Rollup merge of #37583 - michaelwoerister:hir-stats, r=alexcrichton

Add `-Z hir-stats` for collecting statistics on HIR and AST

The data collected will be printed to the commandline and looks like the following:

```
// stats for libcore

PRE EXPANSION AST STATS

Name                Accumulated Size         Count     Item Size
----------------------------------------------------------------
TypeBinding                    2_280            57            40
Mod                            3_560            89            40
PathListItem                   6_516           181            36
Variant                        7_872            82            96
LifetimeDef                   21_280           380            56
StructField                   22_880           260            88
Lifetime                      23_800         1_190            20
Local                         30_192           629            48
ForeignItem                   31_504           179           176
Arm                           42_880           670            64
Mac                           46_960           587            80
FnDecl                        57_792         1_204            48
TraitItem                     69_504           362           192
TyParamBound                  98_280           945           104
Block                        108_384         2_258            48
Stmt                         144_720         3_618            40
ImplItem                     230_272         1_028           224
Item                         467_456         1_826           256
Pat                          517_776         4_623           112
Attribute                    745_680        15_535            48
Ty                         1_114_848         9_954           112
PathSegment                1_218_528        16_924            72
Expr                       3_082_408        20_279           152
----------------------------------------------------------------
Total                      8_095_372

POST EXPANSION AST STATS

Name                Accumulated Size         Count     Item Size
----------------------------------------------------------------
MacroDef                       1_056            12            88
Mod                            3_400            85            40
TypeBinding                    4_280           107            40
PathListItem                   6_516           181            36
Variant                        7_872            82            96
StructField                   24_904           283            88
ForeignItem                   31_504           179           176
TraitItem                     69_504           362           192
Local                         85_008         1_771            48
Arm                          100_288         1_567            64
Lifetime                     123_980         6_199            20
LifetimeDef                  126_728         2_263            56
TyParamBound                 297_128         2_857           104
FnDecl                       305_856         6_372            48
Block                        481_104        10_023            48
Stmt                         535_120        13_378            40
Item                       1_469_952         5_742           256
Attribute                  1_629_840        33_955            48
ImplItem                   1_732_864         7_736           224
Pat                        2_360_176        21_073           112
PathSegment                5_888_448        81_784            72
Ty                         6_237_168        55_689           112
Expr                      12_013_320        79_035           152
----------------------------------------------------------------
Total                     33_536_016

HIR STATS

Name                Accumulated Size         Count     Item Size
----------------------------------------------------------------
MacroDef                         864            12            72
Mod                            2_720            85            32
TypeBinding                    3_424           107            32
PathListItem                   5_068           181            28
Variant                        6_560            82            80
StructField                   20_376           283            72
ForeignItem                   27_208           179           152
WherePredicate                43_776           684            64
TraitItem                     52_128           362           144
Decl                          68_992         2_156            32
Local                         89_184         1_858            48
Arm                           94_368         1_966            48
LifetimeDef                  108_624         2_263            48
Lifetime                     123_980         6_199            20
Stmt                         168_000         4_200            40
TyParamBound                 251_416         2_857            88
FnDecl                       254_880         6_372            40
Block                        583_968        12_166            48
Item                       1_240_272         5_742           216
ImplItem                   1_361_536         7_736           176
Attribute                  1_620_480        33_760            48
Pat                        2_073_120        21_595            96
Path                       2_385_856        74_558            32
Ty                         4_455_040        55_688            80
PathSegment                5_587_904        87_311            64
Expr                       7_588_992        79_052            96
----------------------------------------------------------------
Total                     28_218_736
```

Author: Jonathan Turner

src/librustc/session/config.rs

@@ -918,6 +918,8 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
           "the directory the MIR is dumped into"),
     perf_stats: bool = (false, parse_bool, [UNTRACKED],
           "print some performance-related statistics"),
+    hir_stats: bool = (false, parse_bool, [UNTRACKED],
+          "print some statistics about AST and HIR"),
 }
 
 pub fn default_lib_output() -> CrateType {

src/librustc/util/common.rs

@@ -75,6 +75,26 @@ pub fn duration_to_secs_str(dur: Duration) -> String {
     format!("{:.3}", secs)
 }
 
+pub fn to_readable_str(mut val: usize) -> String {
+    let mut groups = vec![];
+    loop {
+        let group = val % 1000;
+
+        val /= 1000;
+
+        if val == 0 {
+            groups.push(format!("{}", group));
+            break
+        } else {
+            groups.push(format!("{:03}", group));
+        }
+    }
+
+    groups.reverse();
+
+    groups.join("_")
+}
+
 pub fn record_time<T, F>(accu: &Cell<Duration>, f: F) -> T where
     F: FnOnce() -> T,
 {
@@ -264,3 +284,17 @@ pub fn path2cstr(p: &Path) -> CString {
 pub fn path2cstr(p: &Path) -> CString {
     CString::new(p.to_str().unwrap()).unwrap()
 }
+
+
+#[test]
+fn test_to_readable_str() {
+    assert_eq!("0", to_readable_str(0));
+    assert_eq!("1", to_readable_str(1));
+    assert_eq!("99", to_readable_str(99));
+    assert_eq!("999", to_readable_str(999));
+    assert_eq!("1_000", to_readable_str(1_000));
+    assert_eq!("1_001", to_readable_str(1_001));
+    assert_eq!("999_999", to_readable_str(999_999));
+    assert_eq!("1_000_000", to_readable_str(1_000_000));
+    assert_eq!("1_234_567", to_readable_str(1_234_567));
+}

src/librustc_driver/driver.rs

@@ -37,7 +37,8 @@ use rustc_typeck as typeck;
 use rustc_privacy;
 use rustc_plugin::registry::Registry;
 use rustc_plugin as plugin;
-use rustc_passes::{ast_validation, no_asm, loops, consts, rvalues, static_recursion};
+use rustc_passes::{ast_validation, no_asm, loops, consts, rvalues,
+                   static_recursion, hir_stats};
 use rustc_const_eval::check_match;
 use super::Compilation;
 
@@ -513,6 +514,10 @@ pub fn phase_1_parse_input<'a>(sess: &'a Session, input: &Input) -> PResult<'a,
         syntax::show_span::run(sess.diagnostic(), s, &krate);
     }
 
+    if sess.opts.debugging_opts.hir_stats {
+        hir_stats::print_ast_stats(&krate, "PRE EXPANSION AST STATS");
+    }
+
     Ok(krate)
 }
 
@@ -718,6 +723,10 @@ pub fn phase_2_configure_and_expand<'a, F>(sess: &Session,
         println!("Post-expansion node count: {}", count_nodes(&krate));
     }
 
+    if sess.opts.debugging_opts.hir_stats {
+        hir_stats::print_ast_stats(&krate, "POST EXPANSION AST STATS");
+    }
+
     if sess.opts.debugging_opts.ast_json {
         println!("{}", json::as_json(&krate));
     }
@@ -758,7 +767,13 @@ pub fn phase_2_configure_and_expand<'a, F>(sess: &Session,
 
     // Lower ast -> hir.
     let hir_forest = time(sess.time_passes(), "lowering ast -> hir", || {
-        hir_map::Forest::new(lower_crate(sess, &krate, &mut resolver), &sess.dep_graph)
+        let hir_crate = lower_crate(sess, &krate, &mut resolver);
+
+        if sess.opts.debugging_opts.hir_stats {
+            hir_stats::print_hir_stats(&hir_crate);
+        }
+
+        hir_map::Forest::new(hir_crate, &sess.dep_graph)
     });
 
     // Discard hygiene data, which isn't required past lowering to HIR.