[llvm] [MachineLoopInfo] Fix assertion failure on undef use operands (PR #100137)

[Jay Foad via llvm-commits]

================
@@ -0,0 +1,77 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 5
+# RUN: llc -mtriple=amdgcn -mcpu=gfx1100 -run-pass=early-machinelicm %s | FileCheck %s
+
+---
+name: f
+tracksRegLiveness: true
+body: |
+  ; CHECK-LABEL: name: f
+  ; CHECK: bb.0:
+  ; CHECK-NEXT:   successors: %bb.1(0x80000000)
+  ; CHECK-NEXT:   liveins: $vgpr0, $vgpr1
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   [[DEF:%[0-9]+]]:vgpr_32 = IMPLICIT_DEF
+  ; CHECK-NEXT:   [[DEF1:%[0-9]+]]:sreg_32 = IMPLICIT_DEF
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT: bb.1:
+  ; CHECK-NEXT:   successors: %bb.3(0x80000000)
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   [[REG_SEQUENCE:%[0-9]+]]:vreg_64 = REG_SEQUENCE undef %3:vgpr_32, %subreg.sub0, undef [[DEF]], %subreg.sub1
+  ; CHECK-NEXT:   S_BRANCH %bb.3
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT: bb.2:
+  ; CHECK-NEXT:   successors: %bb.5(0x04000000), %bb.1(0x7c000000)
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   $vcc_lo = COPY undef [[DEF1]]
+  ; CHECK-NEXT:   S_CBRANCH_VCCNZ %bb.5, implicit $vcc_lo
+  ; CHECK-NEXT:   S_BRANCH %bb.1
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT: bb.3:
+  ; CHECK-NEXT:   successors: %bb.4(0x04000000), %bb.3(0x7c000000)
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   S_CBRANCH_SCC1 %bb.3, implicit undef $scc
+  ; CHECK-NEXT:   S_BRANCH %bb.4
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT: bb.4:
+  ; CHECK-NEXT:   successors: %bb.2(0x40000000), %bb.1(0x40000000)
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   SI_LOOP undef [[DEF1]], %bb.1, implicit-def dead $exec, implicit-def dead $scc, implicit $exec
+  ; CHECK-NEXT:   S_BRANCH %bb.2
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT: bb.5:
+  ; CHECK-NEXT:   S_ENDPGM 0
+  bb.0:
+    successors: %bb.1(0x80000000)
+    liveins: $vgpr0, $vgpr1
+
+    %59:vgpr_32 = IMPLICIT_DEF
+    %60:sreg_32 = IMPLICIT_DEF
----------------
jayfoad wrote:

Done anyway.

https://github.com/llvm/llvm-project/pull/100137