Move the memoization check for SCEVSignExtendExpr and
SCEVZeroExtendExpr ahead of the most expensive analysis. This
speeds up analysis and helps avoid pathologically bad behavior
on the testcase in PR4534.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75496 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp
index 815a6f2..6a028c1 100644
--- a/lib/Analysis/ScalarEvolution.cpp
+++ b/lib/Analysis/ScalarEvolution.cpp
@@ -772,6 +772,15 @@
if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op))
return getZeroExtendExpr(SZ->getOperand(), Ty);
+ // Before doing any expensive analysis, check to see if we've already
+ // computed a SCEV for this Op and Ty.
+ FoldingSetNodeID ID;
+ ID.AddInteger(scZeroExtend);
+ ID.AddPointer(Op);
+ ID.AddPointer(Ty);
+ void *IP = 0;
+ if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
+
// If the input value is a chrec scev, and we can prove that the value
// did not overflow the old, smaller, value, we can zero extend all of the
// operands (often constants). This allows analysis of something like
@@ -836,11 +845,8 @@
}
}
- FoldingSetNodeID ID;
- ID.AddInteger(scZeroExtend);
- ID.AddPointer(Op);
- ID.AddPointer(Ty);
- void *IP = 0;
+ // The cast wasn't folded; create an explicit cast node.
+ // Recompute the insert position, as it may have been invalidated.
if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
SCEV *S = SCEVAllocator.Allocate<SCEVZeroExtendExpr>();
new (S) SCEVZeroExtendExpr(ID, Op, Ty);
@@ -868,6 +874,15 @@
if (const SCEVSignExtendExpr *SS = dyn_cast<SCEVSignExtendExpr>(Op))
return getSignExtendExpr(SS->getOperand(), Ty);
+ // Before doing any expensive analysis, check to see if we've already
+ // computed a SCEV for this Op and Ty.
+ FoldingSetNodeID ID;
+ ID.AddInteger(scSignExtend);
+ ID.AddPointer(Op);
+ ID.AddPointer(Ty);
+ void *IP = 0;
+ if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
+
// If the input value is a chrec scev, and we can prove that the value
// did not overflow the old, smaller, value, we can sign extend all of the
// operands (often constants). This allows analysis of something like
@@ -916,11 +931,8 @@
}
}
- FoldingSetNodeID ID;
- ID.AddInteger(scSignExtend);
- ID.AddPointer(Op);
- ID.AddPointer(Ty);
- void *IP = 0;
+ // The cast wasn't folded; create an explicit cast node.
+ // Recompute the insert position, as it may have been invalidated.
if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
SCEV *S = SCEVAllocator.Allocate<SCEVSignExtendExpr>();
new (S) SCEVSignExtendExpr(ID, Op, Ty);