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GlobalISel: permit unused vregs without a register-class after ISel. 

This can happen if earlier combining has removed all uses of some VReg, which
is fine and shouldn't flag an error.

llvm-svn: 293537
This commit is contained in:
Tim Northover 2017-01-30 19:12:50 +00:00
parent f2ac1d1df2
commit 480609d0f3
2 changed files with 39 additions and 5 deletions
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14
llvm/lib/CodeGen/GlobalISel/InstructionSelect.cpp
View File

@ -141,15 +141,19 @@ bool InstructionSelect::runOnMachineFunction(MachineFunction &MF) {
for (auto &VRegToType : MRI.getVRegToType()) {
unsigned VReg = VRegToType.first;
auto *RC = MRI.getRegClassOrNull(VReg);
auto *MI = MRI.def_instr_begin(VReg) == MRI.def_instr_end()
? nullptr
: &*MRI.def_instr_begin(VReg);
if (!RC) {
MachineInstr *MI = nullptr;
if (MRI.def_instr_begin(VReg) != MRI.def_instr_end())
MI = &*MRI.def_instr_begin(VReg);
else if (MRI.use_instr_begin(VReg) != MRI.use_instr_end())
MI = &*MRI.use_instr_begin(VReg);
if (MI && !RC) {
if (TPC.isGlobalISelAbortEnabled())
reportSelectionError(MF, MI, "VReg has no regclass after selection");
Failed = true;
break;
}
} else if (!RC)
continue;
if (VRegToType.second.isValid() &&
VRegToType.second.getSizeInBits() > (RC->getSize() * 8)) {

30
llvm/test/CodeGen/AArch64/GlobalISel/no-regclass.mir Normal file
View File

@ -0,0 +1,30 @@
# RUN: llc -O0 -mtriple=aarch64-apple-ios -global-isel -start-before=legalizer -stop-after=instruction-select %s -o - | FileCheck %s
# We run the legalizer to combine the trivial EXTRACT_SEQ pair, leaving %1 and
# %2 orphaned after instruction-selection (no instructions define or use
# them). This shouldn't be a problem.
--- |
target datalayout = "e-m:o-i64:64-i128:128-n32:64-S128"
define void @unused_reg() { ret void }
---
# CHECK-LABEL: name: unused_reg
name: unused_reg
legalized: true
regBankSelected: true
tracksRegLiveness: true
# CHECK: body:
# CHECK: %0 = COPY %w0
# CHECK: %w0 = COPY %0
body: |
bb.0:
liveins: %w0
%0:gpr(s32) = COPY %w0
%1:gpr(s32) = G_SEQUENCE %0(s32), 0
%2:gpr(s32) = G_EXTRACT %1(s32), 0
%w0 = COPY %2(s32)
...