From 089a246333eff6b9d01e5d4510809db14371628f Mon Sep 17 00:00:00 2001
From: Duncan Sands <baldrick@free.fr>
Date: Wed, 27 Apr 2011 10:55:12 +0000
Subject: [PATCH] Stop trying to have instcombine preserve LCSSA form: this was
 not effective in avoiding recomputation of LCSSA form; the widespread use of
 instsimplify (which looks through phi nodes) means it was not preserving
 LCSSA form anyway; and instcombine is no longer scheduled in the middle of
 the loop passes so this doesn't matter anymore.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@130301 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/InstCombine/InstCombine.h            | 1 -
 lib/Transforms/InstCombine/InstCombinePHI.cpp       | 3 ---
 lib/Transforms/InstCombine/InstructionCombining.cpp | 2 --
 3 files changed, 6 deletions(-)

diff --git a/lib/Transforms/InstCombine/InstCombine.h b/lib/Transforms/InstCombine/InstCombine.h
index 6b3c1455843..9c70cf89e48 100644
--- a/lib/Transforms/InstCombine/InstCombine.h
+++ b/lib/Transforms/InstCombine/InstCombine.h
@@ -70,7 +70,6 @@ class LLVM_LIBRARY_VISIBILITY InstCombiner
                              : public FunctionPass,
                                public InstVisitor<InstCombiner, Instruction*> {
   TargetData *TD;
-  bool MustPreserveLCSSA;
   bool MadeIRChange;
 public:
   /// Worklist - All of the instructions that need to be simplified.
diff --git a/lib/Transforms/InstCombine/InstCombinePHI.cpp b/lib/Transforms/InstCombine/InstCombinePHI.cpp
index 8419db68f4f..abf61bbaf3a 100644
--- a/lib/Transforms/InstCombine/InstCombinePHI.cpp
+++ b/lib/Transforms/InstCombine/InstCombinePHI.cpp
@@ -774,9 +774,6 @@ Instruction *InstCombiner::SliceUpIllegalIntegerPHI(PHINode &FirstPhi) {
 // PHINode simplification
 //
 Instruction *InstCombiner::visitPHINode(PHINode &PN) {
-  // If LCSSA is around, don't mess with Phi nodes
-  if (MustPreserveLCSSA) return 0;
-
   if (Value *V = SimplifyInstruction(&PN, TD))
     return ReplaceInstUsesWith(PN, V);
 
diff --git a/lib/Transforms/InstCombine/InstructionCombining.cpp b/lib/Transforms/InstCombine/InstructionCombining.cpp
index 4be671f031e..7a84598c3a0 100644
--- a/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -76,7 +76,6 @@ INITIALIZE_PASS(InstCombiner, "instcombine",
                 "Combine redundant instructions", false, false)
 
 void InstCombiner::getAnalysisUsage(AnalysisUsage &AU) const {
-  AU.addPreservedID(LCSSAID);
   AU.setPreservesCFG();
 }
 
@@ -1637,7 +1636,6 @@ bool InstCombiner::DoOneIteration(Function &F, unsigned Iteration) {
 
 
 bool InstCombiner::runOnFunction(Function &F) {
-  MustPreserveLCSSA = mustPreserveAnalysisID(LCSSAID);
   TD = getAnalysisIfAvailable<TargetData>();