Add a method to ScalarEvolution for telling it when a loop has been

modified in a way that may effect the trip count calculation. Change
IndVars to use this method when it rewrites pointer or floating-point
induction variables instead of using a doInitialization method to
sneak these changes in before ScalarEvolution has a chance to see
the loop. This eliminates the need for LoopPass to depend on
ScalarEvolution.

llvm-svn: 64810

2 files changed, 16 insertions, 3 deletions

diff --git a/llvm/lib/Analysis/LoopPass.cpp b/llvm/lib/Analysis/LoopPass.cpp
index da9ac2749a0..c45c2ef4c0b 100644
--- a/llvm/lib/Analysis/LoopPass.cpp
+++ b/llvm/lib/Analysis/LoopPass.cpp
@@ -14,7 +14,6 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Analysis/LoopPass.h"
-#include "llvm/Analysis/ScalarEvolution.h"
 using namespace llvm;
 
 //===----------------------------------------------------------------------===//
@@ -173,8 +172,6 @@ void LPPassManager::getAnalysisUsage(AnalysisUsage &Info) const {
   // LPPassManager needs LoopInfo. In the long term LoopInfo class will 
   // become part of LPPassManager.
   Info.addRequired<LoopInfo>();
-  // Used by IndVar doInitialization.
-  Info.addRequired<ScalarEvolution>();
   Info.setPreservesAll();
 }
 
diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index 4e0dba7e04b..54f27653542 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -1453,6 +1453,11 @@ namespace {
     /// an analyzable loop-invariant iteration count.
     bool hasLoopInvariantIterationCount(const Loop *L);
 
+    /// forgetLoopIterationCount - This method should be called by the
+    /// client when it has changed a loop in a way that may effect
+    /// ScalarEvolution's ability to compute a trip count.
+    void forgetLoopIterationCount(const Loop *L);
+
     /// getIterationCount - If the specified loop has a predictable iteration
     /// count, return it.  Note that it is not valid to call this method on a
     /// loop without a loop-invariant iteration count.
@@ -1931,6 +1936,13 @@ SCEVHandle ScalarEvolutionsImpl::getIterationCount(const Loop *L) {
   return I->second;
 }
 
+/// forgetLoopIterationCount - This method should be called by the
+/// client when it has changed a loop in a way that may effect
+/// ScalarEvolution's ability to compute a trip count.
+void ScalarEvolutionsImpl::forgetLoopIterationCount(const Loop *L) {
+  IterationCounts.erase(L);
+}
+
 /// ComputeIterationCount - Compute the number of times the specified loop
 /// will iterate.
 SCEVHandle ScalarEvolutionsImpl::ComputeIterationCount(const Loop *L) {
@@ -3091,6 +3103,10 @@ bool ScalarEvolution::hasLoopInvariantIterationCount(const Loop *L) const {
   return !isa<SCEVCouldNotCompute>(getIterationCount(L));
 }
 
+void ScalarEvolution::forgetLoopIterationCount(const Loop *L) {
+  return ((ScalarEvolutionsImpl*)Impl)->forgetLoopIterationCount(L);
+}
+
 SCEVHandle ScalarEvolution::getSCEVAtScope(Value *V, const Loop *L) const {
   return ((ScalarEvolutionsImpl*)Impl)->getSCEVAtScope(getSCEV(V), L);
 }