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Make use of getUMinFromMismatchedTypes when computing backedge-taken 

counts for loops with multiple exits, replacing more conservative code
which only handled constants. This is derived from a patch by
Nick Lewycky.

This also fixes llc aborts in ClamAV and others, as
getUMinFromMismatchedTypes takes care of balancing the types before
working with them.

llvm-svn: 73884
This commit is contained in:
Dan Gohman 2009-06-22 15:09:28 +00:00
parent 2bc22305d2
commit ed627385de
1 changed files with 14 additions and 14 deletions
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28
llvm/lib/Analysis/ScalarEvolution.cpp
View File

@ -2958,18 +2958,18 @@ ScalarEvolution::ComputeBackedgeTakenCountFromExitCond(const Loop *L,
if (L->contains(TBB)) {
// Both conditions must be true for the loop to continue executing.
// Choose the less conservative count.
// TODO: Take the minimum of the exact counts.
if (BTI0.Exact == BTI1.Exact)
if (BTI0.Exact == CouldNotCompute)
BECount = BTI1.Exact;
else if (BTI1.Exact == CouldNotCompute)
BECount = BTI0.Exact;
// TODO: Take the minimum of the maximum counts.
else
BECount = getUMinFromMismatchedTypes(BTI0.Exact, BTI1.Exact);
if (BTI0.Max == CouldNotCompute)
MaxBECount = BTI1.Max;
else if (BTI1.Max == CouldNotCompute)
MaxBECount = BTI0.Max;
else if (const SCEVConstant *C0 = dyn_cast<SCEVConstant>(BTI0.Max))
if (const SCEVConstant *C1 = dyn_cast<SCEVConstant>(BTI1.Max))
MaxBECount = getConstant(APIntOps::umin(C0->getValue()->getValue(),
C1->getValue()->getValue()));
else
MaxBECount = getUMinFromMismatchedTypes(BTI0.Max, BTI1.Max);
} else {
// Both conditions must be true for the loop to exit.
assert(L->contains(FBB) && "Loop block has no successor in loop!");
@ -2992,18 +2992,18 @@ ScalarEvolution::ComputeBackedgeTakenCountFromExitCond(const Loop *L,
if (L->contains(FBB)) {
// Both conditions must be false for the loop to continue executing.
// Choose the less conservative count.
// TODO: Take the minimum of the exact counts.
if (BTI0.Exact == BTI1.Exact)
if (BTI0.Exact == CouldNotCompute)
BECount = BTI1.Exact;
else if (BTI1.Exact == CouldNotCompute)
BECount = BTI0.Exact;
// TODO: Take the minimum of the maximum counts.
else
BECount = getUMinFromMismatchedTypes(BTI0.Exact, BTI1.Exact);
if (BTI0.Max == CouldNotCompute)
MaxBECount = BTI1.Max;
else if (BTI1.Max == CouldNotCompute)
MaxBECount = BTI0.Max;
else if (const SCEVConstant *C0 = dyn_cast<SCEVConstant>(BTI0.Max))
if (const SCEVConstant *C1 = dyn_cast<SCEVConstant>(BTI1.Max))
MaxBECount = getConstant(APIntOps::umin(C0->getValue()->getValue(),
C1->getValue()->getValue()));
else
MaxBECount = getUMinFromMismatchedTypes(BTI0.Max, BTI1.Max);
} else {
// Both conditions must be false for the loop to exit.
assert(L->contains(TBB) && "Loop block has no successor in loop!");