Implement TTI getUnrollingPreferences for PowerPC

The PowerPC A2 core greatly benefits from aggressive concatenation unrolling;
use the new getUnrollingPreferences to enable this by default when targeting
the PPC A2 core.

llvm-svn: 190549

1 files changed, 9 insertions, 0 deletions

diff --git a/llvm/lib/Target/PowerPC/PPCTargetTransformInfo.cpp b/llvm/lib/Target/PowerPC/PPCTargetTransformInfo.cpp
index 2504ba7..8879630 100644
--- a/llvm/lib/Target/PowerPC/PPCTargetTransformInfo.cpp
+++ b/llvm/lib/Target/PowerPC/PPCTargetTransformInfo.cpp
@@ -77,6 +77,7 @@ public:
   /// \name Scalar TTI Implementations
   /// @{
   virtual PopcntSupportKind getPopcntSupport(unsigned TyWidth) const;
+  virtual void getUnrollingPreferences(Loop *L, UnrollingPreferences &UP) const;
 
   /// @}
 
@@ -129,6 +130,14 @@ PPCTTI::PopcntSupportKind PPCTTI::getPopcntSupport(unsigned TyWidth) const {
   return PSK_Software;
 }
 
+void PPCTTI::getUnrollingPreferences(Loop *L, UnrollingPreferences &UP) const {
+  if (ST->getDarwinDirective() == PPC::DIR_A2) {
+    // The A2 is in-order with a deep pipeline, and concatenation unrolling
+    // helps expose latency-hiding opportunities to the instruction scheduler.
+    UP.Partial = UP.Runtime = true;
+  }
+}
+
 unsigned PPCTTI::getNumberOfRegisters(bool Vector) const {
   if (Vector && !ST->hasAltivec())
     return 0;