[llvm-commits] CVS: llvm/lib/VMCore/ConstantFolding.cpp

[Reid Spencer]

Changes in directory llvm/lib/VMCore:

ConstantFolding.cpp updated: 1.105 -> 1.106
---
Log message:

Change inferred casts to explicit casts.


---
Diffs of the changes:  (+23 -12)

 ConstantFolding.cpp |   35 +++++++++++++++++++++++------------
 1 files changed, 23 insertions(+), 12 deletions(-)


Index: llvm/lib/VMCore/ConstantFolding.cpp
diff -u llvm/lib/VMCore/ConstantFolding.cpp:1.105 llvm/lib/VMCore/ConstantFolding.cpp:1.106
--- llvm/lib/VMCore/ConstantFolding.cpp:1.105	Fri Dec  1 13:50:54 2006
+++ llvm/lib/VMCore/ConstantFolding.cpp	Sun Dec  3 20:45:43 2006
@@ -777,7 +777,8 @@
         uint64_t V =
           DoubleToBits(cast<ConstantFP>(CP->getOperand(i))->getValue());
         Constant *C = ConstantInt::get(Type::ULongTy, V);
-        Result.push_back(ConstantExpr::getCast(C, DstEltTy));
+        Result.push_back(
+            ConstantExpr::getInferredCast(C, false, DstEltTy, false));
       }
       return ConstantPacked::get(Result);
     }
@@ -786,7 +787,8 @@
     for (unsigned i = 0; i != SrcNumElts; ++i) {
       uint32_t V = FloatToBits(cast<ConstantFP>(CP->getOperand(i))->getValue());
       Constant *C = ConstantInt::get(Type::UIntTy, V);
-      Result.push_back(ConstantExpr::getCast(C, DstEltTy));
+      Result.push_back(
+        ConstantExpr::getInferredCast(C, false, DstEltTy, false));
     }
     return ConstantPacked::get(Result);
   }
@@ -839,8 +841,7 @@
   // do to try to simplify it.
   if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
     if (CE->isCast()) {
-      // Try hard to fold cast of cast because they are almost always
-      // eliminable.
+      // Try hard to fold cast of cast because they are often eliminable.
       if (unsigned newOpc = foldConstantCastPair(opc, CE, DestTy))
         return ConstantExpr::getCast(newOpc, CE->getOperand(0), DestTy);
     } else if (CE->getOpcode() == Instruction::GetElementPtr) {
@@ -853,6 +854,7 @@
           break;
         }
       if (isAllNull)
+        // This is casting one pointer type to another, always BitCast
         return ConstantExpr::getCast(CE->getOperand(0), DestTy);
     }
   }
@@ -1632,9 +1634,13 @@
         // gep null, C is equal to C*sizeof(nullty).  If nullty is a known llvm
         // type, we can statically fold this.
         Constant *R = ConstantInt::get(Type::UIntTy, ElSize);
-        R = ConstantExpr::getCast(R, Idx0->getType());
-        R = ConstantExpr::getMul(R, Idx0);
-        return ConstantExpr::getCast(R, C->getType());
+        // We know R is unsigned, Idx0 is signed because it must be an index
+        // through a sequential type (gep pointer operand) which is always
+        // signed.
+        R = ConstantExpr::getInferredCast(R, false, Idx0->getType(), true);
+        R = ConstantExpr::getMul(R, Idx0); // signed multiply
+        // R is a signed integer, C is the GEP pointer so -> IntToPtr
+        return ConstantExpr::getCast(Instruction::IntToPtr, R, C->getType());
       }
     }
   }
@@ -1662,11 +1668,16 @@
         // Otherwise it must be an array.
         if (!Idx0->isNullValue()) {
           const Type *IdxTy = Combined->getType();
-          if (IdxTy != Idx0->getType()) IdxTy = Type::LongTy;
-          Combined =
-            ConstantExpr::get(Instruction::Add,
-                              ConstantExpr::getCast(Idx0, IdxTy),
-                              ConstantExpr::getCast(Combined, IdxTy));
+          if (IdxTy != Idx0->getType()) {
+            Constant *C1 = ConstantExpr::getInferredCast(
+                Idx0, true, Type::LongTy, true);
+            Constant *C2 = ConstantExpr::getInferredCast(
+                Combined, true, Type::LongTy, true);
+            Combined = ConstantExpr::get(Instruction::Add, C1, C2);
+          } else {
+            Combined =
+              ConstantExpr::get(Instruction::Add, Idx0, Combined);
+          }
         }
 
         NewIndices.push_back(Combined);