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[RegisterCoalescer] Deferring deletion of instructions in `ErasedInst…
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…rs` until the end of an iteration
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@DianQK
DianQK committed Jan 29, 2024
1 parent 6528a77 commit 9cb9ad2
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Showing 2 changed files with 98 additions and 7 deletions.
16 changes: 11 additions & 5 deletions llvm/lib/CodeGen/RegisterCoalescer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -236,7 +236,8 @@ namespace {
/// was successfully coalesced away. If it is not currently possible to
/// coalesce this interval, but it may be possible if other things get
/// coalesced, then it returns true by reference in 'Again'.
bool joinCopy(MachineInstr *CopyMI, bool &Again);
bool joinCopy(MachineInstr *CopyMI, bool &Again,
SmallPtrSetImpl<MachineInstr *> &CurrentErasedInstrs);

/// Attempt to join these two intervals. On failure, this
/// returns false. The output "SrcInt" will not have been modified, so we
Expand Down Expand Up @@ -1964,7 +1965,9 @@ void RegisterCoalescer::setUndefOnPrunedSubRegUses(LiveInterval &LI,
LIS->shrinkToUses(&LI);
}

bool RegisterCoalescer::joinCopy(MachineInstr *CopyMI, bool &Again) {
bool RegisterCoalescer::joinCopy(
MachineInstr *CopyMI, bool &Again,
SmallPtrSetImpl<MachineInstr *> &CurrentErasedInstrs) {
Again = false;
LLVM_DEBUG(dbgs() << LIS->getInstructionIndex(*CopyMI) << '\t' << *CopyMI);

Expand Down Expand Up @@ -2156,7 +2159,9 @@ bool RegisterCoalescer::joinCopy(MachineInstr *CopyMI, bool &Again) {
// CopyMI has been erased by joinIntervals at this point. Remove it from
// ErasedInstrs since copyCoalesceWorkList() won't add a successful join back
// to the work list. This keeps ErasedInstrs from growing needlessly.
ErasedInstrs.erase(CopyMI);
if (ErasedInstrs.erase(CopyMI))
// But we may encounter the instruction again in this iteration.
CurrentErasedInstrs.insert(CopyMI);

// Rewrite all SrcReg operands to DstReg.
// Also update DstReg operands to include DstIdx if it is set.
Expand Down Expand Up @@ -3982,17 +3987,18 @@ void RegisterCoalescer::lateLiveIntervalUpdate() {
bool RegisterCoalescer::
copyCoalesceWorkList(MutableArrayRef<MachineInstr*> CurrList) {
bool Progress = false;
SmallPtrSet<MachineInstr *, 4> CurrentErasedInstrs;
for (MachineInstr *&MI : CurrList) {
if (!MI)
continue;
// Skip instruction pointers that have already been erased, for example by
// dead code elimination.
if (ErasedInstrs.count(MI)) {
if (ErasedInstrs.count(MI) || CurrentErasedInstrs.count(MI)) {
MI = nullptr;
continue;
}
bool Again = false;
bool Success = joinCopy(MI, Again);
bool Success = joinCopy(MI, Again, CurrentErasedInstrs);
Progress |= Success;
if (Success || !Again)
MI = nullptr;
Expand Down
89 changes: 87 additions & 2 deletions llvm/test/CodeGen/LoongArch/register-coalescer-crash-pr79718.mir
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Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
# XFAIL: *
# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 4
# RUN: llc -o - %s -mtriple=loongarch64 \
# RUN: -run-pass=register-coalescer -join-liveintervals=1 -join-splitedges=0 2>&1 | FileCheck %s
# RUN: -run-pass=register-coalescer -join-liveintervals=1 -join-splitedges=0 | FileCheck %s

--- |
source_filename = "register-coalescer-crash-pr79718.ll"
Expand Down Expand Up @@ -180,6 +180,91 @@ debugValueSubstitutions: []
constants: []
machineFunctionInfo: {}
body: |
; CHECK-LABEL: name: foo
; CHECK: bb.0.start:
; CHECK-NEXT: successors: %bb.1(0x80000000)
; CHECK-NEXT: liveins: $r4, $r5, $r6, $r7, $r8
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: [[COPY:%[0-9]+]]:gpr = COPY $r8
; CHECK-NEXT: [[COPY1:%[0-9]+]]:gpr = COPY $r7
; CHECK-NEXT: [[COPY2:%[0-9]+]]:gpr = COPY $r6
; CHECK-NEXT: [[COPY3:%[0-9]+]]:gpr = COPY $r5
; CHECK-NEXT: [[COPY4:%[0-9]+]]:gpr = COPY $r4
; CHECK-NEXT: [[ANDI:%[0-9]+]]:gpr = ANDI [[COPY3]], 1
; CHECK-NEXT: [[ORI:%[0-9]+]]:gpr = ORI $r0, 1
; CHECK-NEXT: [[ANDI1:%[0-9]+]]:gpr = ANDI [[COPY2]], 1
; CHECK-NEXT: [[ANDI2:%[0-9]+]]:gpr = ANDI [[COPY1]], 1
; CHECK-NEXT: [[ANDI3:%[0-9]+]]:gpr = ANDI [[COPY]], 1
; CHECK-NEXT: [[COPY5:%[0-9]+]]:gpr = COPY $r0
; CHECK-NEXT: [[COPY6:%[0-9]+]]:gpr = COPY $r0
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: bb.1.bb1:
; CHECK-NEXT: successors: %bb.2(0x80000000)
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: [[COPY7:%[0-9]+]]:gpr = COPY [[COPY5]]
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: bb.2.bb2:
; CHECK-NEXT: successors: %bb.3(0x40000000), %bb.4(0x40000000)
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: BEQZ [[ANDI]], %bb.4
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: bb.3:
; CHECK-NEXT: successors: %bb.9(0x80000000)
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: PseudoBR %bb.9
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: bb.4.preheader.preheader:
; CHECK-NEXT: successors: %bb.5(0x80000000)
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: bb.5.preheader:
; CHECK-NEXT: successors: %bb.7(0x7c000000), %bb.6(0x04000000)
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: dead [[LD_D:%[0-9]+]]:gpr = LD_D $r0, 8 :: (volatile load (s64) from `ptr null` + 8, basealign 4294967296)
; CHECK-NEXT: dead [[LD_D1:%[0-9]+]]:gpr = LD_D $r0, 0 :: (volatile load (s64) from `ptr null`, align 4294967296)
; CHECK-NEXT: BNEZ [[ANDI1]], %bb.7
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: bb.6:
; CHECK-NEXT: successors: %bb.11(0x80000000)
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: [[COPY6:%[0-9]+]]:gpr = COPY $r0
; CHECK-NEXT: PseudoBR %bb.11
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: bb.7.bb3:
; CHECK-NEXT: successors: %bb.8(0x7c000000), %bb.10(0x04000000)
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: BEQZ [[ANDI2]], %bb.10
; CHECK-NEXT: PseudoBR %bb.8
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: bb.8.bb4:
; CHECK-NEXT: successors: %bb.9(0x04000000), %bb.5(0x7c000000)
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: [[COPY6:%[0-9]+]]:gpr = ADDI_D [[COPY6]], 1
; CHECK-NEXT: BEQZ [[ANDI3]], %bb.5
; CHECK-NEXT: PseudoBR %bb.9
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: bb.9.loopexit:
; CHECK-NEXT: successors: %bb.12(0x80000000)
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: ST_B $r0, [[COPY4]], 0 :: (store (s8) into %ir.0)
; CHECK-NEXT: PseudoBR %bb.12
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: bb.10.bb3.bb5_crit_edge:
; CHECK-NEXT: successors: %bb.11(0x80000000)
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: [[COPY5:%[0-9]+]]:gpr = ADDI_D [[COPY6]], 1
; CHECK-NEXT: [[COPY6:%[0-9]+]]:gpr = COPY [[ORI]]
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: bb.11.bb5:
; CHECK-NEXT: successors: %bb.12(0x80000000)
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: ST_D $r0, [[COPY4]], 0 :: (store (s64) into %ir.0)
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: bb.12.bb6:
; CHECK-NEXT: successors: %bb.2(0x7c000000), %bb.1(0x04000000)
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: BEQ [[COPY7]], [[ORI]], %bb.2
; CHECK-NEXT: PseudoBR %bb.1
bb.0.start:
successors: %bb.1(0x80000000)
liveins: $r4, $r5, $r6, $r7, $r8
Expand Down

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