RPCS3/llvm-mirror
1
0
Fork 0
mirror of https://github.com/RPCS3/llvm-mirror.git synced 2025-04-03 08:11:52 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

[SCEV] Swap guards estimation sequence. NFC

Browse Source 
Summary:
Loop unroll spends a lot of time in SCEVs processing in case when a function
contains hundreds of simple 'for' loops with a quite complex arrays indexes like

  for (int i = 0; i < 8; ++i) {
    for (int j = 0; j < 32; ++j) {
      C[j*8+i] = B[j*32+i+128] + A[i*64+128];
    }
  }
  for (int i = 0; i < 8; ++i) {
    for (int j = 0; j < 8; ++j) {
      for (int k = 0; k < 32; ++k) {
        D[k*64+i*8+j] = D[k*64+i*8+j] + E[i+16] * C[k*8+j+256];
      }
    }
  }

The patch improves loop unroll speed since isLoopBackedgeGuardedByCond takes
much less time than isLoopEntryGuardedByCond in the edge case.

Reviewers: skatkov, sanjoy, mkazantsev

Reviewed By: sanjoy

Subscribers: fhahn, hiraditya, javed.absar, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D72929
This commit is contained in:
dfukalov 2020-01-20 16:40:02 +03:00
parent 88f429aed2
commit 95ee08dcc0
1 changed files with 5 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
lib/Analysis/ScalarEvolution.cpp
View File

@ -9222,9 +9222,11 @@ bool ScalarEvolution::isKnownViaInduction(ICmpInst::Predicate Pred,
!isAvailableAtLoopEntry(SplitRHS.first, MDL))
return false;
return isLoopEntryGuardedByCond(MDL, Pred, SplitLHS.first, SplitRHS.first) &&
isLoopBackedgeGuardedByCond(MDL, Pred, SplitLHS.second,
SplitRHS.second);
// It seems backedge guard check is faster than entry one so in some cases
// it can speed up whole estimation by short circuit
return isLoopBackedgeGuardedByCond(MDL, Pred, SplitLHS.second,
SplitRHS.second) &&
isLoopEntryGuardedByCond(MDL, Pred, SplitLHS.first, SplitRHS.first);
}
bool ScalarEvolution::isKnownPredicate(ICmpInst::Predicate Pred,