GBE: reserve flag0.0 for large basic block.

As in large basic block, there are more than one IF instruction which
need to use the flag0.0. We have to reserve flag 0.0 to those IF
instructions.

Signed-off-by: Zhigang Gong <zhigang.gong@gmail.com>
Reviewed-by: "Yang, Rong R" <rong.r.yang@intel.com>

diff --git a/backend/src/backend/gen_insn_selection.cpp b/backend/src/backend/gen_insn_selection.cpp
index ab885f2..88ec408 100644 (file)
--- a/backend/src/backend/gen_insn_selection.cpp
+++ b/backend/src/backend/gen_insn_selection.cpp
@@ -196,7 +196,7 @@ namespace gbe
   // SelectionBlock
   ///////////////////////////////////////////////////////////////////////////
 
-  SelectionBlock::SelectionBlock(const ir::BasicBlock *bb) : bb(bb), endifLabel( (ir::LabelIndex) 0){}
+  SelectionBlock::SelectionBlock(const ir::BasicBlock *bb) : bb(bb), isLargeBlock(false), endifLabel( (ir::LabelIndex) 0){}
 
   void SelectionBlock::append(ir::Register reg) { tmp.push_back(reg); }
 
@@ -1501,6 +1501,7 @@ namespace gbe
             this->curr.predicate = GEN_PREDICATE_NORMAL;
             this->IF(GenRegister::immd(0), jip, jip);
           this->pop();
+          this->block->isLargeBlock = true;
         }
 
         if (needEndif) {

diff --git a/backend/src/backend/gen_insn_selection.hpp b/backend/src/backend/gen_insn_selection.hpp
index 018114d..150feb5 100644 (file)
--- a/backend/src/backend/gen_insn_selection.hpp
+++ b/backend/src/backend/gen_insn_selection.hpp
@@ -190,6 +190,7 @@ namespace gbe
     void append(SelectionInstruction *insn);
     /*! Append a new selection instruction at the beginning of the block */
     void prepend(SelectionInstruction *insn);
+    bool isLargeBlock;
     ir::LabelIndex endifLabel;
     int endifOffset;
     bool hasBarrier;

diff --git a/backend/src/backend/gen_reg_allocation.cpp b/backend/src/backend/gen_reg_allocation.cpp
index fd0c1cf..5098f34 100644 (file)
--- a/backend/src/backend/gen_reg_allocation.cpp
+++ b/backend/src/backend/gen_reg_allocation.cpp
@@ -160,6 +160,7 @@ namespace gbe
     vector<GenRegInterval> intervals;
     /*! All the boolean register intervals on the corresponding BB*/
     typedef map<ir::Register, GenRegInterval> RegIntervalMap;
+    set<SelectionBlock *> flag0ReservedBlocks;
     map<SelectionBlock *, RegIntervalMap *> boolIntervalsMap;
     /*! Intervals sorting based on starting point positions */
     vector<GenRegInterval*> starting;
@@ -409,7 +410,7 @@ namespace gbe
       map<ir::Register, uint32_t> allocatedFlags;
       map<const GenRegInterval*, uint32_t> allocatedFlagIntervals;
 
-      const uint32_t flagNum = 3;
+      const uint32_t flagNum = flag0ReservedBlocks.contains(&block) ?  2 : 3;
       uint32_t freeFlags[] = {2, 3, 0};
       uint32_t freeNum = flagNum;
       if (boolIntervalsMap.find(&block) == boolIntervalsMap.end())
@@ -923,6 +924,8 @@ namespace gbe
       // Update the intervals of each used register. Note that we do not
       // register allocate R0, so we skip all sub-registers in r0
       RegIntervalMap *boolsMap = new RegIntervalMap;
+      if (block.isLargeBlock)
+        flag0ReservedBlocks.insert(&block);
       for (auto &insn : block.insnList) {
         const uint32_t srcNum = insn.srcNum, dstNum = insn.dstNum;
         insn.ID  = insnID;
@@ -977,7 +980,17 @@ namespace gbe
             // is out-of the if/endif region, so we have to borrow the f0
             // to get correct bits for all channels.
             boolsMap->find(reg)->second.minID = 0;
+            if (flag0ReservedBlocks.contains(&block))
+              flag0ReservedBlocks.erase(&block);
           }
+        } else {
+          // Make sure that instruction selection stage didn't use physiacl flags incorrectly.
+          GBE_ASSERT ((insn.opcode == SEL_OP_LABEL ||
+                       insn.opcode == SEL_OP_IF ||
+                       insn.opcode == SEL_OP_JMPI ||
+                       insn.state.predicate == GEN_PREDICATE_NONE ||
+                       (block.hasBarrier && insn.opcode == SEL_OP_MOV) ||
+                       (insn.state.flag == 0 && insn.state.subFlag == 1)));
         }
         lastID = insnID;
         insnID++;