[PATCH] D150246: AMDGPU: remove an illegal transform for shl(or)

[Ruiling, Song via Phabricator via llvm-commits]

ruiling updated this revision to Diff 521303.
ruiling added a comment.

fix the issue instead of removing the optimization.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D150246/new/

https://reviews.llvm.org/D150246

Files:
  llvm/lib/Target/AMDGPU/SIISelLowering.cpp
  llvm/test/CodeGen/AMDGPU/shl_add_ptr.ll


Index: llvm/test/CodeGen/AMDGPU/shl_add_ptr.ll
===================================================================
--- llvm/test/CodeGen/AMDGPU/shl_add_ptr.ll
+++ llvm/test/CodeGen/AMDGPU/shl_add_ptr.ll
@@ -410,15 +410,12 @@
   ret void
 }
 
-; FIXME: This or should fold into an offset on the write
 ; GCN-LABEL: {{^}}shl_or_ptr_combine_2use_lds:
-; GCN: v_lshlrev_b32_e32 [[SCALE0:v[0-9]+]], 3, v0
-; GCN: v_or_b32_e32 [[SCALE1:v[0-9]+]], 32, [[SCALE0]]
-; GCN: v_lshlrev_b32_e32 [[SCALE2:v[0-9]+]], 4, v0
-; GCN: ds_write_b32 [[SCALE1]], v{{[0-9]+}}
-; GCN: ds_write_b32 [[SCALE2]], v{{[0-9]+}} offset:64
+; GCN-DAG: ds_write_b32 v{{[0-9]+}}, v{{[0-9]+}} offset:8
+; GCN-DAG: ds_write_b32 v{{[0-9]+}}, v{{[0-9]+}} offset:16
 define void @shl_or_ptr_combine_2use_lds(i32 %idx) #0 {
-  %idx.add = or i32 %idx, 4
+  %idx.shl = shl i32 %idx, 1
+  %idx.add = or i32 %idx.shl, 1
   %shl0 = shl i32 %idx.add, 3
   %shl1 = shl i32 %idx.add, 4
   %ptr0 = inttoptr i32 %shl0 to ptr addrspace(3)
@@ -427,15 +424,13 @@
   store volatile i32 10, ptr addrspace(3) %ptr1
   ret void
 }
-
-; GCN-LABEL: {{^}}shl_or_ptr_combine_2use_max_lds_offset:
+; GCN-LABEL: {{^}}shl_or_ptr_not_combine_2use_lds:
 ; GCN-DAG: v_lshlrev_b32_e32 [[SCALE0:v[0-9]+]], 3, v0
 ; GCN-DAG: v_lshlrev_b32_e32 [[SCALE1:v[0-9]+]], 4, v0
-; GCN-DAG: ds_write_b32 [[SCALE0]], v{{[0-9]+}} offset:65528
-; GCN-DAG: v_or_b32_e32 [[ADD1:v[0-9]+]], 0x1fff0, [[SCALE1]]
-; GCN: ds_write_b32 [[ADD1]], v{{[0-9]+$}}
-define void @shl_or_ptr_combine_2use_max_lds_offset(i32 %idx) #0 {
-  %idx.add = or i32 %idx, 8191
+; GCN-DAG: ds_write_b32 [[SCALE0]], v{{[0-9]+}}
+; GCN-DAG: ds_write_b32 [[SCALE1]], v{{[0-9]+}}
+define void @shl_or_ptr_not_combine_2use_lds(i32 %idx) #0 {
+  %idx.add = or i32 %idx, 1
   %shl0 = shl i32 %idx.add, 3
   %shl1 = shl i32 %idx.add, 4
   %ptr0 = inttoptr i32 %shl0 to ptr addrspace(3)
Index: llvm/lib/Target/AMDGPU/SIISelLowering.cpp
===================================================================
--- llvm/lib/Target/AMDGPU/SIISelLowering.cpp
+++ llvm/lib/Target/AMDGPU/SIISelLowering.cpp
@@ -9550,6 +9550,8 @@
 }
 
 // (shl (add x, c1), c2) -> add (shl x, c2), (shl c1, c2)
+// (shl (or x, c1), c2) -> add (shl x, c2), (shl c1, c2) iff x and c1 share no
+// bits
 
 // This is a variant of
 // (mul (add x, c1), c2) -> add (mul x, c2), (mul c1, c2),
@@ -9572,7 +9574,7 @@
 
   // We only do this to handle cases where it's profitable when there are
   // multiple uses of the add, so defer to the standard combine.
-  if ((N0.getOpcode() != ISD::ADD && N0.getOpcode() != ISD::OR) ||
+  if ((N0.getOpcode() != ISD::ADD && N0->getOpcode() != ISD::OR) ||
       N0->hasOneUse())
     return SDValue();
 
@@ -9584,8 +9586,14 @@
   if (!CAdd)
     return SDValue();
 
-  // If the resulting offset is too large, we can't fold it into the addressing
-  // mode offset.
+  SelectionDAG &DAG = DCI.DAG;
+
+  if (N0->getOpcode() == ISD::OR &&
+      !DAG.haveNoCommonBitsSet(N0.getOperand(0), N0.getOperand(1)))
+    return SDValue();
+
+  // If the resulting offset is too large, we can't fold it into the
+  // addressing mode offset.
   APInt Offset = CAdd->getAPIntValue() << CN1->getAPIntValue();
   Type *Ty = MemVT.getTypeForEVT(*DCI.DAG.getContext());
 
@@ -9595,7 +9603,6 @@
   if (!isLegalAddressingMode(DCI.DAG.getDataLayout(), AM, Ty, AddrSpace))
     return SDValue();
 
-  SelectionDAG &DAG = DCI.DAG;
   SDLoc SL(N);
   EVT VT = N->getValueType(0);
 


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