[llvm] [BOLT][NFC] Clean up MCF (PR #93065)

[Amir Ayupov via llvm-commits]

https://github.com/aaupov created https://github.com/llvm/llvm-project/pull/93065

Drop unimplemented solveMCF and remnants of it.


>From 2fff4cc812a2a49ed2b34cf45da1f86cb0bf0ebb Mon Sep 17 00:00:00 2001
From: Amir Ayupov <aaupov at fb.com>
Date: Wed, 22 May 2024 08:16:35 -0700
Subject: [PATCH] [BOLT][NFC] Clean up MCF

Drop unimplemented solveMCF and remnants of it.
---
 bolt/include/bolt/Passes/MCF.h | 24 ------------------------
 bolt/lib/Passes/MCF.cpp        | 13 -------------
 2 files changed, 37 deletions(-)

diff --git a/bolt/include/bolt/Passes/MCF.h b/bolt/include/bolt/Passes/MCF.h
index feac7f88ac11e..4b87401498fa5 100644
--- a/bolt/include/bolt/Passes/MCF.h
+++ b/bolt/include/bolt/Passes/MCF.h
@@ -15,14 +15,6 @@ namespace bolt {
 class BinaryFunction;
 class DataflowInfoManager;
 
-enum MCFCostFunction : char {
-  MCF_DISABLE = 0,
-  MCF_LINEAR,
-  MCF_QUADRATIC,
-  MCF_LOG,
-  MCF_BLAMEFTS
-};
-
 /// Implement the idea in "SamplePGO - The Power of Profile Guided Optimizations
 /// without the Usability Burden" by Diego Novillo to make basic block counts
 /// equal if we show that A dominates B, B post-dominates A and they are in the
@@ -33,22 +25,6 @@ void equalizeBBCounts(DataflowInfoManager &Info, BinaryFunction &BF);
 /// we only have bb count.
 void estimateEdgeCounts(BinaryFunction &BF);
 
-/// Entry point for computing a min-cost flow for the CFG with the goal
-/// of fixing the flow of the CFG edges, that is, making sure it obeys the
-/// flow-conservation equation  SumInEdges = SumOutEdges.
-///
-/// To do this, we create an instance of the min-cost flow problem in a
-/// similar way as the one discussed in the work of Roy Levin "Completing
-/// Incomplete Edge Profile by Applying Minimum Cost Circulation Algorithms".
-/// We do a few things differently, though. We don't populate edge counts using
-/// weights coming from a static branch prediction technique and we don't
-/// use the same cost function.
-///
-/// If cost function BlameFTs is used, assign all remaining flow to
-/// fall-throughs. This is used when the sampling is based on taken branches
-/// that do not account for them.
-void solveMCF(BinaryFunction &BF, MCFCostFunction CostFunction);
-
 } // end namespace bolt
 } // end namespace llvm
 
diff --git a/bolt/lib/Passes/MCF.cpp b/bolt/lib/Passes/MCF.cpp
index c3898d2dce989..b2723cd8dcb8b 100644
--- a/bolt/lib/Passes/MCF.cpp
+++ b/bolt/lib/Passes/MCF.cpp
@@ -29,19 +29,10 @@ namespace opts {
 
 extern cl::OptionCategory BoltOptCategory;
 
-extern cl::opt<bool> TimeOpts;
-
 static cl::opt<bool> IterativeGuess(
     "iterative-guess",
     cl::desc("in non-LBR mode, guess edge counts using iterative technique"),
     cl::Hidden, cl::cat(BoltOptCategory));
-
-static cl::opt<bool> UseRArcs(
-    "mcf-use-rarcs",
-    cl::desc("in MCF, consider the possibility of cancelling flow to balance "
-             "edges"),
-    cl::Hidden, cl::cat(BoltOptCategory));
-
 } // namespace opts
 
 namespace llvm {
@@ -462,9 +453,5 @@ void estimateEdgeCounts(BinaryFunction &BF) {
   recalculateBBCounts(BF, /*AllEdges=*/false);
 }
 
-void solveMCF(BinaryFunction &BF, MCFCostFunction CostFunction) {
-  llvm_unreachable("not implemented");
-}
-
 } // namespace bolt
 } // namespace llvm