From 883f2fab47ca2f7f6efebb10a5e859f5804bed07 Mon Sep 17 00:00:00 2001 From: Chandler Carruth Date: Mon, 14 Nov 2011 06:51:49 +0000 Subject: [PATCH] Add a cautionary note to this API. It was not at all obvious to me how expensive the most useful interface to this analysis is. Fun story -- it's also not correct. That's getting fixed in another patch. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@144523 91177308-0d34-0410-b5e6-96231b3b80d8 --- include/llvm/CodeGen/MachineBranchProbabilityInfo.h | 3 +++ 1 file changed, 3 insertions(+) diff --git a/include/llvm/CodeGen/MachineBranchProbabilityInfo.h b/include/llvm/CodeGen/MachineBranchProbabilityInfo.h index d9673e2197c..39d2f32982b 100644 --- a/include/llvm/CodeGen/MachineBranchProbabilityInfo.h +++ b/include/llvm/CodeGen/MachineBranchProbabilityInfo.h @@ -62,6 +62,9 @@ public: // Return a probability as a fraction between 0 (0% probability) and // 1 (100% probability), however the value is never equal to 0, and can be 1 // only iff SRC block has only one successor. + // NB: This routine's complexity is linear on the number of successors of + // Src. Querying sequentially for each successor's probability is a quadratic + // query pattern. BranchProbability getEdgeProbability(MachineBasicBlock *Src, MachineBasicBlock *Dst) const;