From 766f920b9faabee1f9af1052305cfa7c7ba1daf0 Mon Sep 17 00:00:00 2001
From: Mark Rousskov <mark.simulacrum@gmail.com>
Date: Sat, 2 Oct 2021 21:06:21 -0400
Subject: [PATCH] Add dep-graph collector

---
 collector/README.md         |  6 ++++++
 collector/src/execute.rs    | 21 +++++++++++++++++++++
 collector/src/main.rs       |  4 ++--
 collector/src/rustc-fake.rs |  9 +++++++++
 4 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/collector/README.md b/collector/README.md
index 459fd3821..6a343f74c 100644
--- a/collector/README.md
+++ b/collector/README.md
@@ -366,6 +366,12 @@ The mandatory `<PROFILER>` argument must be one of the following.
   - **Output**. File per CGU, currently, placed in a directory inside results.
   - **Notes**. Will likely work best with `Full` builds, on either Debug or Opt
     profiles.
+- `dep-graph`: Dump the incremental dependency graph (as produced by
+  -Zdump-dep-graph).
+  - **Purpose**. This is useful when debugging changes to incremental behavior.
+  - **Slowdown**. Equivalent to normal compilation.
+  - **Output**. .dot and .txt file (.txt likely is what you want to see first).
+  - **Notes**. Works primarily with incremental compilation kinds.
 
 The mandatory `<RUSTC>` argument is a patch to a rustc executable, similar to
 `bench_local`.
diff --git a/collector/src/execute.rs b/collector/src/execute.rs
index 1581adc85..fe82e70a2 100644
--- a/collector/src/execute.rs
+++ b/collector/src/execute.rs
@@ -180,6 +180,7 @@ pub enum Profiler {
     Eprintln,
     LlvmLines,
     MonoItems,
+    DepGraph,
 }
 
 impl Profiler {
@@ -201,6 +202,7 @@ impl Profiler {
             "eprintln" => Ok(Profiler::Eprintln),
             "llvm-lines" => Ok(Profiler::LlvmLines),
             "mono-items" => Ok(Profiler::MonoItems),
+            "dep-graph" => Ok(Profiler::DepGraph),
             _ => Err(anyhow!("'{}' is not a known profiler", name)),
         }
     }
@@ -222,6 +224,7 @@ impl Profiler {
             Profiler::Eprintln => "eprintln",
             Profiler::LlvmLines => "llvm-lines",
             Profiler::MonoItems => "mono-items",
+            Profiler::DepGraph => "dep-graph",
         }
     }
 
@@ -241,6 +244,7 @@ impl Profiler {
             | Profiler::Callgrind
             | Profiler::DHAT
             | Profiler::Massif
+            | Profiler::DepGraph
             | Profiler::MonoItems
             | Profiler::Eprintln => {
                 if build_kind == BuildKind::Doc {
@@ -272,6 +276,8 @@ impl Profiler {
             | Profiler::Massif
             | Profiler::MonoItems
             | Profiler::Eprintln => true,
+            // only incremental
+            Profiler::DepGraph => scenario_kind != ScenarioKind::Full,
             Profiler::LlvmLines => scenario_kind == ScenarioKind::Full,
         }
     }
@@ -1183,6 +1189,21 @@ impl<'a> Processor for ProfileProcessor<'a> {
                 }
             }
 
+            Profiler::DepGraph => {
+                let tmp_file = filepath(data.cwd.as_ref(), "dep_graph.txt");
+                let output =
+                    filepath(self.output_dir, &out_file("dep-graph")).with_extension("txt");
+
+                fs::copy(&tmp_file, &output)?;
+
+                let tmp_file = filepath(data.cwd.as_ref(), "dep_graph.dot");
+                let output =
+                    filepath(self.output_dir, &out_file("dep-graph")).with_extension("dot");
+
+                // May not exist if not incremental, but then that's OK.
+                fs::copy(&tmp_file, &output)?;
+            }
+
             // `cargo llvm-lines` writes its output to stdout. We copy that
             // output into a file in the output dir.
             Profiler::LlvmLines => {
diff --git a/collector/src/main.rs b/collector/src/main.rs
index a556af2ff..190961970 100644
--- a/collector/src/main.rs
+++ b/collector/src/main.rs
@@ -674,7 +674,7 @@ fn main_result() -> anyhow::Result<i32> {
             (@arg PROFILER: +required +takes_value
              "One of: 'self-profile', 'time-passes', 'perf-record',\n\
              'oprofile', 'cachegrind', 'callgrind', 'dhat', 'massif',\n\
-             'eprintln', 'llvm-lines', 'mono-items'")
+             'eprintln', 'llvm-lines', 'mono-items', 'dep-graph'")
             (@arg RUSTC:    +required +takes_value "The path to the local rustc to benchmark")
             (@arg ID:       +required +takes_value "Identifier to associate benchmark results with")
 
@@ -703,7 +703,7 @@ fn main_result() -> anyhow::Result<i32> {
             (@arg PROFILER: +required +takes_value
              "One of: 'self-profile', 'time-passes', 'perf-record',\n\
              'oprofile', 'cachegrind', 'callgrind', 'dhat', 'massif',\n\
-             'eprintln', 'llvm-lines', 'mono-items'")
+             'eprintln', 'llvm-lines', 'mono-items', 'dep-graph'")
             (@arg RUSTC_BEFORE: +required +takes_value "The path to the local rustc to benchmark")
             (@arg RUSTC_AFTER:  +required +takes_value "The path to the local rustc to benchmark")
 
diff --git a/collector/src/rustc-fake.rs b/collector/src/rustc-fake.rs
index a6a74dcf4..32e936e3d 100644
--- a/collector/src/rustc-fake.rs
+++ b/collector/src/rustc-fake.rs
@@ -294,6 +294,15 @@ fn main() {
                 assert!(cmd.status().expect("failed to spawn").success());
             }
 
+            "dep-graph" => {
+                args.push("-Zdump-dep-graph".into());
+                args.push("-Zquery-dep-graph".into());
+                let mut cmd = Command::new(tool);
+                cmd.args(&args);
+
+                assert!(cmd.status().expect("failed to spawn").success());
+            }
+
             _ => {
                 panic!("unknown wrapper: {}", wrapper);
             }