From 51bfd452d5d748abc5e65b71b8f7213a13e10569 Mon Sep 17 00:00:00 2001
From: Jakob Stoklund Olesen <stoklund@2pi.dk>
Date: Wed, 5 May 2010 23:07:41 +0000
Subject: [PATCH] Fix PR6520. An earlyclobber physreg must not be allocated to
 anything else.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@103133 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/RegAllocLocal.cpp                 | 14 +++++++--
 .../X86/2010-05-05-LocalAllocEarlyClobber.ll  | 31 +++++++++++++++++++
 2 files changed, 43 insertions(+), 2 deletions(-)
 create mode 100644 test/CodeGen/X86/2010-05-05-LocalAllocEarlyClobber.ll

diff --git a/lib/CodeGen/RegAllocLocal.cpp b/lib/CodeGen/RegAllocLocal.cpp
index 94456d14385..a3d2f9d2c2e 100644
--- a/lib/CodeGen/RegAllocLocal.cpp
+++ b/lib/CodeGen/RegAllocLocal.cpp
@@ -843,8 +843,18 @@ void RALocal::AllocateBasicBlock(MachineBasicBlock &MBB) {
     SmallVector<unsigned, 8> Kills;
     for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
       MachineOperand &MO = MI->getOperand(i);
-      if (!MO.isReg() || !MO.isKill()) continue;
-      
+      if (!MO.isReg()) continue;
+      unsigned Reg = MO.getReg();
+      if (!Reg) continue;
+
+      // Avoid allocating assigned early clobbers below.
+      if (MO.isEarlyClobber() && TargetRegisterInfo::isPhysicalRegister(Reg)) {
+        spillPhysReg(MBB, MI, Reg, true); // Spill any existing value in reg
+        PhysRegsUsed[Reg] = 0;            // It is free and reserved now
+        AddToPhysRegsUseOrder(Reg);
+      }
+
+      if (!MO.isKill()) continue;
       if (!MO.isImplicit())
         Kills.push_back(MO.getReg());
       else if (!isReadModWriteImplicitKill(MI, MO.getReg()))
diff --git a/test/CodeGen/X86/2010-05-05-LocalAllocEarlyClobber.ll b/test/CodeGen/X86/2010-05-05-LocalAllocEarlyClobber.ll
new file mode 100644
index 00000000000..4b6a94d58c3
--- /dev/null
+++ b/test/CodeGen/X86/2010-05-05-LocalAllocEarlyClobber.ll
@@ -0,0 +1,31 @@
+; RUN: llc < %s -O0 -regalloc=local | FileCheck %s
+; PR6520
+target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128-n8:16:32"
+target triple = "i386-apple-darwin10.0.0"
+
+%0 = type { i8*, i8*, i32 }
+
+define i8* @func() nounwind ssp {
+entry:
+  %retval = alloca i8*, align 4                   ; <i8**> [#uses=2]
+  %ret = alloca i8*, align 4                      ; <i8**> [#uses=2]
+  %p = alloca i8*, align 4                        ; <i8**> [#uses=1]
+  %t = alloca i32, align 4                        ; <i32*> [#uses=1]
+; The earlyclobber $1 should only appear once. It should not be shared.
+; CHECK: deafbeef, [[REG:%e.x]]
+; CHECK-NOT: [[REG]]
+; CHECK: InlineAsm End
+  %0 = call %0 asm "mov    $$0xdeafbeef, $1\0A\09mov    $$0xcafebabe, $0\0A\09mov    $0, $2\0A\09", "=&r,=&r,=&{cx},~{dirflag},~{fpsr},~{flags}"() nounwind, !srcloc !0 ; <%0> [#uses=3]
+  %asmresult = extractvalue %0 %0, 0              ; <i8*> [#uses=1]
+  %asmresult1 = extractvalue %0 %0, 1             ; <i8*> [#uses=1]
+  %asmresult2 = extractvalue %0 %0, 2             ; <i32> [#uses=1]
+  store i8* %asmresult, i8** %ret
+  store i8* %asmresult1, i8** %p
+  store i32 %asmresult2, i32* %t
+  %tmp = load i8** %ret                           ; <i8*> [#uses=1]
+  store i8* %tmp, i8** %retval
+  %1 = load i8** %retval                          ; <i8*> [#uses=1]
+  ret i8* %1
+}
+
+!0 = metadata !{i32 79}