[LDist] Match behavior between invoking via optimization pipeline or opt -loop-distribute

In r267672, where the loop distribution pragma was introduced, I tried
it hard to keep the old behavior for opt: when opt is invoked
with -loop-distribute, it should distribute the loop (it's off by
default when ran via the optimization pipeline).

As MichaelZ has discovered this has the unintended consequence of
breaking a very common developer work-flow to reproduce compilations
using opt: First you print the pass pipeline of clang
with -debug-pass=Arguments and then invoking opt with the returned
arguments.

clang -debug-pass will include -loop-distribute but the pass is invoked
with default=off so nothing happens unless the loop carries the pragma.
While through opt (default=on) we will try to distribute all loops.

This changes opt's default to off as well to match clang.  The tests are
modified to explicitly enable the transformation.

llvm-svn: 290235

1 files changed, 1 insertions, 1 deletions

diff --git a/llvm/lib/Transforms/IPO/PassManagerBuilder.cpp b/llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
index 264bc3260b8..724965e27ff 100644
--- a/llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
+++ b/llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
@@ -561,7 +561,7 @@ void PassManagerBuilder::populateModulePassManager(
   // into separate loop that would otherwise inhibit vectorization.  This is
   // currently only performed for loops marked with the metadata
   // llvm.loop.distribute=true or when -enable-loop-distribute is specified.
-  MPM.add(createLoopDistributePass(/*ProcessAllLoopsByDefault=*/false));
+  MPM.add(createLoopDistributePass());
 
   MPM.add(createLoopVectorizePass(DisableUnrollLoops, LoopVectorize));