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[AggressiveInstCombine] Merge consecutive loads of mixed sizes #129263

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Merged
merged 12 commits into from
Mar 5, 2025
Merged

[AggressiveInstCombine] Merge consecutive loads of mixed sizes #129263

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343b383
[InstCombine] Add pre-commit tests. NFC.
Cancelll Feb 28, 2025
16243e2
[InstCombine] Handle mixsize consecutive loads
Cancelll Feb 28, 2025
35098bf
[InstCombine] Modify the comment accordingly. NFC.
Cancelll Feb 28, 2025
f386a1d
[AggressiveInstCombine] Add more tests. NFC.
Cancelll Mar 2, 2025
3ca730d
[AggressiveInstCombine] Add check for LoadSize2 and remove the power …
Cancelll Mar 2, 2025
f45e2db
[AggressiveInstCombine] Modify the comment accordingly. NFC.
Cancelll Mar 2, 2025
b03986b
[AggressiveInstCombine] Rename two tests to more clearly show the pur…
Cancelll Mar 2, 2025
7c7c8fc
[AggressiveInstCombine] Add more negative tests. NFC.
Cancelll Mar 2, 2025
f1e2914
[AggressiveInstCombine] Check load sizes equal to store sizes.
Cancelll Mar 2, 2025
ad75d16
[AggressiveInstCombine] Address review comments. NFC.
Cancelll Mar 3, 2025
1541a9b
[AggressiveInstCombine] Remove unnecessarily repeated tests. NFC.
Cancelll Mar 3, 2025
79aa2da
[AggressiveInstCombine] Fix the format issue. NFC.
Cancelll Mar 5, 2025
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8 changes: 4 additions & 4 deletions llvm/lib/Transforms/AggressiveInstCombine/AggressiveInstCombine.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -675,14 +675,14 @@ static bool foldLoadsRecursive(Value *V, LoadOps &LOps, const DataLayout &DL,
Load2Ptr->stripAndAccumulateConstantOffsets(DL, Offset2,
/* AllowNonInbounds */ true);

// Verify if both loads have same base pointers and load sizes are same.
// Verify if both loads have same base pointers
uint64_t LoadSize1 = LI1->getType()->getPrimitiveSizeInBits();
uint64_t LoadSize2 = LI2->getType()->getPrimitiveSizeInBits();
if (Load1Ptr != Load2Ptr || LoadSize1 != LoadSize2)
if (Load1Ptr != Load2Ptr)
return false;

// Support Loadsizes greater or equal to 8bits and only power of 2.
if (LoadSize1 < 8 || !isPowerOf2_64(LoadSize1))
// Support Loadsizes greater or equal to 8bits.
if (LoadSize1 < 8 || LoadSize2 < 8)
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@nikic nikic Mar 2, 2025

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I think what you want to check at this point is that typeSizeEqualsStoreSize for both loads. Please make sure that something like i9 plus i23 does not fold.

The sum being a power of two is already covered by the isTypeLegal check (well, or the target has non-pow2 legal integers, in which case there's no reason not to do the fold).

return false;

// Alias Analysis to check for stores b/w the loads.
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