From 8cc3474f72388836fa4ca7d3622289fb9ee08b41 Mon Sep 17 00:00:00 2001
From: Hal Finkel <hfinkel@anl.gov>
Date: Sat, 4 Aug 2012 14:10:46 +0000
Subject: [PATCH] Add readcyclecounter lowering on PPC64.

On PPC64, this can be done with a simple TableGen pattern.
To enable this, I've added the (otherwise missing) readcyclecounter
SDNode definition to TargetSelectionDAG.td.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161302 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/Target/TargetSelectionDAG.td  |  3 +++
 lib/Target/PowerPC/PPCISelLowering.cpp     |  4 +++-
 lib/Target/PowerPC/PPCInstr64Bit.td        |  5 +++++
 test/CodeGen/PowerPC/ppc64-cyclecounter.ll | 15 +++++++++++++++
 4 files changed, 26 insertions(+), 1 deletion(-)
 create mode 100644 test/CodeGen/PowerPC/ppc64-cyclecounter.ll

diff --git a/include/llvm/Target/TargetSelectionDAG.td b/include/llvm/Target/TargetSelectionDAG.td
index ff006b609d3..3f81c06bc0b 100644
--- a/include/llvm/Target/TargetSelectionDAG.td
+++ b/include/llvm/Target/TargetSelectionDAG.td
@@ -411,6 +411,9 @@ def prefetch   : SDNode<"ISD::PREFETCH"   , SDTPrefetch,
                         [SDNPHasChain, SDNPMayLoad, SDNPMayStore,
                          SDNPMemOperand]>;
 
+def readcyclecounter : SDNode<"ISD::READCYCLECOUNTER", SDTIntLeaf,
+                     [SDNPHasChain, SDNPSideEffect]>;
+
 def membarrier : SDNode<"ISD::MEMBARRIER" , SDTMemBarrier,
                         [SDNPHasChain, SDNPSideEffect]>;
 
diff --git a/lib/Target/PowerPC/PPCISelLowering.cpp b/lib/Target/PowerPC/PPCISelLowering.cpp
index 13250b33eaa..aa819eeb30a 100644
--- a/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -394,8 +394,10 @@ PPCTargetLowering::PPCTargetLowering(PPCTargetMachine &TM)
     setOperationAction(ISD::BUILD_VECTOR, MVT::v4f32, Custom);
   }
 
-  if (Subtarget->has64BitSupport())
+  if (Subtarget->has64BitSupport()) {
     setOperationAction(ISD::PREFETCH, MVT::Other, Legal);
+    setOperationAction(ISD::READCYCLECOUNTER, MVT::i64, Legal);
+  }
 
   setOperationAction(ISD::ATOMIC_LOAD,  MVT::i32, Expand);
   setOperationAction(ISD::ATOMIC_STORE, MVT::i32, Expand);
diff --git a/lib/Target/PowerPC/PPCInstr64Bit.td b/lib/Target/PowerPC/PPCInstr64Bit.td
index 91c5366e5c2..92a50516546 100644
--- a/lib/Target/PowerPC/PPCInstr64Bit.td
+++ b/lib/Target/PowerPC/PPCInstr64Bit.td
@@ -265,6 +265,11 @@ def MTCTR8 : XFXForm_7_ext<31, 467, 9, (outs), (ins G8RC:$rS),
              PPC970_DGroup_First, PPC970_Unit_FXU;
 }
 
+let Pattern = [(set G8RC:$rT, readcyclecounter)] in
+def MFTB8 : XFXForm_1_ext<31, 371, 268, (outs G8RC:$rT), (ins),
+                          "mftb $rT", SprMFTB>,
+            PPC970_DGroup_First, PPC970_Unit_FXU;
+
 let Defs = [X1], Uses = [X1] in
 def DYNALLOC8 : Pseudo<(outs G8RC:$result), (ins G8RC:$negsize, memri:$fpsi),"",
                        [(set G8RC:$result,
diff --git a/test/CodeGen/PowerPC/ppc64-cyclecounter.ll b/test/CodeGen/PowerPC/ppc64-cyclecounter.ll
new file mode 100644
index 00000000000..c1df3c7ec21
--- /dev/null
+++ b/test/CodeGen/PowerPC/ppc64-cyclecounter.ll
@@ -0,0 +1,15 @@
+target datalayout = "E-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v128:128:128-n32:64"
+target triple = "powerpc64-unknown-linux-gnu"
+; RUN: llc < %s | FileCheck %s
+
+define i64 @test1() nounwind {
+entry:
+  %r = call i64 @llvm.readcyclecounter()
+  ret i64 %r
+}
+
+; CHECK: @test1
+; CHECK: mftb
+
+declare i64 @llvm.readcyclecounter()
+