[PATCH] D120042: [AMDGPU] Fix kill flag on overlapping sgpr copy

[Sebastian Neubauer via Phabricator via llvm-commits]

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

Same as on vgpr copies, we cannot kill the source register if it
overlaps with the destination register. Otherwise, the kill of the
source register will also count as a kill for the destination register.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D120042

Files:
  llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
  llvm/test/CodeGen/AMDGPU/copy-overlap-sgpr-kill.mir


Index: llvm/test/CodeGen/AMDGPU/copy-overlap-sgpr-kill.mir
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/AMDGPU/copy-overlap-sgpr-kill.mir
@@ -0,0 +1,49 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx906 -verify-machineinstrs -run-pass=postrapseudos -o - %s | FileCheck %s
+
+# Don't set a kill of the super register on the last instruction with
+# an overlapping copy. This would kill part of the values in the
+# result copies.
+
+---
+name: overlapping_copy_kill_undef_reg_after_copy
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $sgpr30_sgpr31, $sgpr4_sgpr5_sgpr6_sgpr7_sgpr8_sgpr9_sgpr10_sgpr11
+
+    ; CHECK-LABEL: name: overlapping_copy_kill_undef_reg_after_copy
+    ; CHECK: liveins: $sgpr30_sgpr31, $sgpr4_sgpr5_sgpr6_sgpr7_sgpr8_sgpr9_sgpr10_sgpr11
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: $sgpr0_sgpr1 = S_MOV_B64 $sgpr4_sgpr5, implicit $sgpr4_sgpr5_sgpr6_sgpr7_sgpr8_sgpr9_sgpr10_sgpr11, implicit-def $sgpr0_sgpr1_sgpr2_sgpr3_sgpr4_sgpr5_sgpr6_sgpr7
+    ; CHECK-NEXT: $sgpr2_sgpr3 = S_MOV_B64 $sgpr6_sgpr7, implicit $sgpr4_sgpr5_sgpr6_sgpr7_sgpr8_sgpr9_sgpr10_sgpr11
+    ; CHECK-NEXT: $sgpr4_sgpr5 = S_MOV_B64 $sgpr8_sgpr9, implicit $sgpr4_sgpr5_sgpr6_sgpr7_sgpr8_sgpr9_sgpr10_sgpr11
+    ; CHECK-NEXT: $sgpr6_sgpr7 = S_MOV_B64 $sgpr10_sgpr11, implicit $sgpr4_sgpr5_sgpr6_sgpr7_sgpr8_sgpr9_sgpr10_sgpr11
+    ; CHECK-NEXT: renamable $sgpr1 = S_ADD_I32 0, $sgpr1, implicit-def $scc
+    ; CHECK-NEXT: S_SETPC_B64 $sgpr30_sgpr31, implicit $sgpr0, implicit $sgpr1, implicit $sgpr2, implicit $sgpr3, implicit $sgpr4, implicit $sgpr5, implicit $sgpr6, implicit $sgpr7
+    renamable $sgpr0_sgpr1_sgpr2_sgpr3_sgpr4_sgpr5_sgpr6_sgpr7 = COPY killed renamable $sgpr4_sgpr5_sgpr6_sgpr7_sgpr8_sgpr9_sgpr10_sgpr11
+    renamable $sgpr1 = S_ADD_I32 0, $sgpr1, implicit-def $scc
+    S_SETPC_B64 $sgpr30_sgpr31, implicit $sgpr0, implicit $sgpr1, implicit $sgpr2, implicit $sgpr3, implicit $sgpr4, implicit $sgpr5, implicit $sgpr6, implicit $sgpr7
+
+...
+
+---
+name: nonoverlapping_copy_kill
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $sgpr30_sgpr31, $sgpr3_sgpr4_sgpr5
+
+    ; CHECK-LABEL: name: nonoverlapping_copy_kill
+    ; CHECK: liveins: $sgpr30_sgpr31, $sgpr3_sgpr4_sgpr5
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: $sgpr0 = S_MOV_B32 $sgpr3, implicit $sgpr3_sgpr4_sgpr5, implicit-def $sgpr0_sgpr1_sgpr2
+    ; CHECK-NEXT: $sgpr1 = S_MOV_B32 $sgpr4, implicit $sgpr3_sgpr4_sgpr5
+    ; CHECK-NEXT: $sgpr2 = S_MOV_B32 $sgpr5, implicit killed $sgpr3_sgpr4_sgpr5
+    ; CHECK-NEXT: renamable $sgpr1 = S_ADD_I32 0, $sgpr1, implicit-def $scc
+    ; CHECK-NEXT: S_SETPC_B64 $sgpr30_sgpr31, implicit $sgpr0, implicit $sgpr1, implicit $sgpr2
+    renamable $sgpr0_sgpr1_sgpr2 = COPY killed renamable $sgpr3_sgpr4_sgpr5
+    renamable $sgpr1 = S_ADD_I32 0, $sgpr1, implicit-def $scc
+    S_SETPC_B64 $sgpr30_sgpr31, implicit $sgpr0, implicit $sgpr1, implicit $sgpr2
+
+...
Index: llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
===================================================================
--- llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
+++ llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
@@ -930,7 +930,9 @@
       reportIllegalCopy(this, MBB, MI, DL, DestReg, SrcReg, KillSrc);
       return;
     }
-    expandSGPRCopy(*this, MBB, MI, DL, DestReg, SrcReg, KillSrc, RC, Forward);
+    const bool CanKillSuperReg = KillSrc && !RI.regsOverlap(SrcReg, DestReg);
+    expandSGPRCopy(*this, MBB, MI, DL, DestReg, SrcReg, CanKillSuperReg, RC,
+                   Forward);
     return;
   }
 


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