[Beignet] [PATCH] GBE: correct the instruction replacement logic in scalarize pass.

[Zhigang Gong]

When we want to delete an old instruction and replace it with the new one,
we only call the LLVM IR's replace function which is not sufficient for
the scalarize pass, as we also keep some local reference int eh vecVals
map. We need to replace all of those local reference also.

Otherwise, the deleted values may be used in the subsequent instructions
which causes fatal error latter.

Signed-off-by: Zhigang Gong <zhigang.gong at intel.com>
---
 backend/src/llvm/llvm_scalarize.cpp | 43 +++++++++++++++++++++++++++++--------
 1 file changed, 34 insertions(+), 9 deletions(-)

diff --git a/backend/src/llvm/llvm_scalarize.cpp b/backend/src/llvm/llvm_scalarize.cpp
index b657246..694b008 100644
--- a/backend/src/llvm/llvm_scalarize.cpp
+++ b/backend/src/llvm/llvm_scalarize.cpp
@@ -234,6 +234,20 @@ namespace gbe {
     }
 
     DenseMap<Value*, VectorValues> vectorVals;
+    struct VecValElement{
+      VecValElement(VectorValues *v, uint32_t i) : vecVals(v), id(i) {}
+      VectorValues *vecVals;
+      uint32_t id;
+    };
+    DenseMap<Value*, SmallVector<VecValElement, 16>> usedVecVals;
+
+    void setComponent(VectorValues &vecVals, uint32_t c, llvm::Value* val) {
+      vecVals.setComponent(c, val);
+      usedVecVals[val].push_back(VecValElement(&vecVals, c));
+    }
+
+    void replaceAllUsesOfWith(Instruction* from, Instruction* to);
+
     Module* module;
     IRBuilder<>* builder;
 
@@ -448,7 +462,7 @@ namespace gbe {
       callArgs.push_back(ConstantInt::get(intTy, i));
 
       res = builder->CreateCall(f, callArgs);
-      vVals.setComponent(i, res);
+      setComponent(vVals, i, res);
     }
   }
 
@@ -468,7 +482,7 @@ namespace gbe {
 
       Instruction* res = createScalarInstruction(inst, callArgs);
 
-      vVals.setComponent(i, res);
+      setComponent(vVals, i, res);
       builder->Insert(res);
     }
   }
@@ -549,7 +563,7 @@ namespace gbe {
       int select = sv->getMaskValue(i);
 
       if (select < 0) {
-        vVals.setComponent(i, UndefValue::get(GetBasicType(sv->getOperand(0))));
+        setComponent(vVals, i, UndefValue::get(GetBasicType(sv->getOperand(0))));
         continue;
       }
 
@@ -564,7 +578,7 @@ namespace gbe {
         selectee = sv->getOperand(1);
       }
 
-      vVals.setComponent(i, getComponent(select, selectee));
+      setComponent(vVals, i, getComponent(select, selectee));
     }
 
     return true;
@@ -611,7 +625,7 @@ namespace gbe {
     for (int i = 0; i < GetComponentCount(insn); ++i) {
       Value *cv = ConstantInt::get(intTy, i);
       Value *EI = builder->CreateExtractElement(insn, cv);
-      vVals.setComponent(i, EI);
+      setComponent(vVals, i, EI);
     }
   }
 
@@ -680,6 +694,7 @@ namespace gbe {
       setAppendPoint(bt);
       extractFromVector(bt);
     }
+
     return false;
   }
 
@@ -695,6 +710,16 @@ namespace gbe {
     return false;
   }
 
+  void Scalarize::replaceAllUsesOfWith(Instruction* from, Instruction* to) {
+    GBE_ASSERT(from != NULL);
+    if (from == to)
+      return;
+    for (auto &it : usedVecVals[from])
+      setComponent(*(it.vecVals), it.id, to);
+    usedVecVals[from].clear();
+    from->replaceAllUsesWith(to);
+  }
+
   bool Scalarize::scalarizeExtract(ExtractElementInst* extr)
   {
     //     %res = extractelement <n X ty> %foo, %i
@@ -711,7 +736,7 @@ namespace gbe {
     Value* v = getComponent(component, extr->getOperand(0));
     if(extr == v)
       return false;
-    extr->replaceAllUsesWith(v);
+    replaceAllUsesOfWith(dyn_cast<Instruction>(extr), dyn_cast<Instruction>(v));
 
     return true;
   }
@@ -731,8 +756,8 @@ namespace gbe {
 
     VectorValues& vVals = vectorVals[ins];
     for (int i = 0; i < GetComponentCount(ins); ++i) {
-      vVals.setComponent(i, i == component ? ins->getOperand(1)
-                                           : getComponent(i, ins->getOperand(0)));
+      setComponent(vVals, i, i == component ? ins->getOperand(1)
+                   : getComponent(i, ins->getOperand(0)));
     }
 
     return true;
@@ -816,9 +841,9 @@ namespace gbe {
     }
 
     dce();
-
     incompletePhis.clear();
     vectorVals.clear();
+    usedVecVals.clear();
 
     delete builder;
     builder = 0;
-- 
1.9.1