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MmioPatterns optimisation #1607

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Original file line number Diff line number Diff line change
Expand Up @@ -182,6 +182,23 @@ public static Bytes16 excision(

public static void updateTemporaryTargetRam(
MmuData mmuData, final long targetLimbOffsetToUpdate, final Bytes16 newLimb) {

int limbStart = (int) (LLARGE * targetLimbOffsetToUpdate);
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Maybe we could add a simple unit test to validate the method?

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Agreed, @letypequividelespoubelles, I will need some help on creating a unit test as we don't have one before. I don't visualize yet the real use case.

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Or maybe @OlivierBBB, as Francois is OOO currently.

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This is needed when a (target) limb is updated in two times by a MMU instructions. It's the case for example for MMU instructions generating *TwoTarget MMIO instructions.
We already have some memory tests that triggers those MMIO inst.

Maybe this is the failing unit tests (not much network at the hospital, can't open the test output), but I guess it's MMIO.ram_excision or MMIO.*_to_ram_two_targets constraints that are failing.

int limbEnd = limbStart + LLARGE;
byte[] originalRam = mmuData.targetRamBytes().toArray();
int sliceSize = Math.max(0, originalRam.length - limbEnd);

int size = limbStart + newLimb.size() + sliceSize;
byte[] updatedRam = new byte[size];
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Here the updated ram size should be the same as the original one ram

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What's this method you're modifying is doing : you just want to modify a 16 bytes limb the midldle of your memory so :

  • you wipe everything before the limb (you could keep it, but as you don't need it anymore, tiu can put 0s instead)
  • you modify your 16 bytes limb
  • you keep unchanged everything that's after the unmodified limb

Not sure of what you're doing, I'm on mobile with low network

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@ahamlat ahamlat Dec 4, 2024

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Here the updated ram size should be the same as the original one ram

In my current implementation, it is the case, but any way, we need to follow this logic. The total size is the sum of the parts' sizes that we're putting together.

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Not sure of what you're doing, I'm on mobile with low network

I'm doing the same work, but this implementation is faster as you can see in the flamegraphs

System.arraycopy(newLimb.toArray(), 0, updatedRam, limbStart, newLimb.size());
if (sliceSize > 0)
System.arraycopy(originalRam, limbEnd, updatedRam, limbStart + newLimb.size(), sliceSize);

mmuData.targetRamBytes(Bytes.wrap(updatedRam));
}

public static void updateTemporaryTargetRam0(
MmuData mmuData, final long targetLimbOffsetToUpdate, final Bytes16 newLimb) {
final Bytes bytesPreLimb =
Bytes.repeat(
(byte) 0,
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2 changes: 1 addition & 1 deletion linea-constraints
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this should not be updated.

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Not sure why it was updated, it changed when I checkout the project. I thought it was expected.

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Just point to latest master of constraint and it'll be ok. The tracer is currently pointing to a commit that disables the MMIO (needed for the release)

Submodule linea-constraints updated 148 files
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