6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2025-07-24 22:24:54 +00:00
Code Issues Projects Releases Wiki Activity

Add one more case we compute a max trip count.

Browse Source 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@140979 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nick Lewycky
2011-10-03 01:03:57 +00:00
parent 82f131a017
commit 8fde4f5842
2 changed files with 36 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

12
lib/Analysis/ScalarEvolution.cpp
View File

@@ -5119,7 +5119,7 @@ SolveQuadraticEquation(const SCEVAddRecExpr *AddRec, ScalarEvolution &SE) {
// Compute the two solutions for the quadratic formula.
// The divisions must be performed as signed divisions.
APInt NegB(-B);
APInt TwoA( A << 1 );
APInt TwoA(A << 1);
if (TwoA.isMinValue()) {
const SCEV *CNC = SE.getCouldNotCompute();
return std::make_pair(CNC, CNC);
@@ -5134,7 +5134,7 @@ SolveQuadraticEquation(const SCEVAddRecExpr *AddRec, ScalarEvolution &SE) {
return std::make_pair(SE.getConstant(Solution1),
SE.getConstant(Solution2));
} // end APIntOps namespace
} // end APIntOps namespace
}
/// HowFarToZero - Return the number of times a backedge comparing the specified
@@ -5228,8 +5228,12 @@ ScalarEvolution::HowFarToZero(const SCEV *V, const Loop *L) {
// Handle unitary steps, which cannot wraparound.
// 1*N = -Start; -1*N = Start (mod 2^BW), so:
// N = Distance (as unsigned)
if (StepC->getValue()->equalsInt(1) || StepC->getValue()->isAllOnesValue())
return Distance;
if (StepC->getValue()->equalsInt(1) || StepC->getValue()->isAllOnesValue()) {
ConstantRange CR = getUnsignedRange(Start);
const SCEV *MaxBECount = getConstant(CountDown ? CR.getUnsignedMax()
: ~CR.getUnsignedMin());
return ExitLimit(Distance, MaxBECount);
}
// If the recurrence is known not to wraparound, unsigned divide computes the
// back edge count. We know that the value will either become zero (and thus