Revert my re-instated reverted commit, fixes the bootstrap build on x86-64 linux.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60951 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp
index 1dd5026..2b714de 100644
--- a/lib/Analysis/ScalarEvolution.cpp
+++ b/lib/Analysis/ScalarEvolution.cpp
@@ -2924,12 +2924,8 @@
if (!R)
return true;
- if (isSigned) {
- if (SC->getValue()->isOne())
- return R->getValue()->isMaxValue(true);
-
+ if (isSigned)
return true; // XXX: because we don't have an sdiv scev.
- }
// If negative, it wraps around every iteration, but we don't care about that.
APInt S = SC->getValue()->getValue().abs();
@@ -2975,6 +2971,14 @@
// run (m-n)/s times.
SCEVHandle End = RHS;
+ if (!executesAtLeastOnce(L, isSigned, trueWhenEqual,
+ SE.getMinusSCEV(Start, One), RHS)) {
+ // If not, we get the value of the LHS in the first iteration in which
+ // the above condition doesn't hold. This equals to max(m,n).
+ End = isSigned ? SE.getSMaxExpr(RHS, Start)
+ : SE.getUMaxExpr(RHS, Start);
+ }
+
// If the expression is less-than-or-equal to, we need to extend the
// loop by one iteration.
//
@@ -2983,16 +2987,12 @@
// division would equal one, but the loop runs twice putting the
// induction variable at 12.
- if (trueWhenEqual)
- End = SE.getAddExpr(End, One);
-
- if (!executesAtLeastOnce(L, isSigned, trueWhenEqual,
- SE.getMinusSCEV(Start, One), RHS)) {
- // If not, we get the value of the LHS in the first iteration in which
- // the above condition doesn't hold. This equals to max(m,n).
- End = isSigned ? SE.getSMaxExpr(End, Start)
- : SE.getUMaxExpr(End, Start);
- }
+ if (!trueWhenEqual)
+ // (Stride - 1) is correct only because we know it's unsigned.
+ // What we really want is to decrease the magnitude of Stride by one.
+ Start = SE.getMinusSCEV(Start, SE.getMinusSCEV(Stride, One));
+ else
+ Start = SE.getMinusSCEV(Start, Stride);
// Finally, we subtract these two values to get the number of times the
// backedge is executed: max(m,n)-n.