llvm-project/llvm/test/CodeGen/X86/late-remat-update-2.mir

# RUN: llc -mtriple=x86_64-- -run-pass=simple-register-coalescing -run-pass=regallocbasic -run-pass=virtregrewriter -late-remat-update-threshold=0 %s -o - | FileCheck %s
#
# PR40061: %t2 = %t1 is rematerialized and %t1 is added into toBeUpdated set
# to postpone its live interval update. After the rematerialization, the live
# interval of %t1 is larger than necessary. Then %t1 is merged into %t3 and %t1
# gets removed. After the merge, %t3 contains live interval larger than
# necessary. Because %t3 is not in toBeUpdated set so its live interval is not
# updated after register coalescing, and it will break some assumption in
# regalloc. This test wants to check the live interval is up-to-date after
# register coalescing.
#
# To prevent the test from taking effect only in assert enabled mode, we want
# to achieve the test goal without dumping regalloc trace. We add strong hint
# to allocate both %t1 and %t2 to $rax register. If the %t1's live interval is
# not shrinked properly after register coalescing, %t1 and %t2 will not be
# both allocated to $rax because of inference, and we utilize the fact to
# achieve the test goal. But note that the assumption only holds when we use
# regallocbasic instead of greedy because greedy can update the live interval
# in the process of splitting.
#
# CHECK-LABEL: name: foo
# CHECK: bb.0.entry:
# CHECK: $rax = MOV64ri32 -11
# CHECK: bb.1:
# CHECK: $rax = MOV64ri32 -11
# CHECK: $rax = ADD64ri8 killed renamable $rax, 5
# CHECK: CMP64ri8 renamable $rax
# CHECK: RET 0, $rax
# CHECK: bb.2:
# CHECK: $rax = ADD64ri8 killed renamable $rax, 10
# CHECK: bb.3:
# CHECK: RET 0, $rax
---
name:            foo
body:             |
  bb.0.entry:
    successors: %bb.1(0x15555555), %bb.2(0x6aaaaaab)

    %t1:gr64 = MOV64ri32 -11
    CMP64ri8 %t1, 1, implicit-def $eflags
    JCC_1 %bb.2, 4, implicit killed $eflags
    JMP_1 %bb.1

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

    %t2:gr64 = COPY %t1
    %t2:gr64 = ADD64ri8 %t2, 5, implicit-def $eflags
    $rax = COPY %t2
    CMP64ri8 %t2, 1, implicit-def $eflags
    JCC_1 %bb.1, 4, implicit killed $eflags
    RET 0, $rax

  bb.2:
    successors: %bb.3(0x80000000)
    %t3:gr64 = COPY %t1
    %t3:gr64 = ADD64ri8 %t3, 10, implicit-def $eflags

  bb.3:
    $rax = COPY %t3
    RET 0, $rax

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