It's incorrect. But often a very useful optimization, since code that loops over sizeof(X) is rather common, and this speeds it up a factor of 2 or more.

We need dependency analysis.

/ Per Hedbor ()

Previous text:

2003-03-20 10:26: Subject: for-loop optimization

---

I just wrote a for-loop like this:

string foo="gazonk";

for(int i=0;i<sizeof(foo);i++) {

... do stuff ...

if (sometimes) foo = foo[1..];

... do stuff ...

}

The problem I discoverd was that when the length of foo is changed, the loop still tries to loop over the original length of foo. The problem dissappeard when I replace sizeof(foo) with a variable and update it when changing the length of foo.

Is this the correct behaviour or is the optimizer doing more than it should here?

/ Marcus Agehall (Trådlös)

I don't believe you.

$ cat bug_l9908261.pike int main(int argc, array(string) argv) { string foo="gazonk"; int i;

for(i=0;i<sizeof(foo);i++) { if (i%2) { foo = foo[1..]; } } werror("i:%O\n", i); } $ ./pike -mmaster.pike bug_l9908261.pike i:4

Please provide an example that actually triggers the alleged bug.

/ Henrik Grubbström (Lysator)

Previous text:

2003-03-20 10:26: Subject: for-loop optimization

---

I just wrote a for-loop like this:

string foo="gazonk";

for(int i=0;i<sizeof(foo);i++) {

... do stuff ...

if (sometimes) foo = foo[1..];

... do stuff ...

}

The problem I discoverd was that when the length of foo is changed, the loop still tries to loop over the original length of foo. The problem dissappeard when I replace sizeof(foo) with a variable and update it when changing the length of foo.

Is this the correct behaviour or is the optimizer doing more than it should here?

/ Marcus Agehall (Trådlös)

Pike version?

/ Johan Sundström (folkskådare)

Previous text:

2003-03-20 10:26: Subject: for-loop optimization

---

I just wrote a for-loop like this:

string foo="gazonk";

for(int i=0;i<sizeof(foo);i++) {

... do stuff ...

if (sometimes) foo = foo[1..];

... do stuff ...

}

The problem I discoverd was that when the length of foo is changed, the loop still tries to loop over the original length of foo. The problem dissappeard when I replace sizeof(foo) with a variable and update it when changing the length of foo.

Is this the correct behaviour or is the optimizer doing more than it should here?

/ Marcus Agehall (Trådlös)