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CodeGen: Make computeRegisterLiveness consider successors 

If the end of the block is reached during the scan, check
the live ins of the successors. This was already done in the
other direction if the block entry was reached.

llvm-svn: 341026
This commit is contained in:
Matt Arsenault 2018-08-30 07:17:51 +00:00
parent 06adfa1718
commit eba9e9a266
3 changed files with 83 additions and 7 deletions
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14
llvm/lib/CodeGen/MachineBasicBlock.cpp
View File

@ -1439,6 +1439,20 @@ MachineBasicBlock::computeRegisterLiveness(const TargetRegisterInfo *TRI,
}
}
// If we reached the end, it is safe to clobber Reg at the end of a block of
// no successor has it live in.
if (I == end()) {
for (MachineBasicBlock *S : successors()) {
for (MCSubRegIterator SubReg(Reg, TRI, /*IncludeSelf*/true);
SubReg.isValid(); ++SubReg) {
if (S->isLiveIn(*SubReg))
return LQR_Live;
}
}
return LQR_Dead;
}
// At this point we have no idea of the liveness of the register.
return LQR_Unknown;
}

72
llvm/test/CodeGen/AMDGPU/fold-immediate-operand-shrink.mir
View File

@ -318,14 +318,74 @@ body: |
---
# We know this is OK because vcc isn't live out of the block, even
# though it had a defined value
# We know this is OK because vcc isn't live out of the block.
name: shrink_scalar_imm_vgpr_v_add_i32_e64_known_dead_no_liveout
name: shrink_scalar_imm_vgpr_v_add_i32_e64_known_no_liveout
tracksRegLiveness: true
body: |
; GCN-LABEL: name: shrink_scalar_imm_vgpr_v_add_i32_e64_known_dead_no_liveout
; GCN-LABEL: name: shrink_scalar_imm_vgpr_v_add_i32_e64_known_no_liveout
; GCN: bb.0:
; GCN: successors: %bb.1(0x80000000)
; GCN: [[S_MOV_B32_:%[0-9]+]]:sreg_32_xm0 = S_MOV_B32 12345
; GCN: [[DEF:%[0-9]+]]:vgpr_32 = IMPLICIT_DEF
; GCN: [[V_ADD_I32_e32_:%[0-9]+]]:vgpr_32 = V_ADD_I32_e32 [[S_MOV_B32_]], [[DEF]], implicit-def $vcc, implicit $exec
; GCN: bb.1:
; GCN: S_ENDPGM implicit [[V_ADD_I32_e32_]]
bb.0:
successors: %bb.1
S_NOP 0
S_NOP 0
S_NOP 0
S_NOP 0
S_NOP 0
S_NOP 0
S_NOP 0
S_NOP 0
S_NOP 0
S_NOP 0
S_NOP 0
S_NOP 0
S_NOP 0
S_NOP 0
S_NOP 0
S_NOP 0
S_NOP 0
S_NOP 0
S_NOP 0
S_NOP 0
S_NOP 0
S_NOP 0
S_NOP 0
S_NOP 0
S_NOP 0
S_NOP 0
S_NOP 0
S_NOP 0
S_NOP 0
S_NOP 0
%0:sreg_32_xm0 = S_MOV_B32 12345
%1:vgpr_32 = IMPLICIT_DEF
%2:vgpr_32, %3:sreg_64 = V_ADD_I32_e64 %0, %1, implicit $exec
S_NOP 0
S_NOP 0
bb.1:
S_ENDPGM implicit %2
...
---
# We know this is OK because vcc isn't live out of the block, even
# though it had a defined but unused. value
name: shrink_scalar_imm_vgpr_v_add_i32_e64_known_no_liveout_dead_vcc_def
tracksRegLiveness: true
body: |
; GCN-LABEL: name: shrink_scalar_imm_vgpr_v_add_i32_e64_known_no_liveout_dead_vcc_def
; GCN: bb.0:
; GCN: successors: %bb.1(0x80000000)
; GCN: [[S_MOV_B32_:%[0-9]+]]:sreg_32_xm0 = S_MOV_B32 12345
@ -336,10 +396,12 @@ body: |
bb.0:
successors: %bb.1
$vcc = S_MOV_B64 -1
S_NOP 0, implicit-def $vcc
%0:sreg_32_xm0 = S_MOV_B32 12345
%1:vgpr_32 = IMPLICIT_DEF
%2:vgpr_32, %3:sreg_64 = V_ADD_I32_e64 %0, %1, implicit $exec
S_NOP 0
S_NOP 0
bb.1:
S_ENDPGM implicit %2

4
llvm/test/CodeGen/AMDGPU/split-scalar-i64-add.ll
View File

@ -10,8 +10,8 @@ declare i32 @llvm.amdgcn.workitem.id.x() readnone
; FIXME: SIShrinkInstructions should force immediate fold.
; FUNC-LABEL: {{^}}imp_def_vcc_split_i64_add_0:
; SI: s_movk_i32 [[K:s[0-9]+]], 0x18f
; SI: v_add_i32_e32 v{{[0-9]+}}, vcc, [[K]], v{{[0-9]+}}
; SI: v_mov_b32_e32 [[V_VAL:v[0-9]+]], s
; SI: v_add_i32_e32 v{{[0-9]+}}, vcc, 0x18f, [[V_VAL]]
; SI: v_addc_u32_e32 v{{[0-9]+}}, vcc, 0, v{{[0-9]+}}, vcc
define amdgpu_kernel void @imp_def_vcc_split_i64_add_0(i64 addrspace(1)* %out, i32 addrspace(1)* %in, i32 %s.val) {
%v.val = load volatile i32, i32 addrspace(1)* %in