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.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@64810 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/IndVarSimplify.cpp b/lib/Transforms/Scalar/IndVarSimplify.cpp
index dc4f10b..4cfe359 100644
--- a/lib/Transforms/Scalar/IndVarSimplify.cpp
+++ b/lib/Transforms/Scalar/IndVarSimplify.cpp
@@ -74,8 +74,8 @@
static char ID; // Pass identification, replacement for typeid
IndVarSimplify() : LoopPass(&ID) {}
- bool runOnLoop(Loop *L, LPPassManager &LPM);
- bool doInitialization(Loop *L, LPPassManager &LPM);
+ virtual bool runOnLoop(Loop *L, LPPassManager &LPM);
+
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequired<ScalarEvolution>();
AU.addRequiredID(LCSSAID);
@@ -88,6 +88,8 @@
private:
+ void RewriteNonIntegerIVs(Loop *L);
+
void EliminatePointerRecurrence(PHINode *PN, BasicBlock *Preheader,
SmallPtrSet<Instruction*, 16> &DeadInsts);
void LinearFunctionTestReplace(Loop *L, SCEVHandle IterationCount,
@@ -411,16 +413,13 @@
DeleteTriviallyDeadInstructions(InstructionsToDelete);
}
-bool IndVarSimplify::doInitialization(Loop *L, LPPassManager &LPM) {
-
- Changed = false;
+void IndVarSimplify::RewriteNonIntegerIVs(Loop *L) {
// First step. Check to see if there are any trivial GEP pointer recurrences.
// If there are, change them into integer recurrences, permitting analysis by
// the SCEV routines.
//
BasicBlock *Header = L->getHeader();
BasicBlock *Preheader = L->getLoopPreheader();
- SE = &LPM.getAnalysis<ScalarEvolution>();
SmallPtrSet<Instruction*, 16> DeadInsts;
for (BasicBlock::iterator I = Header->begin(); isa<PHINode>(I); ++I) {
@@ -431,10 +430,14 @@
HandleFloatingPointIV(L, PN, DeadInsts);
}
+ // If the loop previously had a pointer or floating-point IV, ScalarEvolution
+ // may not have been able to compute a trip count. Now that we've done some
+ // re-writing, the trip count may be computable.
+ if (Changed)
+ SE->forgetLoopIterationCount(L);
+
if (!DeadInsts.empty())
DeleteTriviallyDeadInstructions(DeadInsts);
-
- return Changed;
}
/// getEffectiveIndvarType - Determine the widest type that the
@@ -594,8 +597,12 @@
bool IndVarSimplify::runOnLoop(Loop *L, LPPassManager &LPM) {
LI = &getAnalysis<LoopInfo>();
SE = &getAnalysis<ScalarEvolution>();
-
Changed = false;
+
+ // If there are any floating-point or pointer recurrences, attempt to
+ // transform them to use integer recurrences.
+ RewriteNonIntegerIVs(L);
+
BasicBlock *Header = L->getHeader();
BasicBlock *ExitingBlock = L->getExitingBlock();
SmallPtrSet<Instruction*, 16> DeadInsts;