206 lines
		
	
	
		
			6.4 KiB
		
	
	
	
		
			LLVM
		
	
	
	
			
		
		
	
	
			206 lines
		
	
	
		
			6.4 KiB
		
	
	
	
		
			LLVM
		
	
	
	
| ; RUN: opt < %s -analyze -block-freq | FileCheck %s
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| ; RUN: opt < %s -passes='print<block-freq>' -disable-output 2>&1 | FileCheck %s
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| 
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| ; This code contains three loops. One is triple-nested, the
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| ; second is double nested and the third is a single loop. At
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| ; runtime, all three loops execute 1,000,000 times each. We use to
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| ; give different frequencies to each of the loops because loop
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| ; scales were limited to no more than 4,096.
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| ;
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| ; This was penalizing the hotness of the second and third loops
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| ; because BFI was reducing the loop scale for for.cond16 and
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| ; for.cond26 to a max of 4,096.
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| ;
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| ; Without this restriction, all loops are now correctly given the same
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| ; frequency values.
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| ;
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| ; Original C code:
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| ;
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| ;
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| ; int g;
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| ; __attribute__((noinline)) void bar() {
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| ;  g++;
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| ; }
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| ;
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| ; extern int printf(const char*, ...);
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| ;
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| ; int main()
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| ; {
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| ;   int i, j, k;
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| ;
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| ;   g = 0;
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| ;   for (i = 0; i < 100; i++)
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| ;     for (j = 0; j < 100; j++)
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| ;        for (k = 0; k < 100; k++)
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| ;            bar();
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| ;
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| ;   printf ("g = %d\n", g);
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| ;   g = 0;
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| ;
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| ;   for (i = 0; i < 100; i++)
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| ;     for (j = 0; j < 10000; j++)
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| ;         bar();
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| ;
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| ;   printf ("g = %d\n", g);
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| ;   g = 0;
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| ;
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| ;
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| ;   for (i = 0; i < 1000000; i++)
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| ;     bar();
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| ;
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| ;   printf ("g = %d\n", g);
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| ;   g = 0;
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| ; }
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| 
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| @g = common global i32 0, align 4
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| @.str = private unnamed_addr constant [8 x i8] c"g = %d\0A\00", align 1
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| 
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| declare void @bar()
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| declare i32 @printf(i8*, ...)
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| 
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| ; CHECK: Printing analysis {{.*}} for function 'main':
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| ; CHECK-NEXT: block-frequency-info: main
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| define i32 @main() {
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| entry:
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|   %retval = alloca i32, align 4
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|   %i = alloca i32, align 4
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|   %j = alloca i32, align 4
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|   %k = alloca i32, align 4
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|   store i32 0, i32* %retval
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|   store i32 0, i32* @g, align 4
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|   store i32 0, i32* %i, align 4
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|   br label %for.cond
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| 
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| for.cond:                                         ; preds = %for.inc10, %entry
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|   %0 = load i32, i32* %i, align 4
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|   %cmp = icmp slt i32 %0, 100
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|   br i1 %cmp, label %for.body, label %for.end12, !prof !1
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| 
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| for.body:                                         ; preds = %for.cond
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|   store i32 0, i32* %j, align 4
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|   br label %for.cond1
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| 
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| for.cond1:                                        ; preds = %for.inc7, %for.body
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|   %1 = load i32, i32* %j, align 4
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|   %cmp2 = icmp slt i32 %1, 100
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|   br i1 %cmp2, label %for.body3, label %for.end9, !prof !2
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| 
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| for.body3:                                        ; preds = %for.cond1
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|   store i32 0, i32* %k, align 4
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|   br label %for.cond4
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| 
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| for.cond4:                                        ; preds = %for.inc, %for.body3
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|   %2 = load i32, i32* %k, align 4
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|   %cmp5 = icmp slt i32 %2, 100
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|   br i1 %cmp5, label %for.body6, label %for.end, !prof !3
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| 
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| ; CHECK: - for.body6: float = 500000.5, int = 4000004
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| for.body6:                                        ; preds = %for.cond4
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|   call void @bar()
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|   br label %for.inc
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| 
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| for.inc:                                          ; preds = %for.body6
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|   %3 = load i32, i32* %k, align 4
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|   %inc = add nsw i32 %3, 1
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|   store i32 %inc, i32* %k, align 4
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|   br label %for.cond4
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| 
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| for.end:                                          ; preds = %for.cond4
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|   br label %for.inc7
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| 
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| for.inc7:                                         ; preds = %for.end
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|   %4 = load i32, i32* %j, align 4
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|   %inc8 = add nsw i32 %4, 1
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|   store i32 %inc8, i32* %j, align 4
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|   br label %for.cond1
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| 
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| for.end9:                                         ; preds = %for.cond1
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|   br label %for.inc10
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| 
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| for.inc10:                                        ; preds = %for.end9
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|   %5 = load i32, i32* %i, align 4
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|   %inc11 = add nsw i32 %5, 1
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|   store i32 %inc11, i32* %i, align 4
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|   br label %for.cond
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| 
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| for.end12:                                        ; preds = %for.cond
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|   %6 = load i32, i32* @g, align 4
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|   %call = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([8 x i8], [8 x i8]* @.str, i32 0, i32 0), i32 %6)
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|   store i32 0, i32* @g, align 4
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|   store i32 0, i32* %i, align 4
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|   br label %for.cond13
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| 
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| for.cond13:                                       ; preds = %for.inc22, %for.end12
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|   %7 = load i32, i32* %i, align 4
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|   %cmp14 = icmp slt i32 %7, 100
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|   br i1 %cmp14, label %for.body15, label %for.end24, !prof !1
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| 
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| for.body15:                                       ; preds = %for.cond13
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|   store i32 0, i32* %j, align 4
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|   br label %for.cond16
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| 
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| for.cond16:                                       ; preds = %for.inc19, %for.body15
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|   %8 = load i32, i32* %j, align 4
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|   %cmp17 = icmp slt i32 %8, 10000
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|   br i1 %cmp17, label %for.body18, label %for.end21, !prof !4
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| 
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| ; CHECK: - for.body18: float = 499999.9, int = 3999998
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| for.body18:                                       ; preds = %for.cond16
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|   call void @bar()
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|   br label %for.inc19
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| 
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| for.inc19:                                        ; preds = %for.body18
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|   %9 = load i32, i32* %j, align 4
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|   %inc20 = add nsw i32 %9, 1
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|   store i32 %inc20, i32* %j, align 4
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|   br label %for.cond16
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| 
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| for.end21:                                        ; preds = %for.cond16
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|   br label %for.inc22
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| 
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| for.inc22:                                        ; preds = %for.end21
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|   %10 = load i32, i32* %i, align 4
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|   %inc23 = add nsw i32 %10, 1
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|   store i32 %inc23, i32* %i, align 4
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|   br label %for.cond13
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| 
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| for.end24:                                        ; preds = %for.cond13
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|   %11 = load i32, i32* @g, align 4
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|   %call25 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([8 x i8], [8 x i8]* @.str, i32 0, i32 0), i32 %11)
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|   store i32 0, i32* @g, align 4
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|   store i32 0, i32* %i, align 4
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|   br label %for.cond26
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| 
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| for.cond26:                                       ; preds = %for.inc29, %for.end24
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|   %12 = load i32, i32* %i, align 4
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|   %cmp27 = icmp slt i32 %12, 1000000
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|   br i1 %cmp27, label %for.body28, label %for.end31, !prof !5
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| 
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| ; CHECK: - for.body28: float = 499995.2, int = 3999961
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| for.body28:                                       ; preds = %for.cond26
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|   call void @bar()
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|   br label %for.inc29
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| 
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| for.inc29:                                        ; preds = %for.body28
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|   %13 = load i32, i32* %i, align 4
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|   %inc30 = add nsw i32 %13, 1
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|   store i32 %inc30, i32* %i, align 4
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|   br label %for.cond26
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| 
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| for.end31:                                        ; preds = %for.cond26
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|   %14 = load i32, i32* @g, align 4
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|   %call32 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([8 x i8], [8 x i8]* @.str, i32 0, i32 0), i32 %14)
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|   store i32 0, i32* @g, align 4
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|   %15 = load i32, i32* %retval
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|   ret i32 %15
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| }
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| 
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| !llvm.ident = !{!0}
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| 
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| !0 = !{!"clang version 3.7.0 (trunk 232635) (llvm/trunk 232636)"}
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| !1 = !{!"branch_weights", i32 101, i32 2}
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| !2 = !{!"branch_weights", i32 10001, i32 101}
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| !3 = !{!"branch_weights", i32 1000001, i32 10001}
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| !4 = !{!"branch_weights", i32 1000001, i32 101}
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| !5 = !{!"branch_weights", i32 1000001, i32 2}
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