[llvm-dev] vrp

[Anastasiya Ruzhanskaya via llvm-dev]

Hello,
I am trying to figure out, what vrp propagation does in llvm. I tried this
program:
#include <stdio.h>

int main() {
        int s = 0;
        int j = 0;
        for (int i = 0; i < 100; i++) {
                j = j+i+1;
                s+=j;
        }
        return (s+j);
}

And got this under optimized version ( I don't want everything to be
eliminated)
define i32 @main() #0 {
entry:
  br label %for.body

for.body:                                         ; preds = %for.body,
%entry
  %i.03 = phi i32 [ 0, %entry ], [ %inc, %for.body ]
  %s.02 = phi i32 [ 0, %entry ], [ %add2, %for.body ]
  %j.01 = phi i32 [ 0, %entry ], [ %add1, %for.body ]
  %add = add nsw i32 %j.01, %i.03
  %add1 = add nsw i32 %add, 1
  %add2 = add nsw i32 %s.02, %add1
  %inc = add nsw i32 %i.03, 1
  %cmp = icmp slt i32 %i.03, 99
  br i1 %cmp, label %for.body, label %for.end

for.end:                                          ; preds = %for.body
  %add3 = add nsw i32 %add2, %add1
  ret i32 %add3
}


the value range pass was not able to determine any size, even of the
induction variable, is it a correct behavior?
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