 
+load("@rules_cc//cc/action_names.bzl", "OBJ_COPY_ACTION_NAME")
 load("@rules_cc//cc:find_cc_toolchain.bzl", "find_cc_toolchain")
 load("@lowrisc_opentitan//rules:rv.bzl", "rv_rule")
 
 def _bin_to_imm_rom_ext_object_impl(ctx):
     cc_toolchain = find_cc_toolchain(ctx)
+    feature_config = cc_common.configure_features(
+        ctx = ctx,
+        cc_toolchain = cc_toolchain,
+        requested_features = ctx.features,
+        unsupported_features = ctx.disabled_features,
+    )
+    objcopy = cc_common.get_tool_for_action(
+        feature_configuration = feature_config,
+        action_name = OBJ_COPY_ACTION_NAME,
+    )
+
     outputs = []
     for src in ctx.files.srcs:
         if src.extension != "bin":
@@ -30,7 +42,7 @@ def _bin_to_imm_rom_ext_object_impl(ctx):
                 src.path,
                 object.path,
             ],
-            executable = cc_toolchain.objcopy_executable,
+            executable = objcopy,
         )
         outputs.append(object)
     return [DefaultInfo(files = depset(outputs), runfiles = ctx.runfiles(files = outputs))]