Resurrect: rustc_llvm: Add a -Z `print-codegen-stats` option to expose LLVM statistics. #113723

khei4 · 2023-07-15T12:41:59Z

This resurrects PR #104000, which has sat idle for a while. And I want to see the effect of stack-move optimizations on LLVM (like https://reviews.llvm.org/D153453) :).

I have applied the changes requested by @oli-obk and @nagisa #104000 (comment) and #104000 (comment) in the latest commits.

r? @oli-obk

LLVM has a neat statistics feature that tracks how often optimizations kick in. It's very handy for optimization work. Since we expose the LLVM pass timings, I thought it made sense to expose the LLVM statistics too.

(Edit: fix broken link
(Edit2: fix segmentation fault and use malloc

If rustc is built with

[llvm]
assertions = true

Then you can see like

rustc +stage1 -Z print-codegen-stats -C opt-level=3  tmp.rs
===-------------------------------------------------------------------------===
                          ... Statistics Collected ...
===-------------------------------------------------------------------------===
         3 aa                           - Number of MayAlias results
       193 aa                           - Number of MustAlias results
       531 aa                           - Number of NoAlias results
...

And the current default build emits only

$ rustc +stage1 -Z print-codegen-stats -C opt-level=3  tmp.rs
===-------------------------------------------------------------------------===
                          ... Statistics Collected ...
===-------------------------------------------------------------------------===
$

This might be better to emit the message to tell assertion flag necessity, but now I can't find how to do that...

rustbot · 2023-07-15T12:42:07Z

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @oli-obk (or someone else) soon.

Please see the contribution instructions for more information. Namely, in order to ensure the minimum review times lag, PR authors and assigned reviewers should ensure that the review label (S-waiting-on-review and S-waiting-on-author) stays updated, invoking these commands when appropriate:

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rustbot · 2023-07-15T12:42:09Z

Some changes occurred in compiler/rustc_codegen_gcc

cc @antoyo

…ics. LLVM has a neat [statistics] feature that tracks how often optimizations kick in. It's very handy for optimization work. Since we expose the LLVM pass timings, I thought it made sense to expose the LLVM statistics too. [statistics]: https://llvm.org/docs/ProgrammersManual.html#the-statistic-class-stats-option

compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp

compiler/rustc_codegen_llvm/src/lib.rs

oli-obk · 2023-07-19T08:28:46Z

compiler/rustc_codegen_llvm/src/llvm/ffi.rs

@@ -1868,7 +1868,10 @@ extern "C" {
    pub fn LLVMRustGetLastError() -> *const c_char;

    /// Print the pass timings since static dtors aren't picking them up.
-    pub fn LLVMRustPrintPassTimings();
+    pub fn LLVMRustPrintPassTimings(size: *const usize) -> *const c_char;


Nothing else in this file uses usize, please use size_t to make sure we don't rely on funny Rust<->C differences

Oh, thanks! I should have seen around.

compiler/rustc_codegen_llvm/src/lib.rs

compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp

oli-obk · 2023-07-20T07:16:33Z

@bors r-

…rust/pull/113723/files use slice memcpy rather than strcpy and write it on stdout use println on failure Co-authored-by: Oli Scherer <github35764891676564198441@oli-obk.de>

khei4 · 2023-07-20T07:55:42Z

@rustbot label -S-waiting-on-author +S-waiting-on-review

oli-obk · 2023-07-20T08:26:35Z

@bors r=oli-obk,nikic

bors · 2023-07-20T08:26:37Z

📌 Commit c7bf20d has been approved by oli-obk,nikic

It is now in the queue for this repository.

bors · 2023-07-20T12:24:45Z

⌛ Testing commit c7bf20d with merge cd454abe290b5438354e833ebfeca69b11ecfbf2...

bors · 2023-07-20T12:27:23Z

💔 Test failed - checks-actions

rust-log-analyzer · 2023-07-20T12:42:43Z

The job dist-i586-gnu-i586-i686-musl failed! Check out the build log: (web) (plain)

Click to see the possible cause of the failure (guessed by this bot)

lqd · 2023-07-20T12:58:27Z

@bors retry rust-lang/crates.io#6850

…iaskrgr Rollup of 5 pull requests Successful merges: - rust-lang#113380 (style-guide: clean up "must"/"should"/"may") - rust-lang#113723 (Resurrect: rustc_llvm: Add a -Z `print-codegen-stats` option to expose LLVM statistics.) - rust-lang#113780 (Support `--print KIND=PATH` command line syntax) - rust-lang#113810 (Make {Rc,Arc}::allocator associated functions) - rust-lang#113907 (Minor improvements to Windows TLS dtors) Failed merges: - rust-lang#113392 (style-guide: Some cleanups from the fmt-rfcs repo history) r? `@ghost` `@rustbot` modify labels: rollup

…nikic Resurrect: rustc_llvm: Add a -Z `print-codegen-stats` option to expose LLVM statistics. This resurrects PR rust-lang#104000, which has sat idle for a while. And I want to see the effect of stack-move optimizations on LLVM (like https://reviews.llvm.org/D153453) :). I have applied the changes requested by `@oli-obk` and `@nagisa` rust-lang#104000 (comment) and rust-lang#104000 (comment) in the latest commits. r? `@oli-obk` ----- LLVM has a neat [statistics](https://llvm.org/docs/ProgrammersManual.html#the-statistic-class-stats-option) feature that tracks how often optimizations kick in. It's very handy for optimization work. Since we expose the LLVM pass timings, I thought it made sense to expose the LLVM statistics too. ----- (Edit: fix broken link (Edit2: fix segmentation fault and use malloc If `rustc` is built with ```toml [llvm] assertions = true ``` Then you can see like ``` rustc +stage1 -Z print-codegen-stats -C opt-level=3 tmp.rs ===-------------------------------------------------------------------------=== ... Statistics Collected ... ===-------------------------------------------------------------------------=== 3 aa - Number of MayAlias results 193 aa - Number of MustAlias results 531 aa - Number of NoAlias results ... ``` And the current default build emits only ``` $ rustc +stage1 -Z print-codegen-stats -C opt-level=3 tmp.rs ===-------------------------------------------------------------------------=== ... Statistics Collected ... ===-------------------------------------------------------------------------=== $ ``` This might be better to emit the message to tell assertion flag necessity, but now I can't find how to do that...

rustbot assigned oli-obk Jul 15, 2023

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Jul 15, 2023