[ValueTracking] Extend range metadata to call/invoke

Summary:
With this patch, range metadata can be added to call/invoke including
IntrinsicInst. Previously, it could only be added to load.

Rename computeKnownBitsLoad to computeKnownBitsFromRangeMetadata because
range metadata is not only used by load.

Update the language reference to reflect this change.

Test Plan:
Add several tests in range-2.ll to confirm the verifier is happy with
having range metadata on call/invoke.

Add two tests in AddOverFlow.ll to confirm annotating range metadata to
call/invoke can benefit InstCombine.

Reviewers: meheff, nlewycky, reames, hfinkel, eliben

Reviewed By: eliben

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D4187

llvm-svn: 211281

1 files changed, 12 insertions, 5 deletions

diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index 4f48753..9de945e 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -188,7 +188,8 @@ static void computeKnownBitsMul(Value *Op0, Value *Op1, bool NSW,
     KnownOne.setBit(BitWidth - 1);
 }
 
-void llvm::computeKnownBitsLoad(const MDNode &Ranges, APInt &KnownZero) {
+void llvm::computeKnownBitsFromRangeMetadata(const MDNode &Ranges,
+                                             APInt &KnownZero) {
   unsigned BitWidth = KnownZero.getBitWidth();
   unsigned NumRanges = Ranges.getNumOperands() / 2;
   assert(NumRanges >= 1);
@@ -338,7 +339,7 @@ void llvm::computeKnownBits(Value *V, APInt &KnownZero, APInt &KnownOne,
   default: break;
   case Instruction::Load:
     if (MDNode *MD = cast<LoadInst>(I)->getMetadata(LLVMContext::MD_range))
-      computeKnownBitsLoad(*MD, KnownZero);
+      computeKnownBitsFromRangeMetadata(*MD, KnownZero);
     break;
   case Instruction::And: {
     // If either the LHS or the RHS are Zero, the result is zero.
@@ -733,6 +734,12 @@ void llvm::computeKnownBits(Value *V, APInt &KnownZero, APInt &KnownOne,
     break;
   }
   case Instruction::Call:
+  case Instruction::Invoke:
+    if (MDNode *MD = cast<Instruction>(I)->getMetadata(LLVMContext::MD_range))
+      computeKnownBitsFromRangeMetadata(*MD, KnownZero);
+    // If a range metadata is attached to this IntrinsicInst, intersect the
+    // explicit range specified by the metadata and the implicit range of
+    // the intrinsic.
     if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
       switch (II->getIntrinsicID()) {
       default: break;
@@ -742,16 +749,16 @@ void llvm::computeKnownBits(Value *V, APInt &KnownZero, APInt &KnownOne,
         // If this call is undefined for 0, the result will be less than 2^n.
         if (II->getArgOperand(1) == ConstantInt::getTrue(II->getContext()))
           LowBits -= 1;
-        KnownZero = APInt::getHighBitsSet(BitWidth, BitWidth - LowBits);
+        KnownZero |= APInt::getHighBitsSet(BitWidth, BitWidth - LowBits);
         break;
       }
       case Intrinsic::ctpop: {
         unsigned LowBits = Log2_32(BitWidth)+1;
-        KnownZero = APInt::getHighBitsSet(BitWidth, BitWidth - LowBits);
+        KnownZero |= APInt::getHighBitsSet(BitWidth, BitWidth - LowBits);
         break;
       }
       case Intrinsic::x86_sse42_crc32_64_64:
-        KnownZero = APInt::getHighBitsSet(64, 32);
+        KnownZero |= APInt::getHighBitsSet(64, 32);
         break;
       }
     }