From 8f08002f03b9dfe8fbf55aecb50352dfe4ad7470 Mon Sep 17 00:00:00 2001
From: Matthias Braun <matze@braunis.de>
Date: Wed, 10 Dec 2014 01:13:08 +0000
Subject: [PATCH] VirtRegMap: Improve block live-in info if subregister
 liveness is available.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223894 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/VirtRegMap.cpp | 41 +++++++++++++++++++++++++++++---------
 1 file changed, 32 insertions(+), 9 deletions(-)

diff --git a/lib/CodeGen/VirtRegMap.cpp b/lib/CodeGen/VirtRegMap.cpp
index 3d72d204ac4..a43e3341a99 100644
--- a/lib/CodeGen/VirtRegMap.cpp
+++ b/lib/CodeGen/VirtRegMap.cpp
@@ -252,15 +252,38 @@ void VirtRegRewriter::addMBBLiveIns() {
     unsigned PhysReg = VRM->getPhys(VirtReg);
     assert(PhysReg != VirtRegMap::NO_PHYS_REG && "Unmapped virtual register.");
 
-    // Scan the segments of LI.
-    for (LiveInterval::const_iterator I = LI.begin(), E = LI.end(); I != E;
-         ++I) {
-      if (!Indexes->findLiveInMBBs(I->start, I->end, LiveIn))
-        continue;
-      for (unsigned i = 0, e = LiveIn.size(); i != e; ++i)
-        if (!LiveIn[i]->isLiveIn(PhysReg))
-          LiveIn[i]->addLiveIn(PhysReg);
-      LiveIn.clear();
+    if (LI.hasSubRanges()) {
+      for (LiveInterval::subrange_iterator S = LI.subrange_begin(),
+           SE = LI.subrange_end(); S != SE; ++S) {
+        for (LiveRange::const_iterator I = S->begin(), E = S->end(); I != E;
+             ++I) {
+          if (!Indexes->findLiveInMBBs(I->start, I->end, LiveIn))
+            continue;
+          for (MCSubRegIndexIterator SR(PhysReg, TRI); SR.isValid(); ++SR) {
+            unsigned SubReg = SR.getSubReg();
+            unsigned SubRegIndex = SR.getSubRegIndex();
+            unsigned SubRegLaneMask = TRI->getSubRegIndexLaneMask(SubRegIndex);
+            if ((SubRegLaneMask & S->LaneMask) == 0)
+              continue;
+            for (unsigned i = 0, e = LiveIn.size(); i != e; ++i) {
+              if (!LiveIn[i]->isLiveIn(SubReg))
+                LiveIn[i]->addLiveIn(SubReg);
+            }
+          }
+          LiveIn.clear();
+        }
+      }
+    } else {
+      // Scan the segments of LI.
+      for (LiveInterval::const_iterator I = LI.begin(), E = LI.end(); I != E;
+           ++I) {
+        if (!Indexes->findLiveInMBBs(I->start, I->end, LiveIn))
+          continue;
+        for (unsigned i = 0, e = LiveIn.size(); i != e; ++i)
+          if (!LiveIn[i]->isLiveIn(PhysReg))
+            LiveIn[i]->addLiveIn(PhysReg);
+        LiveIn.clear();
+      }
     }
   }
 }