- Add a hook for target to determine whether an instruction def is

  "long latency" enough to hoist even if it may increase spilling. Reloading
  a value from spill slot is often cheaper than performing an expensive
  computation in the loop. For X86, that means machine LICM will hoist
  SQRT, DIV, etc. ARM will be somewhat aggressive with VFP and NEON
  instructions.
- Enable register pressure aware machine LICM by default.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@116781 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 40 insertions, 0 deletions

diff --git a/lib/Target/X86/X86InstrInfo.cpp b/lib/Target/X86/X86InstrInfo.cpp
index 40ef3db..79d9872 100644
--- a/lib/Target/X86/X86InstrInfo.cpp
+++ b/lib/Target/X86/X86InstrInfo.cpp
@@ -3152,6 +3152,41 @@ void X86InstrInfo::getNoopForMachoTarget(MCInst &NopInst) const {
   NopInst.setOpcode(X86::NOOP);
 }
 
+bool X86InstrInfo::
+hasHighOperandLatency(const InstrItineraryData *ItinData,
+                      const MachineRegisterInfo *MRI,
+                      const MachineInstr *DefMI, unsigned DefIdx,
+                      const MachineInstr *UseMI, unsigned UseIdx) const {
+  switch (DefMI->getOpcode()) {
+  default: return false;
+  case X86::DIVSDrm:
+  case X86::DIVSDrm_Int:
+  case X86::DIVSDrr:
+  case X86::DIVSDrr_Int:
+  case X86::DIVSSrm:
+  case X86::DIVSSrm_Int:
+  case X86::DIVSSrr:
+  case X86::DIVSSrr_Int:
+  case X86::SQRTPDm:
+  case X86::SQRTPDm_Int:
+  case X86::SQRTPDr:
+  case X86::SQRTPDr_Int:
+  case X86::SQRTPSm:
+  case X86::SQRTPSm_Int:
+  case X86::SQRTPSr:
+  case X86::SQRTPSr_Int:
+  case X86::SQRTSDm:
+  case X86::SQRTSDm_Int:
+  case X86::SQRTSDr:
+  case X86::SQRTSDr_Int:
+  case X86::SQRTSSm:
+  case X86::SQRTSSm_Int:
+  case X86::SQRTSSr:
+  case X86::SQRTSSr_Int:
+    return true;
+  }
+}
+
 namespace {
   /// CGBR - Create Global Base Reg pass. This initializes the PIC
   /// global base register for x86-32.
diff --git a/lib/Target/X86/X86InstrInfo.h b/lib/Target/X86/X86InstrInfo.h
index e43cfac..5060ad8 100644
--- a/lib/Target/X86/X86InstrInfo.h
+++ b/lib/Target/X86/X86InstrInfo.h
@@ -864,6 +864,11 @@ public:
                                       unsigned OpNum,
                                       const SmallVectorImpl<MachineOperand> &MOs,
                                       unsigned Size, unsigned Alignment) const;
+
+  bool hasHighOperandLatency(const InstrItineraryData *ItinData,
+                             const MachineRegisterInfo *MRI,
+                             const MachineInstr *DefMI, unsigned DefIdx,
+                             const MachineInstr *UseMI, unsigned UseIdx) const;
   
 private:
   MachineInstr * convertToThreeAddressWithLEA(unsigned MIOpc,