Fix llvm::ComputeNumSignBits with some operations and llvm.assume

Currently ComputeNumSignBits does early exit while processing some
of the operations (add, sub, mul, and select). This prevents the
function from using AssumptionCacheTracker if passed.

Differential Revision: https://reviews.llvm.org/D49759

llvm-svn: 337936

1 files changed, 7 insertions, 7 deletions

diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index 54828e392d4..04a7b73c22b 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -2337,7 +2337,7 @@ static unsigned ComputeNumSignBitsImpl(const Value *V, unsigned Depth,
 
   case Instruction::Select:
     Tmp = ComputeNumSignBits(U->getOperand(1), Depth + 1, Q);
-    if (Tmp == 1) return 1;  // Early out.
+    if (Tmp == 1) break;
     Tmp2 = ComputeNumSignBits(U->getOperand(2), Depth + 1, Q);
     return std::min(Tmp, Tmp2);
 
@@ -2345,7 +2345,7 @@ static unsigned ComputeNumSignBitsImpl(const Value *V, unsigned Depth,
     // Add can have at most one carry bit.  Thus we know that the output
     // is, at worst, one more bit than the inputs.
     Tmp = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q);
-    if (Tmp == 1) return 1;  // Early out.
+    if (Tmp == 1) break;
 
     // Special case decrementing a value (ADD X, -1):
     if (const auto *CRHS = dyn_cast<Constant>(U->getOperand(1)))
@@ -2365,12 +2365,12 @@ static unsigned ComputeNumSignBitsImpl(const Value *V, unsigned Depth,
       }
 
     Tmp2 = ComputeNumSignBits(U->getOperand(1), Depth + 1, Q);
-    if (Tmp2 == 1) return 1;
+    if (Tmp2 == 1) break;
     return std::min(Tmp, Tmp2)-1;
 
   case Instruction::Sub:
     Tmp2 = ComputeNumSignBits(U->getOperand(1), Depth + 1, Q);
-    if (Tmp2 == 1) return 1;
+    if (Tmp2 == 1) break;
 
     // Handle NEG.
     if (const auto *CLHS = dyn_cast<Constant>(U->getOperand(0)))
@@ -2393,15 +2393,15 @@ static unsigned ComputeNumSignBitsImpl(const Value *V, unsigned Depth,
     // Sub can have at most one carry bit.  Thus we know that the output
     // is, at worst, one more bit than the inputs.
     Tmp = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q);
-    if (Tmp == 1) return 1;  // Early out.
+    if (Tmp == 1) break;
     return std::min(Tmp, Tmp2)-1;
 
   case Instruction::Mul: {
     // The output of the Mul can be at most twice the valid bits in the inputs.
     unsigned SignBitsOp0 = ComputeNumSignBits(U->getOperand(0), Depth + 1, Q);
-    if (SignBitsOp0 == 1) return 1;  // Early out.
+    if (SignBitsOp0 == 1) break;
     unsigned SignBitsOp1 = ComputeNumSignBits(U->getOperand(1), Depth + 1, Q);
-    if (SignBitsOp1 == 1) return 1;
+    if (SignBitsOp1 == 1) break;
     unsigned OutValidBits =
         (TyBits - SignBitsOp0 + 1) + (TyBits - SignBitsOp1 + 1);
     return OutValidBits > TyBits ? 1 : TyBits - OutValidBits + 1;