From 1873998b1643ab2b3628f790fbdc47a75788a627 Mon Sep 17 00:00:00 2001
From: Matthias Braun <matze@braunis.de>
Date: Wed, 3 Aug 2016 22:37:47 +0000
Subject: [PATCH] RenameIndependentSubregs: Fix liveness query in
 rewriteOperands()

rewriteOperands() always performed liveness queries at the base index
rather than the RegSlot/Base as apropriate for the machine operand. This
could lead to illegal rewriting in some cases.

llvm-svn: 277661
---
 llvm/lib/CodeGen/RenameIndependentSubregs.cpp      | 13 +++----
 .../CodeGen/AMDGPU/rename-independent-subregs.mir  | 44 +++++++++++++++++++++-
 2 files changed, 48 insertions(+), 9 deletions(-)

diff --git a/llvm/lib/CodeGen/RenameIndependentSubregs.cpp b/llvm/lib/CodeGen/RenameIndependentSubregs.cpp
index ea952d9..bd5a608 100644
--- a/llvm/lib/CodeGen/RenameIndependentSubregs.cpp
+++ b/llvm/lib/CodeGen/RenameIndependentSubregs.cpp
@@ -219,9 +219,9 @@ void RenameIndependentSubregs::rewriteOperands(const IntEqClasses &Classes,
     if (!MO.isDef() && !MO.readsReg())
       continue;
 
-    MachineInstr &MI = *MO.getParent();
-
-    SlotIndex Pos = LIS->getInstructionIndex(MI);
+    SlotIndex Pos = LIS->getInstructionIndex(*MO.getParent());
+    Pos = MO.isDef() ? Pos.getRegSlot(MO.isEarlyClobber())
+                     : Pos.getBaseIndex();
     unsigned SubRegIdx = MO.getSubReg();
     LaneBitmask LaneMask = TRI.getSubRegIndexLaneMask(SubRegIdx);
 
@@ -230,13 +230,12 @@ void RenameIndependentSubregs::rewriteOperands(const IntEqClasses &Classes,
       const LiveInterval::SubRange &SR = *SRInfo.SR;
       if ((SR.LaneMask & LaneMask) == 0)
         continue;
-      LiveRange::const_iterator I = SR.find(Pos);
-      if (I == SR.end())
+      const VNInfo *VNI = SR.getVNInfoAt(Pos);
+      if (VNI == nullptr)
         continue;
 
-      const VNInfo &VNI = *I->valno;
       // Map to local representant ID.
-      unsigned LocalID = SRInfo.ConEQ.getEqClass(&VNI);
+      unsigned LocalID = SRInfo.ConEQ.getEqClass(VNI);
       // Global ID
       ID = Classes[LocalID + SRInfo.Index];
       break;
diff --git a/llvm/test/CodeGen/AMDGPU/rename-independent-subregs.mir b/llvm/test/CodeGen/AMDGPU/rename-independent-subregs.mir
index cbca323..b928bc7 100644
--- a/llvm/test/CodeGen/AMDGPU/rename-independent-subregs.mir
+++ b/llvm/test/CodeGen/AMDGPU/rename-independent-subregs.mir
@@ -1,6 +1,7 @@
-# RUN: llc -march=amdgcn -run-pass rename-independent-subregs -o - %s | FileCheck %s
+# RUN: llc -march=amdgcn -verify-machineinstrs -run-pass simple-register-coalescing,rename-independent-subregs -o - %s | FileCheck %s
 --- |
   define void @test0() { ret void }
+  define void @test1() { ret void }
 ...
 ---
 # In the test below we have two independent def+use pairs of subregister1 which
@@ -15,7 +16,6 @@
 # CHECK: S_NOP 0, implicit-def %0.sub1
 # CHECK: S_NOP 0, implicit %0
 name: test0
-isSSA: true
 registers:
   - { id: 0, class: sreg_128 }
 body: |
@@ -28,3 +28,43 @@ body: |
     S_NOP 0, implicit-def %0.sub1
     S_NOP 0, implicit %0
 ...
+---
+# Test for a bug where we would incorrectly query liveness at the instruction
+# index in rewriteOperands(). This should pass the verifier afterwards.
+# CHECK-LABEL: test1
+# CHECK: bb.0
+# CHECK: S_NOP 0, implicit-def undef %2.sub2
+# CHECK: bb.1
+# CHECK: S_NOP 0, implicit-def %2.sub1
+# CHECK-NEXT: S_NOP 0, implicit-def %2.sub3
+# CHECK-NEXT: S_NOP 0, implicit %2
+# CHECK-NEXT: S_NOP 0, implicit-def undef %0.sub0
+# CHECK-NEXT: S_NOP 0, implicit %2.sub1
+# CHECK-NEXT: S_NOP 0, implicit %0.sub0
+# CHECK: bb.2
+# CHECK: S_NOP 0, implicit %2.sub
+name: test1
+registers:
+  - { id: 0, class: sreg_128 }
+  - { id: 1, class: sreg_128 }
+body: |
+  bb.0:
+    successors: %bb.1, %bb.2
+    S_NOP 0, implicit-def undef %0.sub2
+    S_CBRANCH_VCCNZ %bb.1, implicit undef %vcc
+    S_BRANCH %bb.2
+
+  bb.1:
+    S_NOP 0, implicit-def %0.sub1
+    S_NOP 0, implicit-def %0.sub3
+    %1 = COPY %0
+    S_NOP 0, implicit %1
+
+    S_NOP 0, implicit-def %1.sub0
+    S_NOP 0, implicit %1.sub1
+    S_NOP 0, implicit %1.sub0
+
+  bb.2:
+    S_NOP 0, implicit %0.sub2
+
+...
-- 
2.7.4