[LLVMdev] Question about IndVarSimplify

[Sorin Baltateanu]

Hi guys,

I am trying to use the indvars pass, but i don't see any changes in the IL
representation.

For this simple function

void init_array(int k)
{
    int A[20];
    for (int i=2; i<10; i++)
        A[i] = 0;
}

i run *clang test-simple.c -S -emit-llvm -o test.il* and i obtain the
following il representation

define void @init_array(i32 %k) nounwind {
entry:
  %k.addr = alloca i32, align 4
  %A = alloca [20 x i32], align 4
  %i = alloca i32, align 4
  store i32 %k, i32* %k.addr, align 4
  store i32 2, i32* %i, align 4
  br label %for.cond

for.cond:                                         ; preds = %for.inc, %entry
  %tmp = load i32* %i, align 4
  %cmp = icmp slt i32 %tmp, 10
  br i1 %cmp, label %for.body, label %for.end

for.body:                                         ; preds = %for.cond
  %tmp1 = load i32* %i, align 4
  %arrayidx = getelementptr inbounds [20 x i32]* %A, i32 0, i32 %tmp1
  store i32 0, i32* %arrayidx, align 4
  br label %for.inc

for.inc:                                          ; preds = %for.body
  %tmp2 = load i32* %i, align 4
  %inc = add nsw i32 %tmp2, 1
  store i32 %inc, i32* %i, align 4
  br label %for.cond

for.end:                                          ; preds = %for.cond
  ret void
}

Running *opt -loop-simplify < test.il -S* gives me the same output, which is
what i would expect.
The problem is that running *opt -indvars < test.il -S* gives, again, the
same output, but i would expect that i starts from 0 and is, eventualy,
defined using a PHYNode.

What it's wrong with what i'm doing?

Thank you.
Have a nice day
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