if_hand.ll

; ModuleID = 'if.c'
source_filename = "if.c"
;target information,copy from gcd_array.ll
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"


;define main function
define dso_local i32 @main() #0 {
	;the first basic block
	;Here is some boring but meaningful experience
	;At the beginning of the lab,I thought about the extra variation in
	;the code geneated by clang for a long time
	;After reading the gcd_array.ll generated by clang,I got its' use
	;All in all,the function will move into the basic block especially for returning 
	;a value from every basic block.
	;Maybe we can return a value in different basic blocks,but to make the code clear
	;,we should use this variation to return a value in the same block 
	;define the return variation
	%1=alloca i32
	;define a
	%2=alloca float
	;set initial value of return variation
	store i32 0,i32* %1
	;set a=5.555
	;Learning from the example and the Internet,we have to use the way that float 
	;number stored in the memory to show the 5.555
	store float 0x40163851E0000000,float* %2
	;compare a with 1
	%3=load float,float* %2
	%4=fcmp ugt float %3,1.0
	;if a>1,goto return 233,or skip the action of if
	br i1 %4,label %5,label %6
	
;the second basic block
5:			;preds=%0
	;To be honest,we can just'ret i32 233' and don't 'br'
	;set return value 233 and goto the return
	store i32 233,i32* %1
	br label %7

;the third basic block
6:			;preds=%0
	;set return value 0 and goto the return
	store i32 0,i32* %1
	br label %7

;the forth basic block	
7:			;preds=%5,%6
	;get the return value
	%8=load i32,i32* %1
	;return
	ret i32 %8

}


;other information,copy from gcd_array.ll
attributes #0 = { noinline nounwind optnone uwtable "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "frame-pointer"="all" "less-precise-fpmad"="false" "min-legal-vector-width"="0" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }

!llvm.module.flags = !{!0}
!llvm.ident = !{!1}

!0 = !{i32 1, !"wchar_size", i32 4}
!1 = !{!"clang version 10.0.1 "}