From 1d338fc6a4c6f2711d90350ce18e8cdff58be7eb Mon Sep 17 00:00:00 2001
From: Owen Anderson <resistor@mac.com>
Date: Tue, 7 Oct 2008 20:22:28 +0000
Subject: [PATCH] Add an option to enable StrongPHIElimination, for ease of
 testing.

llvm-svn: 57259
---
 llvm/include/llvm/Target/TargetOptions.h       | 4 ++++
 llvm/lib/CodeGen/LiveIntervalAnalysis.cpp      | 9 +++++++--
 llvm/lib/CodeGen/RegAllocLinearScan.cpp        | 3 +++
 llvm/lib/CodeGen/SimpleRegisterCoalescing.cpp  | 6 +++++-
 llvm/lib/CodeGen/TwoAddressInstructionPass.cpp | 6 +++++-
 llvm/lib/Target/TargetMachine.cpp              | 7 +++++++
 6 files changed, 31 insertions(+), 4 deletions(-)

diff --git a/llvm/include/llvm/Target/TargetOptions.h b/llvm/include/llvm/Target/TargetOptions.h
index b7b27a47ed20..2419376c5396 100644
--- a/llvm/include/llvm/Target/TargetOptions.h
+++ b/llvm/include/llvm/Target/TargetOptions.h
@@ -102,6 +102,10 @@ namespace llvm {
   /// which trades away generated code quality in favor of reducing
   /// compile time.
   extern bool EnableFastISel;
+  
+  /// StrongPHIElim - This flag enables more aggressive PHI elimination
+  /// wth earlier copy coalescing.
+  extern bool StrongPHIElim;
 
 } // End llvm namespace
 
diff --git a/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp b/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
index 98ff22ce6e0c..ff247ad4597f 100644
--- a/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
+++ b/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -30,6 +30,7 @@
 #include "llvm/Target/TargetRegisterInfo.h"
 #include "llvm/Target/TargetInstrInfo.h"
 #include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetOptions.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/ADT/Statistic.h"
@@ -67,8 +68,12 @@ void LiveIntervals::getAnalysisUsage(AnalysisUsage &AU) const {
   AU.addRequired<LiveVariables>();
   AU.addPreservedID(MachineLoopInfoID);
   AU.addPreservedID(MachineDominatorsID);
-  AU.addPreservedID(PHIEliminationID);
-  AU.addRequiredID(PHIEliminationID);
+  
+  if (!StrongPHIElim) {
+    AU.addPreservedID(PHIEliminationID);
+    AU.addRequiredID(PHIEliminationID);
+  }
+  
   AU.addRequiredID(TwoAddressInstructionPassID);
   MachineFunctionPass::getAnalysisUsage(AU);
 }
diff --git a/llvm/lib/CodeGen/RegAllocLinearScan.cpp b/llvm/lib/CodeGen/RegAllocLinearScan.cpp
index 7291e12bbea4..31e47f96b4cd 100644
--- a/llvm/lib/CodeGen/RegAllocLinearScan.cpp
+++ b/llvm/lib/CodeGen/RegAllocLinearScan.cpp
@@ -26,6 +26,7 @@
 #include "llvm/CodeGen/RegisterCoalescer.h"
 #include "llvm/Target/TargetRegisterInfo.h"
 #include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetOptions.h"
 #include "llvm/Target/TargetInstrInfo.h"
 #include "llvm/ADT/EquivalenceClasses.h"
 #include "llvm/ADT/Statistic.h"
@@ -107,6 +108,8 @@ namespace {
 
     virtual void getAnalysisUsage(AnalysisUsage &AU) const {
       AU.addRequired<LiveIntervals>();
+      if (StrongPHIElim)
+        AU.addRequiredID(StrongPHIEliminationID);
       // Make sure PassManager knows which analyses to make available
       // to coalescing and which analyses coalescing invalidates.
       AU.addRequiredTransitive<RegisterCoalescer>();
diff --git a/llvm/lib/CodeGen/SimpleRegisterCoalescing.cpp b/llvm/lib/CodeGen/SimpleRegisterCoalescing.cpp
index b6aae65f1e92..0a77826a24eb 100644
--- a/llvm/lib/CodeGen/SimpleRegisterCoalescing.cpp
+++ b/llvm/lib/CodeGen/SimpleRegisterCoalescing.cpp
@@ -25,6 +25,7 @@
 #include "llvm/CodeGen/RegisterCoalescer.h"
 #include "llvm/Target/TargetInstrInfo.h"
 #include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetOptions.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/ADT/SmallSet.h"
@@ -72,7 +73,10 @@ void SimpleRegisterCoalescing::getAnalysisUsage(AnalysisUsage &AU) const {
   AU.addRequired<MachineLoopInfo>();
   AU.addPreserved<MachineLoopInfo>();
   AU.addPreservedID(MachineDominatorsID);
-  AU.addPreservedID(PHIEliminationID);
+  if (StrongPHIElim)
+    AU.addPreservedID(StrongPHIEliminationID);
+  else
+    AU.addPreservedID(PHIEliminationID);
   AU.addPreservedID(TwoAddressInstructionPassID);
   MachineFunctionPass::getAnalysisUsage(AU);
 }
diff --git a/llvm/lib/CodeGen/TwoAddressInstructionPass.cpp b/llvm/lib/CodeGen/TwoAddressInstructionPass.cpp
index dbfd770b733c..7d9e44ab2045 100644
--- a/llvm/lib/CodeGen/TwoAddressInstructionPass.cpp
+++ b/llvm/lib/CodeGen/TwoAddressInstructionPass.cpp
@@ -37,6 +37,7 @@
 #include "llvm/Target/TargetRegisterInfo.h"
 #include "llvm/Target/TargetInstrInfo.h"
 #include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetOptions.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/ADT/BitVector.h"
@@ -76,7 +77,10 @@ namespace {
       AU.addPreserved<LiveVariables>();
       AU.addPreservedID(MachineLoopInfoID);
       AU.addPreservedID(MachineDominatorsID);
-      AU.addPreservedID(PHIEliminationID);
+      if (StrongPHIElim)
+        AU.addPreservedID(StrongPHIEliminationID);
+      else
+        AU.addPreservedID(PHIEliminationID);
       MachineFunctionPass::getAnalysisUsage(AU);
     }
 
diff --git a/llvm/lib/Target/TargetMachine.cpp b/llvm/lib/Target/TargetMachine.cpp
index 90efb74bc91a..c05efd041ead 100644
--- a/llvm/lib/Target/TargetMachine.cpp
+++ b/llvm/lib/Target/TargetMachine.cpp
@@ -39,6 +39,7 @@ namespace llvm {
   bool RealignStack;
   bool VerboseAsm;
   bool DisableJumpTables;
+  bool StrongPHIElim;
 }
 
 static cl::opt<bool, true> PrintCode("print-machineinstrs",
@@ -157,6 +158,12 @@ DisableSwitchTables(cl::Hidden, "disable-jump-tables",
            cl::location(DisableJumpTables),
            cl::init(false));
 
+static cl::opt<bool, true>
+EnableStrongPHIElim(cl::Hidden, "strong-phi-elim",
+           cl::desc("Use strong PHI elimination."),
+           cl::location(StrongPHIElim),
+           cl::init(false));
+
 //---------------------------------------------------------------------------
 // TargetMachine Class
 //