From 6148c02591bd83da7b957589c4bbf6f9720d503f Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Mon, 3 Dec 2001 17:28:42 +0000
Subject: [PATCH] Initial checkin of indvar stuff

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@1404 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/Scalar/IndVarSimplify.cpp | 69 ++++++++++++++++++++++++
 lib/Transforms/Scalar/Makefile           |  6 +++
 2 files changed, 75 insertions(+)
 create mode 100644 lib/Transforms/Scalar/IndVarSimplify.cpp
 create mode 100644 lib/Transforms/Scalar/Makefile

diff --git a/lib/Transforms/Scalar/IndVarSimplify.cpp b/lib/Transforms/Scalar/IndVarSimplify.cpp
new file mode 100644
index 00000000000..7e465e560e8
--- /dev/null
+++ b/lib/Transforms/Scalar/IndVarSimplify.cpp
@@ -0,0 +1,69 @@
+//===- IndVarSimplify.cpp - Induction Variable Elimination ----------------===//
+//
+// InductionVariableSimplify - Transform induction variables in a program
+//   to all use a single cannonical induction variable per loop.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Scalar/IndVarSimplify.h"
+#include "llvm/Analysis/InductionVariable.h"
+#include "llvm/Analysis/LoopInfo.h"
+#include "llvm/Analysis/Dominators.h"
+#include "llvm/iPHINode.h"
+#include "Support/STLExtras.h"
+
+static bool TransformLoop(cfg::LoopInfo *Loops, cfg::Loop *Loop) {
+  // Transform all subloops before this loop...
+  bool Changed = reduce_apply_bool(Loop->getSubLoops().begin(),
+                                   Loop->getSubLoops().end(),
+                                   std::bind1st(ptr_fun(TransformLoop), Loops));
+  // Get the header node for this loop.  All of the phi nodes that could be
+  // induction variables must live in this basic block.
+  BasicBlock *Header = (BasicBlock*)Loop->getBlocks().front();
+  
+  // Loop over all of the PHI nodes in the basic block, calculating the
+  // induction variables that they represent... stuffing the induction variable
+  // info into a vector...
+  //
+  vector<InductionVariable> IndVars;    // Induction variables for block
+  for (BasicBlock::iterator I = Header->begin(); 
+       PHINode *PN = dyn_cast<PHINode>(*I); ++I)
+    IndVars.push_back(InductionVariable(PN, Loops));
+
+  // If there are phi nodes in this basic block, there can't be indvars...
+  if (IndVars.empty()) return Changed;
+  
+  // Loop over the induction variables, looking for a cannonical induction
+  // variable, and checking to make sure they are not all unknown induction
+  // variables.
+  //
+  bool FoundIndVars = false;
+  InductionVariable *Cannonical = 0;
+  for (unsigned i = 0; i < IndVars.size(); ++i) {
+    if (IndVars[i].InductionType == InductionVariable::Cannonical)
+      Cannonical = &IndVars[i];
+    if (IndVars[i].InductionType != InductionVariable::Unknown)
+      FoundIndVars = true;
+  }
+
+  // No induction variables, bail early... don't add a cannonnical indvar
+  if (!FoundIndVars) return Changed;
+
+  // Okay, we want to convert other induction variables to use a cannonical
+  // indvar.  If we don't have one, add one now...
+  if (!Cannonical) {
+
+  }
+
+  return Changed;
+}
+
+bool InductionVariableSimplify::doit(Method *M) {
+  // Figure out the loop structure of the method...
+  cfg::LoopInfo Loops(M);
+
+  // Induction Variables live in the header nodes of the loops of the method...
+  return reduce_apply_bool(Loops.getTopLevelLoops().begin(),
+                           Loops.getTopLevelLoops().end(),
+                           std::bind1st(std::ptr_fun(TransformLoop), &Loops));
+}
diff --git a/lib/Transforms/Scalar/Makefile b/lib/Transforms/Scalar/Makefile
new file mode 100644
index 00000000000..fed3412dfd3
--- /dev/null
+++ b/lib/Transforms/Scalar/Makefile
@@ -0,0 +1,6 @@
+LEVEL = ../../..
+
+LIBRARYNAME = scalaropts
+
+include $(LEVEL)/Makefile.common
+
-- 
2.34.1