src/llvm-project/llvm/test/CodeGen/X86/coalescer-implicit-def-regression.mir

# RUN: llc -mtriple=x86_64-unknown-linux-gnu -run-pass=register-coalescer -o - %s

# An implicit-def will be added to SUBREG_TO_REG during coalescing
---
name:  rematerialize_subreg_to_reg_added_impdef_0
tracksRegLiveness: true
body:             |
  bb.0:
    successors: %bb.1(0x2aaaaaab), %bb.2(0x55555555)
    liveins: $edi

    %0:gr32 = MOV32r0 implicit-def dead $eflags
    %1:gr8 = COPY %0.sub_8bit
    %2:gr64 = SUBREG_TO_REG 0, killed %0, %subreg.sub_32bit
    JCC_1 %bb.2, 5, implicit killed undef $eflags

  bb.1:
    %4:gr8 = COPY %1
    %5:gr8 = COPY killed undef %1
    JMP_1 %bb.5

  bb.2:
    %6:gr64 = IMPLICIT_DEF
    %2:gr64 = COPY killed %6
    %5:gr8 = MOV8ri 1

  bb.5:
    successors: %bb.6(0x30000000), %bb.7(0x50000000)

    TEST8rr killed undef %5, %5, implicit-def $eflags
    JCC_1 %bb.7, 5, implicit killed undef $eflags

  bb.6:
    $al = COPY killed %1
    RET 0, killed undef $al

  bb.7:
    MOV64mr undef $noreg, 1, undef $noreg, 0, undef $noreg, killed %2 :: (store (s64))
    RET 0, killed undef $al

...


# Reduced version of previous with the SUBREG_TO_REG already folded
# away.
#
# The mov32r0 defines a subregister and has an implicit-def of the
# super register. After coalescing, the full register implicit def of
# %2 becomes a different subregister def.

---
name:  rematerialize_subreg_to_reg_coalesces_to_subreg_impdef
tracksRegLiveness: true
body:             |
  bb.0:
    successors: %bb.1(0x2aaaaaab), %bb.2(0x55555555)
    liveins: $edi

    undef %2.sub_32bit:gr64_with_sub_8bit = MOV32r0 implicit-def dead $eflags, implicit-def %2
    %1:gr8 = COPY %2.sub_8bit
    JCC_1 %bb.2, 5, implicit killed undef $eflags

  bb.1:
    successors: %bb.3(0x80000000)

    dead %3:gr8 = COPY %1
    %4:gr8 = COPY undef %1
    JMP_1 %bb.3

  bb.2:
    successors: %bb.3(0x80000000)

    %5:gr64 = IMPLICIT_DEF
    %2:gr64_with_sub_8bit = COPY %5
    %4:gr8 = MOV8ri 1

  bb.3:
    successors: %bb.4(0x30000000), %bb.5(0x50000000)

    TEST8rr undef %4, %4, implicit-def $eflags
    JCC_1 %bb.5, 5, implicit killed undef $eflags

  bb.4:
    $al = COPY %1
    RET 0, killed undef $al

  bb.5:
    MOV64mr undef $noreg, 1, undef $noreg, 0, undef $noreg, %2 :: (store (s64))
    RET 0, killed undef $al

...