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Step #3 to improving trip count analysis: If we fold

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a + {b,+,stride} into {a+b,+,stride}  (because a is LIV),
then the resultant AddRec is NUW/NSW if the client says it
is.

llvm-svn: 123133
This commit is contained in:
Chris Lattner 2011-01-09 22:31:26 +00:00
parent b6a67a9068
commit 4efcd276de
1 changed files with 8 additions and 4 deletions
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12
lib/Analysis/ScalarEvolution.cpp
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@ -1560,10 +1560,14 @@ const SCEV *ScalarEvolution::getAddExpr(SmallVectorImpl<const SCEV *> &Ops,
AddRecOps[0] = getAddExpr(LIOps);
// Build the new addrec. Propagate the NUW and NSW flags if both the
// outer add and the inner addrec are guaranteed to have no overflow.
const SCEV *NewRec = getAddRecExpr(AddRecOps, AddRecLoop,
HasNUW && AddRec->hasNoUnsignedWrap(),
HasNSW && AddRec->hasNoSignedWrap());
// outer add and the inner addrec are guaranteed to have no overflow or if
// there is no outer part.
if (Ops.size() != 1) {
HasNUW &= AddRec->hasNoUnsignedWrap();
HasNSW &= AddRec->hasNoSignedWrap();
}
const SCEV *NewRec = getAddRecExpr(AddRecOps, AddRecLoop, HasNUW, HasNSW);
// If all of the other operands were loop invariant, we are done.
if (Ops.size() == 1) return NewRec;