[AMDGPU] Do not combine dpp with physreg def

We will remove dpp mov along with the physreg def otherwise.

Differential Revision: https://reviews.llvm.org/D69063

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@375030 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/AMDGPU/GCNDPPCombine.cpp b/lib/Target/AMDGPU/GCNDPPCombine.cpp
index a517250ae244523d1fc343a6eedbfd1792b95a6f..f8adda72950b03e76117209df7b19d1cbf28ec77 100644 (file)
--- a/lib/Target/AMDGPU/GCNDPPCombine.cpp
+++ b/lib/Target/AMDGPU/GCNDPPCombine.cpp
@@ -353,6 +353,10 @@ bool GCNDPPCombine::combineDPPMov(MachineInstr &MovMI) const {
   auto *DstOpnd = TII->getNamedOperand(MovMI, AMDGPU::OpName::vdst);
   assert(DstOpnd && DstOpnd->isReg());
   auto DPPMovReg = DstOpnd->getReg();
+  if (DPPMovReg.isPhysical()) {
+    LLVM_DEBUG(dbgs() << "  failed: dpp move writes physreg\n");
+    return false;
+  }
   if (execMayBeModifiedBeforeAnyUse(*MRI, DPPMovReg, MovMI)) {
     LLVM_DEBUG(dbgs() << "  failed: EXEC mask should remain the same"
                          " for all uses\n");

diff --git a/test/CodeGen/AMDGPU/dpp_combine.mir b/test/CodeGen/AMDGPU/dpp_combine.mir
index 613b6c90eadbea2a9e70d2aaabc72c1a7d1b699b..b58b2ee0edbff7413c7db153da6d1afed3401148 100644 (file)
--- a/test/CodeGen/AMDGPU/dpp_combine.mir
+++ b/test/CodeGen/AMDGPU/dpp_combine.mir
@@ -563,6 +563,18 @@ body: |
     %3:vgpr_32 = V_CEIL_F32_e32 %2, implicit $exec
 ...
 
+# Do not combine a dpp mov which writes a physreg.
+# GCN-LABEL: name: phys_dpp_mov_dst
+# GCN: $vgpr0 = V_MOV_B32_dpp undef %0:vgpr_32, undef %1:vgpr_32, 1, 15, 15, 1, implicit $exec
+# GCN: %2:vgpr_32 = V_CEIL_F32_e32 $vgpr0, implicit $exec
+name: phys_dpp_mov_dst
+tracksRegLiveness: true
+body: |
+  bb.0:
+    $vgpr0 = V_MOV_B32_dpp undef %1:vgpr_32, undef %0:vgpr_32, 1, 15, 15, 1, implicit $exec
+    %2:vgpr_32 = V_CEIL_F32_e32 $vgpr0, implicit $exec
+...
+
 # GCN-LABEL: name: dpp_reg_sequence_both_combined
 # GCN: %0:vreg_64 = COPY $vgpr0_vgpr1
 # GCN: %1:vreg_64 = COPY $vgpr2_vgpr3