AArch64: Do not test for CPUs, use SubtargetFeatures

Testing for specific CPUs has a number of problems, better use subtarget
features:
- When some tweak is added for a specific CPU it is often desirable for
  the next version of that CPU as well, yet we often forget to add it.
- It is hard to keep track of checks scattered around the target code;
  Declaring all target specifics together with the CPU in the tablegen
  file is a clear representation.
- Subtarget features can be tweaked from the command line.

To discourage people from using CPU checks in the future I removed the
isCortexXX(), isCyclone(), ... functions. I added an getProcFamily()
function for exceptional circumstances but made it clear in the comment
that usage is discouraged.

Reformat feature list in AArch64.td to have 1 feature per line in
alphabetical order to simplify merging and sorting for out of tree
tweaks.

No functional change intended.

Differential Revision: http://reviews.llvm.org/D20762

llvm-svn: 271555

1 files changed, 4 insertions, 11 deletions

diff --git a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
index c6c47ab148b..8d9124670b0 100644
--- a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
+++ b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
@@ -634,9 +634,7 @@ AArch64TargetLowering::AArch64TargetLowering(const TargetMachine &TM,
     }
   }
 
-  // Prefer likely predicted branches to selects on out-of-order cores.
-  if (Subtarget->isCortexA57() || Subtarget->isKryo())
-    PredictableSelectIsExpensive = true;
+  PredictableSelectIsExpensive = Subtarget->predictableSelectIsExpensive();
 }
 
 void AArch64TargetLowering::addTypeForNEON(MVT VT, MVT PromotedBitwiseVT) {
@@ -814,12 +812,9 @@ bool AArch64TargetLowering::allowsMisalignedMemoryAccesses(EVT VT,
   if (Subtarget->requiresStrictAlign())
     return false;
 
-  // FIXME: This is mostly true for Cyclone, but not necessarily others.
   if (Fast) {
-    // FIXME: Define an attribute for slow unaligned accesses instead of
-    // relying on the CPU type as a proxy.
-    // On Cyclone, unaligned 128-bit stores are slow.
-    *Fast = !Subtarget->isCyclone() || VT.getStoreSize() != 16 ||
+    // Some CPUs are fine with unaligned stores except for 128-bit ones.
+    *Fast = !Subtarget->isMisaligned128StoreSlow() || VT.getStoreSize() != 16 ||
             // See comments in performSTORECombine() for more details about
             // these conditions.
 
@@ -8792,9 +8787,7 @@ static SDValue split16BStores(SDNode *N, TargetLowering::DAGCombinerInfo &DCI,
   // be included in TLI.allowsMisalignedMemoryAccesses(), and there should be
   // a call to that function here.
 
-  // Cyclone has bad performance on unaligned 16B stores when crossing line and
-  // page boundaries. We want to split such stores.
-  if (!Subtarget->isCyclone())
+  if (!Subtarget->isMisaligned128StoreSlow())
     return SDValue();
 
   // Don't split at -Oz.