From: Matt Arsenault <Matthew.Arsenault@amd.com>
Date: Mon, 14 Oct 2019 18:30:31 +0000 (+0000)
Subject: AMDGPU: Fix redundant setting of m0 for atomic load/store
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=f6735ac38cbad69242ca93983f465fe745b6b552;p=llvm

AMDGPU: Fix redundant setting of m0 for atomic load/store

Atomic load/store would have their setting of m0 handled twice, which
happened to be optimized out later.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@374801 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Target/AMDGPU/AMDGPUISelDAGToDAG.cpp b/lib/Target/AMDGPU/AMDGPUISelDAGToDAG.cpp
index 631a2366062..0355f79eb6b 100644
--- a/lib/Target/AMDGPU/AMDGPUISelDAGToDAG.cpp
+++ b/lib/Target/AMDGPU/AMDGPUISelDAGToDAG.cpp
@@ -714,12 +714,17 @@ void AMDGPUDAGToDAGISel::Select(SDNode *N) {
     return;   // Already selected.
   }
 
-  if (isa<AtomicSDNode>(N) ||
+  // isa<MemSDNode> almost works but is slightly too permissive for some DS
+  // intrinsics.
+  if (Opc == ISD::LOAD || Opc == ISD::STORE || isa<AtomicSDNode>(N) ||
       (Opc == AMDGPUISD::ATOMIC_INC || Opc == AMDGPUISD::ATOMIC_DEC ||
        Opc == ISD::ATOMIC_LOAD_FADD ||
        Opc == AMDGPUISD::ATOMIC_LOAD_FMIN ||
-       Opc == AMDGPUISD::ATOMIC_LOAD_FMAX))
+       Opc == AMDGPUISD::ATOMIC_LOAD_FMAX)) {
     N = glueCopyToM0LDSInit(N);
+    SelectCode(N);
+    return;
+  }
 
   switch (Opc) {
   default:
@@ -816,14 +821,6 @@ void AMDGPUDAGToDAGISel::Select(SDNode *N) {
     ReplaceNode(N, buildSMovImm64(DL, Imm, N->getValueType(0)));
     return;
   }
-  case ISD::LOAD:
-  case ISD::STORE:
-  case ISD::ATOMIC_LOAD:
-  case ISD::ATOMIC_STORE: {
-    N = glueCopyToM0LDSInit(N);
-    break;
-  }
-
   case AMDGPUISD::BFE_I32:
   case AMDGPUISD::BFE_U32: {
     // There is a scalar version available, but unlike the vector version which