[SystemZ] Recognize Load On Condition Immediate (LOCHI/LOGHI) opportunities

Summary: Add support for the z13 instructions LOCHI and LOCGHI which
conditionally load immediate values.  Add target instruction info hooks so
that if conversion will allow predication of LHI/LGHI.

Author: RolandF

Reviewers: uweigand

Subscribers: zhanjunl

Commiting on behalf of Roland.

Differential Revision: http://reviews.llvm.org/D22117

llvm-svn: 275086

1 files changed, 20 insertions, 0 deletions

diff --git a/llvm/lib/Target/SystemZ/SystemZInstrInfo.cpp b/llvm/lib/Target/SystemZ/SystemZInstrInfo.cpp
index d2e2e27f397..072b64474f7 100644
--- a/llvm/lib/Target/SystemZ/SystemZInstrInfo.cpp
+++ b/llvm/lib/Target/SystemZ/SystemZInstrInfo.cpp
@@ -530,10 +530,20 @@ static unsigned getConditionalMove(unsigned Opcode) {
   }
 }
 
+static unsigned getConditionalLoadImmediate(unsigned Opcode) {
+  switch (Opcode) {
+  case SystemZ::LHI:  return SystemZ::LOCHI;
+  case SystemZ::LGHI: return SystemZ::LOCGHI;
+  default:           return 0;
+  }
+}
+
 bool SystemZInstrInfo::isPredicable(MachineInstr &MI) const {
   unsigned Opcode = MI.getOpcode();
   if (STI.hasLoadStoreOnCond() && getConditionalMove(Opcode))
     return true;
+  if (STI.hasLoadStoreOnCond2() && getConditionalLoadImmediate(Opcode))
+    return true;
   if (Opcode == SystemZ::Return ||
       Opcode == SystemZ::Trap ||
       Opcode == SystemZ::CallJG ||
@@ -595,6 +605,16 @@ bool SystemZInstrInfo::PredicateInstruction(
       return true;
     }
   }
+  if (STI.hasLoadStoreOnCond2()) {
+    if (unsigned CondOpcode = getConditionalLoadImmediate(Opcode)) {
+      MI.setDesc(get(CondOpcode));
+      MachineInstrBuilder(*MI.getParent()->getParent(), MI)
+          .addImm(CCValid)
+          .addImm(CCMask)
+          .addReg(SystemZ::CC, RegState::Implicit);
+      return true;
+    }
+  }
   if (Opcode == SystemZ::Trap) {
     MI.setDesc(get(SystemZ::CondTrap));
     MachineInstrBuilder(*MI.getParent()->getParent(), MI)