[PATCH] D127109: llvm-reduce: Don't assert on functions which don't track liveness

[Matt Arsenault via Phabricator via llvm-commits]

arsenm created this revision.
arsenm added reviewers: qcolombet, MatzeB.
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I still do not understand why this is a property that exists. The
queries for block liveins assert that this is true. However, it's
possible to have block live ins set without this set. In order to
accurately clone the function, we should either remove the assertion
from the liveins() query, or have the verifier check that there are no
block live ins for !TracksLiveness.


https://reviews.llvm.org/D127109

Files:
  llvm/test/tools/llvm-reduce/mir/tracks-reg-liveness.mir
  llvm/tools/llvm-reduce/ReducerWorkItem.cpp


Index: llvm/tools/llvm-reduce/ReducerWorkItem.cpp
===================================================================
--- llvm/tools/llvm-reduce/ReducerWorkItem.cpp
+++ llvm/tools/llvm-reduce/ReducerWorkItem.cpp
@@ -190,6 +190,9 @@
       SrcMF->getFunctionNumber(), DestMMI);
   DenseMap<MachineBasicBlock *, MachineBasicBlock *> Src2DstMBB;
 
+  const bool TracksRegLiveness =
+    SrcMF->getProperties().hasProperty(MachineFunctionProperties::Property::TracksLiveness);
+
   auto *SrcMRI = &SrcMF->getRegInfo();
   auto *DstMRI = &DstMF->getRegInfo();
 
@@ -270,8 +273,11 @@
       auto *DstSuccMBB = Src2DstMBB[SrcSuccMBB];
       DstMBB->addSuccessor(DstSuccMBB, SrcMBB.getSuccProbability(It));
     }
-    for (auto &LI : SrcMBB.liveins())
-      DstMBB->addLiveIn(LI);
+
+    if (TracksRegLiveness) {
+      for (auto &LI : SrcMBB.liveins())
+        DstMBB->addLiveIn(LI);
+    }
 
     // Make sure MRI knows about registers clobbered by unwinder.
     if (DstMBB->isEHPad()) {
Index: llvm/test/tools/llvm-reduce/mir/tracks-reg-liveness.mir
===================================================================
--- /dev/null
+++ llvm/test/tools/llvm-reduce/mir/tracks-reg-liveness.mir
@@ -0,0 +1,27 @@
+# REQUIRES: amdgpu-registered-target
+# RUN: llvm-reduce -simplify-mir --delta-passes=instructions -mtriple=amdgcn-amd-amdhsa --test FileCheck --test-arg --check-prefix=CHECK-INTERESTINGNESS --test-arg %s --test-arg --input-file %s -o %t 2> %t.log
+# RUN: FileCheck --check-prefix=RESULT %s < %t
+
+# CHECK-INTERESTINGNESS: V_MOV_B32_e32 $vgpr0
+# CHECK-INTERESTINGNESS: S_NOP 0
+
+# The liveins list on the block was not carried through.
+
+# RESULT: bb.0:
+# RESULT-NEXT: %0:vgpr_32 = V_MOV_B32_e32 $vgpr0, implicit $exec
+# RESULT-NEXT: S_NOP 0
+# RESULT-NEXT: S_ENDPGM 0, implicit %0, implicit %0
+
+---
+name: func
+tracksRegLiveness: false
+body:             |
+  bb.0:
+    liveins: $vgpr0, $vgpr1_vgpr2
+    S_WAITCNT 0
+    %0:vgpr_32 = V_MOV_B32_e32 $vgpr0, implicit $exec
+    %1:vgpr_32 = V_MOV_B32_e32 $vgpr1, implicit $exec
+    S_NOP 0
+    S_ENDPGM 0, implicit %0, implicit %1
+...
+


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