From d77d4f98fbdeaf3d1b0ba99b547b7ac4ec43b834 Mon Sep 17 00:00:00 2001
From: Evan Cheng <evan.cheng@apple.com>
Date: Wed, 28 May 2008 17:40:10 +0000
Subject: [PATCH] Fix PR2289: vr defined by multiple implicit_def as result of
 coalescing.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@51648 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/SimpleRegisterCoalescing.cpp    | 15 +++++++++------
 test/CodeGen/X86/2008-05-28-CoalescerBug.ll | 10 ++++++++++
 2 files changed, 19 insertions(+), 6 deletions(-)
 create mode 100644 test/CodeGen/X86/2008-05-28-CoalescerBug.ll

diff --git a/lib/CodeGen/SimpleRegisterCoalescing.cpp b/lib/CodeGen/SimpleRegisterCoalescing.cpp
index 8916d9a9c5f..ce5235c3192 100644
--- a/lib/CodeGen/SimpleRegisterCoalescing.cpp
+++ b/lib/CodeGen/SimpleRegisterCoalescing.cpp
@@ -751,7 +751,7 @@ bool SimpleRegisterCoalescing::CanCoalesceWithImpDef(MachineInstr *CopyMI,
 /// identity copies so they will be removed.
 void SimpleRegisterCoalescing::RemoveCopiesFromValNo(LiveInterval &li,
                                                      VNInfo *VNI) {
-  MachineInstr *ImpDef = NULL;
+  SmallVector<MachineInstr*, 4> ImpDefs;
   MachineOperand *LastUse = NULL;
   unsigned LastUseIdx = li_->getUseIndex(VNI->def);
   for (MachineRegisterInfo::reg_iterator RI = mri_->reg_begin(li.reg),
@@ -761,8 +761,7 @@ void SimpleRegisterCoalescing::RemoveCopiesFromValNo(LiveInterval &li,
     ++RI;
     if (MO->isDef()) {
       if (MI->getOpcode() == TargetInstrInfo::IMPLICIT_DEF) {
-        assert(!ImpDef && "Multiple implicit_def defining same register?");
-        ImpDef = MI;
+        ImpDefs.push_back(MI);
       }
       continue;
     }
@@ -790,9 +789,13 @@ void SimpleRegisterCoalescing::RemoveCopiesFromValNo(LiveInterval &li,
   if (LastUse)
     LastUse->setIsKill();
   else {
-    // Remove dead implicit_def.
-    li_->RemoveMachineInstrFromMaps(ImpDef);
-    ImpDef->eraseFromParent();
+    // Remove dead implicit_def's.
+    while (!ImpDefs.empty()) {
+      MachineInstr *ImpDef = ImpDefs.back();
+      ImpDefs.pop_back();
+      li_->RemoveMachineInstrFromMaps(ImpDef);
+      ImpDef->eraseFromParent();
+    }
   }
 }
 
diff --git a/test/CodeGen/X86/2008-05-28-CoalescerBug.ll b/test/CodeGen/X86/2008-05-28-CoalescerBug.ll
new file mode 100644
index 00000000000..68f6ccea4ee
--- /dev/null
+++ b/test/CodeGen/X86/2008-05-28-CoalescerBug.ll
@@ -0,0 +1,10 @@
+; RUN: llvm-as < %s | llc -mtriple=x86_64-unknown-linux-gnu
+; PR2289
+
+define void @_ada_ca11001() {
+entry:
+        %tmp59 = call i16 @ca11001_0__cartesian_assign( i8 zeroext  0, i8 zeroext  0, i16 undef )               ; <i16> [#uses=0]
+        unreachable
+}
+
+declare i16 @ca11001_0__cartesian_assign(i8 zeroext , i8 zeroext , i16)
-- 
2.34.1