[LLVMdev] Optimization of array access

[Michael Smith]

Tried 5 and 50, doesn't seem to make any difference.

-----Original Message-----
From: Eli Friedman [mailto:eli.friedman at gmail.com] 
Sent: Monday, November 21, 2011 1:20 PM
To: Michael Smith
Cc: Cameron Zwarich; llvmdev at cs.uiuc.edu
Subject: Re: [LLVMdev] Optimization of array access

On Mon, Nov 21, 2011 at 1:03 PM, Michael Smith
<Michael.Smith at synopsys.com> wrote:
> Sorry, Dead Store Elimination.

Hmm... does tweaking the value of BlockScanLimit in
MemoryDependenceAnalysis.cpp help?

-Eli

>
>
>
> From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu] On
> Behalf Of Michael Smith
> Sent: Monday, November 21, 2011 12:20 PM
> To: Cameron Zwarich
>
> Cc: llvmdev at cs.uiuc.edu
> Subject: Re: [LLVMdev] Optimization of array access
>
>
>
> Dead Code Elimination. I'm going to try re-working it following some of the
> insights Don Quixote provided.
>
>
>
> From: Cameron Zwarich [mailto:zwarich at apple.com]
> Sent: Monday, November 21, 2011 12:17 PM
> To: Michael Smith
> Cc: llvmdev at cs.uiuc.edu
> Subject: Re: [LLVMdev] Optimization of array access
>
>
>
> Where does the -time-passes option say the time is going?
>
> Sent from my iPhone
>
> On Nov 21, 2011, at 8:58 AM, Michael Smith <Michael.Smith at synopsys.com>
> wrote:
>
> I've attached a 2 examples of patterns for updating an array. They're
> simplified examples of some code generation I'm doing where I need to pass a
> large, unknown number of arguments (ints, doubles, pointers to other
> information) to a function.
>
>
>
> The two patterns are:
>
>                 Stack[0] = 0;
>
>                 Stack[1] = 1;
>
>                 Stack[2] = 42;
>
> And
>
>                 Int I = 0;
>
>                 Stack[i++] = 0;
>
>                 Stack[i++] = 1;
>
>                 Stack[i++] = 42;
>
>
>
> I've found that the optimizer is much faster at handling the 2nd pattern
> than the 1st. With 3000 assignments - as in the examples attached - "opt
> -std-compile-opts -S func1.ll -o func1.opt" takes 10 seconds, while func2.ll
> takes 0.2s. Anyone have any ideas why?
>
>
>
> I've tested with LLVM 2.9, and LLVM 3.0 RC1.
>
>
>
> Regards,
>
> Michael
>
> <opt.zip>
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>
>