From 99b7a993762a926f042e7cb582e45c577ede596d Mon Sep 17 00:00:00 2001 From: Nadav Rotem Date: Mon, 24 Dec 2012 05:51:12 +0000 Subject: [PATCH] Update the docs of the cost model. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171016 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Analysis/CostModel.cpp | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/lib/Analysis/CostModel.cpp b/lib/Analysis/CostModel.cpp index 0d0a8933b35..28d6a864707 100644 --- a/lib/Analysis/CostModel.cpp +++ b/lib/Analysis/CostModel.cpp @@ -8,9 +8,12 @@ //===----------------------------------------------------------------------===// // // This file defines the cost model analysis. It provides a very basic cost -// estimation for LLVM-IR. The cost result can be thought of as cycles, but it -// is really unit-less. The estimated cost is ment to be used for comparing -// alternatives. +// estimation for LLVM-IR. This analysis uses the services of the codegen +// to approximate the cost of any IR instruction when lowered to machine +// instructions. The cost results are unit-less and the cost number represents +// the throughput of the machine assuming that all loads hit the cache, all +// branches are predicted, etc. The cost numbers can be added in order to +// compare two or more transformation alternatives. // //===----------------------------------------------------------------------===//