[PATCH] D48026: [ScopHelper] Provide support for recognising collective invariant loads

[SAHIL GIRISH YERAWAR via Phabricator via llvm-commits]

cs15btech11044 created this revision.
cs15btech11044 added reviewers: bollu, philip.pfaffe, Meinersbur.
Herald added a subscriber: llvm-commits.

This patch aims to provide support for detecting load patterns which are collectively invariant but right now `isHoistableLoad()`is checking each load instruction individually which cannot detect the load pattern as a whole.


Repository:
  rPLO Polly

https://reviews.llvm.org/D48026

Files:
  include/polly/Support/ScopHelper.h
  lib/Analysis/ScopDetection.cpp
  lib/Support/ScopHelper.cpp


Index: lib/Support/ScopHelper.cpp
===================================================================
--- lib/Support/ScopHelper.cpp
+++ lib/Support/ScopHelper.cpp
@@ -442,9 +442,22 @@
 }
 
 bool polly::isHoistableLoad(LoadInst *LInst, Region &R, LoopInfo &LI,
-                            ScalarEvolution &SE, const DominatorTree &DT) {
+                            ScalarEvolution &SE, const DominatorTree &DT,
+                            InvariantLoadsSetTy &RequiredILS) {
   Loop *L = LI.getLoopFor(LInst->getParent());
   auto *Ptr = LInst->getPointerOperand();
+
+  auto *ptr_operand = dyn_cast<Instruction>(Ptr);
+  if (ptr_operand && isa<GetElementPtrInst>(ptr_operand)) {
+    auto *prev_inst = dyn_cast<Instruction>(ptr_operand->getOperand(0));
+    if (prev_inst && isa<LoadInst>(prev_inst)) {
+      auto *lt = dyn_cast<LoadInst>(prev_inst);
+      for (int i = 0; i < RequiredILS.size(); i++)
+        if (RequiredILS[i] == lt)
+          return true;
+    }
+  }
+
   const SCEV *PtrSCEV = SE.getSCEVAtScope(Ptr, L);
   while (L && R.contains(L)) {
     if (!SE.isLoopInvariant(PtrSCEV, L))
Index: lib/Analysis/ScopDetection.cpp
===================================================================
--- lib/Analysis/ScopDetection.cpp
+++ lib/Analysis/ScopDetection.cpp
@@ -484,7 +484,7 @@
     if (Context.RequiredILS.count(Load))
       continue;
 
-    if (!isHoistableLoad(Load, CurRegion, LI, SE, DT))
+    if (!isHoistableLoad(Load, CurRegion, LI, SE, DT, RequiredILS))
       return false;
 
     for (auto NonAffineRegion : Context.NonAffineSubRegionSet) {
@@ -938,7 +938,7 @@
       auto *V = dyn_cast<Value>(Unknown->getValue());
       if (auto *Load = dyn_cast<LoadInst>(V)) {
         if (Context.CurRegion.contains(Load) &&
-            isHoistableLoad(Load, CurRegion, LI, SE, DT))
+            isHoistableLoad(Load, CurRegion, LI, SE, DT, Context.RequiredILS))
           Context.RequiredILS.insert(Load);
         continue;
       }
@@ -1152,7 +1152,8 @@
         Instruction *Inst = dyn_cast<Instruction>(Ptr.getValue());
         if (Inst && Context.CurRegion.contains(Inst)) {
           auto *Load = dyn_cast<LoadInst>(Inst);
-          if (Load && isHoistableLoad(Load, Context.CurRegion, LI, SE, DT)) {
+          if (Load && isHoistableLoad(Load, Context.CurRegion, LI, SE, DT,
+                                      Context.RequiredILS)) {
             Context.RequiredILS.insert(Load);
             continue;
           }
Index: include/polly/Support/ScopHelper.h
===================================================================
--- include/polly/Support/ScopHelper.h
+++ include/polly/Support/ScopHelper.h
@@ -394,7 +394,8 @@
 ///
 /// @return True if @p LInst can be hoisted in @p R.
 bool isHoistableLoad(llvm::LoadInst *LInst, llvm::Region &R, llvm::LoopInfo &LI,
-                     llvm::ScalarEvolution &SE, const llvm::DominatorTree &DT);
+                     llvm::ScalarEvolution &SE, const llvm::DominatorTree &DT,
+                     InvariantLoadsSetTy &RequiredILS);
 
 /// Return true iff @p V is an intrinsic that we ignore during code
 ///        generation.


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