feat: expose a build's options to the run step as {build_opts_file}

A run step that compiles for itself instead of loading the build's
snapshot has to compile the way the build did.  Every build now records
its options in build_opts.f, named by the hjson as {build_opts_file}.

Signed-off-by: Martin Velay <mvelay@lowrisc.org>

Author: martin-velay

src/dvsim/job/deploy.py

@@ -36,6 +36,10 @@
     "Deploy",
 )
 
+# Name of the file that records the options a build used. It sits in the build directory, and
+# SimCfg turns it into the {build_opts_file} substitution variable the HJson can name.
+BUILD_OPTS_FILE_NAME = "build_opts.f"
+
 
 class Deploy:
     """Abstraction to create and maintain a runnable job (builds, runs, etc.)."""
@@ -431,6 +435,7 @@ def __init__(self, build_mode: "BuildMode", sim_cfg: "SimCfg") -> None:
         self.build_cmd: str = ""
         self.build_dir: str = ""
         self.build_opts: list[str] = []
+        self.build_opts_file: str = ""
         self.post_build_cmds: list[str] = []
         self.build_fail_patterns: list[str] = []
         self.build_pass_patterns: list[str] = []
@@ -485,6 +490,7 @@ def _define_attrs(self) -> None:
         self.mandatory_misc_attrs.update(
             {
                 "build_fail_patterns": False,
+                "build_opts_file": False,
                 "build_pass_patterns": False,
                 "build_timeout_mins": False,
                 "cov_db_dir": False,
@@ -509,6 +515,23 @@ def _set_attrs(self) -> None:
         if self.sim_cfg.args.build_timeout_mins is not None:
             self.build_timeout_mins = self.sim_cfg.args.build_timeout_mins
 
+    def _write_build_opts_file(self) -> None:
+        """Record the options this build used, in the build directory.
+
+        A run step that compiles and elaborates for itself, rather than loading the snapshot the
+        build produced, has to compile the way the build did: build modes and individual cfgs each
+        add their own defines, include paths and libraries, and a run compiled with a different set
+        would simulate a differently configured design. The merged option list exists only here, so
+        it is written out in a form the tools accept as an option file, for the run step to read
+        back with {build_opts_file}.
+        """
+        opts_file = Path(self.build_opts_file)
+        opts_file.parent.mkdir(parents=True, exist_ok=True)
+        opts_file.write_text(
+            "".join(f"{opt.strip()}\n" for opt in self.build_opts if opt.strip()),
+            encoding="UTF-8",
+        )
+
     def pre_launch(self) -> Callable[[], None]:
         """Get pre-launch callback."""
 
@@ -518,6 +541,8 @@ def callback() -> None:
             # need to do this because the build directory is not 'renewed'.
             rm_path(Path(self.cov_db_dir))
 
+            self._write_build_opts_file()
+
         return callback
 
     def get_timeout_mins(self) -> float:

src/dvsim/sim/flow.py

@@ -17,6 +17,7 @@
 from dvsim.flow.base import FlowCfg
 from dvsim.job.data import CompletedJobStatus, JobSpec
 from dvsim.job.deploy import (
+    BUILD_OPTS_FILE_NAME,
     CompileSim,
     CovAnalyze,
     CovMerge,
@@ -200,6 +201,11 @@ def _expand(self) -> None:
         if self.args.verbosity is not None:
             self.verbosity = self.args.verbosity
 
+        # Where each build records the options it compiled with, for a run step that compiles for
+        # itself rather than loading the snapshot the build produced, see
+        # CompileSim._write_build_opts_file().
+        self.build_opts_file = "{build_dir}/" + BUILD_OPTS_FILE_NAME
+
         super()._expand()
 
         if self.variant:

tests/job/test_deploy.py

@@ -5,6 +5,7 @@
 """Test Job deployment models."""
 
 from collections.abc import Mapping
+from pathlib import Path
 
 import pytest
 from hamcrest import assert_that, equal_to
@@ -48,6 +49,7 @@ def __init__(self) -> None:
         self.pre_build_cmds = ["A", "B"]
         self.post_build_cmds = ["C", "D"]
         self.build_dir = "build/dir"
+        self.build_opts_file = "{build_dir}/build_opts.f"
         self.build_pass_patterns = None
         self.build_fail_patterns = None
         self.build_seed = 123
@@ -202,6 +204,24 @@ def test_seed(
 
         assert_that(job.seed, equal_to(seed))
 
+    @staticmethod
+    def test_build_opts_file(tmp_path: Path) -> None:
+        """Test that a CompileSim records the options it built with, for the run step."""
+        build_dir = tmp_path / "build" / "dir"
+        job = _build_compile_sim(
+            sim_overrides={"build_dir": str(build_dir), "cov_db_dir": str(tmp_path / "cov")},
+        )
+
+        assert_that(job.build_opts_file, equal_to(str(build_dir / "build_opts.f")))
+
+        # The build directory does not exist until the build job launches.
+        job.pre_launch()()
+
+        assert_that(
+            Path(job.build_opts_file).read_text(encoding="UTF-8"),
+            equal_to('-b path/here\n-a "Quoted"\n'),
+        )
+
     @staticmethod
     @pytest.mark.parametrize(
         ("cli_args_overrides", "build_overrides", "timeout"),