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

[michaelwoerister]

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

[rust-highfive]

r? @Aatch

(rust_highfive has picked a reviewer for you, use r? to override)

[alexcrichton]

@bors: r+

NIce!

[bors]

📌 Commit 94e655e has been approved by alexcrichton

[nnethercote]

A number of types (e.g. Expr, Ty, Lifetime, possibly more) exist in both ast and hir. The "item size" column suggests that the first two tables are for the ast types and the third table is for the hir types, but I'm not certain about that. Explicit module qualification would help a lot :)

[Mark-Simulacrum]

Can you clarify what the sizes are in? I assume bytes?

[michaelwoerister]

@nnethercote, @Mark-Simulacrum: I'm not sure if I break the rollup if I r- now. I'll make the suggested improvements in another PR.

[nnethercote]

Another question: are you just measuring hir::Expr instances themselves? Tuples and arrays (and probably other variants) contain a HirVec<P<Expr>> -- is the space required for the HirVec elements measured?

[michaelwoerister]

Yes, that is taken care of by the HIR visitor which recurses into these elements.

[nnethercote]

Sorry, I didn't make my question clear. HirVec<P<Expr>> is a typedef for P<[P<Expr>]>. Are you measuring the slice of Ps as well as all the Exprs?

[michaelwoerister]

Nope, for a HirVec<P<Expr>> the space occupied by the pointers in the vec is not measured in this version.