llvm-project/llvm/test/CodeGen/AMDGPU/subreg-split-live-in-error.mir

# RUN: llc -march=amdgcn -mcpu=gfx900 -amdgpu-vgpr-index-mode -run-pass=greedy -stress-regalloc=16 -o - %s | FileCheck -check-prefixes=GCN %s

# An interval for a register that was partially defined was split, creating
# a new use (a COPY) which was reached by the undef point. In particular,
# there was a subrange of the new register which was reached by an "undef"
# point. When the code in extendSegmentsToUses verified value numbers between
# the new and the old live ranges, it did not account for this kind of a
# situation and asserted expecting the old value to exist. For a PHI node
# it is legal to have a missing predecessor value as long as the end of
# the predecessor is jointly dominated by the undefs.
#
# A simplified form of this can be illustrated as
#
# bb.1:
#   %0:vreg_64 = IMPLICIT_DEF
#   ...
#   S_CBRANCH_SCC1 %bb.2, implicit $vcc
#   S_BRANCH %bb.3
#
# bb.2:
# ; predecessors: %bb.1, %bb.4
#   dead %1:vreg_64 = COPY %0:vreg_64 ; This is the point of the inserted split
#   ...
#   S_BRANCH %bb.5
#
# bb.3:
# ; predecessors: %bb.1
#   undef %0.sub0:vreg_64 = COPY %123:sreg_32 ; undef point for %0.sub1
#   ...
#   S_BRANCH %bb.4
#
# bb.4
# ; predecessors: %bb.4
#   ...
#   S_BRANCH %bb.2
#
# This test exposes this scenario which caused previously caused an assert

---
name:            _amdgpu_ps_main
tracksRegLiveness: true
liveins:
  - { reg: '$vgpr2', virtual-reg: '%0' }
  - { reg: '$vgpr3', virtual-reg: '%1' }
  - { reg: '$vgpr4', virtual-reg: '%2' }
body: |
  bb.0:
    successors: %bb.1(0x40000000), %bb.2(0x40000000)
    liveins: $vgpr2, $vgpr3, $vgpr4
    %2:vgpr_32 = COPY $vgpr4
    %1:vgpr_32 = COPY $vgpr3
    %0:vgpr_32 = COPY $vgpr2
    S_CBRANCH_SCC0 %bb.2, implicit undef $scc

  bb.1:
    successors: %bb.5(0x80000000)
    undef %3.sub0:vreg_128 = V_MOV_B32_e32 0, implicit $exec
    %3.sub1:vreg_128 = COPY %3.sub0
    %3.sub2:vreg_128 = COPY %3.sub0
    S_BRANCH %bb.5

  bb.2:
    successors: %bb.3(0x40000000), %bb.4(0x40000000)
    S_CBRANCH_SCC0 %bb.4, implicit undef $scc

  bb.3:
    successors: %bb.5(0x80000000)
    undef %3.sub0:vreg_128 = V_MOV_B32_e32 0, implicit $exec
    %3.sub1:vreg_128 = COPY %3.sub0
    S_BRANCH %bb.5

  bb.4:
    successors: %bb.5(0x80000000)
    %3:vreg_128 = IMPLICIT_DEF

  bb.5:
    successors: %bb.6(0x40000000), %bb.22(0x40000000)
    %4:vgpr_32 = V_MOV_B32_e32 0, implicit $exec
    S_CBRANCH_SCC1 %bb.22, implicit undef $scc
    S_BRANCH %bb.6

  bb.6:
    successors: %bb.8(0x40000000), %bb.11(0x40000000)
    %5:vgpr_32 = V_MOV_B32_e32 0, implicit $exec
    dead %6:vgpr_32 = V_MUL_F32_e32 0, undef %7:vgpr_32, implicit $exec
    dead %8:vgpr_32 = V_MUL_F32_e32 0, %2, implicit $exec
    undef %9.sub1:vreg_64 = V_MUL_F32_e32 0, %1, implicit $exec
    undef %10.sub0:vreg_128 = V_MUL_F32_e32 0, %0, implicit $exec
    undef %11.sub0:sreg_256 = S_MOV_B32 0
    %11.sub1:sreg_256 = COPY %11.sub0
    %11.sub2:sreg_256 = COPY %11.sub0
    %11.sub3:sreg_256 = COPY %11.sub0
    %11.sub4:sreg_256 = COPY %11.sub0
    %11.sub5:sreg_256 = COPY %11.sub0
    %11.sub6:sreg_256 = COPY %11.sub0
    %11.sub7:sreg_256 = COPY %11.sub0
    %12:vreg_128 = IMAGE_SAMPLE_LZ_V4_V2 %9, %11, undef %13:sreg_128, 15, 0, 0, 0, 0, 0, 0, 0, 0, implicit $exec :: (dereferenceable load 16 from constant-pool, addrspace 4)
    %14:vgpr_32 = V_MOV_B32_e32 -1, implicit $exec
    %15:vreg_128 = IMPLICIT_DEF
    S_CBRANCH_SCC1 %bb.8, implicit undef $scc
    S_BRANCH %bb.11

  bb.7:
    successors: %bb.13(0x80000000)

    ; In reality we are checking that this code doesn't assert when splitting
    ; and inserting a spill. Here we just check that the point where the error
    ; occurs we see a correctly generated spill.
    ; GCN-LABEL: bb.7:
    ; GCN: SI_SPILL_V128_SAVE %{{[0-9]+}}, %stack.1, $sgpr0_sgpr1_sgpr2_sgpr3, $sgpr5, 0, implicit $exec

    undef %15.sub0:vreg_128 = V_MOV_B32_e32 0, implicit $exec
    %15.sub1:vreg_128 = COPY %15.sub0
    %15.sub2:vreg_128 = COPY %15.sub0
    %5:vgpr_32 = IMPLICIT_DEF
    S_BRANCH %bb.13

  bb.8:
    successors: %bb.9(0x40000000), %bb.10(0x40000000)
    S_CBRANCH_SCC0 %bb.10, implicit undef $scc

  bb.9:
    successors: %bb.12(0x80000000)

    ; GCN-LABEL: bb.9:
    ; GCN: SI_SPILL_V128_SAVE %{{[0-9]+}}, %stack.1, $sgpr0_sgpr1_sgpr2_sgpr3, $sgpr5, 0, implicit $exec

    undef %15.sub0:vreg_128 = V_MOV_B32_e32 0, implicit $exec
    %15.sub1:vreg_128 = COPY %15.sub0
    %15.sub2:vreg_128 = COPY %15.sub0
    S_BRANCH %bb.12

  bb.10:
    successors: %bb.12(0x80000000)

    ; GCN-LABEL: bb.10:
    ; GCN: SI_SPILL_V128_SAVE %{{[0-9]+}}, %stack.1, $sgpr0_sgpr1_sgpr2_sgpr3, $sgpr5, 0, implicit $exec

    undef %15.sub0:vreg_128 = V_MOV_B32_e32 2143289344, implicit $exec
    %15.sub1:vreg_128 = COPY %15.sub0
    %15.sub2:vreg_128 = COPY %15.sub0
    S_BRANCH %bb.12

  bb.11:
    successors: %bb.7(0x40000000), %bb.13(0x40000000)
    %16:sreg_64 = V_CMP_NE_U32_e64 0, %14, implicit $exec
    %17:sreg_64 = S_AND_B64 $exec, %16, implicit-def dead $scc
    $vcc = COPY %17
    S_CBRANCH_VCCNZ %bb.7, implicit $vcc
    S_BRANCH %bb.13

  bb.12:
    successors: %bb.11(0x80000000)
    %14:vgpr_32 = V_MOV_B32_e32 0, implicit $exec
    %5:vgpr_32 = V_MOV_B32_e32 -1, implicit $exec
    S_BRANCH %bb.11

  bb.13:
    successors: %bb.15(0x40000000), %bb.14(0x40000000)

    %18:vgpr_32 = V_MAD_F32 0, %10.sub0, 0, target-flags(amdgpu-gotprel) 1073741824, 0, -1082130432, 0, 0, implicit $exec
    %19:vgpr_32 = V_MAD_F32 0, %12.sub0, 0, target-flags(amdgpu-gotprel) 0, 0, 0, 0, 0, implicit $exec
    %20:sreg_128 = S_BUFFER_LOAD_DWORDX4_IMM undef %21:sreg_128, 1040, 0 :: (dereferenceable invariant load 16)
    %22:vgpr_32 = V_ADD_F32_e32 0, %19, implicit $exec
    %23:vgpr_32 = V_MAD_F32 0, %18, 0, 0, 0, 0, 0, 0, implicit $exec
    %24:vgpr_32 = COPY %20.sub3
    %25:vgpr_32 = V_MUL_F32_e64 0, target-flags(amdgpu-gotprel32-lo) 0, 0, %20.sub1, 0, 0, implicit $exec
    %26:sreg_128 = S_BUFFER_LOAD_DWORDX4_IMM undef %27:sreg_128, 1056, 0 :: (dereferenceable invariant load 16)
    %28:vgpr_32 = V_MAD_F32 0, %18, 0, %26.sub0, 0, 0, 0, 0, implicit $exec
    %29:vgpr_32 = V_ADD_F32_e32 %28, %19, implicit $exec
    %30:vgpr_32 = V_RCP_F32_e32 %29, implicit $exec
    %25:vgpr_32 = V_MAC_F32_e32 0, %18, %25, implicit $exec
    %31:vgpr_32 = V_MAD_F32 0, target-flags(amdgpu-gotprel) 0, 0, %12.sub0, 0, %24, 0, 0, implicit $exec
    %32:vgpr_32 = V_ADD_F32_e32 %25, %31, implicit $exec
    %33:vgpr_32 = V_MUL_F32_e32 %22, %30, implicit $exec
    %34:vgpr_32 = V_MUL_F32_e32 %23, %30, implicit $exec
    %35:vgpr_32 = V_MUL_F32_e32 %32, %30, implicit $exec
    %36:vgpr_32 = V_MUL_F32_e32 0, %34, implicit $exec
    %36:vgpr_32 = V_MAC_F32_e32 0, %33, %36, implicit $exec
    %37:vgpr_32 = V_MAD_F32 0, %35, 0, 0, 0, 0, 0, 0, implicit $exec
    %38:sreg_64_xexec = V_CMP_NE_U32_e64 0, %5, implicit $exec
    %39:vgpr_32 = V_CNDMASK_B32_e64 0, 1, %38, implicit $exec
    V_CMP_NE_U32_e32 1, %39, implicit-def $vcc, implicit $exec
    $vcc = S_AND_B64 $exec, $vcc, implicit-def dead $scc
    %40:vgpr_32 = V_ADD_F32_e32 %36, %37, implicit $exec
    S_CBRANCH_VCCZ %bb.15, implicit $vcc

  bb.14:
    successors: %bb.17(0x80000000)
    S_BRANCH %bb.17

  bb.15:
    successors: %bb.16(0x40000000), %bb.18(0x40000000)
    %41:vgpr_32 = V_MAD_F32 0, %40, 0, 0, 0, 0, 0, 0, implicit $exec
    %42:sreg_64 = V_CMP_LE_F32_e64 0, 0, 0, %41, 0, implicit $exec
    %43:sreg_64 = V_CMP_GE_F32_e64 0, 1065353216, 0, %41, 0, implicit $exec
    %44:sreg_64 = S_AND_B64 %43, %43, implicit-def dead $scc
    %45:sreg_64 = S_AND_B64 %42, %42, implicit-def dead $scc
    %46:sreg_64 = S_AND_B64 %45, %44, implicit-def dead $scc
    %47:sreg_64 = COPY $exec, implicit-def $exec
    %48:sreg_64 = S_AND_B64 %47, %46, implicit-def dead $scc
    $exec = S_MOV_B64_term %48
    SI_MASK_BRANCH %bb.18, implicit $exec
    S_BRANCH %bb.16

  bb.16:
    successors: %bb.18(0x80000000)
    S_BRANCH %bb.18

  bb.17:
    successors: %bb.21(0x40000000), %bb.23(0x40000000)
    %49:sreg_64 = V_CMP_NE_U32_e64 0, %5, implicit $exec
    %50:sreg_64 = S_AND_B64 $exec, %49, implicit-def dead $scc
    %51:vreg_128 = IMPLICIT_DEF
    $vcc = COPY %50
    S_CBRANCH_VCCNZ %bb.21, implicit $vcc
    S_BRANCH %bb.23

  bb.18:
    successors: %bb.20(0x40000000), %bb.19(0x40000000)
    $exec = S_OR_B64 $exec, %47, implicit-def $scc
    %52:vgpr_32 = V_MAD_F32 0, %3.sub1, 0, target-flags(amdgpu-gotprel32-lo) 0, 1, %3.sub0, 0, 0, implicit $exec
    %53:vgpr_32 = V_MUL_F32_e32 -2147483648, %3.sub1, implicit $exec
    %53:vgpr_32 = V_MAC_F32_e32 target-flags(amdgpu-gotprel32-hi) 1065353216, %3.sub2, %53, implicit $exec
    %54:vgpr_32 = V_MUL_F32_e32 %53, %53, implicit $exec
    %54:vgpr_32 = V_MAC_F32_e32 %52, %52, %54, implicit $exec
    %55:vgpr_32 = V_SQRT_F32_e32 %54, implicit $exec
    %5:vgpr_32 = V_MOV_B32_e32 0, implicit $exec
    %56:vgpr_32 = V_MOV_B32_e32 981668463, implicit $exec
    %57:sreg_64 = V_CMP_NGT_F32_e64 0, %55, 0, %56, 0, implicit $exec
    %58:sreg_64 = S_AND_B64 $exec, %57, implicit-def dead $scc
    $vcc = COPY %58
    S_CBRANCH_VCCZ %bb.20, implicit $vcc

  bb.19:
    successors: %bb.17(0x80000000)
    S_BRANCH %bb.17

  bb.20:
    successors: %bb.17(0x80000000)
    S_BRANCH %bb.17

  bb.21:
    successors: %bb.23(0x80000000)
    %59:sreg_32 = S_MOV_B32 0
    undef %51.sub0:vreg_128 = COPY %59
    S_BRANCH %bb.23

  bb.22:
    successors: %bb.24(0x80000000)
    S_BRANCH %bb.24

  bb.23:
    successors: %bb.22(0x80000000)
    undef %60.sub1:vreg_64 = V_CVT_I32_F32_e32 %1, implicit $exec
    %60.sub0:vreg_64 = V_CVT_I32_F32_e32 %0, implicit $exec
    undef %61.sub0:sreg_256 = S_MOV_B32 0
    %61.sub1:sreg_256 = COPY %61.sub0
    %61.sub2:sreg_256 = COPY %61.sub0
    %61.sub3:sreg_256 = COPY %61.sub0
    %61.sub4:sreg_256 = COPY %61.sub0
    %61.sub5:sreg_256 = COPY %61.sub0
    %61.sub6:sreg_256 = COPY %61.sub0
    %61.sub7:sreg_256 = COPY %61.sub0
    %62:vgpr_32 = V_MOV_B32_e32 1033100696, implicit $exec
    %63:vgpr_32 = V_MUL_F32_e32 1060575065, %15.sub1, implicit $exec
    %63:vgpr_32 = V_MAC_F32_e32 1046066128, %15.sub0, %63, implicit $exec
    %64:vgpr_32 = IMAGE_LOAD_V1_V2 %60, %61, 1, -1, 0, 0, 0, 0, 0, 0, 0, implicit $exec :: (dereferenceable load 16 from constant-pool, addrspace 4)
    %64:vgpr_32 = V_MAC_F32_e32 target-flags(amdgpu-gotprel) 0, %51.sub0, %64, implicit $exec
    %65:vgpr_32 = V_MUL_F32_e32 0, %64, implicit $exec
    %66:vgpr_32 = V_MUL_F32_e32 0, %65, implicit $exec
    %67:vgpr_32 = V_MAD_F32 0, %66, 0, %62, 0, 0, 0, 0, implicit $exec
    %63:vgpr_32 = V_MAC_F32_e32 %15.sub2, %62, %63, implicit $exec
    %4:vgpr_32 = V_ADD_F32_e32 %63, %67, implicit $exec
    S_BRANCH %bb.22

  bb.24:
    %68:vgpr_32 = V_MUL_F32_e32 0, %4, implicit $exec
    %69:vgpr_32 = V_CVT_PKRTZ_F16_F32_e64 0, undef %70:vgpr_32, 0, %68, 0, 0, implicit $exec
    EXP 0, undef %71:vgpr_32, %69, undef %72:vgpr_32, undef %73:vgpr_32, -1, -1, 15, implicit $exec
    S_ENDPGM 0
...