淺談編譯器最佳化技術

淺談 Compiler 最佳化技術

Hsinchu Tech Chat Group

Date : Dec 7th, 2014 Kito Cheng

[email protected]

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自我介紹

安第斯山脈Compiler Team專業打雜工

3

Compiler?

4

Compiler?

5

Compilation Flow

[1] Compilers: Principles, Techniques, and Tools (2nd Edition) p.5

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Compilation Flow


通常大學部編譯器課程僅能涵蓋 Parser 部份

以及陽春的 Code Generation

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Compilation Flow


但 Compiler 超好玩超神奇的部份其實都在最佳化的地方

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Compilation Flow


但 Compiler 超好玩超神奇的部份其實都在最佳化的地方

透過最佳化 ,程式可以變得又小又快！

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Compilation Flow


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•這次分享基本上不會涉及太多高深理論 , 僅會透過介紹概念並透過範例來講解

•使用 LLVM 來作為說明以及展示的輔助工具

11基礎知識惡補

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基礎知識惡補

• Basic Block• Control Flow Graph• Static Single Assignment Form

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Basic Block

•單一進入點 , 單一出口點的程式區段

• http://en.wikipedia.org/wiki/Basic_block

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Control Flow Graph

•簡稱 CFG, 簡單來說就是程式的流程圖

• http://en.wikipedia.org/wiki/Control_flow_graph

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Basic Block

int foo (ini n){ int ret; if (n > 10) ret = n * 2; else ret = n + 2; return ret;}

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Basic Block


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Basic Block


int ret;if (n > 10)

ret = n * 2; ret = n + 2;

return ret;

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CFG


int ret;if (n > 10)

ret = n * 2; ret = n + 2;

return ret;

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Basic Block

int sum (int n){ int ret = 0; int i; for (i = 0; i < n; ++i) ret += i; return ret;}

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Basic Block


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Basic Block


int ret = 0;int i;

i = 0;

i < n;

ret += i;

++i

return ret

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CFG


int ret = 0;int i;

i = 0;

i < n;

ret += i;

++i

return ret

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Static Single Assignment

•將變數標上版本

•每個值只會賦值 /寫入一次

• http://en.wikipedia.org/wiki/Static_single_assignment_form

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SSA

int foo (){ int ret; ret = 10; ret = 20; return ret;}

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SSA


int foo (){ int ret; ret1 = 10; ret2 = 20; return ret2;}

每次賦值都會一個版本號

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SSA


int foo (){ int ret; ret1 = 10; ret2 = 20; return ret2;}

每次賦值都會一個版本號

標完後可以馬上知道是使用哪個運算式的結果

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SSA


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SSA


int foo (ini n){ int ret; if (n > 10) ret1 = n * 2; else ret2 = n + 2; return ret?;}

程式中有分歧點會合時無法判定是從何而來

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SSA


int foo (ini n){ int ret; if (n > 10) ret1 = n * 2; else ret2 = n + 2; ret3 = Φ (ret1, ret2) return ret3;}

此時需要使用Φ來處理這種情況 ,表示值的定義

需由程式流程決定並給予新的版本號

30L L V M

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LLVM

•好用好玩而且最近很夯的 Compiler, 安裝方法如下 :– sudo apt-get install llvm clang xdot– sudo yum install llvm clang python-xdot python-setuptools

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LLVM


xdot 是要看圖用的

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LLVM


xdot 是要看圖用的

這個嘛 ...Fedora 套件系統相依性沒設定好 , xdot 的相依套件

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LLVM


– 不是 apt-get 或 yum ? 那就假設你是高手會自己想辦法 XD

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LLVM



– Windows !? 聽說官網有安裝檔 ?

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LLVM



– Windows !? 聽說官網有安裝檔 ?– 建議自己 build, 不然會沒有部份 debug功能

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LLVM IR

• v = operation type op1, op2, opn...– %sum = add i32 %op1, %op2

運算元

型態

運算子們

運算結果

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空空的 LLVM函數

define void @empty() { ret void}

宣告函數的起手式

回傳型態

@函數名稱

參數列

回傳 + 型態

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有一個參數的 LLVM函數

define void @arg1(i32 %a) { ret void}

參數列 , 有一個參數叫 %a

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有一個參數並且直接回傳的 LLVM函數

define i32 @arg1(i32 %a) { ret i32 %a}

回傳值是 i32

回傳 + 型態 + 回傳值

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有一個參數並且回傳其參數加十的 LLVM函數

define i32 @arg1(i32 %a) { %t = add i32 %a, 10 ret i32 %t}

%a加 10放到 %1

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LLVM IR

• SSA-Based IR– %sum = add i32 %op1, %op2– %sum = mul i32 %op1, %op2– error: multiple definition of local value named 'sum'

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SSA!?

•對編譯器來講 SSA Form 很友善 , 但對於正常人來說寫 SSA Form 不太直覺 ...

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SSA!?

•對編譯器來講 SSA Form 很友善 , 但對於正常人來說寫 SSA Form 不太直覺 ...– 習慣 Functional programming者例外 ...XD

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SSA!?

•對編譯器來講 SSA Form 很友善 , 但對於正常人來說寫 SSA Form 不太直覺 ...– 習慣 Functional programming者例外 ...XD

•手動插入 PHI 更是件麻煩事

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alloca

•用來產生區域變數– 分配到的空間放到 stack

• 使用上有點類似 C語言的 malloc, 但概念不太一樣

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alloca

define void @foo() { %var = alloca i32 ret void}

型別所產生的位置 , 可以看作是一個 i32*

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alloca

•每次存取都必須透過 load/store– 但在最佳化過程中 , 若非必要則會變為Register ( 透過 mem2reg pass)

•若為 array 或必須對其取位址 , 則可能無法變成 Register

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alloca/store

define void @foo() { %var = alloca i32 store i32 10, i32* %var ret void}

型別跟要存的目標位置要存的值與型別

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alloca/load

define void @foo() { %var = alloca i32 store i32 10, i32* %var %t0 = load i32* %var ret void}

讀取回來的值型別跟要讀取的目標位置

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LLVM/Clang

•今天的分享中只會使用以下兩個工具 :– clang : 把 c 變成 LLVM IR– opt : 進行最佳化以及觀察的工具

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View CFG by LLVM

• clang foo.c -S -emit-llvm• opt foo.ll -veiw-cfg

int foo(int a, int b){ if (a > b) return a; else return b;}

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View CFG by LLVM

垃圾指令有點多 ,但在觀察階段開最佳化 ,

又會干擾學習

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View CFG by LLVM

垃圾指令有點多 ,但在觀察階段開最佳化 ,

又會干擾學習

opt foo.ll -O1 -veiw-cfg開完最佳化後剩三道指令一個 BB...

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opt 使用注意事項 (1/3)

•參數的位置很重要 !!

opt foo.ll -view-cfg -O1

先秀出 CFG 再進行最佳化

opt foo.ll -O1 -view-cfg

先進行最佳化再來看 CFG

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•參數可以重複下

opt foo.ll -view-cfg -O1 -view-cfg

先秀出 CFG

再進行最佳化

最後再看一次 CFG

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•參數可以重複下 , 最佳化也可以重複作

opt foo.ll -O1 -view-cfg -O1 -view-cfg

再進行最佳化

進行最佳化

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mem2reg

• mem2reg: 不必要的 alloca 以及 load/store 砍掉

•並且把程式變得比較有 SSA Form 的樣子

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mem2reg

opt foo.ll -mem2reg -view-cfg

phi node 出現了 !並且也將 alloca

以及 load/store 砍光

60Compiler Optimization

編譯器最佳化

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Propagation

• Propagation: 傳遞– Constant Propagation– Copy Propagation

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Constant Propagation

int foo(int a){ int magic_num = 10; return a + magic_num;}

int foo(int a){ int magic_num = 10; return a + 10;}

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opt foo.ll -mem2reg -view-cfg

這種最佳化太基本了 ,在 mem2reg 過程順便作掉



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千萬不要覺得寫成右邊那樣會比較快就寫一堆

該死的 Magic Number!!!!



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Copy Propagation

b = ac = b

b = ac = a

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Constant Folding

• Constant Folding: 常數折疊！– 若運算對象都是常數 ,那就先算出來！

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Constant Folding


• a = 123 + 456

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Constant Folding


• a = 123 + 456– a = 579

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Constant Folding


• a = 123 + 456– a = 579

•程式中不一定有一堆這種常數運算 , 但經過 Constant Propagation 後會慢慢出現

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Constant Folding

a = 10b = 100 + a

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Constant Folding

a = 10b = 100 + a

a = 10b = 100 + 10


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Constant Folding

a = 10b = 100 + a

a = 10b = 100 + 10

a = 10b = 110


Constant Folding

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•程式中哪來中這麼多常數可以玩 !?

• Propagation跟 Folding 都是基礎小招 , 與其它最佳化搭配起來可發揮最大效用 !

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• LLVM 這幾樣基礎最佳化都是順便做的 , 難以獨立觀察 ...

• Copy/Constant Propagation 基本上都會在 mem2reg 過程中順便處理掉

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觀察 Constant Folding

• Constant Folding 則可以在 LLVM 的 Constant Propagation Pass 中處理

define i32 @folding() { %t = add i32 10, 20 ret i32 %t}

opt -S cfolding.ll -constprop

define i32 @folding() { ret i32 30}

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Function Inline

• Inline: 行內函數 ? 內嵌函數 ?

•概念就是把函數內容複製一份到呼叫端

•節省掉函數的呼叫並且可探索更多的最佳化機會 !

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Inline + Propagation

• Inline 後原本參數的傳遞變成單純的拷貝行為– Copy Propagation– Constant Propagation

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Inline + Propagationint add(int a, int b){ return a + b;}

int foo(int n){ int sum = 0; int i, t; for (i = 0; i < n ;++i) { t = add(10, 20); sum = add(sum, i); sum = add(sum, t); } return sum;}

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Inline + Propagationint add(int a, int b){ return a + b;}

int foo(int n){ int sum = 0; int i, t; for (i = 0; i < n ;++i) { t = add(10, 20); sum = add(sum, i); sum = add(sum, t); } return sum;}

define i32 @add(i32 %a, i32 %b) { %1 = add i32 %a, %b ret i32 %1}

define i32 @foo(i32 %n) { br label %1; <label>:1 %sum.0 = phi i32 [ 0, %0 ], [ %6, %7 ] %i.0 = phi i32 [ 0, %0 ], [ %8, %7 ] %2 = icmp slt i32 %i.0, %n br i1 %2, label %3, label %9; <label>:3 %4 = call i32 @add(i32 10, i32 20) %5 = call i32 @add(i32 %sum.0, i32 %i.0) %6 = call i32 @add(i32 %5, i32 %4) br label %7; <label>:7 %8 = add i32 %i.0, 1 br label %1; <label>:9 ret i32 %sum.0}

clang -emit-llvm -S inline.copt inline.ll -mem2reg -S

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Inline + Propagationdefine i32 @add(i32 %a, i32 %b) { %1 = add i32 %a, %b ret i32 %1}

define i32 @foo(i32 %n) { br label %1; <label>:1 %sum.0 = phi i32 [ 0, %0 ], [ %6, %7 ] %i.0 = phi i32 [ 0, %0 ], [ %8, %7 ] %2 = icmp slt i32 %i.0, %n br i1 %2, label %3, label %9; <label>:3 %4 = call i32 @add(i32 10, i32 20) %5 = call i32 @add(i32 %sum.0, i32 %i.0) %6 = call i32 @add(i32 %5, i32 %4) br label %7; <label>:7 %8 = add i32 %i.0, 1 br label %1; <label>:9 ret i32 %sum.0}

define i32 @foo(i32 %n) { br label %1

; <label>:1 %sum.0 = phi i32 [ 0, %0 ], [ %5, %6 ] %i.0 = phi i32 [ 0, %0 ], [ %7, %6 ] %2 = icmp slt i32 %i.0, %n br i1 %2, label %3, label %8

; <label>:3 %4 = add i32 %sum.0, %i.0 %5 = add i32 %4, 30 br label %6

; <label>:6 %7 = add i32 %i.0, 1 br label %1

; <label>:8 ret i32 %sum.0}

opt inline.ll -mem2reg -inline -S

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DCE

• DCE: Dead Code Elimination,死碼消除 ?

•在經過前面介紹的幾樣最佳化後 , 慢慢的會出現一些冗於的程式碼 , 以及一些明顯永遠不會成立的跳躍條件

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DCEint foo(){ a = 5; if (a > 10) b = 10; else b = 20; return b;}

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int foo(){ a = 5; if (5 > 10) b = 10; else b = 20; return b;}


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int foo(){ a = 5; if (false) b = 10; else b = 20; return b;}


ConstantFolding

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int foo(){ b = 20; return b;}


ConstantFolding

DCE

86




int foo(){ b = 20; return b;}

int foo(){ return 20;}


ConstantFolding

DCEConstantPropagation

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用 LLVM觀察 DCE (1/5)

int foo(){ int a; int b; a = 5; if (a > 10) b = a + 10; else b = a + 20; return b;}

clang -S -emit-llvm dce.c

define i32 @foo() {entry: %a = alloca i32 %b = alloca i32 store i32 5, i32* %a %0 = load i32* %a %cmp = icmp sgt i32 %0, 10 br i1 %cmp, label %if.then, label %if.else

if.then: %1 = load i32* %a %add = add i32 %1, 10 store i32 %add, i32* %b br label %if.end

if.else: %2 = load i32* %a %add1 = add i32 %2, 20 store i32 %add1, i32* %b br label %if.end

if.end: %3 = load i32* %b ret i32 %3}

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opt dce.c -mem2reg -S

define i32 @foo() {entry: %a = alloca i32 %b = alloca i32 store i32 5, i32* %a %0 = load i32* %a %cmp = icmp sgt i32 %0, 10 br i1 %cmp, label %if.then, label %if.else

if.then: %1 = load i32* %a %add = add i32 %1, 10 store i32 %add, i32* %b br label %if.end

if.else: %2 = load i32* %a %add1 = add i32 %2, 20 store i32 %add1, i32* %b br label %if.end

if.end: %3 = load i32* %b ret i32 %3}

define i32 @foo() {entry: %cmp = icmp sgt i32 5, 10 br i1 %cmp, label %if.then, label %if.else

if.then: %add = add i32 5, 10 br label %if.end

if.else: %add1 = add i32 5, 20 br label %if.end

if.end: %b.0 = phi i32 [ %add, %if.then ], [ %add1, %if.else ] ret i32 %b.0}

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opt dce.ll -mem2reg -constprop -S




if.end: %if.else, %if.then %b.0 = phi i32 [ %add, %if.then ], [ %add1, %if.else ] ret i32 %b.0}

-constprop

define i32 @foo() {entry: br i1 false, label %if.then, label %if.else

if.then: br label %if.end

if.else: br label %if.end

if.end: %b.0 = phi i32 [ 15, %if.then ], [ 25, %if.else ] ret i32 %b.0}

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opt dce.ll -mem2reg -constprop -dce -S

-dce









91


-dce









看起來好像沒變化 ??opt dce.ll -mem2reg -constprop -dce -S

92


-dce









看起來好像沒變化 ??LLVM 將 CFG 化簡部份交給 -simplifycfg pass

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opt dce.ll -mem2reg -constprop -simplifycfg -S

-simplifycfg





define i32 @foo() {entry: ret i32 25}

94

用 LLVM觀察 DCE - 2 (1/2)

opt dce.ll -mem2reg -simplifycfg -S

-simplifycfg

define i32 @foo() {entry: %cmp = icmp sgt i32 5, 10 %add = add i32 5, 10 %add1 = add i32 5, 20 %b.0 = select i1 %cmp, i32 %add, i32 %add1 ret i32 %b.0}




if.end: %if.else, %if.then %b.0 = phi i32 [ %add, %if.then ], [ %add1, %if.else ] ret i32 %b.0}

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用 LLVM觀察 DCE - 2 (2/2)

opt dce.ll -mem2reg -simplifycfg -constprop -S

-constprop

define i32 @foo() {entry: %cmp = icmp sgt i32 5, 10 %add = add i32 5, 10 %add1 = add i32 5, 20 %b.0 = select i1 %cmp, i32 %add, i32 %add1 ret i32 %b.0}


96

CSE

• CSE:Common subexpression elimination– 把可以共用的部份共用 !

97

CSE

a = b * c + g;d = b * c * e;

t = b * c;a = t + g;d = t * e;

98

用 LLVM觀察 CSE (1/2)

define i32 @foo(i32 %b, i32 %c, i32 %g, i32 %e) {entry: %mul = mul i32 %b, %c %add = add i32 %mul, %g %mul1 = mul i32 %b, %c %mul2 = mul i32 %mul1, %e %add3 = add i32 %add, %mul2 ret i32 %add3}

int foo(int b, int c, int g, int e){ int a = b * c + g; int d = b * c * e; return a + d;}

clang -emit-llvm -S cse.copt cse.ll -mem2reg -S

99

用 LLVM觀察 CSE (2/2)

define i32 @foo(i32 %b, i32 %c, i32 %g, i32 %e) {entry: %mul = mul i32 %b, %c %add = add i32 %mul, %g %mul1 = mul i32 %b, %c %mul2 = mul i32 %mul1, %e %add3 = add i32 %add, %mul2 ret i32 %add3}

opt cse.ll -mem2reg -early-cse -S

define i32 @foo(i32 %b, i32 %c, i32 %g, i32 %e) {entry: %mul = mul i32 %b, %c %add = add i32 %mul, %g %mul2 = mul i32 %mul, %e %add3 = add i32 %add, %mul2 ret i32 %add3}

-early-cse

100

Loop Unroll

• Loop Unroll:迴圈展開– 跳躍指令在大多數架構下比一般運算指令貴– 展開後 Loop index 可能從變數變成常數

sum = 0;for (i = 0; i < 3; ++i) sum = sum + i

sum = 0;sum = sum + 0sum = sum + 1sum = sum + 2

101

用 LLVM觀察 Loop Unroll (1/8)

int add(int a, int b){ return a + b;}int foo(){ int sum = 0; int i; for (i = 0; i < 3; ++i) sum = add(sum, i); return sum;}

clang -emit-llvm -S for.copt for.ll -mem2reg -S

define i32 @add(i32 %a, i32 %b) {entry: %add = add i32 %a, %b ret i32 %add}

define i32 @foo() {entry: br label %for.condfor.cond: %i.0 = phi i32 [ 0, %entry ], [ %inc, %for.inc ] %sum.0 = phi i32 [ 0, %entry ], [ %call, %for.inc ] %cmp = icmp slt i32 %i.0, 3 br i1 %cmp, label %for.body, label %for.endfor.body: %call = call i32 @add(i32 %sum.0, i32 %i.0) br label %for.incfor.inc: %inc = add i32 %i.0, 1 br label %for.condfor.end: ret i32 %sum.0}

102


opt for.ll -mem2reg -loop-unroll -S


define i32 @foo() {entry: br label %for.condfor.cond: %i.0 = phi i32 [ 0, %entry ], [ %inc, %for.inc ] %sum.0 = phi i32 [ 0, %entry ], [ %call, %for.inc ] %cmp = icmp slt i32 %i.0, 3 br i1 %cmp, label %for.body, label %for.endfor.body: %call = call i32 @add(i32 %sum.0, i32 %i.0) br label %for.incfor.inc: %inc = add i32 %i.0, 1 br label %for.condfor.end: %sum.0.lcssa = phi i32 [ %sum.0, %for.cond ] ret i32 %sum.0.lcssa}

-loop-unroll

103


opt for.ll -mem2reg -loop-unroll -S


define i32 @foo() {entry: br label %for.condfor.cond: %i.0 = phi i32 [ 0, %entry ], [ %inc, %for.inc ] %sum.0 = phi i32 [ 0, %entry ], [ %call, %for.inc ] %cmp = icmp slt i32 %i.0, 3 br i1 %cmp, label %for.body, label %for.endfor.body: %call = call i32 @add(i32 %sum.0, i32 %i.0) br label %for.incfor.inc: %inc = add i32 %i.0, 1 br label %for.condfor.end: %sum.0.lcssa = phi i32 [ %sum.0, %for.cond ] ret i32 %sum.0.lcssa}

似乎 Unroll 不開 ????

-loop-unroll

104


opt for.ll -mem2reg -loop-unroll -S -debug


$ opt -mem2reg -S for.ll -loop-unroll -debugArgs: opt -mem2reg -S for.ll -loop-unroll -debug Loop Unroll: F[foo] Loop %for.cond Loop Size = 8 Can't unroll; loop not terminated by a conditional branch.

跟你抱怨這個 Loop,Loop Unroll Pass 認不得 !?

-loop-unroll-debug

105


opt for.ll -mem2reg -loop-rotate -S


define i32 @foo() {entry: br label %for.body

for.body: %sum.02 = phi i32 [ 0, %entry ], [ %call, %for.inc ] %i.01 = phi i32 [ 0, %entry ], [ %inc, %for.inc ] %call = call i32 @add(i32 %sum.02, i32 %i.01) br label %for.inc

for.inc: %inc = add i32 %i.01, 1 %cmp = icmp slt i32 %inc, 3 br i1 %cmp, label %for.body, label %for.end

for.end: %sum.0.lcssa = phi i32 [ %call, %for.inc ] ret i32 %sum.0.lcssa}

翻轉吧！迴圈！

-loop-rorate

106


opt for.ll -mem2reg -view-cfg -loop-rotate -view-cfg -S翻轉吧！迴圈！

-loop-rorate

107


opt for.ll -mem2reg -loop-rotate -loop-unroll -view-cfg -S

-loop-unroll

108


opt for.ll -mem2reg -loop-rotate -loop-unroll -simplifycfg -view-cfg -S

-simplifycfg

define i32 @foo() {entry: br label %for.body

for.body: %call = call i32 @add(i32 0, i32 0) br label %for.inc

for.inc: %call.1 = call i32 @add(i32 %call, i32 1) br label %for.inc.1

for.inc.1: %call.2 = call i32 @add(i32 %call.1, i32 2) br label %for.inc.2

for.inc.2: ret i32 %call.2}

define i32 @foo() {entry: %call = call i32 @add(i32 0, i32 0) %call.1 = call i32 @add(i32 %call, i32 1) %call.2 = call i32 @add(i32 %call.1, i32 2) ret i32 %call.2}

109


opt for.ll -mem2reg -loop-rotate -loop-unroll -simplifycfg \ -inline -constprop -S

-inline



define i32 @foo() {entry: %add.i = add i32 1, 2 ret i32 %add.i}

110


opt for.ll -mem2reg -loop-rotate -loop-unroll -simplifycfg \ -inline -constprop -S

-inline



define i32 @foo() {entry: %add.i = add i32 1, 2 ret i32 %add.i}


-constprop

111

Compiler Optimization

•編譯器不同最佳化之間可以交互作用

•順序也會影響最佳化結果

112

LLVM

•透過 opt -help 可以看到

114

Overview of GCC Optimization Pass$ gcc a.c -fdump-tree-all -fdump-rtl-all -O3$ ls a.c.*a.c.001t.tu a.c.059t.forwprop2 a.c.093t.sink a.c.138t.copyrename4 a.c.204r.outof_cfglayouta.c.003t.original a.c.060t.objsz1 a.c.096t.loop a.c.139t.crited2 a.c.205r.split1a.c.004t.gimple a.c.061t.alias a.c.097t.loopinit a.c.141t.uncprop1 a.c.206r.subreg2a.c.006t.omplower a.c.062t.retslot a.c.098t.lim1 a.c.142t.local-pure-const2 a.c.208r.mode_swa.c.007t.lower a.c.063t.fre2 a.c.099t.copyprop5 a.c.168t.nrv a.c.209r.asmconsa.c.010t.eh a.c.064t.copyprop3 a.c.100t.dceloop1 a.c.169t.optimized a.c.213r.iraa.c.011t.cfg a.c.065t.mergephi2 a.c.101t.unswitch a.c.170r.expand a.c.214r.reloada.c.015t.ssa a.c.066t.vrp1 a.c.102t.sccp a.c.171r.vregs a.c.215r.postreloada.c.017t.inline_param1 a.c.067t.dce1 a.c.104t.ldist a.c.172r.into_cfglayout a.c.216r.gcse2a.c.018t.einline a.c.068t.cdce a.c.105t.copyprop6 a.c.173r.jump a.c.217r.split2a.c.019t.early_optimizations a.c.069t.cselim a.c.111t.ivcanon a.c.174r.subreg1 a.c.218r.reea.c.020t.copyrename1 a.c.070t.ifcombine a.c.113t.ifcvt a.c.175r.dfinit a.c.221r.pro_and_epiloguea.c.021t.ccp1 a.c.071t.phiopt1 a.c.114t.vect a.c.176r.cse1 a.c.222r.dse2a.c.022t.forwprop1 a.c.072t.tailr2 a.c.115t.dceloop3 a.c.177r.fwprop1 a.c.223r.csaa.c.023t.ealias a.c.073t.ch a.c.116t.pcom a.c.178r.cprop1 a.c.224r.jump2a.c.024t.esra a.c.075t.cplxlower1 a.c.117t.cunroll a.c.179r.pre a.c.225r.peephole2a.c.025t.fre1 a.c.076t.sra a.c.118t.slp a.c.181r.cprop2 a.c.226r.ce3a.c.026t.copyprop1 a.c.077t.copyrename3 a.c.120t.ivopts a.c.184r.ce1 a.c.228r.cprop_hardrega.c.027t.mergephi1 a.c.078t.dom1 a.c.121t.lim3 a.c.185r.reginfo a.c.229r.rtl_dcea.c.028t.cddce1 a.c.079t.isolate-paths a.c.122t.loopdone a.c.186r.loop2 a.c.230r.compgotosa.c.029t.eipa_sra a.c.080t.phicprop1 a.c.123t.veclower21 a.c.187r.loop2_init a.c.231r.bbroa.c.030t.tailr1 a.c.081t.dse1 a.c.125t.reassoc2 a.c.188r.loop2_invariant a.c.233r.split4a.c.031t.switchconv a.c.082t.reassoc1 a.c.126t.slsr a.c.189r.loop2_unswitch a.c.234r.sched2a.c.033t.profile_estimate a.c.083t.dce2 a.c.127t.dom2 a.c.192r.loop2_done a.c.236r.stacka.c.034t.local-pure-const1 a.c.084t.forwprop3 a.c.128t.phicprop2 a.c.194r.cprop3 a.c.237r.alignmentsa.c.035t.fnsplit a.c.085t.phiopt2 a.c.129t.vrp2 a.c.195r.cse2 a.c.239r.macha.c.036t.release_ssa a.c.086t.strlen a.c.130t.cddce2 a.c.196r.dse1 a.c.240r.barriersa.c.037t.inline_param2 a.c.087t.ccp3 a.c.132t.dse2 a.c.197r.fwprop2 a.c.244r.shortena.c.054t.copyrename2 a.c.088t.copyprop4 a.c.133t.forwprop4 a.c.199r.init-regs a.c.245r.nothrowa.c.055t.ccp2 a.c.089t.sincos a.c.134t.phiopt3 a.c.200r.ud_dce a.c.246r.dwarf2a.c.056t.copyprop2 a.c.090t.bswap a.c.135t.fab1 a.c.201r.combine a.c.247r.finala.c.057t.cunrolli a.c.091t.crited1 a.c.136t.widening_mul a.c.202r.ce2 a.c.248r.dfinisha.c.058t.phiprop a.c.092t.pre a.c.137t.tailc a.c.203r.bbpart a.c.249t.statistics

共 165 個 pass 的 dump file!

115

Propagation$ gcc a.c -fdump-tree-all -fdump-rtl-all -O3$ ls a.c.*a.c.001t.tu a.c.059t.forwprop2 a.c.093t.sink a.c.138t.copyrename4 a.c.204r.outof_cfglayouta.c.003t.original a.c.060t.objsz1 a.c.096t.loop a.c.139t.crited2 a.c.205r.split1a.c.004t.gimple a.c.061t.alias a.c.097t.loopinit a.c.141t.uncprop1 a.c.206r.subreg2a.c.006t.omplower a.c.062t.retslot a.c.098t.lim1 a.c.142t.local-pure-const2 a.c.208r.mode_swa.c.007t.lower a.c.063t.fre2 a.c.099t.copyprop5 a.c.168t.nrv a.c.209r.asmconsa.c.010t.eh a.c.064t.copyprop3 a.c.100t.dceloop1 a.c.169t.optimized a.c.213r.iraa.c.011t.cfg a.c.065t.mergephi2 a.c.101t.unswitch a.c.170r.expand a.c.214r.reloada.c.015t.ssa a.c.066t.vrp1 a.c.102t.sccp a.c.171r.vregs a.c.215r.postreloada.c.017t.inline_param1 a.c.067t.dce1 a.c.104t.ldist a.c.172r.into_cfglayout a.c.216r.gcse2a.c.018t.einline a.c.068t.cdce a.c.105t.copyprop6 a.c.173r.jump a.c.217r.split2a.c.019t.early_optimizations a.c.069t.cselim a.c.111t.ivcanon a.c.174r.subreg1 a.c.218r.reea.c.020t.copyrename1 a.c.070t.ifcombine a.c.113t.ifcvt a.c.175r.dfinit a.c.221r.pro_and_epiloguea.c.021t.ccp1 a.c.071t.phiopt1 a.c.114t.vect a.c.176r.cse1 a.c.222r.dse2a.c.022t.forwprop1 a.c.072t.tailr2 a.c.115t.dceloop3 a.c.177r.fwprop1 a.c.223r.csaa.c.023t.ealias a.c.073t.ch a.c.116t.pcom a.c.178r.cprop1 a.c.224r.jump2a.c.024t.esra a.c.075t.cplxlower1 a.c.117t.cunroll a.c.179r.pre a.c.225r.peephole2a.c.025t.fre1 a.c.076t.sra a.c.118t.slp a.c.181r.cprop2 a.c.226r.ce3a.c.026t.copyprop1 a.c.077t.copyrename3 a.c.120t.ivopts a.c.184r.ce1 a.c.228r.cprop_hardrega.c.027t.mergephi1 a.c.078t.dom1 a.c.121t.lim3 a.c.185r.reginfo a.c.229r.rtl_dcea.c.028t.cddce1 a.c.079t.isolate-paths a.c.122t.loopdone a.c.186r.loop2 a.c.230r.compgotosa.c.029t.eipa_sra a.c.080t.phicprop1 a.c.123t.veclower21 a.c.187r.loop2_init a.c.231r.bbroa.c.030t.tailr1 a.c.081t.dse1 a.c.125t.reassoc2 a.c.188r.loop2_invariant a.c.233r.split4a.c.031t.switchconv a.c.082t.reassoc1 a.c.126t.slsr a.c.189r.loop2_unswitch a.c.234r.sched2a.c.033t.profile_estimate a.c.083t.dce2 a.c.127t.dom2 a.c.192r.loop2_done a.c.236r.stacka.c.034t.local-pure-const1 a.c.084t.forwprop3 a.c.128t.phicprop2 a.c.194r.cprop3 a.c.237r.alignmentsa.c.035t.fnsplit a.c.085t.phiopt2 a.c.129t.vrp2 a.c.195r.cse2 a.c.239r.macha.c.036t.release_ssa a.c.086t.strlen a.c.130t.cddce2 a.c.196r.dse1 a.c.240r.barriersa.c.037t.inline_param2 a.c.087t.ccp3 a.c.132t.dse2 a.c.197r.fwprop2 a.c.244r.shortena.c.054t.copyrename2 a.c.088t.copyprop4 a.c.133t.forwprop4 a.c.199r.init-regs a.c.245r.nothrowa.c.055t.ccp2 a.c.089t.sincos a.c.134t.phiopt3 a.c.200r.ud_dce a.c.246r.dwarf2a.c.056t.copyprop2 a.c.090t.bswap a.c.135t.fab1 a.c.201r.combine a.c.247r.finala.c.057t.cunrolli a.c.091t.crited1 a.c.136t.widening_mul a.c.202r.ce2 a.c.248r.dfinisha.c.058t.phiprop a.c.092t.pre a.c.137t.tailc a.c.203r.bbpart a.c.249t.statistics

28 / 165 的 pass 在 Propagation!

116

Inline$ gcc a.c -fdump-tree-all -fdump-rtl-all -O3$ ls a.c.*a.c.001t.tu a.c.059t.forwprop2 a.c.093t.sink a.c.138t.copyrename4 a.c.204r.outof_cfglayouta.c.003t.original a.c.060t.objsz1 a.c.096t.loop a.c.139t.crited2 a.c.205r.split1a.c.004t.gimple a.c.061t.alias a.c.097t.loopinit a.c.141t.uncprop1 a.c.206r.subreg2a.c.006t.omplower a.c.062t.retslot a.c.098t.lim1 a.c.142t.local-pure-const2 a.c.208r.mode_swa.c.007t.lower a.c.063t.fre2 a.c.099t.copyprop5 a.c.168t.nrv a.c.209r.asmconsa.c.010t.eh a.c.064t.copyprop3 a.c.100t.dceloop1 a.c.169t.optimized a.c.213r.iraa.c.011t.cfg a.c.065t.mergephi2 a.c.101t.unswitch a.c.170r.expand a.c.214r.reloada.c.015t.ssa a.c.066t.vrp1 a.c.102t.sccp a.c.171r.vregs a.c.215r.postreloada.c.017t.inline_param1 a.c.067t.dce1 a.c.104t.ldist a.c.172r.into_cfglayout a.c.216r.gcse2a.c.018t.einline a.c.068t.cdce a.c.105t.copyprop6 a.c.173r.jump a.c.217r.split2a.c.019t.early_optimizations a.c.069t.cselim a.c.111t.ivcanon a.c.174r.subreg1 a.c.218r.reea.c.020t.copyrename1 a.c.070t.ifcombine a.c.113t.ifcvt a.c.175r.dfinit a.c.221r.pro_and_epiloguea.c.021t.ccp1 a.c.071t.phiopt1 a.c.114t.vect a.c.176r.cse1 a.c.222r.dse2a.c.022t.forwprop1 a.c.072t.tailr2 a.c.115t.dceloop3 a.c.177r.fwprop1 a.c.223r.csaa.c.023t.ealias a.c.073t.ch a.c.116t.pcom a.c.178r.cprop1 a.c.224r.jump2a.c.024t.esra a.c.075t.cplxlower1 a.c.117t.cunroll a.c.179r.pre a.c.225r.peephole2a.c.025t.fre1 a.c.076t.sra a.c.118t.slp a.c.181r.cprop2 a.c.226r.ce3a.c.026t.copyprop1 a.c.077t.copyrename3 a.c.120t.ivopts a.c.184r.ce1 a.c.228r.cprop_hardrega.c.027t.mergephi1 a.c.078t.dom1 a.c.121t.lim3 a.c.185r.reginfo a.c.229r.rtl_dcea.c.028t.cddce1 a.c.079t.isolate-paths a.c.122t.loopdone a.c.186r.loop2 a.c.230r.compgotosa.c.029t.eipa_sra a.c.080t.phicprop1 a.c.123t.veclower21 a.c.187r.loop2_init a.c.231r.bbroa.c.030t.tailr1 a.c.081t.dse1 a.c.125t.reassoc2 a.c.188r.loop2_invariant a.c.233r.split4a.c.031t.switchconv a.c.082t.reassoc1 a.c.126t.slsr a.c.189r.loop2_unswitch a.c.234r.sched2a.c.033t.profile_estimate a.c.083t.dce2 a.c.127t.dom2 a.c.192r.loop2_done a.c.236r.stacka.c.034t.local-pure-const1 a.c.084t.forwprop3 a.c.128t.phicprop2 a.c.194r.cprop3 a.c.237r.alignmentsa.c.035t.fnsplit a.c.085t.phiopt2 a.c.129t.vrp2 a.c.195r.cse2 a.c.239r.macha.c.036t.release_ssa a.c.086t.strlen a.c.130t.cddce2 a.c.196r.dse1 a.c.240r.barriersa.c.037t.inline_param2 a.c.087t.ccp3 a.c.132t.dse2 a.c.197r.fwprop2 a.c.244r.shortena.c.054t.copyrename2 a.c.088t.copyprop4 a.c.133t.forwprop4 a.c.199r.init-regs a.c.245r.nothrowa.c.055t.ccp2 a.c.089t.sincos a.c.134t.phiopt3 a.c.200r.ud_dce a.c.246r.dwarf2a.c.056t.copyprop2 a.c.090t.bswap a.c.135t.fab1 a.c.201r.combine a.c.247r.finala.c.057t.cunrolli a.c.091t.crited1 a.c.136t.widening_mul a.c.202r.ce2 a.c.248r.dfinisha.c.058t.phiprop a.c.092t.pre a.c.137t.tailc a.c.203r.bbpart a.c.249t.statistics

3 / 165 的 pass 在 Inline!

117

DCE$ gcc a.c -fdump-tree-all -fdump-rtl-all -O3$ ls a.c.*a.c.001t.tu a.c.059t.forwprop2 a.c.093t.sink a.c.138t.copyrename4 a.c.204r.outof_cfglayouta.c.003t.original a.c.060t.objsz1 a.c.096t.loop a.c.139t.crited2 a.c.205r.split1a.c.004t.gimple a.c.061t.alias a.c.097t.loopinit a.c.141t.uncprop1 a.c.206r.subreg2a.c.006t.omplower a.c.062t.retslot a.c.098t.lim1 a.c.142t.local-pure-const2 a.c.208r.mode_swa.c.007t.lower a.c.063t.fre2 a.c.099t.copyprop5 a.c.168t.nrv a.c.209r.asmconsa.c.010t.eh a.c.064t.copyprop3 a.c.100t.dceloop1 a.c.169t.optimized a.c.213r.iraa.c.011t.cfg a.c.065t.mergephi2 a.c.101t.unswitch a.c.170r.expand a.c.214r.reloada.c.015t.ssa a.c.066t.vrp1 a.c.102t.sccp a.c.171r.vregs a.c.215r.postreloada.c.017t.inline_param1 a.c.067t.dce1 a.c.104t.ldist a.c.172r.into_cfglayout a.c.216r.gcse2a.c.018t.einline a.c.068t.cdce a.c.105t.copyprop6 a.c.173r.jump a.c.217r.split2a.c.019t.early_optimizations a.c.069t.cselim a.c.111t.ivcanon a.c.174r.subreg1 a.c.218r.reea.c.020t.copyrename1 a.c.070t.ifcombine a.c.113t.ifcvt a.c.175r.dfinit a.c.221r.pro_and_epiloguea.c.021t.ccp1 a.c.071t.phiopt1 a.c.114t.vect a.c.176r.cse1 a.c.222r.dse2a.c.022t.forwprop1 a.c.072t.tailr2 a.c.115t.dceloop3 a.c.177r.fwprop1 a.c.223r.csaa.c.023t.ealias a.c.073t.ch a.c.116t.pcom a.c.178r.cprop1 a.c.224r.jump2a.c.024t.esra a.c.075t.cplxlower1 a.c.117t.cunroll a.c.179r.pre a.c.225r.peephole2a.c.025t.fre1 a.c.076t.sra a.c.118t.slp a.c.181r.cprop2 a.c.226r.ce3a.c.026t.copyprop1 a.c.077t.copyrename3 a.c.120t.ivopts a.c.184r.ce1 a.c.228r.cprop_hardrega.c.027t.mergephi1 a.c.078t.dom1 a.c.121t.lim3 a.c.185r.reginfo a.c.229r.rtl_dcea.c.028t.cddce1 a.c.079t.isolate-paths a.c.122t.loopdone a.c.186r.loop2 a.c.230r.compgotosa.c.029t.eipa_sra a.c.080t.phicprop1 a.c.123t.veclower21 a.c.187r.loop2_init a.c.231r.bbroa.c.030t.tailr1 a.c.081t.dse1 a.c.125t.reassoc2 a.c.188r.loop2_invariant a.c.233r.split4a.c.031t.switchconv a.c.082t.reassoc1 a.c.126t.slsr a.c.189r.loop2_unswitch a.c.234r.sched2a.c.033t.profile_estimate a.c.083t.dce2 a.c.127t.dom2 a.c.192r.loop2_done a.c.236r.stacka.c.034t.local-pure-const1 a.c.084t.forwprop3 a.c.128t.phicprop2 a.c.194r.cprop3 a.c.237r.alignmentsa.c.035t.fnsplit a.c.085t.phiopt2 a.c.129t.vrp2 a.c.195r.cse2 a.c.239r.macha.c.036t.release_ssa a.c.086t.strlen a.c.130t.cddce2 a.c.196r.dse1 a.c.240r.barriersa.c.037t.inline_param2 a.c.087t.ccp3 a.c.132t.dse2 a.c.197r.fwprop2 a.c.244r.shortena.c.054t.copyrename2 a.c.088t.copyprop4 a.c.133t.forwprop4 a.c.199r.init-regs a.c.245r.nothrowa.c.055t.ccp2 a.c.089t.sincos a.c.134t.phiopt3 a.c.200r.ud_dce a.c.246r.dwarf2a.c.056t.copyprop2 a.c.090t.bswap a.c.135t.fab1 a.c.201r.combine a.c.247r.finala.c.057t.cunrolli a.c.091t.crited1 a.c.136t.widening_mul a.c.202r.ce2 a.c.248r.dfinisha.c.058t.phiprop a.c.092t.pre a.c.137t.tailc a.c.203r.bbpart a.c.249t.statistics

13 / 165 的 pass 在 DCE!

118

CSE$ gcc a.c -fdump-tree-all -fdump-rtl-all -O3$ ls a.c.*a.c.001t.tu a.c.059t.forwprop2 a.c.093t.sink a.c.138t.copyrename4 a.c.204r.outof_cfglayouta.c.003t.original a.c.060t.objsz1 a.c.096t.loop a.c.139t.crited2 a.c.205r.split1a.c.004t.gimple a.c.061t.alias a.c.097t.loopinit a.c.141t.uncprop1 a.c.206r.subreg2a.c.006t.omplower a.c.062t.retslot a.c.098t.lim1 a.c.142t.local-pure-const2 a.c.208r.mode_swa.c.007t.lower a.c.063t.fre2 a.c.099t.copyprop5 a.c.168t.nrv a.c.209r.asmconsa.c.010t.eh a.c.064t.copyprop3 a.c.100t.dceloop1 a.c.169t.optimized a.c.213r.iraa.c.011t.cfg a.c.065t.mergephi2 a.c.101t.unswitch a.c.170r.expand a.c.214r.reloada.c.015t.ssa a.c.066t.vrp1 a.c.102t.sccp a.c.171r.vregs a.c.215r.postreloada.c.017t.inline_param1 a.c.067t.dce1 a.c.104t.ldist a.c.172r.into_cfglayout a.c.216r.gcse2a.c.018t.einline a.c.068t.cdce a.c.105t.copyprop6 a.c.173r.jump a.c.217r.split2a.c.019t.early_optimizations a.c.069t.cselim a.c.111t.ivcanon a.c.174r.subreg1 a.c.218r.reea.c.020t.copyrename1 a.c.070t.ifcombine a.c.113t.ifcvt a.c.175r.dfinit a.c.221r.pro_and_epiloguea.c.021t.ccp1 a.c.071t.phiopt1 a.c.114t.vect a.c.176r.cse1 a.c.222r.dse2a.c.022t.forwprop1 a.c.072t.tailr2 a.c.115t.dceloop3 a.c.177r.fwprop1 a.c.223r.csaa.c.023t.ealias a.c.073t.ch a.c.116t.pcom a.c.178r.cprop1 a.c.224r.jump2a.c.024t.esra a.c.075t.cplxlower1 a.c.117t.cunroll a.c.179r.pre a.c.225r.peephole2a.c.025t.fre1 a.c.076t.sra a.c.118t.slp a.c.181r.cprop2 a.c.226r.ce3a.c.026t.copyprop1 a.c.077t.copyrename3 a.c.120t.ivopts a.c.184r.ce1 a.c.228r.cprop_hardrega.c.027t.mergephi1 a.c.078t.dom1 a.c.121t.lim3 a.c.185r.reginfo a.c.229r.rtl_dcea.c.028t.cddce1 a.c.079t.isolate-paths a.c.122t.loopdone a.c.186r.loop2 a.c.230r.compgotosa.c.029t.eipa_sra a.c.080t.phicprop1 a.c.123t.veclower21 a.c.187r.loop2_init a.c.231r.bbroa.c.030t.tailr1 a.c.081t.dse1 a.c.125t.reassoc2 a.c.188r.loop2_invariant a.c.233r.split4a.c.031t.switchconv a.c.082t.reassoc1 a.c.126t.slsr a.c.189r.loop2_unswitch a.c.234r.sched2a.c.033t.profile_estimate a.c.083t.dce2 a.c.127t.dom2 a.c.192r.loop2_done a.c.236r.stacka.c.034t.local-pure-const1 a.c.084t.forwprop3 a.c.128t.phicprop2 a.c.194r.cprop3 a.c.237r.alignmentsa.c.035t.fnsplit a.c.085t.phiopt2 a.c.129t.vrp2 a.c.195r.cse2 a.c.239r.macha.c.036t.release_ssa a.c.086t.strlen a.c.130t.cddce2 a.c.196r.dse1 a.c.240r.barriersa.c.037t.inline_param2 a.c.087t.ccp3 a.c.132t.dse2 a.c.197r.fwprop2 a.c.244r.shortena.c.054t.copyrename2 a.c.088t.copyprop4 a.c.133t.forwprop4 a.c.199r.init-regs a.c.245r.nothrowa.c.055t.ccp2 a.c.089t.sincos a.c.134t.phiopt3 a.c.200r.ud_dce a.c.246r.dwarf2a.c.056t.copyprop2 a.c.090t.bswap a.c.135t.fab1 a.c.201r.combine a.c.247r.finala.c.057t.cunrolli a.c.091t.crited1 a.c.136t.widening_mul a.c.202r.ce2 a.c.248r.dfinisha.c.058t.phiprop a.c.092t.pre a.c.137t.tailc a.c.203r.bbpart a.c.249t.statistics

4 / 165 的 pass 在 CSE!

119

Unroll$ gcc a.c -fdump-tree-all -fdump-rtl-all -O3$ ls a.c.*a.c.001t.tu a.c.059t.forwprop2 a.c.093t.sink a.c.138t.copyrename4 a.c.204r.outof_cfglayouta.c.003t.original a.c.060t.objsz1 a.c.096t.loop a.c.139t.crited2 a.c.205r.split1a.c.004t.gimple a.c.061t.alias a.c.097t.loopinit a.c.141t.uncprop1 a.c.206r.subreg2a.c.006t.omplower a.c.062t.retslot a.c.098t.lim1 a.c.142t.local-pure-const2 a.c.208r.mode_swa.c.007t.lower a.c.063t.fre2 a.c.099t.copyprop5 a.c.168t.nrv a.c.209r.asmconsa.c.010t.eh a.c.064t.copyprop3 a.c.100t.dceloop1 a.c.169t.optimized a.c.213r.iraa.c.011t.cfg a.c.065t.mergephi2 a.c.101t.unswitch a.c.170r.expand a.c.214r.reloada.c.015t.ssa a.c.066t.vrp1 a.c.102t.sccp a.c.171r.vregs a.c.215r.postreloada.c.017t.inline_param1 a.c.067t.dce1 a.c.104t.ldist a.c.172r.into_cfglayout a.c.216r.gcse2a.c.018t.einline a.c.068t.cdce a.c.105t.copyprop6 a.c.173r.jump a.c.217r.split2a.c.019t.early_optimizations a.c.069t.cselim a.c.111t.ivcanon a.c.174r.subreg1 a.c.218r.reea.c.020t.copyrename1 a.c.070t.ifcombine a.c.113t.ifcvt a.c.175r.dfinit a.c.221r.pro_and_epiloguea.c.021t.ccp1 a.c.071t.phiopt1 a.c.114t.vect a.c.176r.cse1 a.c.222r.dse2a.c.022t.forwprop1 a.c.072t.tailr2 a.c.115t.dceloop3 a.c.177r.fwprop1 a.c.223r.csaa.c.023t.ealias a.c.073t.ch a.c.116t.pcom a.c.178r.cprop1 a.c.224r.jump2a.c.024t.esra a.c.075t.cplxlower1 a.c.117t.cunroll a.c.179r.pre a.c.225r.peephole2a.c.025t.fre1 a.c.076t.sra a.c.118t.slp a.c.181r.cprop2 a.c.226r.ce3a.c.026t.copyprop1 a.c.077t.copyrename3 a.c.120t.ivopts a.c.184r.ce1 a.c.228r.cprop_hardrega.c.027t.mergephi1 a.c.078t.dom1 a.c.121t.lim3 a.c.185r.reginfo a.c.229r.rtl_dcea.c.028t.cddce1 a.c.079t.isolate-paths a.c.122t.loopdone a.c.186r.loop2 a.c.230r.compgotosa.c.029t.eipa_sra a.c.080t.phicprop1 a.c.123t.veclower21 a.c.187r.loop2_init a.c.231r.bbroa.c.030t.tailr1 a.c.081t.dse1 a.c.125t.reassoc2 a.c.188r.loop2_invariant a.c.233r.split4a.c.031t.switchconv a.c.082t.reassoc1 a.c.126t.slsr a.c.189r.loop2_unswitch a.c.234r.sched2a.c.033t.profile_estimate a.c.083t.dce2 a.c.127t.dom2 a.c.192r.loop2_done a.c.236r.stacka.c.034t.local-pure-const1 a.c.084t.forwprop3 a.c.128t.phicprop2 a.c.194r.cprop3 a.c.237r.alignmentsa.c.035t.fnsplit a.c.085t.phiopt2 a.c.129t.vrp2 a.c.195r.cse2 a.c.239r.macha.c.036t.release_ssa a.c.086t.strlen a.c.130t.cddce2 a.c.196r.dse1 a.c.240r.barriersa.c.037t.inline_param2 a.c.087t.ccp3 a.c.132t.dse2 a.c.197r.fwprop2 a.c.244r.shortena.c.054t.copyrename2 a.c.088t.copyprop4 a.c.133t.forwprop4 a.c.199r.init-regs a.c.245r.nothrowa.c.055t.ccp2 a.c.089t.sincos a.c.134t.phiopt3 a.c.200r.ud_dce a.c.246r.dwarf2a.c.056t.copyprop2 a.c.090t.bswap a.c.135t.fab1 a.c.201r.combine a.c.247r.finala.c.057t.cunrolli a.c.091t.crited1 a.c.136t.widening_mul a.c.202r.ce2 a.c.248r.dfinisha.c.058t.phiprop a.c.092t.pre a.c.137t.tailc a.c.203r.bbpart a.c.249t.statistics

2 / 165 的 pass 在 Unroll!

120

Propagation + DCE + CSE + Inline + Unroll

a.c.001t.tu a.c.059t.forwprop2 a.c.093t.sink a.c.138t.copyrename4 a.c.204r.outof_cfglayouta.c.003t.original a.c.060t.objsz1 a.c.096t.loop a.c.139t.crited2 a.c.205r.split1a.c.004t.gimple a.c.061t.alias a.c.097t.loopinit a.c.141t.uncprop1 a.c.206r.subreg2a.c.006t.omplower a.c.062t.retslot a.c.098t.lim1 a.c.142t.local-pure-const2 a.c.208r.mode_swa.c.007t.lower a.c.063t.fre2 a.c.099t.copyprop5 a.c.168t.nrv a.c.209r.asmconsa.c.010t.eh a.c.064t.copyprop3 a.c.100t.dceloop1 a.c.169t.optimized a.c.213r.iraa.c.011t.cfg a.c.065t.mergephi2 a.c.101t.unswitch a.c.170r.expand a.c.214r.reloada.c.015t.ssa a.c.066t.vrp1 a.c.102t.sccp a.c.171r.vregs a.c.215r.postreloada.c.017t.inline_param1 a.c.067t.dce1 a.c.104t.ldist a.c.172r.into_cfglayout a.c.216r.gcse2a.c.018t.einline a.c.068t.cdce a.c.105t.copyprop6 a.c.173r.jump a.c.217r.split2a.c.019t.early_optimizations a.c.069t.cselim a.c.111t.ivcanon a.c.174r.subreg1 a.c.218r.reea.c.020t.copyrename1 a.c.070t.ifcombine a.c.113t.ifcvt a.c.175r.dfinit a.c.221r.pro_and_epiloguea.c.021t.ccp1 a.c.071t.phiopt1 a.c.114t.vect a.c.176r.cse1 a.c.222r.dse2a.c.022t.forwprop1 a.c.072t.tailr2 a.c.115t.dceloop3 a.c.177r.fwprop1 a.c.223r.csaa.c.023t.ealias a.c.073t.ch a.c.116t.pcom a.c.178r.cprop1 a.c.224r.jump2a.c.024t.esra a.c.075t.cplxlower1 a.c.117t.cunroll a.c.179r.pre a.c.225r.peephole2a.c.025t.fre1 a.c.076t.sra a.c.118t.slp a.c.181r.cprop2 a.c.226r.ce3a.c.026t.copyprop1 a.c.077t.copyrename3 a.c.120t.ivopts a.c.184r.ce1 a.c.228r.cprop_hardrega.c.027t.mergephi1 a.c.078t.dom1 a.c.121t.lim3 a.c.185r.reginfo a.c.229r.rtl_dcea.c.028t.cddce1 a.c.079t.isolate-paths a.c.122t.loopdone a.c.186r.loop2 a.c.230r.compgotosa.c.029t.eipa_sra a.c.080t.phicprop1 a.c.123t.veclower21 a.c.187r.loop2_init a.c.231r.bbroa.c.030t.tailr1 a.c.081t.dse1 a.c.125t.reassoc2 a.c.188r.loop2_invariant a.c.233r.split4a.c.031t.switchconv a.c.082t.reassoc1 a.c.126t.slsr a.c.189r.loop2_unswitch a.c.234r.sched2a.c.033t.profile_estimate a.c.083t.dce2 a.c.127t.dom2 a.c.192r.loop2_done a.c.236r.stacka.c.034t.local-pure-const1 a.c.084t.forwprop3 a.c.128t.phicprop2 a.c.194r.cprop3 a.c.237r.alignmentsa.c.035t.fnsplit a.c.085t.phiopt2 a.c.129t.vrp2 a.c.195r.cse2 a.c.239r.macha.c.036t.release_ssa a.c.086t.strlen a.c.130t.cddce2 a.c.196r.dse1 a.c.240r.barriersa.c.037t.inline_param2 a.c.087t.ccp3 a.c.132t.dse2 a.c.197r.fwprop2 a.c.244r.shortena.c.054t.copyrename2 a.c.088t.copyprop4 a.c.133t.forwprop4 a.c.199r.init-regs a.c.245r.nothrowa.c.055t.ccp2 a.c.089t.sincos a.c.134t.phiopt3 a.c.200r.ud_dce a.c.246r.dwarf2a.c.056t.copyprop2 a.c.090t.bswap a.c.135t.fab1 a.c.201r.combine a.c.247r.finala.c.057t.cunrolli a.c.091t.crited1 a.c.136t.widening_mul a.c.202r.ce2 a.c.248r.dfinisha.c.058t.phiprop a.c.092t.pre a.c.137t.tailc a.c.203r.bbpart a.c.249t.statistics

50 / 165 !

121

Propagation + DCE + CSE + Inline + Unroll

a.c.001t.tu a.c.059t.forwprop2 a.c.093t.sink a.c.138t.copyrename4 a.c.204r.outof_cfglayouta.c.003t.original a.c.060t.objsz1 a.c.096t.loop a.c.139t.crited2 a.c.205r.split1a.c.004t.gimple a.c.061t.alias a.c.097t.loopinit a.c.141t.uncprop1 a.c.206r.subreg2a.c.006t.omplower a.c.062t.retslot a.c.098t.lim1 a.c.142t.local-pure-const2 a.c.208r.mode_swa.c.007t.lower a.c.063t.fre2 a.c.099t.copyprop5 a.c.168t.nrv a.c.209r.asmconsa.c.010t.eh a.c.064t.copyprop3 a.c.100t.dceloop1 a.c.169t.optimized a.c.213r.iraa.c.011t.cfg a.c.065t.mergephi2 a.c.101t.unswitch a.c.170r.expand a.c.214r.reloada.c.015t.ssa a.c.066t.vrp1 a.c.102t.sccp a.c.171r.vregs a.c.215r.postreloada.c.017t.inline_param1 a.c.067t.dce1 a.c.104t.ldist a.c.172r.into_cfglayout a.c.216r.gcse2a.c.018t.einline a.c.068t.cdce a.c.105t.copyprop6 a.c.173r.jump a.c.217r.split2a.c.019t.early_optimizations a.c.069t.cselim a.c.111t.ivcanon a.c.174r.subreg1 a.c.218r.reea.c.020t.copyrename1 a.c.070t.ifcombine a.c.113t.ifcvt a.c.175r.dfinit a.c.221r.pro_and_epiloguea.c.021t.ccp1 a.c.071t.phiopt1 a.c.114t.vect a.c.176r.cse1 a.c.222r.dse2a.c.022t.forwprop1 a.c.072t.tailr2 a.c.115t.dceloop3 a.c.177r.fwprop1 a.c.223r.csaa.c.023t.ealias a.c.073t.ch a.c.116t.pcom a.c.178r.cprop1 a.c.224r.jump2a.c.024t.esra a.c.075t.cplxlower1 a.c.117t.cunroll a.c.179r.pre a.c.225r.peephole2a.c.025t.fre1 a.c.076t.sra a.c.118t.slp a.c.181r.cprop2 a.c.226r.ce3a.c.026t.copyprop1 a.c.077t.copyrename3 a.c.120t.ivopts a.c.184r.ce1 a.c.228r.cprop_hardrega.c.027t.mergephi1 a.c.078t.dom1 a.c.121t.lim3 a.c.185r.reginfo a.c.229r.rtl_dcea.c.028t.cddce1 a.c.079t.isolate-paths a.c.122t.loopdone a.c.186r.loop2 a.c.230r.compgotosa.c.029t.eipa_sra a.c.080t.phicprop1 a.c.123t.veclower21 a.c.187r.loop2_init a.c.231r.bbroa.c.030t.tailr1 a.c.081t.dse1 a.c.125t.reassoc2 a.c.188r.loop2_invariant a.c.233r.split4a.c.031t.switchconv a.c.082t.reassoc1 a.c.126t.slsr a.c.189r.loop2_unswitch a.c.234r.sched2a.c.033t.profile_estimate a.c.083t.dce2 a.c.127t.dom2 a.c.192r.loop2_done a.c.236r.stacka.c.034t.local-pure-const1 a.c.084t.forwprop3 a.c.128t.phicprop2 a.c.194r.cprop3 a.c.237r.alignmentsa.c.035t.fnsplit a.c.085t.phiopt2 a.c.129t.vrp2 a.c.195r.cse2 a.c.239r.macha.c.036t.release_ssa a.c.086t.strlen a.c.130t.cddce2 a.c.196r.dse1 a.c.240r.barriersa.c.037t.inline_param2 a.c.087t.ccp3 a.c.132t.dse2 a.c.197r.fwprop2 a.c.244r.shortena.c.054t.copyrename2 a.c.088t.copyprop4 a.c.133t.forwprop4 a.c.199r.init-regs a.c.245r.nothrowa.c.055t.ccp2 a.c.089t.sincos a.c.134t.phiopt3 a.c.200r.ud_dce a.c.246r.dwarf2a.c.056t.copyprop2 a.c.090t.bswap a.c.135t.fab1 a.c.201r.combine a.c.247r.finala.c.057t.cunrolli a.c.091t.crited1 a.c.136t.widening_mul a.c.202r.ce2 a.c.248r.dfinisha.c.058t.phiprop a.c.092t.pre a.c.137t.tailc a.c.203r.bbpart a.c.249t.statistics

50 / 165 !

聽完這次的分享等於已經略懂約三分之一 GCC惹！！！

122Machine Dependent Compiler Optimization

機器相依的編譯器最佳化

123

Machine Dependent Compiler Optimization

• Register Allocation• Instruction Scheduling• Peephole Optimization

124Advanced Compiler Optimization

高階編譯器最佳化

125

Advanced Compiler Optimization

• Loop Optimization• Inter Procedure Optimization• Auto Vectorization • Auto Parallelization

126

總結

• Compiler Optimization 很有趣 , 但開始玩之前一定要先讀一些基礎理論

• LLVM則是一個相當好的理論與實作的接軌

127

工商時間安第斯山脈工商時間

128

工商時間安第斯山脈

好山好水好無聊準時下班氣氛佳

工商時間

129



Open Source++

工商時間

130



Toolchain 長期徵人中 ~

Open Source++

工商時間

淺談編譯器最佳化技術

Software