AMDGPU: fix overlapping copies in copyPhysReg

Summary:
When copying aggregate registers within the same register class, there may
be an overlap between source and destination that forces us to do the copy
backwards.

Do the simplest possible thing that guarantees the correct order of moves
when there are overlaps, and does whatever when there is no overlap. (The
last part forces some trivial adjustments to test cases.)

Together with r255906, this fixes a VM fault in Unreal Elemental Demo.

While at it, change the generation of kill and def flags to something that
looks more reasonable. This method is used very late during compilation, so
it probably doesn't matter in practice, and to be honest, I don't know if
this change is actually correct because the semantics in connection with
aggregate registers vs. sub-registers are not clear to me.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=93264

Reviewers: arsenm, tstellarAMD

Subscribers: arsenm, llvm-commits

Differential Revision: http://reviews.llvm.org/D15622

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@256072 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 32 insertions, 14 deletions

diff --git a/lib/Target/AMDGPU/SIInstrInfo.cpp b/lib/Target/AMDGPU/SIInstrInfo.cpp
index 6c4cb011ef2..a37f8ecaaa4 100644
--- a/lib/Target/AMDGPU/SIInstrInfo.cpp
+++ b/lib/Target/AMDGPU/SIInstrInfo.cpp
@@ -323,28 +323,29 @@ SIInstrInfo::copyPhysReg(MachineBasicBlock &MBB,
     AMDGPU::sub0, AMDGPU::sub1, AMDGPU::sub2, AMDGPU::sub3,
     AMDGPU::sub4, AMDGPU::sub5, AMDGPU::sub6, AMDGPU::sub7,
     AMDGPU::sub8, AMDGPU::sub9, AMDGPU::sub10, AMDGPU::sub11,
-    AMDGPU::sub12, AMDGPU::sub13, AMDGPU::sub14, AMDGPU::sub15, 0
+    AMDGPU::sub12, AMDGPU::sub13, AMDGPU::sub14, AMDGPU::sub15,
   };
 
   static const int16_t Sub0_7[] = {
     AMDGPU::sub0, AMDGPU::sub1, AMDGPU::sub2, AMDGPU::sub3,
-    AMDGPU::sub4, AMDGPU::sub5, AMDGPU::sub6, AMDGPU::sub7, 0
+    AMDGPU::sub4, AMDGPU::sub5, AMDGPU::sub6, AMDGPU::sub7,
   };
 
   static const int16_t Sub0_3[] = {
-    AMDGPU::sub0, AMDGPU::sub1, AMDGPU::sub2, AMDGPU::sub3, 0
+    AMDGPU::sub0, AMDGPU::sub1, AMDGPU::sub2, AMDGPU::sub3,
   };
 
   static const int16_t Sub0_2[] = {
-    AMDGPU::sub0, AMDGPU::sub1, AMDGPU::sub2, 0
+    AMDGPU::sub0, AMDGPU::sub1, AMDGPU::sub2,
   };
 
   static const int16_t Sub0_1[] = {
-    AMDGPU::sub0, AMDGPU::sub1, 0
+    AMDGPU::sub0, AMDGPU::sub1,
   };
 
   unsigned Opcode;
-  const int16_t *SubIndices;
+  ArrayRef<int16_t> SubIndices;
+  bool Forward;
 
   if (AMDGPU::SReg_32RegClass.contains(DestReg)) {
     assert(AMDGPU::SReg_32RegClass.contains(SrcReg));
@@ -428,13 +429,27 @@ SIInstrInfo::copyPhysReg(MachineBasicBlock &MBB,
     llvm_unreachable("Can't copy register!");
   }
 
-  while (unsigned SubIdx = *SubIndices++) {
+  if (RI.getHWRegIndex(DestReg) <= RI.getHWRegIndex(SrcReg))
+    Forward = true;
+  else
+    Forward = false;
+
+  for (unsigned Idx = 0; Idx < SubIndices.size(); ++Idx) {
+    unsigned SubIdx;
+    if (Forward)
+      SubIdx = SubIndices[Idx];
+    else
+      SubIdx = SubIndices[SubIndices.size() - Idx - 1];
+
     MachineInstrBuilder Builder = BuildMI(MBB, MI, DL,
       get(Opcode), RI.getSubReg(DestReg, SubIdx));
 
-    Builder.addReg(RI.getSubReg(SrcReg, SubIdx), getKillRegState(KillSrc));
+    Builder.addReg(RI.getSubReg(SrcReg, SubIdx));
+
+    if (Idx == SubIndices.size() - 1)
+      Builder.addReg(SrcReg, RegState::Kill | RegState::Implicit);
 
-    if (*SubIndices)
+    if (Idx == 0)
       Builder.addReg(DestReg, RegState::Define | RegState::Implicit);
   }
 }
diff --git a/test/CodeGen/AMDGPU/ctpop64.ll b/test/CodeGen/AMDGPU/ctpop64.ll
index dd2840bd851..ec2971e9803 100644
--- a/test/CodeGen/AMDGPU/ctpop64.ll
+++ b/test/CodeGen/AMDGPU/ctpop64.ll
@@ -117,8 +117,8 @@ define void @v_ctpop_v4i64(<4 x i32> addrspace(1)* noalias %out, <4 x i64> addrs
 ; SI: s_load_dwordx2 s{{\[}}[[LOVAL:[0-9]+]]:[[HIVAL:[0-9]+]]{{\]}}, s[{{[0-9]+:[0-9]+}}], 0xd
 ; VI: s_load_dwordx2 s{{\[}}[[LOVAL:[0-9]+]]:[[HIVAL:[0-9]+]]{{\]}}, s[{{[0-9]+:[0-9]+}}], 0x34
 ; GCN: s_bcnt1_i32_b64 [[RESULT:s[0-9]+]], {{s\[}}[[LOVAL]]:[[HIVAL]]{{\]}}
-; GCN: v_mov_b32_e32 v[[VLO:[0-9]+]], [[RESULT]]
-; GCN: v_mov_b32_e32 v[[VHI:[0-9]+]], s[[HIVAL]]
+; GCN-DAG: v_mov_b32_e32 v[[VLO:[0-9]+]], [[RESULT]]
+; GCN-DAG: v_mov_b32_e32 v[[VHI:[0-9]+]], s[[HIVAL]]
 ; GCN: buffer_store_dwordx2 {{v\[}}[[VLO]]:[[VHI]]{{\]}}
 ; GCN: s_endpgm
 define void @ctpop_i64_in_br(i64 addrspace(1)* %out, i64 addrspace(1)* %in, i64 %ctpop_arg, i32 %cond) {
diff --git a/test/CodeGen/AMDGPU/flat-address-space.ll b/test/CodeGen/AMDGPU/flat-address-space.ll
index 4b56d6f1983..d65b757a4c4 100644
--- a/test/CodeGen/AMDGPU/flat-address-space.ll
+++ b/test/CodeGen/AMDGPU/flat-address-space.ll
@@ -11,9 +11,12 @@
 ; remove generic pointers.
 
 ; CHECK-LABEL: {{^}}store_flat_i32:
-; CHECK: v_mov_b32_e32 v[[DATA:[0-9]+]], {{s[0-9]+}}
-; CHECK: v_mov_b32_e32 v[[LO_VREG:[0-9]+]], {{s[0-9]+}}
-; CHECK: v_mov_b32_e32 v[[HI_VREG:[0-9]+]], {{s[0-9]+}}
+; CHECK-DAG: s_load_dwordx2 s{{\[}}[[LO_SREG:[0-9]+]]:[[HI_SREG:[0-9]+]]],
+; CHECK-DAG: s_load_dword s[[SDATA:[0-9]+]],
+; CHECK: s_waitcnt lgkmcnt(0)
+; CHECK-DAG: v_mov_b32_e32 v[[DATA:[0-9]+]], s[[SDATA]]
+; CHECK-DAG: v_mov_b32_e32 v[[LO_VREG:[0-9]+]], s[[LO_SREG]]
+; CHECK-DAG: v_mov_b32_e32 v[[HI_VREG:[0-9]+]], s[[HI_SREG]]
 ; CHECK: flat_store_dword v[[DATA]], v{{\[}}[[LO_VREG]]:[[HI_VREG]]{{\]}}
 define void @store_flat_i32(i32 addrspace(1)* %gptr, i32 %x) #0 {
   %fptr = addrspacecast i32 addrspace(1)* %gptr to i32 addrspace(4)*