Reword and tidy up some comments.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@70416 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/LoopIndexSplit.cpp b/lib/Transforms/Scalar/LoopIndexSplit.cpp
index 9f5f2cf..ffa1d90 100644
--- a/lib/Transforms/Scalar/LoopIndexSplit.cpp
+++ b/lib/Transforms/Scalar/LoopIndexSplit.cpp
@@ -10,33 +10,44 @@
// This file implements Loop Index Splitting Pass. This pass handles three
// kinds of loops.
//
-// [1] Loop is eliminated when loop body is executed only once. For example,
+// [1] A loop may be eliminated if the body is executed exactly once.
+// For example,
+//
// for (i = 0; i < N; ++i) {
-// if ( i == X) {
+// if (i == X) {
+// body;
+// }
+// }
+//
+// is transformed to
+//
+// i = X;
+// body;
+//
+// [2] A loop's iteration space may be shrunk if the loop body is executed
+// for a proper sub-range of the loop's iteration space. For example,
+//
+// for (i = 0; i < N; ++i) {
+// if (i > A && i < B) {
// ...
// }
// }
//
-// [2] Loop's iteration space is shrunk if loop body is executed for certain
-// range only. For example,
-//
-// for (i = 0; i < N; ++i) {
-// if ( i > A && i < B) {
-// ...
-// }
-// }
-// is trnasformed to iterators from A to B, if A > 0 and B < N.
+// is transformed to iterators from A to B, if A > 0 and B < N.
//
-// [3] Loop is split if the loop body is dominated by an branch. For example,
+// [3] A loop may be split if the loop body is dominated by a branch.
+// For example,
//
// for (i = LB; i < UB; ++i) { if (i < SV) A; else B; }
//
// is transformed into
+//
// AEV = BSV = SV
// for (i = LB; i < min(UB, AEV); ++i)
// A;
// for (i = max(LB, BSV); i < UB; ++i);
// B;
+//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "loop-index-split"
@@ -1060,7 +1071,7 @@
DT->changeImmediateDominator(B_ExitBlock, B_ExitingBlock);
DF->changeImmediateDominator(B_ExitBlock, B_ExitingBlock, DT);
- //[*] Split ALoop's exit edge. This creates a new block which
+ //[*] Split ALoop's exit edge. This creates a new block which
// serves two purposes. First one is to hold PHINode defnitions
// to ensure that ALoop's LCSSA form. Second use it to act
// as a preheader for BLoop.