conditional move

[Lukas Stadler]

There's a heuristic in the canonicalization of IfNodes that says that it is only beneficial to create a ConditionalNode if the two values are constant integers or constant longs.
You can see it in IfNode.removeOrMaterializeIf. This restriction on types is AMD64 - specific, and I think we should remove it anyway.
(because the only downside could be that we have to create the if again at a lower level).

The restriction on constants, however, makes sense - because if we need to do work to calculate the values then this work should happen only if we need it.

- Lukas

On Jun 19, 2013, at 3:07 PM, "Deneau, Tom" <tom.deneau at amd.com> wrote:

> Wondering whether anyone knows the reason for the problem below?
> For the HSAIL backend, we would like both to emit conditional moves.
> Is there a backend property that enables this?
> 
> -- Tom
> 
> 
> -----Original Message-----
> From: Deneau, Tom 
> Sent: Friday, May 24, 2013 6:42 PM
> To: 'Doug Simon'; Frost, Gary
> Cc: Lukas Stadler; graal-dev at openjdk.java.net
> Subject: RE: conditional move
> 
> I noticed that this code emits a Conditional Move node
> 
> 	public int test(int a, int b) {
> 		return (a < b ? 1 : 2);
> 	}
> 
> but this one does not
> 	public float test(int a, int b) {
> 		return (a < b ? 1.0f : 2.0f);
> 	}
> 
> -- Tom
> 
> -----Original Message-----
> From: Doug Simon [mailto:doug.simon at oracle.com] 
> Sent: Friday, May 24, 2013 10:28 AM
> To: Frost, Gary
> Cc: Lukas Stadler; Deneau, Tom; graal-dev at openjdk.java.net
> Subject: Re: conditional move
> 
> Yes, because ternaries are compiled by javac as if-statements.
> 
> On May 24, 2013, at 5:17 PM, "Frost, Gary" <Gary.Frost at amd.com> wrote:
> 
>> Presumably, ternaries are good candidates for this. 
>> 
>> boolean isOdd(int i){
>>   boolean odd=((i%2)!=0)?0:1;
>>   return odd;
>> }
>> 
>> -----Original Message-----
>> From: graal-dev-bounces at openjdk.java.net [mailto:graal-dev-bounces at openjdk.java.net] On Behalf Of Lukas Stadler
>> Sent: Friday, May 24, 2013 3:51 AM
>> To: Deneau, Tom
>> Cc: graal-dev at openjdk.java.net
>> Subject: Re: conditional move
>> 
>> The ConditionalNode is most of the time not created by the GraphBuilder directly, but it will appear later when a simple if/then/else is canonicalized.
>> So a simple snippet that boils down to a conditional move could look like this:
>> 
>> public static int testSnippet(int i) {
>> if (i == 0) {
>>   return 1;
>> } else {
>>   return 2;
>> }
>> }
>> 
>> - Lukas
>> 
>> 
>> On May 24, 2013, at 1:04 AM, "Deneau, Tom" <tom.deneau at amd.com> wrote:
>> 
>>> While compiling a larger chunk of code we were handed a 
>>> ConditionalMove node (which we have not implemented yet).  I would 
>>> like to make a smaller test case for this but java patterns that I 
>>> thought would be mapping to conditional move aren't doing so.  What 
>>> would be a typical small test case for generating the ConditionalMove node?
>>> 
>>> -- Tom Deneau
>>> 
>> 
>> 
>> 
> 
> 
>