From: Nick Lewycky <nicholas@mxc.ca>
Date: Fri, 11 Jul 2008 08:16:26 +0000 (+0000)
Subject: Document 'mask' in this calculation.
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=7d9843fc374296e85769c820ec9c333be1e74c0a;p=oota-llvm.git

Document 'mask' in this calculation.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@53454 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index 31525102c71..5864a626777 100644
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -5498,6 +5498,7 @@ Instruction *InstCombiner::visitICmpInst(ICmpInst &I) {
         case Instruction::Mul:
           if (ConstantInt *CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) {
             // a * Cst icmp eq/ne b * Cst --> a & Mask icmp b & Mask
+            // Mask = -1 >> count-trailing-zeros(Cst).
             if (!CI->isZero() && !CI->isOne()) {
               const APInt &AP = CI->getValue();
               ConstantInt *Mask = ConstantInt::get(