llvm dev - Feb 2015 - [LLVMdev] Eliminating redundant loads

On 23 February 2015 at 11:22, David Jones <djones at xtreme-eda.com>
wrote:
> You have not installed the DataLayout in the Module, as I had pointed out
> earlier.
>
Hi David,

I reported earlier that I tried this but there was no improvement.
Well I ran another test to be sure. The results are below. As you can
see the loads are still present.

; ModuleID = 'ravi_module_ravif1'
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-pc-windows-msvc-elf"

%0 = type { %ravi.TValue*, i32*, i64 }

....

  %6 = load %ravi.TValue** %base
  %srcvalue = getelementptr inbounds %ravi.TValue* %5, i32 0, i32 0, i32 0
  %destvalue = getelementptr inbounds %ravi.TValue* %6, i32 0, i32 0, i32 0
  %7 = load double* %srcvalue
  store double %7, double* %destvalue
  %srctype = getelementptr inbounds %ravi.TValue* %5, i32 0, i32 1
  %desttype = getelementptr inbounds %ravi.TValue* %6, i32 0, i32 1
  %8 = load i32* %srctype
  store i32 %8, i32* %desttype
  %9 = load %ravi.TValue** %base
  %10 = getelementptr inbounds %ravi.TValue* %9, i32 1
  %11 = getelementptr inbounds %ravi.TValue* %5, i32 1
  %srcvalue1 = getelementptr inbounds %ravi.TValue* %11, i32 0, i32 0, i32 0
  %destvalue2 = getelementptr inbounds %ravi.TValue* %10, i32 0, i32 0, i32 0
  %12 = load double* %srcvalue1
  store double %12, double* %destvalue2
  %srctype3 = getelementptr inbounds %ravi.TValue* %11, i32 0, i32 1
  %desttype4 = getelementptr inbounds %ravi.TValue* %10, i32 0, i32 1
  %13 = load i32* %srctype3
  store i32 %13, i32* %desttype4
  %14 = load %ravi.TValue** %base
  %15 = getelementptr inbounds %ravi.TValue* %14, i32 2
  %16 = getelementptr inbounds %ravi.TValue* %5, i32 2
  %srcvalue5 = getelementptr inbounds %ravi.TValue* %16, i32 0, i32 0, i32 0
  %destvalue6 = getelementptr inbounds %ravi.TValue* %15, i32 0, i32 0, i32 0
  %17 = load double* %srcvalue5
  store double %17, double* %destvalue6
  %srctype7 = getelementptr inbounds %ravi.TValue* %16, i32 0, i32 1
  %desttype8 = getelementptr inbounds %ravi.TValue* %15, i32 0, i32 1
  %18 = load i32* %srctype7
  store i32 %18, i32* %desttype8
  %19 = load %ravi.TValue** %base

Hi,

Is it the case that I need to generate tbaa metadata and associate
with store/load instructions? If so, is there any doc on how to get
started with this?

Thanks and Regards
Dibyendu

Hi Dibyendu,

Aliasing might pose a problem in your case.
I didn't look into the depth of your code.
But, you could try running -tbaa optimization pass with opt.
You should appropriate metadata information generated for this.

There are other optimization routines as well. Try exploring them.

Regards,
Kamal Sharma


On Mon, Feb 23, 2015 at 2:18 PM, Dibyendu Majumdar <mobile at
majumdar.org.uk>
wrote:
> Hi,
>
> Is it the case that I need to generate tbaa metadata and associate
> with store/load instructions? If so, is there any doc on how to get
> started with this?
>
> Thanks and Regards
> Dibyendu
>
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