LLVM DAG中的粘连和链式依赖关系是什么？

我已经决定使用下面的命令

llc -view-sched-dags hello_world.ll

我得到了真正的大图用不同的依赖关系类型生成一个DAG。 “开始使用LLVM核心库”一书中解释说：

黑色箭头意味着数据流的依赖
红色箭头指胶水的依赖
蓝色虚线箭头意味着链依赖性

我清楚地记得，在我的编译器课上谈论数据流依赖关系。但我不记得谈论其他两个。有人可以解释其他依赖关系的含义吗？任何帮助表示赞赏。

hello_world.cpp

#include <stdio.h> 
#include <assert.h> 

int sum(int a, int b) { 
    return a + b; 
} 

int main(int argc, char** argv) { 
    printf("Hello World! %d\n", sum(argc, 1)); 
    return 0; 
}

hello_world.ll

; ModuleID = 'hello_world.cpp' 
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128" 
target triple = "x86_64-unknown-linux-gnu" 

@.str = private unnamed_addr constant [17 x i8] c"Hello World! %d\0A\00", align 1 

; Function Attrs: nounwind uwtable 
define i32 @_Z3sumii(i32 %a, i32 %b) #0 { 
entry: 
    %a.addr = alloca i32, align 4 
    %b.addr = alloca i32, align 4 
    store i32 %a, i32* %a.addr, align 4 
    store i32 %b, i32* %b.addr, align 4 
    %0 = load i32* %a.addr, align 4 
    %1 = load i32* %b.addr, align 4 
    %add = add nsw i32 %0, %1 
    ret i32 %add 
} 

; Function Attrs: uwtable 
define i32 @main(i32 %argc, i8** %argv) #1 { 
entry: 
    %retval = alloca i32, align 4 
    %argc.addr = alloca i32, align 4 
    %argv.addr = alloca i8**, align 8 
    store i32 0, i32* %retval 
    store i32 %argc, i32* %argc.addr, align 4 
    store i8** %argv, i8*** %argv.addr, align 8 
    %0 = load i32* %argc.addr, align 4 
    %call = call i32 @_Z3sumii(i32 %0, i32 1) 
    %call1 = call i32 (i8*, ...)* @printf(i8* getelementptr inbounds ([17 x i8]* @.str, i32 0, i32 0), i32 %call) 
    ret i32 0 
} 

declare i32 @printf(i8*, ...) #2 

attributes #0 = { nounwind uwtable "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" } 
attributes #1 = { uwtable "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" } 
attributes #2 = { "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" } 

!llvm.ident = !{!0} 

!0 = metadata !{metadata !"clang version 3.5.0 "}

hello_world.main.jpg