From f8a63a1507cfc20dbb74dc38ccbdc64460d9f547 Mon Sep 17 00:00:00 2001
From: Jakob Stoklund Olesen <stoklund@2pi.dk>
Date: Wed, 4 Jul 2012 00:09:54 +0000
Subject: Add an experimental early if-conversion pass, off by default.

This pass performs if-conversion on SSA form machine code by
speculatively executing both sides of the branch and using a cmov
instruction to select the result. This can help lower the number of
branch mispredictions on architectures like x86 that don't have
predicable instructions.

The current implementation is very aggressive, and causes regressions on
mosts tests. It needs good heuristics that have yet to be implemented.

llvm-svn: 159694
---
 llvm/lib/CodeGen/CodeGen.cpp | 1 +
 1 file changed, 1 insertion(+)

(limited to 'llvm/lib/CodeGen/CodeGen.cpp')

diff --git a/llvm/lib/CodeGen/CodeGen.cpp b/llvm/lib/CodeGen/CodeGen.cpp
index 7b015d850d3..fb2c2e83f1b 100644
--- a/llvm/lib/CodeGen/CodeGen.cpp
+++ b/llvm/lib/CodeGen/CodeGen.cpp
@@ -23,6 +23,7 @@ void llvm::initializeCodeGen(PassRegistry &Registry) {
   initializeCalculateSpillWeightsPass(Registry);
   initializeCodePlacementOptPass(Registry);
   initializeDeadMachineInstructionElimPass(Registry);
+  initializeEarlyIfConverterPass(Registry);
   initializeExpandPostRAPass(Registry);
   initializeExpandISelPseudosPass(Registry);
   initializeFinalizeMachineBundlesPass(Registry);
-- 
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