From 32b44f6a34ffbcf3f429527c2f9a9a993211ab18 Mon Sep 17 00:00:00 2001
From: Haicheng Wu <haicheng@codeaurora.org>
Date: Tue, 12 Jul 2016 15:31:41 +0000
Subject: [PATCH] [AArch64] Set FMOVS0 and FMOVD0 as isAsCheapAsAMove when
 needed.

If a subtarget has both ZCZeroing and CustomCheapAsMoveHandling features (now
only Kryo has both), set FMOVS0 and FMOVD0 isAsCheapAsAMove.

Differential Revision: http://reviews.llvm.org/D22256

llvm-svn: 275178
---
 lib/Target/AArch64/AArch64InstrInfo.cpp          | 6 ++++++
 test/CodeGen/AArch64/arm64-zero-cycle-zeroing.ll | 8 ++++----
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/lib/Target/AArch64/AArch64InstrInfo.cpp b/lib/Target/AArch64/AArch64InstrInfo.cpp
index f5a5dd5894a..de881e75ce4 100644
--- a/lib/Target/AArch64/AArch64InstrInfo.cpp
+++ b/lib/Target/AArch64/AArch64InstrInfo.cpp
@@ -620,6 +620,12 @@ bool AArch64InstrInfo::isAsCheapAsAMove(const MachineInstr &MI) const {
     return canBeExpandedToORR(MI, 32);
   case AArch64::MOVi64imm:
     return canBeExpandedToORR(MI, 64);
+
+  // It is cheap to move #0 to float registers if the subtarget has 
+  // ZeroCycleZeroing feature.
+  case AArch64::FMOVS0:
+  case AArch64::FMOVD0:
+    return Subtarget.hasZeroCycleZeroing();
   }
 
   llvm_unreachable("Unknown opcode to check as cheap as a move!");
diff --git a/test/CodeGen/AArch64/arm64-zero-cycle-zeroing.ll b/test/CodeGen/AArch64/arm64-zero-cycle-zeroing.ll
index 8946466b18d..ae77f7e099d 100644
--- a/test/CodeGen/AArch64/arm64-zero-cycle-zeroing.ll
+++ b/test/CodeGen/AArch64/arm64-zero-cycle-zeroing.ll
@@ -13,9 +13,9 @@ entry:
 ; CYCLONE: movi.2d v2, #0000000000000000
 ; CYCLONE: movi.2d v3, #0000000000000000
 ; KRYO: movi v0.2d, #0000000000000000
-; KRYO: mov v1.16b, v0.16b 
-; KRYO: mov v2.16b, v0.16b 
-; KRYO: mov v3.16b, v0.16b
+; KRYO: movi v1.2d, #0000000000000000
+; KRYO: movi v2.2d, #0000000000000000
+; KRYO: movi v3.2d, #0000000000000000
   tail call void @bar(double 0.000000e+00, double 0.000000e+00, double 0.000000e+00, double 0.000000e+00) nounwind
   ret void
 }
@@ -46,7 +46,7 @@ define void @t4() nounwind ssp {
 ; CYCLONE: movi.2d v0, #0000000000000000
 ; CYCLONE: movi.2d v1, #0000000000000000
 ; KRYO: movi v0.2d, #0000000000000000
-; KRYO: mov v1.16b, v0.16b
+; KRYO: movi v1.2d, #0000000000000000
   tail call void @barf(float 0.000000e+00, float 0.000000e+00) nounwind
   ret void
 }