From 170c519ff84c5b24877b1adfc9f8d29d1b5fd4d7 Mon Sep 17 00:00:00 2001
From: Dan Gohman <gohman@apple.com>
Date: Mon, 26 Jul 2010 18:11:16 +0000
Subject: Remove LCSSA's bogus dependence on LoopSimplify and LoopSimplify's
 bogus dependence on DominanceFrontier. Instead, add an explicit
 DominanceFrontier pass in StandardPasses.h to ensure that it gets scheduled
 at the right time.

Declare that loop unrolling preserves ScalarEvolution, and shuffle some
getAnalysisUsages.

This eliminates one LoopSimplify and one LCCSA run in the standard
compile opts sequence.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@109413 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/Utils/LoopSimplify.cpp | 13 ++++---------
 1 file changed, 4 insertions(+), 9 deletions(-)

(limited to 'lib/Transforms/Utils/LoopSimplify.cpp')

diff --git a/lib/Transforms/Utils/LoopSimplify.cpp b/lib/Transforms/Utils/LoopSimplify.cpp
index 6b1eaad..1571fe8 100644
--- a/lib/Transforms/Utils/LoopSimplify.cpp
+++ b/lib/Transforms/Utils/LoopSimplify.cpp
@@ -77,22 +77,17 @@ namespace {
 
     virtual void getAnalysisUsage(AnalysisUsage &AU) const {
       // We need loop information to identify the loops...
-      AU.addRequiredTransitive<DominatorTree>();
+      AU.addRequired<DominatorTree>();
       AU.addPreserved<DominatorTree>();
 
-      // Request DominanceFrontier now, even though LoopSimplify does
-      // not use it. This allows Pass Manager to schedule Dominance
-      // Frontier early enough such that one LPPassManager can handle
-      // multiple loop transformation passes.
-      AU.addRequired<DominanceFrontier>();
-      AU.addPreserved<DominanceFrontier>();
-
-      AU.addRequiredTransitive<LoopInfo>();
+      AU.addRequired<LoopInfo>();
       AU.addPreserved<LoopInfo>();
 
       AU.addPreserved<AliasAnalysis>();
       AU.addPreserved<ScalarEvolution>();
       AU.addPreservedID(BreakCriticalEdgesID);  // No critical edges added.
+      AU.addPreserved<DominanceFrontier>();
+      AU.addPreservedID(LCSSAID);
     }
 
     /// verifyAnalysis() - Verify LoopSimplifyForm's guarantees.
-- 
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