Hi Kartik,
On Sun, 10 Feb 2013 15:41:17 +0530, Kartik Singhal
<kartiksing...@gmail.com> wrote:
Thanks Richard for pointing out tree-ssa-sccvn.c
On Wed, Feb 6, 2013 at 8:14 PM, Richard Biener
<richard.guent...@gmail.com> wrote:
Well, to ignore SSA form simply treat each SSA name as separate
variable.
You of course need to handle PHI nodes as copies on CFG edges then.
I am not sure if I understood this correctly.
Consider the following example:
if (...)
a_1 = 5;
else if (...)
a_2 = 2;
else
a_3 = 13;
# a_4 = PHI <a_1, a_2, a_3>
return a_4;
Do you mean that I treat a_1, a_2 and a_3 as 3 different variables?
In
this approach, I lose the information that they are actually the same
variables.
Or should I write a mini lexer function to convert the SSA names into
original variable names by removing _1, _2, etc. as suffix from each?
Regarding PHI nodes, I think you mean, I should treat them as
identity
functions, but I am not clear exactly how in the first approach
above.
In second, I can just treat it as a=a.
Richard means that you can treat the above code as
if (...) {
a_1 = 5;
a_4 = a_1;
} else if (...) {
a_2 = 2;
a_4 = a_2;
} else {
a_3 = 13;
a_4 = a_3;
}
return a_4;
The extra code above is "copies on CFG edges".
Andrey
--
Kartik
http://k4rtik.wordpress.com/
