[PATCH] R600: Implement TargetInstrInfo::isLegalToSplitMBBAt()

[Tom Stellard]

From: Tom Stellard <thomas.stellard at amd.com>

Splitting a basic block will create a new ALU clause, so we need to make
sure we aren't moving uses of registers that are local to their
current clause into a new one.

I had a test case for this, but unfortunately unrelated schedule changes
invalidated it, and I wasn't been able to come up with another one.
---
 lib/Target/R600/R600InstrInfo.cpp | 12 ++++++++++++
 lib/Target/R600/R600InstrInfo.h   |  2 ++
 2 files changed, 14 insertions(+)

diff --git a/lib/Target/R600/R600InstrInfo.cpp b/lib/Target/R600/R600InstrInfo.cpp
index 3987b2d..ce5c05c 100644
--- a/lib/Target/R600/R600InstrInfo.cpp
+++ b/lib/Target/R600/R600InstrInfo.cpp
@@ -77,6 +77,18 @@ R600InstrInfo::copyPhysReg(MachineBasicBlock &MBB,
   }
 }
 
+/// \returns true if \p MBBI can be moved into a new basic.
+bool R600InstrInfo::isLegalToSplitMBBAt(MachineBasicBlock &MBB,
+                                       MachineBasicBlock::iterator MBBI) const {
+  for (MachineInstr::const_mop_iterator I = MII->operands_begin(),
+                                        E = MII->operands_end(); I != E; ++I) {
+    if (I->isReg() && !TargetInstrInfo::getVirtualRegister(I->getReg()) &&
+        && I->isUse() && RI.isPhysRegLiveAcrossClauses(I->getReg()))
+      return false;
+  }
+  return true;
+}
+
 unsigned R600InstrInfo::getIEQOpcode() const {
   return AMDGPU::SETE_INT;
 }
diff --git a/lib/Target/R600/R600InstrInfo.h b/lib/Target/R600/R600InstrInfo.h
index b29b91f..13d9810 100644
--- a/lib/Target/R600/R600InstrInfo.h
+++ b/lib/Target/R600/R600InstrInfo.h
@@ -55,6 +55,8 @@ namespace llvm {
                            MachineBasicBlock::iterator MI, DebugLoc DL,
                            unsigned DestReg, unsigned SrcReg,
                            bool KillSrc) const;
+  bool isLegalToSplitMBBAt(MachineBasicBlock &MBB,
+                           MachineBasicBlock::iterator MBBI) const;
 
   bool isTrig(const MachineInstr &MI) const;
   bool isPlaceHolderOpcode(unsigned opcode) const;
-- 
1.8.1.4