indvars: Added getInsertPointForUses to find a valid place to truncate the IV.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@135568 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/IndVarSimplify.cpp b/lib/Transforms/Scalar/IndVarSimplify.cpp
index 3a26748..50140d9 100644
--- a/lib/Transforms/Scalar/IndVarSimplify.cpp
+++ b/lib/Transforms/Scalar/IndVarSimplify.cpp
@@ -216,6 +216,36 @@
return true;
}
+/// Determine the insertion point for this user. By default, insert immediately
+/// before the user. SCEVExpander or LICM will hoist loop invariants out of the
+/// loop. For PHI nodes, there may be multiple uses, so compute the nearest
+/// common dominator for the incoming blocks.
+static Instruction *getInsertPointForUses(Instruction *User, Value *Def,
+ DominatorTree *DT) {
+ PHINode *PHI = dyn_cast<PHINode>(User);
+ if (!PHI)
+ return User;
+
+ Instruction *InsertPt = 0;
+ for (unsigned i = 0, e = PHI->getNumIncomingValues(); i != e; ++i) {
+ if (PHI->getIncomingValue(i) != Def)
+ continue;
+
+ BasicBlock *InsertBB = PHI->getIncomingBlock(i);
+ if (!InsertPt) {
+ InsertPt = InsertBB->getTerminator();
+ continue;
+ }
+ InsertBB = DT->findNearestCommonDominator(InsertPt->getParent(), InsertBB);
+ InsertPt = InsertBB->getTerminator();
+ }
+ assert(InsertPt && "Missing phi operand");
+ assert(!isa<Instruction>(Def) ||
+ DT->dominates(cast<Instruction>(Def), InsertPt) &&
+ "def does not dominate all uses");
+ return InsertPt;
+}
+
//===----------------------------------------------------------------------===//
// RewriteNonIntegerIVs and helpers. Prefer integer IVs.
//===----------------------------------------------------------------------===//
@@ -697,18 +727,7 @@
// hoist loop invariants out of the loop. For PHI nodes, there may be
// multiple uses, so compute the nearest common dominator for the
// incoming blocks.
- Instruction *InsertPt = User;
- if (PHINode *PHI = dyn_cast<PHINode>(InsertPt))
- for (unsigned i = 0, e = PHI->getNumIncomingValues(); i != e; ++i)
- if (PHI->getIncomingValue(i) == Op) {
- if (InsertPt == User)
- InsertPt = PHI->getIncomingBlock(i)->getTerminator();
- else
- InsertPt =
- DT->findNearestCommonDominator(InsertPt->getParent(),
- PHI->getIncomingBlock(i))
- ->getTerminator();
- }
+ Instruction *InsertPt = getInsertPointForUses(User, Op, DT);
// Now expand it into actual Instructions and patch it into place.
Value *NewVal = Rewriter.expandCodeFor(AR, UseTy, InsertPt);
@@ -1023,9 +1042,7 @@
// This user does not evaluate to a recurence after widening, so don't
// follow it. Instead insert a Trunc to kill off the original use,
// eventually isolating the original narrow IV so it can be removed.
- Use *U = std::find(DU.NarrowUse->op_begin(), DU.NarrowUse->op_end(),
- DU.NarrowDef);
- IRBuilder<> Builder(*U);
+ IRBuilder<> Builder(getInsertPointForUses(DU.NarrowUse, DU.NarrowDef, DT));
Value *Trunc = Builder.CreateTrunc(DU.WideDef, DU.NarrowDef->getType());
DU.NarrowUse->replaceUsesOfWith(DU.NarrowDef, Trunc);
return 0;