[instcombine] miscompilation of setcc or setcc in some cases

[markus-oberhumer]

Bugzilla Link	548
Resolution	FIXED
Resolved on	Mar 06, 2010 13:58
Version	1.4
OS	All

Extended Description

The current (20050418) CVS version miscompiles this small program.

int foo(int s) {
return (s == -1 || s > 0);
}

int bar(void) {
return foo(-1);
}

[lattner]

hrm, that would be bad. How can I reproduce this? Using:

llvm-gcc t.c -c -o - | llvm-dis

compiles bar into "ret int 1", which is correct. What are you using?

-Chris

[markus-oberhumer]

I get this:

/* Function Bodies */

int foo(int l1_s) {

return ((int )(l1_s > -1));
}

int bar(void) {

return 0;
}

[lattner]

What command are you using? I definitely do not get that.

-Chris

[lattner]

ah, by changing the program a bit I was able to trigger this problem.

I'm on it.

-Chris

[lattner]

This looks like a bug in a patch that went in Sep 28, 2004. Thanks a lot for
bringing this to my attention. Here's the fix:

http://mail.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20050418/025474.html

-Chris

[markus-oberhumer]

Many thanks for the quick fix. Still I wonder how this could get unnoticed for
such a long time...

~Markus