to the RHS. This simple change allows to compute loop iteration count
for loops with condition similar to the one in the testcase (which seems
to be quite common).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@46959
91177308-0d34-0410-b5e6-
96231b3b80d8
// At this point, we would like to compute how many iterations of the
// loop the predicate will return true for these inputs.
- if (isa<SCEVConstant>(LHS) && !isa<SCEVConstant>(RHS)) {
- // If there is a constant, force it into the RHS.
+ if (LHS->isLoopInvariant(L) && !RHS->isLoopInvariant(L)) {
+ // If there is a loop-invariant, force it into the RHS.
std::swap(LHS, RHS);
Cond = ICmpInst::getSwappedPredicate(Cond);
}
--- /dev/null
+; RUN: llvm-as < %s | opt -scalar-evolution -analyze | not grep Unpredictable
+
+define void @foo(i32 %n) {
+entry:
+ br label %header
+header:
+ %i = phi i32 [ 0, %entry ], [ %i.inc, %next ]
+ %cond = icmp sgt i32 %n, %i
+ br i1 %cond, label %next, label %return
+next:
+ %i.inc = add i32 %i, 1
+ br label %header
+return:
+ ret void
+}