Revert "Revert "[Unroll] Implement a conservative and monotonically increasing cost tracking system during the full unroll heuristic analysis that avoids counting any instruction cost until that instruction becomes "live" through a side-effect or use outside the...""

This reverts commit r269395.

Try to reapply with a fix from chapuni.

llvm-svn: 269486

1 files changed, 7 insertions, 3 deletions

diff --git a/llvm/unittests/Analysis/UnrollAnalyzer.cpp b/llvm/unittests/Analysis/UnrollAnalyzer.cpp
index 83d57f52469..6d11ab1f2f1 100644
--- a/llvm/unittests/Analysis/UnrollAnalyzer.cpp
+++ b/llvm/unittests/Analysis/UnrollAnalyzer.cpp
@@ -134,6 +134,7 @@ TEST(UnrollAnalyzerTest, OuterLoopSimplification) {
       "  br label %outer.loop\n"
       "outer.loop:\n"
       "  %iv.outer = phi i64 [ 0, %entry ], [ %iv.outer.next, %outer.loop.latch ]\n"
+      "  %iv.outer.next = add nuw nsw i64 %iv.outer, 1\n"
       "  br label %inner.loop\n"
       "inner.loop:\n"
       "  %iv.inner = phi i64 [ 0, %outer.loop ], [ %iv.inner.next, %inner.loop ]\n"
@@ -141,7 +142,6 @@ TEST(UnrollAnalyzerTest, OuterLoopSimplification) {
       "  %exitcond.inner = icmp eq i64 %iv.inner.next, 1000\n"
       "  br i1 %exitcond.inner, label %outer.loop.latch, label %inner.loop\n"
       "outer.loop.latch:\n"
-      "  %iv.outer.next = add nuw nsw i64 %iv.outer, 1\n"
       "  %exitcond.outer = icmp eq i64 %iv.outer.next, 40\n"
       "  br i1 %exitcond.outer, label %exit, label %outer.loop\n"
       "exit:\n"
@@ -163,11 +163,15 @@ TEST(UnrollAnalyzerTest, OuterLoopSimplification) {
   BasicBlock *InnerBody = &*FI++;
 
   BasicBlock::iterator BBI = Header->begin();
-  Instruction *Y1 = &*BBI++;
+  BBI++;
+  Instruction *Y1 = &*BBI;
   BBI = InnerBody->begin();
-  Instruction *Y2 = &*BBI++;
+  BBI++;
+  Instruction *Y2 = &*BBI;
   // Check that we can simplify IV of the outer loop, but can't simplify the IV
   // of the inner loop if we only know the iteration number of the outer loop.
+  //
+  //  Y1 is %iv.outer.next, Y2 is %iv.inner.next
   auto I1 = SimplifiedValuesVector[0].find(Y1);
   EXPECT_TRUE(I1 != SimplifiedValuesVector[0].end());
   auto I2 = SimplifiedValuesVector[0].find(Y2);