[PowerPC] Always use aggressive interleaving on the A2

On the A2, with an eye toward QPX unaligned-load merging, we should always use
aggressive interleaving. It is generally superior to only using concatenation
unrolling.

llvm-svn: 246819

1 files changed, 7 insertions, 0 deletions

diff --git a/llvm/lib/Target/PowerPC/PPCTargetTransformInfo.cpp b/llvm/lib/Target/PowerPC/PPCTargetTransformInfo.cpp
index 937d9c6810d..124556e2d17 100644
--- a/llvm/lib/Target/PowerPC/PPCTargetTransformInfo.cpp
+++ b/llvm/lib/Target/PowerPC/PPCTargetTransformInfo.cpp
@@ -197,6 +197,13 @@ void PPCTTIImpl::getUnrollingPreferences(Loop *L,
 }
 
 bool PPCTTIImpl::enableAggressiveInterleaving(bool LoopHasReductions) {
+  // On the A2, always unroll aggressively. For QPX unaligned loads, we depend
+  // on combining the loads generated for consecutive accesses, and failure to
+  // do so is particularly expensive. This makes it much more likely (compared
+  // to only using concatenation unrolling).
+  if (ST->getDarwinDirective() == PPC::DIR_A2)
+    return true;
+
   return LoopHasReductions;
 }