[PATCH] D156999: [Inline Spiller] Consider bundles when marking defs as dead

[Piotr Sobczak via Phabricator via llvm-commits]

This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rG80abbeca8e52: [Inline Spiller] Consider bundles when marking defs as dead (authored by piotr).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D156999/new/

https://reviews.llvm.org/D156999

Files:
  llvm/lib/CodeGen/InlineSpiller.cpp
  llvm/test/CodeGen/AMDGPU/dead_bundle.mir


Index: llvm/test/CodeGen/AMDGPU/dead_bundle.mir
===================================================================
--- llvm/test/CodeGen/AMDGPU/dead_bundle.mir
+++ llvm/test/CodeGen/AMDGPU/dead_bundle.mir
@@ -1,7 +1,7 @@
 # NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
-# RUN: llc -mtriple=amdgcn--amdpal -march=amdgcn -mcpu=gfx1100 -verify-machineinstrs=0 -start-before=greedy,0 -stop-after=virtregrewriter,0 -stress-regalloc=5 %s -o - | FileCheck %s
+# RUN: llc -mtriple=amdgcn--amdpal -march=amdgcn -mcpu=gfx1100 -verify-machineinstrs=1 -start-before=greedy,0 -stop-after=virtregrewriter,0 -stress-regalloc=5 %s -o - | FileCheck %s
 
-# This test currently fails with verify-machineinstrs=1 due to dead bundle mishandling: "Live range continues after dead def flag".
+# This test checks that dead bundles are handled correctly.
 ---
 name: psmain
 tracksRegLiveness: true
@@ -20,7 +20,6 @@
     ; CHECK-NEXT: renamable $sgpr1 = KILL undef $sgpr1
     ; CHECK-NEXT: renamable $sgpr4_sgpr5_sgpr6_sgpr7_sgpr8_sgpr9_sgpr10_sgpr11 = S_BUFFER_LOAD_DWORDX8_IMM undef renamable $sgpr0_sgpr1_sgpr2_sgpr3, 416, 0 :: (dereferenceable invariant load (s256), align 4)
     ; CHECK-NEXT: dead [[V_CVT_U32_F32_e64_:%[0-9]+]]:vgpr_32 = V_CVT_U32_F32_e64 0, $sgpr4, 0, 0, implicit $mode, implicit $exec
-    ; CHECK-NEXT: SI_SPILL_S256_SAVE renamable $sgpr4_sgpr5_sgpr6_sgpr7_sgpr8_sgpr9_sgpr10_sgpr11, %stack.0, implicit $exec, implicit $sgpr32 :: (store (s256) into %stack.0, align 4, addrspace 5)
     ; CHECK-NEXT: dead renamable $sgpr4_sgpr5_sgpr6_sgpr7_sgpr8_sgpr9_sgpr10_sgpr11_sgpr12_sgpr13_sgpr14_sgpr15_sgpr16_sgpr17_sgpr18_sgpr19 = IMPLICIT_DEF
     ; CHECK-NEXT: renamable $sgpr4_sgpr5_sgpr6_sgpr7_sgpr8_sgpr9_sgpr10_sgpr11 = S_BUFFER_LOAD_DWORDX8_IMM undef renamable $sgpr0_sgpr1_sgpr2_sgpr3, 416, 0 :: (dereferenceable invariant load (s256), align 4)
     ; CHECK-NEXT: renamable $sgpr3 = COPY killed renamable $sgpr7
Index: llvm/lib/CodeGen/InlineSpiller.cpp
===================================================================
--- llvm/lib/CodeGen/InlineSpiller.cpp
+++ llvm/lib/CodeGen/InlineSpiller.cpp
@@ -753,6 +753,35 @@
         continue;
       LLVM_DEBUG(dbgs() << "All defs dead: " << *MI);
       DeadDefs.push_back(MI);
+      // If MI is a bundle header, also try removing copies inside the bundle,
+      // otherwise the verifier would complain "live range continues after dead
+      // def flag".
+      if (MI->isBundledWithSucc() && !MI->isBundledWithPred()) {
+        MachineBasicBlock::instr_iterator BeginIt = MI->getIterator(),
+                                          EndIt = MI->getParent()->instr_end();
+        ++BeginIt; // Skip MI that was already handled.
+
+        bool OnlyDeadCopies = true;
+        for (MachineBasicBlock::instr_iterator It = BeginIt;
+             It != EndIt && It->isBundledWithPred(); ++It) {
+
+          auto DestSrc = TII.isCopyInstr(*It);
+          bool IsCopyToDeadReg =
+              DestSrc && DestSrc->Destination->getReg() == Reg;
+          if (!IsCopyToDeadReg) {
+            OnlyDeadCopies = false;
+            break;
+          }
+        }
+        if (OnlyDeadCopies) {
+          for (MachineBasicBlock::instr_iterator It = BeginIt;
+               It != EndIt && It->isBundledWithPred(); ++It) {
+            It->addRegisterDead(Reg, &TRI);
+            LLVM_DEBUG(dbgs() << "All defs dead: " << *It);
+            DeadDefs.push_back(&*It);
+          }
+        }
+      }
     }
   }
 


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D156999.557889.patch
Type: text/x-patch
Size: 3501 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20231026/936e244b/attachment.bin>