[LLVMdev] problem with loopinfo

[Wei Jiang]

I did run the indvars pass, but it seemed that it didn't work.
-Wei
----- Original Message ----- 
From: "Chris Lattner" <sabre at nondot.org>
To: "LLVM Developers Mailing List" <llvmdev at cs.uiuc.edu>
Sent: Thursday, June 15, 2006 3:35 PM
Subject: Re: [LLVMdev] problem with loopinfo


> On Thu, 15 Jun 2006, Wei Jiang wrote:
>> hi,
>>    The loopinfo pass failed to recognize the Tripcount of a simple 
>> program constructed by me, can you help me to figure out why this 
>> happened? Thanks.
>>    The C program and corresponding .ll files are shown below. I used 
>> llvm1.7 to develop my own pass, and want to use the loop information.
>
> What passes are you running before your pass?  trip count information is 
> generally only available after the "indvars" pass runs.
>
> -Chris
>
>> Test.c:
>> #include "stdio.h"
>> #define N 40
>> void func1() {
>>  int a[N];
>>  int i,j;
>>  for (i=0; i<N; i++) {
>>      if (i==0)
>>        a[i] = i*N;
>>      else
>>        a[i] = i*i;
>>  }
>> }
>>
>> Test.ll:
>> void %func1() {
>> entry:
>>        %a = alloca [40 x int]          ; <[40 x int]*> [#uses=1]
>>        br label %no_exit
>>
>> no_exit:                ; preds = %else, %then, %entry
>>        %i.0.0 = phi int [ 0, %entry ], [ %inc9, %then ], [ %inc, %else ] 
>> ; <int> [#uses=7]
>>        %tmp.4 = seteq int %i.0.0, 0            ; <bool> [#uses=1]
>>        %tmp.7 = getelementptr [40 x int]* %a, int 0, int %i.0.0 
>> ; <int*> [#uses=2]
>>        br bool %tmp.4, label %then, label %else
>>
>> then:           ; preds = %no_exit
>>        %tmp.9 = mul int %i.0.0, 40             ; <int> [#uses=1]
>>        store int %tmp.9, int* %tmp.7
>>        %inc9 = add int %i.0.0, 1               ; <int> [#uses=2]
>>        %tmp.112 = setlt int %inc9, 40          ; <bool> [#uses=1]
>>        br bool %tmp.112, label %no_exit, label %return
>>
>> else:           ; preds = %no_exit
>>        %tmp.14 = mul int %i.0.0, %i.0.0                ; <int> [#uses=1]
>>        store int %tmp.14, int* %tmp.7
>>        %inc = add int %i.0.0, 1                ; <int> [#uses=2]
>>        %tmp.1 = setlt int %inc, 40             ; <bool> [#uses=1]
>>        br bool %tmp.1, label %no_exit, label %return
>>
>> return:         ; preds = %else, %then
>>        ret void
>> }
>>
>
> -Chris
>
> -- 
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