Code change:
I was in the middle of bisecting on system llvm and running when I noticed that, in fact, while each step was rebuilding the compiler with the changed llvm correctly, the test that was being run was never recompiled, such that the same one was always running, and my bisect was guided by wrong results. STR: Run once Touch anything that is part of e.g. , e.g. Run again Expected result: Both and the test are rebuilt, and the rebuilt test executed. Actual result: is rebuilt, the test is not, and the test built before the codegen changes is executed.

Related discussion:
text: let mut cargo = Command::new(&self.initial_cargo); let out_dir = self.stage_out(compiler, mode); <del> // command specific path, we call clear_if_dirty with this let mut my_out = match cmd { "build" => self.cargo_out(compiler, mode, target), // This is the intended out directory for crate documentation. "doc" | "rustdoc" =>  self.crate_doc_out(target), _ => self.stage_out(compiler, mode), }; // This is for the original compiler, but if we're forced to use stage 1, then // std/test/rustc stamps won't exist in stage 2, so we need to get those from stage 1, since // we copy the libs forward. let cmp = self.compiler_for(compiler.stage, compiler.host, target); let libstd_stamp = match cmd { "check" | "clippy" | "fix" => check::libstd_stamp(self, cmp, target), _ => compile::libstd_stamp(self, cmp, target), }; let libtest_stamp = match cmd { "check" | "clippy" | "fix" => check::libtest_stamp(self, cmp, target), _ => compile::libtest_stamp(self, cmp, target), }; let librustc_stamp = match cmd { "check" | "clippy" | "fix" => check::librustc_stamp(self, cmp, target), _ => compile::librustc_stamp(self, cmp, target), }; </del> <ins> // Codegen backends are not yet tracked by -Zbinary-dep-depinfo, // so we need to explicitly clear out if they've been updated. for backend in self.codegen_backends(compiler) { self.clear_if_dirty(&out_dir, &backend); } </ins> if cmd == "doc" || cmd == "rustdoc" { <del> if mode == Mode::Rustc || mode == Mode::ToolRustc || mode == Mode::Codegen { </del> <ins> let my_out = match mode { </ins> // This is the intended out directory for compiler documentation. <del> my_out = self.compiler_doc_out(target); } </del> <ins> Mode::Rustc | Mode::ToolRustc | Mode::Codegen => self.compiler_doc_out(target), _ => self.crate_doc_out(target), }; </ins> let rustdoc = self.rustdoc(compiler); self.clear_if_dirty(&my_out, &rustdoc); <del> } else if cmd != "test" { match mode { Mode::Std => { self.clear_if_dirty(&my_out, &self.rustc(compiler)); for backend in self.codegen_backends(compiler) { self.clear_if_dirty(&my_out, &backend); } }, Mode::Test => { self.clear_if_dirty(&my_out, &libstd_stamp); }, Mode::Rustc => { self.clear_if_dirty(&my_out, &self.rustc(compiler)); self.clear_if_dirty(&my_out, &libstd_stamp); self.clear_if_dirty(&my_out, &libtest_stamp); }, Mode::Codegen => { self.clear_if_dirty(&my_out, &librustc_stamp); }, Mode::ToolBootstrap => { }, Mode::ToolStd => { self.clear_if_dirty(&my_out, &libstd_stamp); }, Mode::ToolTest => { self.clear_if_dirty(&my_out, &libstd_stamp); self.clear_if_dirty(&my_out, &libtest_stamp); }, Mode::ToolRustc => { self.clear_if_dirty(&my_out, &libstd_stamp); self.clear_if_dirty(&my_out, &libtest_stamp); self.clear_if_dirty(&my_out, &librustc_stamp); }, } </del> } cargo