commit 0d80a2b616913f1706e648b4b05513c1e642be26
author Cherry Zhang <cherryyz@google.com> Mon Dec 10 15:14:52 2018 -0500
committer Cherry Zhang <cherryyz@google.com> Tue Dec 11 16:18:02 2018 +0000
tree c7b60cbe27b3bc0c080cdea3415610468bd5ffed
parent 403842538352d01355650fa30817c715649b1f93

passes: don't treat frame dead at landing pad

Treating the frame dead at a landing pad is problematic: at
least, function results need to be live, in case there is a
deferred function that recovers.

Change-Id: Ifb3f88ccb0d6cc30b3d09a1190f2c69fa3bd086e
Reviewed-on: https://go-review.googlesource.com/c/153439
Reviewed-by: Than McIntosh <thanm@google.com>

passes/GoStatepoints.cpp

diff --git a/passes/GoStatepoints.cpp b/passes/GoStatepoints.cpp
index c303582..46c08d7 100644
--- a/passes/GoStatepoints.cpp
+++ b/passes/GoStatepoints.cpp
@@ -2435,10 +2435,8 @@
     Data.LiveSet[&BB].clear();
     computeLiveInValues(BB.rbegin(), BB.rend(), Data.LiveSet[&BB], AddrTakenAllocas, DVCache);
     computeAllocaDefs(BB.begin(), BB.end(), Data.AllocaDefSet[&BB], Data.AllocaKillSet[&BB], DVCache);
-    if (!BB.isLandingPad()) {
-      Data.AllocaDefAny[&BB] = Data.AllocaDefSet[&BB];
-      Data.AllocaDefAny[&BB].set_subtract(Data.AllocaKillSet[&BB]);
-    }
+    Data.AllocaDefAny[&BB] = Data.AllocaDefSet[&BB];
+    Data.AllocaDefAny[&BB].set_subtract(Data.AllocaKillSet[&BB]);
     Data.LiveOut[&BB] = SetVector<Value *>();
     computeLiveOutSeed(&BB, Data.LiveOut[&BB], DVCache);
 
@@ -2453,13 +2451,6 @@
   while (changed) {
     changed = false;
     for (BasicBlock &BB : F) {
-      // Don't propagate through landing pad. The whole frame is
-      // essentially dead when an exception is thrown.
-      if (BB.isLandingPad()) {
-        assert(Data.AllocaDefAny[&BB].empty());
-        continue;
-      }
-
       unsigned OldSize = Data.AllocaDefAny[&BB].size();
       for (BasicBlock *Pred : predecessors(&BB))
         Data.AllocaDefAny[&BB].set_union(Data.AllocaDefAny[Pred]);
@@ -2531,9 +2522,6 @@
     SetVector<Value *> LiveOut = Data.LiveOut[BB];
     const auto OldLiveOutSize = LiveOut.size();
     for (BasicBlock *Succ : successors(BB)) {
-      if (Succ->isLandingPad())
-        // Don't propagate through landing pad. The frame should be dead at this point.
-        continue;
       assert(Data.LiveIn.count(Succ));
       LiveOut.set_union(Data.LiveIn[Succ]);
     }