From e8fb8c36ca0de817b3d30f603d6d6b3c56e8b0be Mon Sep 17 00:00:00 2001

From: Josh Stone <jistone@redhat.com>

Date: Fri, 5 Apr 2024 15:07:58 -0700

Subject: [PATCH] bootstrap: move all of rustc's flags to `rustc_cargo`

This ensures that `RUSTFLAGS` will be consistent between all modes of

building the compiler, so they won't trigger a rebuild by cargo. This

kind of fix was started in #119414 just for LTO flags, but it's

applicable to all kinds of flags that might be configured.

---

 src/bootstrap/src/core/build_steps/check.rs   |   2 +-

 src/bootstrap/src/core/build_steps/compile.rs | 107 +++++++++---------

 src/bootstrap/src/core/build_steps/doc.rs     |   2 +-

 src/bootstrap/src/core/build_steps/test.rs    |   2 +-

 4 files changed, 59 insertions(+), 54 deletions(-)

diff --git a/src/bootstrap/src/core/build_steps/check.rs b/src/bootstrap/src/core/build_steps/check.rs

index 55180a82885b..37d91b14ca1b 100644

--- a/src/bootstrap/src/core/build_steps/check.rs

+++ b/src/bootstrap/src/core/build_steps/check.rs

@@ -296,7 +296,7 @@ fn run(self, builder: &Builder<'_>) {

             cargo_subcommand(builder.kind),

         );

-        rustc_cargo(builder, &mut cargo, target, compiler.stage);

+        rustc_cargo(builder, &mut cargo, target, &compiler);

         // For ./x.py clippy, don't run with --all-targets because

         // linting tests and benchmarks can produce very noisy results

diff --git a/src/bootstrap/src/core/build_steps/compile.rs b/src/bootstrap/src/core/build_steps/compile.rs

index e03997181ee5..9420e40d6c2b 100644

--- a/src/bootstrap/src/core/build_steps/compile.rs

+++ b/src/bootstrap/src/core/build_steps/compile.rs

@@ -945,55 +945,10 @@ fn run(self, builder: &Builder<'_>) -> u32 {

             "build",

         );

-        rustc_cargo(builder, &mut cargo, target, compiler.stage);

+        rustc_cargo(builder, &mut cargo, target, &compiler);

-        if builder.config.rust_profile_use.is_some()

-            && builder.config.rust_profile_generate.is_some()

-        {

-            panic!("Cannot use and generate PGO profiles at the same time");

-        }

-

-        // With LLD, we can use ICF (identical code folding) to reduce the executable size

-        // of librustc_driver/rustc and to improve i-cache utilization.

-        //

-        // -Wl,[link options] doesn't work on MSVC. However, /OPT:ICF (technically /OPT:REF,ICF)

-        // is already on by default in MSVC optimized builds, which is interpreted as --icf=all:

-        // https://github.com/llvm/llvm-project/blob/3329cec2f79185bafd678f310fafadba2a8c76d2/lld/COFF/Driver.cpp#L1746

-        // https://github.com/rust-lang/rust/blob/f22819bcce4abaff7d1246a56eec493418f9f4ee/compiler/rustc_codegen_ssa/src/back/linker.rs#L827

-        if builder.config.lld_mode.is_used() && !compiler.host.is_msvc() {

-            cargo.rustflag("-Clink-args=-Wl,--icf=all");

-        }

-

-        let is_collecting = if let Some(path) = &builder.config.rust_profile_generate {

-            if compiler.stage == 1 {

-                cargo.rustflag(&format!("-Cprofile-generate={path}"));

-                // Apparently necessary to avoid overflowing the counters during

-                // a Cargo build profile

-                cargo.rustflag("-Cllvm-args=-vp-counters-per-site=4");

-                true

-            } else {

-                false

-            }

-        } else if let Some(path) = &builder.config.rust_profile_use {

-            if compiler.stage == 1 {

-                cargo.rustflag(&format!("-Cprofile-use={path}"));

-                if builder.is_verbose() {

-                    cargo.rustflag("-Cllvm-args=-pgo-warn-missing-function");

-                }

-                true

-            } else {

-                false

-            }

-        } else {

-            false

-        };

-        if is_collecting {

-            // Ensure paths to Rust sources are relative, not absolute.

-            cargo.rustflag(&format!(

-                "-Cllvm-args=-static-func-strip-dirname-prefix={}",

-                builder.config.src.components().count()

-            ));

-        }

+        // NB: all RUSTFLAGS should be added to `rustc_cargo()` so they will be

+        // consistently applied by check/doc/test modes too.

         for krate in &*self.crates {

             cargo.arg("-p").arg(krate);

@@ -1044,7 +999,12 @@ fn run(self, builder: &Builder<'_>) -> u32 {

     }

 }

-pub fn rustc_cargo(builder: &Builder<'_>, cargo: &mut Cargo, target: TargetSelection, stage: u32) {

+pub fn rustc_cargo(

+    builder: &Builder<'_>,

+    cargo: &mut Cargo,

+    target: TargetSelection,

+    compiler: &Compiler,

+) {

     cargo

         .arg("--features")

         .arg(builder.rustc_features(builder.kind, target))

@@ -1055,7 +1015,7 @@ pub fn rustc_cargo(builder: &Builder<'_>, cargo: &mut Cargo, target: TargetSelec

     // We currently don't support cross-crate LTO in stage0. This also isn't hugely necessary

     // and may just be a time sink.

-    if stage != 0 {

+    if compiler.stage != 0 {

         match builder.config.rust_lto {

             RustcLto::Thin | RustcLto::Fat => {

                 // Since using LTO for optimizing dylibs is currently experimental,

@@ -1081,7 +1041,52 @@ pub fn rustc_cargo(builder: &Builder<'_>, cargo: &mut Cargo, target: TargetSelec

         cargo.rustflag("-Clto=off");

     }

-    rustc_cargo_env(builder, cargo, target, stage);

+    // With LLD, we can use ICF (identical code folding) to reduce the executable size

+    // of librustc_driver/rustc and to improve i-cache utilization.

+    //

+    // -Wl,[link options] doesn't work on MSVC. However, /OPT:ICF (technically /OPT:REF,ICF)

+    // is already on by default in MSVC optimized builds, which is interpreted as --icf=all:

+    // https://github.com/llvm/llvm-project/blob/3329cec2f79185bafd678f310fafadba2a8c76d2/lld/COFF/Driver.cpp#L1746

+    // https://github.com/rust-lang/rust/blob/f22819bcce4abaff7d1246a56eec493418f9f4ee/compiler/rustc_codegen_ssa/src/back/linker.rs#L827

+    if builder.config.lld_mode.is_used() && !compiler.host.is_msvc() {

+        cargo.rustflag("-Clink-args=-Wl,--icf=all");

+    }

+

+    if builder.config.rust_profile_use.is_some() && builder.config.rust_profile_generate.is_some() {

+        panic!("Cannot use and generate PGO profiles at the same time");

+    }

+    let is_collecting = if let Some(path) = &builder.config.rust_profile_generate {

+        if compiler.stage == 1 {

+            cargo.rustflag(&format!("-Cprofile-generate={path}"));

+            // Apparently necessary to avoid overflowing the counters during

+            // a Cargo build profile

+            cargo.rustflag("-Cllvm-args=-vp-counters-per-site=4");

+            true

+        } else {

+            false

+        }

+    } else if let Some(path) = &builder.config.rust_profile_use {

+        if compiler.stage == 1 {

+            cargo.rustflag(&format!("-Cprofile-use={path}"));

+            if builder.is_verbose() {

+                cargo.rustflag("-Cllvm-args=-pgo-warn-missing-function");

+            }

+            true

+        } else {

+            false

+        }

+    } else {

+        false

+    };

+    if is_collecting {

+        // Ensure paths to Rust sources are relative, not absolute.

+        cargo.rustflag(&format!(

+            "-Cllvm-args=-static-func-strip-dirname-prefix={}",

+            builder.config.src.components().count()

+        ));

+    }

+

+    rustc_cargo_env(builder, cargo, target, compiler.stage);

 }

 pub fn rustc_cargo_env(

diff --git a/src/bootstrap/src/core/build_steps/doc.rs b/src/bootstrap/src/core/build_steps/doc.rs

index 51b5cdc05657..a22cbeacf016 100644

--- a/src/bootstrap/src/core/build_steps/doc.rs

+++ b/src/bootstrap/src/core/build_steps/doc.rs

@@ -804,7 +804,7 @@ fn run(self, builder: &Builder<'_>) {

         // see https://github.com/rust-lang/rust/pull/122066#issuecomment-1983049222

         // cargo.rustdocflag("--generate-link-to-definition");

-        compile::rustc_cargo(builder, &mut cargo, target, compiler.stage);

+        compile::rustc_cargo(builder, &mut cargo, target, &compiler);

         cargo.arg("-Zunstable-options");

         cargo.arg("-Zskip-rustdoc-fingerprint");

diff --git a/src/bootstrap/src/core/build_steps/test.rs b/src/bootstrap/src/core/build_steps/test.rs

index bacf5f0d33ce..5277c38a4ad0 100644

--- a/src/bootstrap/src/core/build_steps/test.rs

+++ b/src/bootstrap/src/core/build_steps/test.rs

@@ -2671,7 +2671,7 @@ fn run(self, builder: &Builder<'_>) {

                 }

             }

             Mode::Rustc => {

-                compile::rustc_cargo(builder, &mut cargo, target, compiler.stage);

+                compile::rustc_cargo(builder, &mut cargo, target, &compiler);

             }

             _ => panic!("can only test libraries"),

         };

-- 

2.44.0