Revert r270518, which re-enabled "[LoopUnroll] Enable advanced unroll…

…ing analysis by default.

Chromium builds are still hitting the assert in PR27874.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@270577 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/Scalar/LoopUnrollPass.cpp

@@ -45,18 +45,18 @@ static cl::opt<unsigned>
                     cl::desc("The baseline cost threshold for loop unrolling"));
 
 static cl::opt<unsigned> UnrollPercentDynamicCostSavedThreshold(
-    "unroll-percent-dynamic-cost-saved-threshold", cl::init(50), cl::Hidden,
+    "unroll-percent-dynamic-cost-saved-threshold", cl::Hidden,
     cl::desc("The percentage of estimated dynamic cost which must be saved by "
              "unrolling to allow unrolling up to the max threshold."));
 
 static cl::opt<unsigned> UnrollDynamicCostSavingsDiscount(
-    "unroll-dynamic-cost-savings-discount", cl::init(100), cl::Hidden,
+    "unroll-dynamic-cost-savings-discount", cl::Hidden,
     cl::desc("This is the amount discounted from the total unroll cost when "
              "the unrolled form has a high dynamic cost savings (triggered by "
              "the '-unroll-perecent-dynamic-cost-saved-threshold' flag)."));
 
 static cl::opt<unsigned> UnrollMaxIterationsCountToAnalyze(
-    "unroll-max-iteration-count-to-analyze", cl::init(10), cl::Hidden,
+    "unroll-max-iteration-count-to-analyze", cl::init(0), cl::Hidden,
     cl::desc("Don't allow loop unrolling to simulate more than this number of"
              "iterations when checking full unroll profitability"));
 

test/Transforms/LoopUnroll/partial-unroll-const-bounds.ll

@@ -1,4 +1,4 @@
-; RUN: opt < %s -S -unroll-threshold=20 -loop-unroll -unroll-allow-partial -unroll-runtime -unroll-dynamic-cost-savings-discount=0 | FileCheck %s
+; RUN: opt < %s -S -unroll-threshold=20 -loop-unroll -unroll-allow-partial -unroll-runtime | FileCheck %s
 
 ; The Loop TripCount is 9. However unroll factors 3 or 9 exceed given threshold.
 ; The test checks that we choose a smaller, power-of-two, unroll count and do not give up on unrolling.