llvm-project/llvm/test/CodeGen/AMDGPU/detect-dead-lanes.mir

# RUN: llc -march=amdgcn -run-pass detect-dead-lanes -o /dev/null %s 2>&1 | FileCheck %s
--- |
  define void @test0() { ret void }
  define void @test1() { ret void }
  define void @test2() { ret void }
  define void @test3() { ret void }
  define void @test4() { ret void }
  define void @loop0() { ret void }
  define void @loop1() { ret void }
  define void @loop2() { ret void }
...
---
# Combined use/def transfer check, the basics.
# CHECK-LABEL: name: test0
# CHECK: S_NOP 0, implicit-def %0
# CHECK: S_NOP 0, implicit-def %1
# CHECK: S_NOP 0, implicit-def dead %2
# CHECK: %3 = REG_SEQUENCE %0, {{[0-9]+}}, %1, {{[0-9]+}}, undef %2, {{[0-9]+}}
# CHECK: S_NOP 0, implicit %3:sub0
# CHECK: S_NOP 0, implicit %3:sub1
# CHECK: S_NOP 0, implicit undef %3:sub2
# CHECK: %4 = COPY %3:sub0_sub1
# CHECK: %5 = COPY %3:sub2_sub3
# CHECK: S_NOP 0, implicit %4:sub0
# CHECK: S_NOP 0, implicit %4:sub1
# CHECK: S_NOP 0, implicit undef %5:sub0
name: test0
isSSA: true
registers:
  - { id: 0, class: sreg_32 }
  - { id: 1, class: sreg_32 }
  - { id: 2, class: sreg_32 }
  - { id: 3, class: sreg_128 }
  - { id: 4, class: sreg_64 }
  - { id: 5, class: sreg_64 }
body: |
  bb.0:
    S_NOP 0, implicit-def %0
    S_NOP 0, implicit-def %1
    S_NOP 0, implicit-def %2
    %3 = REG_SEQUENCE %0, %subreg.sub0, %1, %subreg.sub1, %2, %subreg.sub3
    S_NOP 0, implicit %3:sub0
    S_NOP 0, implicit %3:sub1
    S_NOP 0, implicit %3:sub2
    %4 = COPY %3:sub0_sub1
    %5 = COPY %3:sub2_sub3
    S_NOP 0, implicit %4:sub0
    S_NOP 0, implicit %4:sub1
    S_NOP 0, implicit %5:sub0
...
---
# Check defined lanes transfer; Includes checking for some special cases like
# undef operands or IMPLICIT_DEF definitions.
# CHECK-LABEL: name: test1
# CHECK: %0 = REG_SEQUENCE %sgpr0, {{[0-9]+}}, %sgpr0, {{[0-9]+}}
# CHECK: %1 = INSERT_SUBREG %0, %sgpr1, {{[0-9]+}}
# CHECK: %2 = INSERT_SUBREG %0:sub2_sub3, %sgpr42, {{[0-9]+}}
# CHECK: S_NOP 0, implicit %1:sub0
# CHECK: S_NOP 0, implicit undef %1:sub1
# CHECK: S_NOP 0, implicit %1:sub2
# CHECK: S_NOP 0, implicit %1:sub3
# CHECK: S_NOP 0, implicit %2:sub0
# CHECK: S_NOP 0, implicit undef %2:sub1

# CHECK: %3 = IMPLICIT_DEF
# CHECK: %4 = INSERT_SUBREG %0, undef %3, {{[0-9]+}}
# CHECK: S_NOP 0, implicit undef %4:sub0
# CHECK: S_NOP 0, implicit undef %4:sub1
# CHECK: S_NOP 0, implicit %4:sub2
# CHECK: S_NOP 0, implicit undef %4:sub3

# CHECK: %5 = EXTRACT_SUBREG %0, {{[0-9]+}}
# CHECK: %6 = EXTRACT_SUBREG %5, {{[0-9]+}}
# CHECK: %7 = EXTRACT_SUBREG %5, {{[0-9]+}}
# CHECK: S_NOP 0, implicit %5
# CHECK: S_NOP 0, implicit %6
# CHECK: S_NOP 0, implicit undef %7

# CHECK: %8 = IMPLICIT_DEF
# CHECK: %9 = EXTRACT_SUBREG undef %8, {{[0-9]+}}
# CHECK: S_NOP 0, implicit undef %9

# CHECK: %10 = EXTRACT_SUBREG undef %0, {{[0-9]+}}
# CHECK: S_NOP 0, implicit undef %10
name: test1
isSSA: true
registers:
  - { id: 0, class: sreg_128 }
  - { id: 1, class: sreg_128 }
  - { id: 2, class: sreg_64 }
  - { id: 3, class: sreg_32 }
  - { id: 4, class: sreg_128 }
  - { id: 5, class: sreg_64 }
  - { id: 6, class: sreg_32 }
  - { id: 7, class: sreg_32 }
  - { id: 8, class: sreg_64 }
  - { id: 9, class: sreg_32 }
  - { id: 10, class: sreg_128 }
body: |
  bb.0:
    %0 = REG_SEQUENCE %sgpr0, %subreg.sub0, %sgpr0, %subreg.sub2
    %1 = INSERT_SUBREG %0, %sgpr1, %subreg.sub3
    %2 = INSERT_SUBREG %0:sub2_sub3, %sgpr42, %subreg.sub0
    S_NOP 0, implicit %1:sub0
    S_NOP 0, implicit %1:sub1
    S_NOP 0, implicit %1:sub2
    S_NOP 0, implicit %1:sub3
    S_NOP 0, implicit %2:sub0
    S_NOP 0, implicit %2:sub1

    %3 = IMPLICIT_DEF
    %4 = INSERT_SUBREG %0, %3, %subreg.sub0
    S_NOP 0, implicit %4:sub0
    S_NOP 0, implicit %4:sub1
    S_NOP 0, implicit %4:sub2
    S_NOP 0, implicit %4:sub3

    %5 = EXTRACT_SUBREG %0, %subreg.sub0_sub1
    %6 = EXTRACT_SUBREG %5, %subreg.sub0
    %7 = EXTRACT_SUBREG %5, %subreg.sub1
    S_NOP 0, implicit %5
    S_NOP 0, implicit %6
    S_NOP 0, implicit %7

    %8 = IMPLICIT_DEF
    %9 = EXTRACT_SUBREG %8, %subreg.sub1
    S_NOP 0, implicit %9

    %10 = EXTRACT_SUBREG undef %0, %subreg.sub2_sub3
    S_NOP 0, implicit %10
...
---
# Check used lanes transfer; Includes checking for some special cases like
# undef operands.
# CHECK-LABEL: name: test2
# CHECK: S_NOP 0, implicit-def dead %0
# CHECK: S_NOP 0, implicit-def %1
# CHECK: S_NOP 0, implicit-def %2
# CHECK: %3 = REG_SEQUENCE undef %0, {{[0-9]+}}, %1, {{[0-9]+}}, %2, {{[0-9]+}}
# CHECK: S_NOP 0, implicit %3:sub1
# CHECK: S_NOP 0, implicit %3:sub3

# CHECK: S_NOP 0, implicit-def %4
# CHECK: S_NOP 0, implicit-def dead %5
# CHECK: %6 = REG_SEQUENCE %4, {{[0-9]+}}, undef %5, {{[0-9]+}}
# CHECK: S_NOP 0, implicit %6

# CHECK: S_NOP 0, implicit-def dead %7
# CHECK: S_NOP 0, implicit-def %8
# CHECK: %9 = INSERT_SUBREG undef %7, %8, {{[0-9]+}}
# CHECK: S_NOP 0, implicit %9:sub2

# CHECK: S_NOP 0, implicit-def %10
# CHECK: S_NOP 0, implicit-def dead %11
# CHECK: %12 = INSERT_SUBREG %10, undef %11, {{[0-9]+}}
# CHECK: S_NOP 0, implicit %12:sub3

# CHECK: S_NOP 0, implicit-def %13
# CHECK: S_NOP 0, implicit-def dead %14
# CHECK: %15 = REG_SEQUENCE %13, {{[0-9]+}}, undef %14, {{[0-9]+}}
# CHECK: %16 = EXTRACT_SUBREG %15, {{[0-9]+}}
# CHECK: S_NOP 0, implicit %16:sub1

name: test2
isSSA: true
registers:
  - { id: 0, class: sreg_32 }
  - { id: 1, class: sreg_32 }
  - { id: 2, class: sreg_64 }
  - { id: 3, class: sreg_128 }
  - { id: 4, class: sreg_32 }
  - { id: 5, class: sreg_32 }
  - { id: 6, class: sreg_64 }
  - { id: 7, class: sreg_128 }
  - { id: 8, class: sreg_64 }
  - { id: 9, class: sreg_128 }
  - { id: 10, class: sreg_128 }
  - { id: 11, class: sreg_64 }
  - { id: 12, class: sreg_128 }
  - { id: 13, class: sreg_64 }
  - { id: 14, class: sreg_64 }
  - { id: 15, class: sreg_128 }
  - { id: 16, class: sreg_64 }
body: |
  bb.0:
    S_NOP 0, implicit-def %0
    S_NOP 0, implicit-def %1
    S_NOP 0, implicit-def %2
    %3 = REG_SEQUENCE %0, %subreg.sub0, %1, %subreg.sub1, %2, %subreg.sub2_sub3
    S_NOP 0, implicit %3:sub1
    S_NOP 0, implicit %3:sub3

    S_NOP 0, implicit-def %4
    S_NOP 0, implicit-def %5
    %6 = REG_SEQUENCE %4, %subreg.sub0, undef %5, %subreg.sub1
    S_NOP 0, implicit %6

    S_NOP 0, implicit-def %7
    S_NOP 0, implicit-def %8
    %9 = INSERT_SUBREG %7, %8, %subreg.sub2_sub3
    S_NOP 0, implicit %9:sub2

    S_NOP 0, implicit-def %10
    S_NOP 0, implicit-def %11
    %12 = INSERT_SUBREG %10, %11, %subreg.sub0_sub1
    S_NOP 0, implicit %12:sub3

    S_NOP 0, implicit-def %13
    S_NOP 0, implicit-def %14
    %15 = REG_SEQUENCE %13, %subreg.sub0_sub1, %14, %subreg.sub2_sub3
    %16 = EXTRACT_SUBREG %15, %subreg.sub0_sub1
    S_NOP 0, implicit %16:sub1
...
---
# Check that copies to physregs use all lanes, copies from physregs define all
# lanes. So we should not get a dead/undef flag here.
# CHECK-LABEL: name: test3
# CHECK: S_NOP 0, implicit-def %0
# CHECK: %vcc = COPY %0
# CHECK: %1 = COPY %vcc
# CHECK: S_NOP 0, implicit %1
name: test3
isSSA: true
tracksRegLiveness: true
registers:
  - { id: 0, class: sreg_64 }
  - { id: 1, class: sreg_64 }
body: |
  bb.0:
    S_NOP 0, implicit-def %0
    %vcc = COPY %0

    %1 = COPY %vcc
    S_NOP 0, implicit %1
...
---
# Check that implicit-def/kill do not count as def/uses.
# CHECK-LABEL: name: test4
# CHECK: S_NOP 0, implicit-def dead %0
# CHECK: KILL undef %0
# CHECK: %1 = IMPLICIT_DEF
# CHECK: S_NOP 0, implicit undef %1
name: test4
isSSA: true
tracksRegLiveness: true
registers:
  - { id: 0, class: sreg_64 }
  - { id: 1, class: sreg_64 }
body: |
  bb.0:
    S_NOP 0, implicit-def %0
    KILL %0

    %1 = IMPLICIT_DEF
    S_NOP 0, implicit %1
...
---
# Check "optimistic" dataflow fixpoint in phi-loops.
# CHECK-LABEL: name: loop0
# CHECK: bb.0:
# CHECK: S_NOP 0, implicit-def %0
# CHECK: S_NOP 0, implicit-def dead %1
# CHECK: S_NOP 0, implicit-def dead %2
# CHECK: %3 = REG_SEQUENCE %0, {{[0-9]+}}, undef %1, {{[0-9]+}}, undef %2, {{[0-9]+}}

# CHECK: bb.1:
# CHECK: %4 = PHI %3, %bb.0, %5, %bb.1

# CHECK: bb.2:
# CHECK:   S_NOP 0, implicit %4:sub0
# CHECK:   S_NOP 0, implicit undef %4:sub3
name: loop0
isSSA: true
tracksRegLiveness: true
registers:
  - { id: 0, class: sreg_32 }
  - { id: 1, class: sreg_32 }
  - { id: 2, class: sreg_32 }
  - { id: 3, class: sreg_128 }
  - { id: 4, class: sreg_128 }
  - { id: 5, class: sreg_128 }
body: |
  bb.0:
    successors: %bb.1
    S_NOP 0, implicit-def %0
    S_NOP 0, implicit-def %1
    S_NOP 0, implicit-def %2
    %3 = REG_SEQUENCE %0, %subreg.sub0, %1, %subreg.sub1, %2, %subreg.sub2
    S_BRANCH %bb.1

  bb.1:
    successors: %bb.1, %bb.2
    %4 = PHI %3, %bb.0, %5, %bb.1

    ; let's swiffle some lanes around for fun...
    %5 = REG_SEQUENCE %4:sub0, %subreg.sub0, %4:sub2, %subreg.sub1, %4:sub1, %subreg.sub2, %4:sub3, %subreg.sub3

    S_CBRANCH_VCCNZ %bb.1, implicit undef %vcc
    S_BRANCH %bb.2

  bb.2:
    S_NOP 0, implicit %4:sub0
    S_NOP 0, implicit %4:sub3
...
---
# Check a loop that needs to be traversed multiple times to reach the fixpoint
# for the used lanes. The example reads sub3 lane at the end, however with each
# loop iteration we should get 1 more lane marked as we cycles the sublanes
# along. Sublanes sub0, sub1 and sub3 are rotate in the loop so only sub2
# should be dead.
# CHECK-LABEL: name: loop1
# CHECK: bb.0:
# CHECK: S_NOP 0, implicit-def %0
# CHECK: S_NOP 0, implicit-def %1
# CHECK: S_NOP 0, implicit-def dead %2
# CHECK: S_NOP 0, implicit-def %3
# CHECK: %4 = REG_SEQUENCE %0, {{[0-9]+}}, %1, {{[0-9]+}}, undef %2, {{[0-9]+}}, %3, {{[0-9]+}}

# CHECK: bb.1:
# CHECK: %5 = PHI %4, %bb.0, %6, %bb.1

# CHECK: %6 = REG_SEQUENCE %5:sub1, {{[0-9]+}}, %5:sub3, {{[0-9]+}}, undef %5:sub2, {{[0-9]+}}, %5:sub0, {{[0-9]+}}

# CHECK: bb.2:
# CHECK:   S_NOP 0, implicit %6:sub3
name: loop1
isSSA: true
tracksRegLiveness: true
registers:
  - { id: 0, class: sreg_32 }
  - { id: 1, class: sreg_32 }
  - { id: 2, class: sreg_32 }
  - { id: 3, class: sreg_32 }
  - { id: 4, class: sreg_128 }
  - { id: 5, class: sreg_128 }
  - { id: 6, class: sreg_128 }
body: |
  bb.0:
    successors: %bb.1
    S_NOP 0, implicit-def %0
    S_NOP 0, implicit-def %1
    S_NOP 0, implicit-def dead %2
    S_NOP 0, implicit-def %3
    %4 = REG_SEQUENCE %0, %subreg.sub0, %1, %subreg.sub1, %2, %subreg.sub2, %3, %subreg.sub3
    S_BRANCH %bb.1

  bb.1:
    successors: %bb.1, %bb.2
    %5 = PHI %4, %bb.0, %6, %bb.1

    ; rotate lanes, but skip sub2 lane...
    %6 = REG_SEQUENCE %5:sub1, %subreg.sub0, %5:sub3, %subreg.sub1, %5:sub2, %subreg.sub2, %5:sub0, %subreg.sub3

    S_CBRANCH_VCCNZ %bb.1, implicit undef %vcc
    S_BRANCH %bb.2

  bb.2:
    S_NOP 0, implicit %6:sub3
...
---
# Similar to loop1 test, but check for fixpoint of defined lanes.
# Lanes are rotate between sub0, sub2, sub3 so only sub1 should be dead/undef.
# CHECK-LABEL: name: loop2
# CHECK: bb.0:
# CHECK: S_NOP 0, implicit-def %0
# CHECK: %1 = REG_SEQUENCE %0, {{[0-9]+}}

# CHECK: bb.1:
# CHECK: %2 = PHI %1, %bb.0, %3, %bb.1

# CHECK: %3 = REG_SEQUENCE %2:sub3, {{[0-9]+}}, undef %2:sub1, {{[0-9]+}}, %2:sub0, {{[0-9]+}}, %2:sub2, {{[0-9]+}}

# CHECK: bb.2:
# CHECK:   S_NOP 0, implicit %2:sub0
# CHECK:   S_NOP 0, implicit undef %2:sub1
# CHECK:   S_NOP 0, implicit %2:sub2
# CHECK:   S_NOP 0, implicit %2:sub3
name: loop2
isSSA: true
tracksRegLiveness: true
registers:
  - { id: 0, class: sreg_32 }
  - { id: 1, class: sreg_128 }
  - { id: 2, class: sreg_128 }
  - { id: 3, class: sreg_128 }
body: |
  bb.0:
    successors: %bb.1
    S_NOP 0, implicit-def %0
    %1 = REG_SEQUENCE %0, %subreg.sub0
    S_BRANCH %bb.1

  bb.1:
    successors: %bb.1, %bb.2
    %2 = PHI %1, %bb.0, %3, %bb.1

    ; rotate subreg lanes, skipping sub1
    %3 = REG_SEQUENCE %2:sub3, %subreg.sub0, %2:sub1, %subreg.sub1, %2:sub0, %subreg.sub2, %2:sub2, %subreg.sub3

    S_CBRANCH_VCCNZ %bb.1, implicit undef %vcc
    S_BRANCH %bb.2

  bb.2:
    S_NOP 0, implicit %2:sub0
    S_NOP 0, implicit undef %2:sub1
    S_NOP 0, implicit %2:sub2
    S_NOP 0, implicit %2:sub3
...