Verify variable directly.

[oota-llvm.git] / lib / Analysis / InstructionSimplify.cpp

diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp
index b53ac13925b17a7930f7c32cf103a419278831a8..dbefc2dedb2b41a5a605c4cfff9057c48536a754 100644 (file)
--- a/lib/Analysis/InstructionSimplify.cpp
+++ b/lib/Analysis/InstructionSimplify.cpp
@@ -194,11 +194,10 @@ Value *llvm::SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
   const Type *ITy = GetCompareTy(LHS);
   
   // icmp X, X -> true/false
-  if (LHS == RHS)
+  // X icmp undef -> true/false.  For example, icmp ugt %X, undef -> false
+  // because X could be 0.
+  if (LHS == RHS || isa<UndefValue>(RHS))
     return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred));
-
-  if (isa<UndefValue>(RHS))                  // X icmp undef -> undef
-    return UndefValue::get(ITy);
   
   // icmp <global/alloca*/null>, <global/alloca*/null> - Global/Stack value
   // addresses never equal each other!  We already know that Op0 != Op1.
@@ -283,12 +282,67 @@ Value *llvm::SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
         // True if unordered.
         return ConstantInt::getTrue(CFP->getContext());
       }
+      // Check whether the constant is an infinity.
+      if (CFP->getValueAPF().isInfinity()) {
+        if (CFP->getValueAPF().isNegative()) {
+          switch (Pred) {
+          case FCmpInst::FCMP_OLT:
+            // No value is ordered and less than negative infinity.
+            return ConstantInt::getFalse(CFP->getContext());
+          case FCmpInst::FCMP_UGE:
+            // All values are unordered with or at least negative infinity.
+            return ConstantInt::getTrue(CFP->getContext());
+          default:
+            break;
+          }
+        } else {
+          switch (Pred) {
+          case FCmpInst::FCMP_OGT:
+            // No value is ordered and greater than infinity.
+            return ConstantInt::getFalse(CFP->getContext());
+          case FCmpInst::FCMP_ULE:
+            // All values are unordered with and at most infinity.
+            return ConstantInt::getTrue(CFP->getContext());
+          default:
+            break;
+          }
+        }
+      }
     }
   }
   
   return 0;
 }
 
+/// SimplifySelectInst - Given operands for a SelectInst, see if we can fold
+/// the result.  If not, this returns null.
+Value *llvm::SimplifySelectInst(Value *CondVal, Value *TrueVal, Value *FalseVal,
+                                const TargetData *TD) {
+  // select true, X, Y  -> X
+  // select false, X, Y -> Y
+  if (ConstantInt *CB = dyn_cast<ConstantInt>(CondVal))
+    return CB->getZExtValue() ? TrueVal : FalseVal;
+  
+  // select C, X, X -> X
+  if (TrueVal == FalseVal)
+    return TrueVal;
+  
+  if (isa<UndefValue>(TrueVal))   // select C, undef, X -> X
+    return FalseVal;
+  if (isa<UndefValue>(FalseVal))   // select C, X, undef -> X
+    return TrueVal;
+  if (isa<UndefValue>(CondVal)) {  // select undef, X, Y -> X or Y
+    if (isa<Constant>(TrueVal))
+      return TrueVal;
+    return FalseVal;
+  }
+  
+  
+  
+  return 0;
+}
+
+
 /// SimplifyGEPInst - Given operands for an GetElementPtrInst, see if we can
 /// fold the result.  If not, this returns null.
 Value *llvm::SimplifyGEPInst(Value *const *Ops, unsigned NumOps,
@@ -366,6 +420,9 @@ Value *llvm::SimplifyInstruction(Instruction *I, const TargetData *TD) {
   case Instruction::FCmp:
     return SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(),
                             I->getOperand(0), I->getOperand(1), TD);
+  case Instruction::Select:
+    return SimplifySelectInst(I->getOperand(0), I->getOperand(1),
+                              I->getOperand(2), TD);
   case Instruction::GetElementPtr: {
     SmallVector<Value*, 8> Ops(I->op_begin(), I->op_end());
     return SimplifyGEPInst(&Ops[0], Ops.size(), TD);