From 0247b97b82ff5b95a5d9d35bd0b8978a638f2050 Mon Sep 17 00:00:00 2001
From: Fred Chow <fred.chow@yandex.com>
Date: Fri, 4 Feb 2022 16:13:14 -0800
Subject: [PATCH] in ssupre for restores, if there is redundancy among the
 saves (assumed true for now), disable the optimization to insert restores as
 late as possible

---
 src/mapleall/maple_be/include/cg/cg_ssu_pre.h |  4 +-
 src/mapleall/maple_be/src/cg/cg_ssu_pre.cpp   | 39 +++++++++++++------
 2 files changed, 31 insertions(+), 12 deletions(-)

diff --git a/src/mapleall/maple_be/include/cg/cg_ssu_pre.h b/src/mapleall/maple_be/include/cg/cg_ssu_pre.h
index 2e9f67c2be..899b8e837a 100644
--- a/src/mapleall/maple_be/include/cg/cg_ssu_pre.h
+++ b/src/mapleall/maple_be/include/cg/cg_ssu_pre.h
@@ -155,7 +155,7 @@ class SKillOcc : public SOcc {
 
 class SSUPre {
  public:
-  SSUPre(CGFunc *cgfunc, PostDomAnalysis *pd, MemPool *memPool, SPreWorkCand *wkcand, bool enDebug)
+  SSUPre(CGFunc *cgfunc, PostDomAnalysis *pd, MemPool *memPool, SPreWorkCand *wkcand, bool redSaves, bool enDebug)
       : cgFunc(cgfunc),
         pdom(pd),
         spreMp(memPool),
@@ -169,6 +169,7 @@ class SSUPre {
         allOccs(spreAllocator.Adapter()),
         lambdaOccs(spreAllocator.Adapter()),
         entryOccs(spreAllocator.Adapter()),
+        redundanciesAmongSaves(redSaves), 
         enabledDebug(enDebug) {
     CreateEntryOcc(cgfunc->GetFirstBB());
   }
@@ -227,6 +228,7 @@ class SSUPre {
   MapleVector<SOcc*> allOccs;
   MapleVector<SLambdaOcc*> lambdaOccs;
   MapleVector<SEntryOcc*> entryOccs;
+  bool redundanciesAmongSaves; // if there is redundancy among the input saves
   bool enabledDebug;
 };
 
diff --git a/src/mapleall/maple_be/src/cg/cg_ssu_pre.cpp b/src/mapleall/maple_be/src/cg/cg_ssu_pre.cpp
index 46508d2885..41b3d7df64 100644
--- a/src/mapleall/maple_be/src/cg/cg_ssu_pre.cpp
+++ b/src/mapleall/maple_be/src/cg/cg_ssu_pre.cpp
@@ -521,22 +521,38 @@ void SSUPre::PropagateNotAvail(BB *bb, std::set<BB*, BBIdCmp> *visitedBBs) {
 }
 
 void SSUPre::FormReals() {
-  std::set<BB*, BBIdCmp> visitedBBs;
-  fullyAvailBBs[cgFunc->GetCommonExitBB()->GetId()] = false;
-  PropagateNotAvail(cgFunc->GetFirstBB(), &visitedBBs);
-
-  for (uint32 i = 0; i < pdom->GetPdtPreOrderSize(); i++) {
-    BBId bbid = pdom->GetPdtPreOrderItem(i);
-    BB *cgbb = cgFunc->GetAllBBs()[bbid];
-    if (fullyAvailBBs[cgbb->GetId()]) {
-      SRealOcc *realOcc = spreMp->New<SRealOcc>(cgbb);
-      realOccs.push_back(realOcc);
+  if (redundanciesAmongSaves) {
+    for (uint32 i = 0; i < pdom->GetPdtPreOrderSize(); i++) {
+      BBId bbid = pdom->GetPdtPreOrderItem(i);
+      BB *cgbb = cgFunc->GetAllBBs()[bbid];
       if (workCand->saveBBs.count(cgbb->GetId()) != 0) {
+        SRealOcc *realOcc = spreMp->New<SRealOcc>(cgbb);
+        realOccs.push_back(realOcc);
         SKillOcc *killOcc = spreMp->New<SKillOcc>(cgbb);
         realOccs.push_back(killOcc);
+      } else if (workCand->occBBs.count(cgbb->GetId()) != 0) {
+        SRealOcc *realOcc = spreMp->New<SRealOcc>(cgbb);
+        realOccs.push_back(realOcc);
+      }
+    }
+  } else {
+    std::set<BB*, BBIdCmp> visitedBBs;
+    fullyAvailBBs[cgFunc->GetCommonExitBB()->GetId()] = false;
+    PropagateNotAvail(cgFunc->GetFirstBB(), &visitedBBs);
+    for (uint32 i = 0; i < pdom->GetPdtPreOrderSize(); i++) {
+      BBId bbid = pdom->GetPdtPreOrderItem(i);
+      BB *cgbb = cgFunc->GetAllBBs()[bbid];
+      if (fullyAvailBBs[cgbb->GetId()]) {
+        SRealOcc *realOcc = spreMp->New<SRealOcc>(cgbb);
+        realOccs.push_back(realOcc);
+        if (workCand->saveBBs.count(cgbb->GetId()) != 0) {
+          SKillOcc *killOcc = spreMp->New<SKillOcc>(cgbb);
+          realOccs.push_back(killOcc);
+        }
       }
     }
   }
+
   if (enabledDebug) {
     LogInfo::MapleLogger() << "Placement Optimization for callee-save restores" << '\n';
     LogInfo::MapleLogger() << "-----------------------------------------------" << '\n';
@@ -577,7 +593,8 @@ void SSUPre::ApplySSUPre() {
 
 void DoRestorePlacementOpt(CGFunc *f, PostDomAnalysis *pdom, SPreWorkCand *workCand) {
   MemPool *tempMP = memPoolCtrler.NewMemPool("cg_ssu_pre", true);
-  SSUPre cgssupre(f, pdom, tempMP, workCand, false/*enabledDebug*/);
+  SSUPre cgssupre(f, pdom, tempMP, workCand, true/*redundanciesAmongSaves*/,
+                  false/*enabledDebug*/);
 
   cgssupre.ApplySSUPre();
 
-- 
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