From 50608bac2fe1d3eb4753b6acdac06292eae7b980 Mon Sep 17 00:00:00 2001
From: Evan Cheng <evan.cheng@apple.com>
Date: Wed, 4 Nov 2009 08:33:14 +0000
Subject: [PATCH] RangeIsDefinedByCopyFromReg() should check for subreg_to_reg,
 insert_subreg, and extract_subreg as a "copy" that defines a valno. Also
 fixes a typo. These two issues prevent a simple subreg coalescing from
 happening before.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86022 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/SimpleRegisterCoalescing.cpp      | 28 +++++++++++++++----
 .../X86/2009-11-04-SubregCoalescingBug.ll     | 15 ++++++++++
 2 files changed, 37 insertions(+), 6 deletions(-)
 create mode 100644 test/CodeGen/X86/2009-11-04-SubregCoalescingBug.ll

diff --git a/lib/CodeGen/SimpleRegisterCoalescing.cpp b/lib/CodeGen/SimpleRegisterCoalescing.cpp
index e711a06be77..b5d6b471f47 100644
--- a/lib/CodeGen/SimpleRegisterCoalescing.cpp
+++ b/lib/CodeGen/SimpleRegisterCoalescing.cpp
@@ -1369,7 +1369,7 @@ bool SimpleRegisterCoalescing::JoinCopy(CopyRec &TheCopy, bool &Again) {
     if (SrcSubIdx)
       SrcSubRC = SrcRC->getSubRegisterRegClass(SrcSubIdx);
     assert(SrcSubRC && "Illegal subregister index");
-    if (!SrcSubRC->contains(DstReg)) {
+    if (!SrcSubRC->contains(DstSubReg)) {
       DEBUG(errs() << "\tIncompatible source regclass: "
                    << tri_->getName(DstSubReg) << " not in "
                    << SrcSubRC->getName() << ".\n");
@@ -1834,6 +1834,25 @@ static bool InVector(VNInfo *Val, const SmallVector<VNInfo*, 8> &V) {
   return std::find(V.begin(), V.end(), Val) != V.end();
 }
 
+static bool isValNoDefMove(const MachineInstr *MI, unsigned DR, unsigned SR,
+                           const TargetInstrInfo *TII,
+                           const TargetRegisterInfo *TRI) {
+  unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
+  if (TII->isMoveInstr(*MI, SrcReg, DstReg, SrcSubIdx, DstSubIdx))
+    ;
+  else if (MI->getOpcode() == TargetInstrInfo::EXTRACT_SUBREG) {
+    DstReg = MI->getOperand(0).getReg();
+    SrcReg = MI->getOperand(1).getReg();
+  } else if (MI->getOpcode() == TargetInstrInfo::SUBREG_TO_REG ||
+             MI->getOpcode() == TargetInstrInfo::INSERT_SUBREG) {
+    DstReg = MI->getOperand(0).getReg();
+    SrcReg = MI->getOperand(2).getReg();
+  } else
+    return false;
+  return (SrcReg == SR || TRI->isSuperRegister(SR, SrcReg)) &&
+         (DstReg == DR || TRI->isSuperRegister(DR, DstReg));
+}
+
 /// RangeIsDefinedByCopyFromReg - Return true if the specified live range of
 /// the specified live interval is defined by a copy from the specified
 /// register.
@@ -1850,12 +1869,9 @@ bool SimpleRegisterCoalescing::RangeIsDefinedByCopyFromReg(LiveInterval &li,
     // It's a sub-register live interval, we may not have precise information.
     // Re-compute it.
     MachineInstr *DefMI = li_->getInstructionFromIndex(LR->start);
-    unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
-    if (DefMI &&
-        tii_->isMoveInstr(*DefMI, SrcReg, DstReg, SrcSubIdx, DstSubIdx) &&
-        DstReg == li.reg && SrcReg == Reg) {
+    if (DefMI && isValNoDefMove(DefMI, li.reg, Reg, tii_, tri_)) {
       // Cache computed info.
-      LR->valno->def  = LR->start;
+      LR->valno->def = LR->start;
       LR->valno->setCopy(DefMI);
       return true;
     }
diff --git a/test/CodeGen/X86/2009-11-04-SubregCoalescingBug.ll b/test/CodeGen/X86/2009-11-04-SubregCoalescingBug.ll
new file mode 100644
index 00000000000..d84b63a21be
--- /dev/null
+++ b/test/CodeGen/X86/2009-11-04-SubregCoalescingBug.ll
@@ -0,0 +1,15 @@
+; RUN: llc < %s -mtriple=x86_64-apple-darwin11 | FileCheck %s
+; rdar://7362871
+
+define void @bar(i32 %b, i32 %a) nounwind optsize ssp {
+entry:
+; CHECK:     leal 15(%rsi), %edi
+; CHECK-NOT: movl
+; CHECK:     call _foo
+  %0 = add i32 %a, 15                             ; <i32> [#uses=1]
+  %1 = zext i32 %0 to i64                         ; <i64> [#uses=1]
+  tail call void @foo(i64 %1) nounwind
+  ret void
+}
+
+declare void @foo(i64)