Skip to content

[PHIElimination] Verify reappropriated COPY is of similar register class, update livevars. #146337

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

Merged
merged 1 commit into from
Jul 1, 2025
Merged

[PHIElimination] Verify reappropriated COPY is of similar register class, update livevars. #146337

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
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
6 changes: 5 additions & 1 deletion llvm/lib/CodeGen/PHIElimination.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -584,9 +584,13 @@ void PHIEliminationImpl::LowerPHINode(MachineBasicBlock &MBB,
// Reuse an existing copy in the block if possible.
if (IncomingReg.isVirtual()) {
MachineInstr *DefMI = MRI->getUniqueVRegDef(SrcReg);
const TargetRegisterClass *SrcRC = MRI->getRegClass(SrcReg);
const TargetRegisterClass *IncomingRC = MRI->getRegClass(IncomingReg);
if (DefMI && DefMI->isCopy() && DefMI->getParent() == &opBlock &&
MRI->use_empty(SrcReg)) {
MRI->use_empty(SrcReg) && IncomingRC->hasSuperClassEq(SrcRC)) {
DefMI->getOperand(0).setReg(IncomingReg);
if (LV)
LV->getVarInfo(SrcReg).AliveBlocks.clear();
continue;
}
}
Expand Down
102 changes: 88 additions & 14 deletions llvm/test/CodeGen/AArch64/PHIElimination-reuse-copy.mir
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 5
# RUN: llc -run-pass=phi-node-elimination -mtriple=aarch64-linux-gnu -o - %s | FileCheck %s
# RUN: llc -run-pass=livevars,phi-node-elimination -verify-machineinstrs -mtriple=aarch64-linux-gnu -o - %s | FileCheck %s

# Verify that the original COPY in bb.1 is reappropriated as the PHI source in bb.2,
# instead of creating a new COPY with the same source register.
Expand All @@ -13,18 +13,18 @@ body: |
; CHECK-NEXT: successors: %bb.2(0x40000000), %bb.1(0x40000000)
; CHECK-NEXT: liveins: $nzcv, $w0
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: %a:gpr32 = COPY $w0
; CHECK-NEXT: %a:gpr32 = COPY killed $w0
; CHECK-NEXT: [[DEF:%[0-9]+]]:gpr32 = IMPLICIT_DEF
; CHECK-NEXT: Bcc 8, %bb.2, implicit $nzcv
; CHECK-NEXT: Bcc 8, %bb.2, implicit killed $nzcv
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: bb.1:
; CHECK-NEXT: successors: %bb.2(0x80000000)
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: [[DEF:%[0-9]+]]:gpr32 = COPY %a
; CHECK-NEXT: [[DEF:%[0-9]+]]:gpr32 = COPY killed %a
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: bb.2:
; CHECK-NEXT: %c:gpr32 = COPY [[DEF]]
; CHECK-NEXT: %d:gpr32 = COPY %c
; CHECK-NEXT: %c:gpr32 = COPY killed [[DEF]]
; CHECK-NEXT: dead %d:gpr32 = COPY killed %c
bb.0:
liveins: $nzcv, $w0
%a:gpr32 = COPY $w0
Expand All @@ -46,16 +46,16 @@ body: |
; CHECK-NEXT: liveins: $nzcv, $w0
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: [[DEF:%[0-9]+]]:gpr32 = IMPLICIT_DEF
; CHECK-NEXT: Bcc 8, %bb.2, implicit $nzcv
; CHECK-NEXT: Bcc 8, %bb.2, implicit killed $nzcv
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: bb.1:
; CHECK-NEXT: successors: %bb.2(0x80000000)
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: $x0 = IMPLICIT_DEF
; CHECK-NEXT: [[DEF:%[0-9]+]]:gpr32 = COPY $w0
; CHECK-NEXT: dead $x0 = IMPLICIT_DEF implicit-def $w0
; CHECK-NEXT: [[DEF:%[0-9]+]]:gpr32 = COPY killed $w0
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: bb.2:
; CHECK-NEXT: %b:gpr32 = COPY [[DEF]]
; CHECK-NEXT: dead %b:gpr32 = COPY killed [[DEF]]
bb.0:
liveins: $nzcv, $w0
Bcc 8, %bb.2, implicit $nzcv
Expand Down Expand Up @@ -83,15 +83,15 @@ body: |
; CHECK-NEXT: bb.1:
; CHECK-NEXT: successors: %bb.2(0x80000000)
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: [[DEF:%[0-9]+]]:gpr64 = IMPLICIT_DEF
; CHECK-NEXT: [[DEF1:%[0-9]+]]:gpr64 = IMPLICIT_DEF
; CHECK-NEXT: dead [[DEF:%[0-9]+]]:gpr64 = IMPLICIT_DEF
; CHECK-NEXT: dead [[DEF1:%[0-9]+]]:gpr64 = IMPLICIT_DEF
; CHECK-NEXT: B %bb.2
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: bb.2:
; CHECK-NEXT: successors: %bb.1(0x80000000)
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: [[DEF2:%[0-9]+]]:gpr64 = IMPLICIT_DEF
; CHECK-NEXT: [[DEF3:%[0-9]+]]:gpr64 = IMPLICIT_DEF
; CHECK-NEXT: dead [[DEF2:%[0-9]+]]:gpr64 = IMPLICIT_DEF
; CHECK-NEXT: dead [[DEF3:%[0-9]+]]:gpr64 = IMPLICIT_DEF
; CHECK-NEXT: B %bb.1
bb.0:
liveins: $wzr, $xzr
Expand All @@ -117,3 +117,77 @@ body: |

...

---
name: update_livevars
tracksRegLiveness: true
body: |
; CHECK-LABEL: name: update_livevars
; CHECK: bb.0:
; CHECK-NEXT: successors: %bb.1(0x80000000)
; CHECK-NEXT: liveins: $w0, $w1, $nzcv
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: [[COPY:%[0-9]+]]:gpr32 = COPY killed $w0
; CHECK-NEXT: [[COPY1:%[0-9]+]]:gpr32 = COPY killed $w1
; CHECK-NEXT: B %bb.1
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: bb.1:
; CHECK-NEXT: successors: %bb.2(0x40000000), %bb.1(0x40000000)
; CHECK-NEXT: liveins: $nzcv
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: dead [[COPY2:%[0-9]+]]:gpr32 = COPY killed [[COPY1]]
; CHECK-NEXT: [[COPY1:%[0-9]+]]:gpr32 = COPY [[COPY]]
; CHECK-NEXT: Bcc 1, %bb.1, implicit $nzcv
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: bb.2:
; CHECK-NEXT: successors: %bb.1(0x80000000)
; CHECK-NEXT: liveins: $nzcv
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: [[COPY1:%[0-9]+]]:gpr32 = IMPLICIT_DEF
; CHECK-NEXT: B %bb.1
bb.0:
successors: %bb.1
liveins: $w0, $w1, $nzcv

%0:gpr32 = COPY killed $w0
%1:gpr32 = COPY killed $w1
B %bb.1

bb.1:
successors: %bb.2, %bb.1
liveins: $nzcv

%2:gpr32 = PHI %3, %bb.2, %1, %bb.0, %3, %bb.1
%3:gpr32 = COPY %0
Bcc 1, %bb.1, implicit $nzcv

bb.2:
successors: %bb.1
liveins: $nzcv

B %bb.1
...

---
name: copy_subreg
tracksRegLiveness: true
body: |
; CHECK-LABEL: name: copy_subreg
; CHECK: bb.0:
; CHECK-NEXT: successors: %bb.1(0x80000000)
; CHECK-NEXT: liveins: $x0
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: [[COPY:%[0-9]+]]:gpr64 = COPY killed $x0
; CHECK-NEXT: [[COPY1:%[0-9]+]]:gpr64 = COPY killed [[COPY]]
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: bb.1:
; CHECK-NEXT: dead [[COPY2:%[0-9]+]]:gpr32 = COPY killed [[COPY1]].sub_32
bb.0:
successors: %bb.1
liveins: $x0

%0:gpr64 = COPY killed $x0
%1:gpr64 = COPY killed %0

bb.1:
%2:gpr32 = PHI %1.sub_32, %bb.0
...
16 changes: 8 additions & 8 deletions llvm/test/CodeGen/AArch64/tbl-loops.ll
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -17,18 +17,18 @@ define void @loop1(ptr noalias nocapture noundef writeonly %dst, ptr nocapture n
; CHECK-NEXT: .LBB0_3: // %vector.ph
; CHECK-NEXT: add x11, x8, #1
; CHECK-NEXT: mov w8, #1132396544 // =0x437f0000
; CHECK-NEXT: add x13, x0, #4
; CHECK-NEXT: add x12, x0, #4
; CHECK-NEXT: and x10, x11, #0x1fffffff8
; CHECK-NEXT: dup v0.4s, w8
; CHECK-NEXT: add x14, x1, #16
; CHECK-NEXT: add x13, x1, #16
; CHECK-NEXT: add x8, x1, x10, lsl #2
; CHECK-NEXT: mov x12, x10
; CHECK-NEXT: add x9, x0, x10
; CHECK-NEXT: mov x14, x10
; CHECK-NEXT: .LBB0_4: // %vector.body
; CHECK-NEXT: // =>This Inner Loop Header: Depth=1
; CHECK-NEXT: ldp q1, q2, [x14, #-16]
; CHECK-NEXT: subs x12, x12, #8
; CHECK-NEXT: add x14, x14, #32
; CHECK-NEXT: ldp q1, q2, [x13, #-16]
; CHECK-NEXT: subs x14, x14, #8
; CHECK-NEXT: add x13, x13, #32
; CHECK-NEXT: fcmgt v3.4s, v1.4s, v0.4s
; CHECK-NEXT: fcmgt v4.4s, v2.4s, v0.4s
; CHECK-NEXT: fcmlt v5.4s, v1.4s, #0.0
Expand All @@ -44,8 +44,8 @@ define void @loop1(ptr noalias nocapture noundef writeonly %dst, ptr nocapture n
; CHECK-NEXT: uzp1 v1.8b, v1.8b, v0.8b
; CHECK-NEXT: uzp1 v2.8b, v2.8b, v0.8b
; CHECK-NEXT: mov v1.s[1], v2.s[0]
; CHECK-NEXT: stur d1, [x13, #-4]
; CHECK-NEXT: add x13, x13, #8
; CHECK-NEXT: stur d1, [x12, #-4]
; CHECK-NEXT: add x12, x12, #8
; CHECK-NEXT: b.ne .LBB0_4
; CHECK-NEXT: // %bb.5: // %middle.block
; CHECK-NEXT: cmp x11, x10
Expand Down