[PATCH] D117821: [AMDGPU] Disable rematerialization of cndmask

[Stanislav Mekhanoshin via Phabricator via llvm-commits]

rampitec created this revision.
rampitec added reviewers: arsenm, sebastian-ne, vangthao.
Herald added subscribers: foad, kerbowa, hiraditya, t-tye, tpr, dstuttard, yaxunl, nhaehnle, jvesely, kzhuravl.
rampitec requested review of this revision.
Herald added a subscriber: wdng.
Herald added a project: LLVM.

VOP2e promoted to VOP3 is marked as rematerializable because it does
not use implicit vcc, but that shall exclude cndmask. A result of
the cndmask instruction uses exec as a mask, so I believe it may not
move across basic blocks.


https://reviews.llvm.org/D117821

Files:
  llvm/lib/Target/AMDGPU/VOP2Instructions.td
  llvm/test/CodeGen/AMDGPU/remat-vop.mir


Index: llvm/test/CodeGen/AMDGPU/remat-vop.mir
===================================================================
--- llvm/test/CodeGen/AMDGPU/remat-vop.mir
+++ llvm/test/CodeGen/AMDGPU/remat-vop.mir
@@ -1446,16 +1446,22 @@
     S_ENDPGM 0
 ...
 ---
-name:            test_remat_v_cndmask_b32_e64
+name:            test_no_remat_v_cndmask_b32_e64
 tracksRegLiveness: true
+machineFunctionInfo:
+  stackPtrOffsetReg:  $sgpr32
 body:             |
   bb.0:
-    ; GCN-LABEL: name: test_remat_v_cndmask_b32_e64
+    ; GCN-LABEL: name: test_no_remat_v_cndmask_b32_e64
     ; GCN: renamable $vgpr0 = V_CNDMASK_B32_e64 0, 1, 0, 2, undef $sgpr0_sgpr1, implicit $exec
+    ; GCN-NEXT: SI_SPILL_V32_SAVE killed $vgpr0, %stack.1, $sgpr32, 0, implicit $exec :: (store (s32) into %stack.1, addrspace 5)
     ; GCN-NEXT: renamable $vgpr1 = V_CNDMASK_B32_e64 0, 1, 0, 2, undef $sgpr0_sgpr1, implicit $exec
+    ; GCN-NEXT: renamable $vgpr0 = V_CNDMASK_B32_e64 0, 1, 0, 2, undef $sgpr0_sgpr1, implicit $exec
+    ; GCN-NEXT: SI_SPILL_V32_SAVE killed $vgpr0, %stack.0, $sgpr32, 0, implicit $exec :: (store (s32) into %stack.0, addrspace 5)
+    ; GCN-NEXT: renamable $vgpr0 = SI_SPILL_V32_RESTORE %stack.1, $sgpr32, 0, implicit $exec :: (load (s32) from %stack.1, addrspace 5)
     ; GCN-NEXT: S_NOP 0, implicit killed renamable $vgpr0
     ; GCN-NEXT: S_NOP 0, implicit killed renamable $vgpr1
-    ; GCN-NEXT: renamable $vgpr0 = V_CNDMASK_B32_e64 0, 1, 0, 2, undef $sgpr0_sgpr1, implicit $exec
+    ; GCN-NEXT: renamable $vgpr0 = SI_SPILL_V32_RESTORE %stack.0, $sgpr32, 0, implicit $exec :: (load (s32) from %stack.0, addrspace 5)
     ; GCN-NEXT: S_NOP 0, implicit killed renamable $vgpr0
     ; GCN-NEXT: S_ENDPGM 0
     %1:vgpr_32 = V_CNDMASK_B32_e64 0, 1, 0, 2, undef %0:sreg_64_xexec, implicit $exec
Index: llvm/lib/Target/AMDGPU/VOP2Instructions.td
===================================================================
--- llvm/lib/Target/AMDGPU/VOP2Instructions.td
+++ llvm/lib/Target/AMDGPU/VOP2Instructions.td
@@ -480,6 +480,7 @@
 // VOP2 Instructions
 //===----------------------------------------------------------------------===//
 
+let isReMaterializable = 0 in
 defm V_CNDMASK_B32 : VOP2eInst <"v_cndmask_b32", VOP2e_I32_I32_I32_I1>;
 let SubtargetPredicate = HasMadMacF32Insts, isReMaterializable = 1 in
 def V_MADMK_F32 : VOP2_Pseudo <"v_madmk_f32", VOP_MADMK_F32, []>;


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D117821.401717.patch
Type: text/x-patch
Size: 2371 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20220120/c730e1a4/attachment-0001.bin>