[Beignet] [PATCH 7/9] GBE: Don't try to remove instructions when liveness is in dynamic update phase.

[Zhigang Gong]

As we want to avoid liveness update all the time, we maintain the liveness
information dynamically during the phi mov optimization. Instruction(self-copy)
remving bring unecessary complexity here. Let's avoid do that here, and do
the self-copy removing latter in removeMOVs().

Signed-off-by: Zhigang Gong <zhigang.gong at intel.com>
---
 backend/src/ir/value.cpp              |  6 +++---
 backend/src/llvm/llvm_gen_backend.cpp | 21 +++++++--------------
 2 files changed, 10 insertions(+), 17 deletions(-)

diff --git a/backend/src/ir/value.cpp b/backend/src/ir/value.cpp
index d2f0c2e..b0ed9c2 100644
--- a/backend/src/ir/value.cpp
+++ b/backend/src/ir/value.cpp
@@ -190,7 +190,7 @@ namespace ir {
       // Do not transfer dead values
       if (info.inLiveOut(reg) == false) continue;
       // If we overwrite it, do not transfer the initial value
-      if (info.inVarKill(reg) == true) continue;
+      if ((info.inVarKill(reg) == true) && (info.inUpwardUsed(reg))) continue;
       ValueDef *def = const_cast<ValueDef*>(this->dag.getDefAddress(&arg));
       auto it = blockDefMap->find(reg);
       GBE_ASSERT(it != blockDefMap->end());
@@ -205,7 +205,7 @@ namespace ir {
       // Do not transfer dead values
       if (info.inLiveOut(reg) == false) continue;
       // If we overwrite it, do not transfer the initial value
-      if (info.inVarKill(reg) == true) continue;
+      if ((info.inVarKill(reg) == true) && (info.inUpwardUsed(reg))) continue;
       ValueDef *def = const_cast<ValueDef*>(this->dag.getDefAddress(reg));
       auto it = blockDefMap->find(reg);
       GBE_ASSERT(it != blockDefMap->end());
@@ -219,7 +219,7 @@ namespace ir {
       // Do not transfer dead values
       if (info.inLiveOut(reg) == false) continue;
       // If we overwrite it, do not transfer the initial value
-      if (info.inVarKill(reg) == true) continue;
+      if ((info.inVarKill(reg) == true) && (info.inUpwardUsed(reg))) continue;
       ValueDef *def = const_cast<ValueDef*>(this->dag.getDefAddress(&pushed.second));
       auto it = blockDefMap->find(reg);
       GBE_ASSERT(it != blockDefMap->end());
diff --git a/backend/src/llvm/llvm_gen_backend.cpp b/backend/src/llvm/llvm_gen_backend.cpp
index b0b97e7..dc2e3e8 100644
--- a/backend/src/llvm/llvm_gen_backend.cpp
+++ b/backend/src/llvm/llvm_gen_backend.cpp
@@ -2149,6 +2149,11 @@ namespace gbe
     // destinations)
     uint32_t insnID = 2;
     bb.foreach([&](ir::Instruction &insn) {
+      if (insn.getOpcode() == ir::OP_MOV &&
+          insn.getDst(0) == insn.getSrc(0)) {
+        insn.remove();
+        return;
+      }
       const uint32_t dstNum = insn.getDstNum();
       const uint32_t srcNum = insn.getSrcNum();
       for (uint32_t srcID = 0; srcID < srcNum; ++srcID) {
@@ -2245,8 +2250,7 @@ namespace gbe
               ++iter;
             }
             if (!phiPhiCopySrcInterfere) {
-              // phiCopy source can be coaleased with phiCopy
-              const_cast<Instruction *>(phiCopyDefInsn)->remove();
+              replaceSrc(const_cast<Instruction *>(phiCopyDefInsn), phiCopySrc, phiCopy);
 
               for (auto &s : *phiCopySrcDef) {
                 const Instruction *phiSrcDefInsn = s->getInstruction();
@@ -2300,7 +2304,7 @@ namespace gbe
       // coalease phi and phiCopy
       if (isOpt) {
         for (auto &x : *phiDef) {
-          const_cast<Instruction *>(x->getInstruction())->remove();
+          replaceDst(const_cast<Instruction *>(x->getInstruction()), phi, phiCopy);
         }
         for (auto &x : *phiUse) {
           const Instruction *phiUseInsn = x->getInstruction();
@@ -2361,21 +2365,11 @@ namespace gbe
           const ir::UseSet *phiCopySrcUse = dag->getRegUse(phiCopySrc);
           for (auto &s : *phiCopySrcDef) {
             const Instruction *phiSrcDefInsn = s->getInstruction();
-            if (phiSrcDefInsn->getOpcode() == ir::OP_MOV &&
-                phiSrcDefInsn->getSrc(0) == phiCopy) {
-               const_cast<Instruction *>(phiSrcDefInsn)->remove();
-               continue;
-            }
             replaceDst(const_cast<Instruction *>(phiSrcDefInsn), phiCopySrc, phiCopy);
           }
 
           for (auto &s : *phiCopySrcUse) {
             const Instruction *phiSrcUseInsn = s->getInstruction();
-            if (phiSrcUseInsn->getOpcode() == ir::OP_MOV &&
-                phiSrcUseInsn->getDst(0) == phiCopy) {
-               const_cast<Instruction *>(phiSrcUseInsn)->remove();
-               continue;
-            }
             replaceSrc(const_cast<Instruction *>(phiSrcUseInsn), phiCopySrc, phiCopy);
           }
 
@@ -2405,7 +2399,6 @@ namespace gbe
       } else
         break;
 
-      break;
       nextRedundant->clear();
       replacedRegs.clear();
       revReplacedRegs.clear();
-- 
1.9.1