Skip to content

[CodeGen] Check physical def kill flag in MachineInstr::isDead #168684

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
wants to merge 3 commits into
base: main
Choose a base branch
from
+116 −1
Open

[CodeGen] Check physical def kill flag in MachineInstr::isDead #168684

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
74c8f1b
Precommit tests
lukel97 Nov 19, 2025
215423a
[CodeGen] Check physical def kill flag in MachineInstr::isDead
lukel97 Nov 19, 2025
577cf9a
Check for tracksRegLiveness
lukel97 Nov 19, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
4 changes: 3 additions & 1 deletion llvm/lib/CodeGen/MachineInstr.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1398,7 +1398,9 @@ bool MachineInstr::isDead(const MachineRegisterInfo &MRI,
Register Reg = MO.getReg();
if (Reg.isPhysical()) {
// Don't delete live physreg defs, or any reserved register defs.
if (!LivePhysRegs || !LivePhysRegs->available(Reg) || MRI.isReserved(Reg))
if ((!(MRI.tracksLiveness() && MO.isDead()) &&
(!LivePhysRegs || !LivePhysRegs->available(Reg))) ||
MRI.isReserved(Reg))
return false;
} else {
if (MO.isDead())
Expand Down
113 changes: 113 additions & 0 deletions llvm/test/CodeGen/RISCV/machine-sink.mir
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,113 @@
# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 6
# RUN: llc -mtriple=riscv64 -run-pass machine-sink -sink-insts-to-avoid-spills -o - %s | FileCheck %s
---
name: no_delete_live_phys_def
tracksRegLiveness: true
body: |
; CHECK-LABEL: name: no_delete_live_phys_def
; CHECK: bb.0:
; CHECK-NEXT: successors: %bb.1(0x80000000)
; CHECK-NEXT: liveins: $x8
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: %x:gpr = COPY $x8
; CHECK-NEXT: %y:gpr = COPY %x, implicit-def $x8
; CHECK-NEXT: PseudoBR %bb.1
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: bb.1:
; CHECK-NEXT: successors: %bb.1(0x80000000)
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: %z:gpr = ADDI %y, 1
; CHECK-NEXT: PseudoBR %bb.1
bb.0:
liveins: $x8
%x:gpr = COPY $x8
%y:gpr = COPY %x, implicit-def $x8
PseudoBR %bb.1
bb.1:
%z:gpr = ADDI %y, 1
PseudoBR %bb.1
...
---
name: delete_dead_phys_def
tracksRegLiveness: true
body: |
; CHECK-LABEL: name: delete_dead_phys_def
; CHECK: bb.0:
; CHECK-NEXT: successors: %bb.1(0x80000000)
; CHECK-NEXT: liveins: $x8
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: %x:gpr = COPY $x8
; CHECK-NEXT: PseudoBR %bb.1
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: bb.1:
; CHECK-NEXT: successors: %bb.1(0x80000000)
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: [[COPY:%[0-9]+]]:gpr = COPY %x, implicit-def dead $x8
; CHECK-NEXT: %z:gpr = ADDI [[COPY]], 1
; CHECK-NEXT: PseudoBR %bb.1
bb.0:
liveins: $x8
%x:gpr = COPY $x8
%y:gpr = COPY %x, implicit-def dead $x8
PseudoBR %bb.1
bb.1:
%z:gpr = ADDI %y, 1
PseudoBR %bb.1
...
---
name: no_delete_dead_phys_def_no_tracksregliveness
tracksRegLiveness: false
body: |
; CHECK-LABEL: name: no_delete_dead_phys_def_no_tracksregliveness
; CHECK: bb.0:
; CHECK-NEXT: successors: %bb.1(0x80000000)
; CHECK-NEXT: liveins: $x8
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: %x:gpr = COPY $x8
; CHECK-NEXT: %y:gpr = COPY %x, implicit-def dead $x8
; CHECK-NEXT: PseudoBR %bb.1
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: bb.1:
; CHECK-NEXT: successors: %bb.1(0x80000000)
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: [[COPY:%[0-9]+]]:gpr = COPY %x, implicit-def dead $x8
; CHECK-NEXT: %z:gpr = ADDI [[COPY]], 1
; CHECK-NEXT: PseudoBR %bb.1
bb.0:
liveins: $x8
%x:gpr = COPY $x8
%y:gpr = COPY %x, implicit-def dead $x8
PseudoBR %bb.1
bb.1:
%z:gpr = ADDI %y, 1
PseudoBR %bb.1
...
---
name: reserved_phys_def
tracksRegLiveness: true
body: |
; CHECK-LABEL: name: reserved_phys_def
; CHECK: bb.0:
; CHECK-NEXT: successors: %bb.1(0x80000000)
; CHECK-NEXT: liveins: $x8
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: %x:gpr = COPY $x8
; CHECK-NEXT: %y:gpr = COPY %x, implicit-def dead $x2
; CHECK-NEXT: PseudoBR %bb.1
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: bb.1:
; CHECK-NEXT: successors: %bb.1(0x80000000)
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: [[COPY:%[0-9]+]]:gpr = COPY %x, implicit-def dead $x2
; CHECK-NEXT: %z:gpr = ADDI [[COPY]], 1
; CHECK-NEXT: PseudoBR %bb.1
bb.0:
liveins: $x8
%x:gpr = COPY $x8
%y:gpr = COPY %x, implicit-def dead $x2
PseudoBR %bb.1

bb.1:
%z:gpr = ADDI %y, 1
PseudoBR %bb.1
...