Fix ICmpInst::makeConstantRange to use ConstantRange's API properly

in the case of empty and full ranges.

llvm-svn: 94548

1 files changed, 30 insertions, 2 deletions

diff --git a/llvm/lib/VMCore/Instructions.cpp b/llvm/lib/VMCore/Instructions.cpp
index e2b920e6f5b..eee160e488b 100644
--- a/llvm/lib/VMCore/Instructions.cpp
+++ b/llvm/lib/VMCore/Instructions.cpp
@@ -2865,25 +2865,53 @@ ICmpInst::makeConstantRange(Predicate pred, const APInt &C) {
   default: llvm_unreachable("Invalid ICmp opcode to ConstantRange ctor!");
   case ICmpInst::ICMP_EQ: Upper++; break;
   case ICmpInst::ICMP_NE: Lower++; break;
-  case ICmpInst::ICMP_ULT: Lower = APInt::getMinValue(BitWidth); break;
-  case ICmpInst::ICMP_SLT: Lower = APInt::getSignedMinValue(BitWidth); break;
+  case ICmpInst::ICMP_ULT:
+    Lower = APInt::getMinValue(BitWidth);
+    // Check for an empty-set condition.
+    if (Lower == Upper)
+      return ConstantRange(BitWidth, /*isFullSet=*/false);
+    break;
+  case ICmpInst::ICMP_SLT:
+    Lower = APInt::getSignedMinValue(BitWidth);
+    // Check for an empty-set condition.
+    if (Lower == Upper)
+      return ConstantRange(BitWidth, /*isFullSet=*/false);
+    break;
   case ICmpInst::ICMP_UGT: 
     Lower++; Upper = APInt::getMinValue(BitWidth);        // Min = Next(Max)
+    // Check for an empty-set condition.
+    if (Lower == Upper)
+      return ConstantRange(BitWidth, /*isFullSet=*/false);
     break;
   case ICmpInst::ICMP_SGT:
     Lower++; Upper = APInt::getSignedMinValue(BitWidth);  // Min = Next(Max)
+    // Check for an empty-set condition.
+    if (Lower == Upper)
+      return ConstantRange(BitWidth, /*isFullSet=*/false);
     break;
   case ICmpInst::ICMP_ULE: 
     Lower = APInt::getMinValue(BitWidth); Upper++; 
+    // Check for a full-set condition.
+    if (Lower == Upper)
+      return ConstantRange(BitWidth, /*isFullSet=*/true);
     break;
   case ICmpInst::ICMP_SLE: 
     Lower = APInt::getSignedMinValue(BitWidth); Upper++; 
+    // Check for a full-set condition.
+    if (Lower == Upper)
+      return ConstantRange(BitWidth, /*isFullSet=*/true);
     break;
   case ICmpInst::ICMP_UGE:
     Upper = APInt::getMinValue(BitWidth);        // Min = Next(Max)
+    // Check for a full-set condition.
+    if (Lower == Upper)
+      return ConstantRange(BitWidth, /*isFullSet=*/true);
     break;
   case ICmpInst::ICMP_SGE:
     Upper = APInt::getSignedMinValue(BitWidth);  // Min = Next(Max)
+    // Check for a full-set condition.
+    if (Lower == Upper)
+      return ConstantRange(BitWidth, /*isFullSet=*/true);
     break;
   }
   return ConstantRange(Lower, Upper);