From: Evan Cheng <evan.cheng@apple.com>
Date: Thu, 26 Nov 2009 00:32:36 +0000 (+0000)
Subject: When all defs of a vr are implicit_def, delete all of the defs.
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=40ea0e22b2380236c137e5a4b17d2eae38286a5e;p=oota-llvm.git

When all defs of a vr are implicit_def, delete all of the defs.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@89905 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/ProcessImplicitDefs.cpp b/lib/CodeGen/ProcessImplicitDefs.cpp
index a484beccb9e..c9a33d88515 100644
--- a/lib/CodeGen/ProcessImplicitDefs.cpp
+++ b/lib/CodeGen/ProcessImplicitDefs.cpp
@@ -183,19 +183,23 @@ bool ProcessImplicitDefs::runOnMachineFunction(MachineFunction &fn) {
       // is not an implicit_def, do not insert implicit_def's before the
       // uses.
       bool Skip = false;
+      SmallVector<MachineInstr*, 4> DeadImpDefs;
       for (MachineRegisterInfo::def_iterator DI = mri_->def_begin(Reg),
              DE = mri_->def_end(); DI != DE; ++DI) {
-        if (DI->getOpcode() != TargetInstrInfo::IMPLICIT_DEF) {
+        MachineInstr *DeadImpDef = &*DI;
+        if (DeadImpDef->getOpcode() != TargetInstrInfo::IMPLICIT_DEF) {
           Skip = true;
           break;
         }
+        DeadImpDefs.push_back(DeadImpDef);
       }
       if (Skip)
         continue;
 
       // The only implicit_def which we want to keep are those that are live
       // out of its block.
-      MI->eraseFromParent();
+      for (unsigned j = 0, ee = DeadImpDefs.size(); j != ee; ++j)
+        DeadImpDefs[j]->eraseFromParent();
       Changed = true;
 
       // Process each use instruction once.