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bpf: add missing RegState to notify MachineInstr verifier necessary register usage

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Errors like the following are reported by:

  https://urldefense.proofpoint.com/v2/url?u=http-3A__lab.llvm.org-3A8011_builders_llvm-2Dclang-2Dx86-5F64-2Dexpensive-2Dchecks-2Dwin_builds_11261&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=DA8e1B5r073vIqRrFz7MRA&m=929oWPCf7Bf2qQnir4GBtowB8ZAlIRWsAdTfRkDaK-g&s=9k-wbEUVpUm474hhzsmAO29VXVvbxJPWD9RTgCD71fQ&e=

  *** Bad machine code: Explicit definition marked as use ***
  - function:    cal_align1
  - basic block: %bb.0 entry (0x47edd98)
  - instruction: LDB $r3, $r2, 0
  - operand 0:   $r3

This is because RegState info was missing for ScratchReg inside
expandMEMCPY. This caused incomplete register usage information to
MachineInstr verifier which then would complain as there could be potential
code-gen issue if the complained MachineInstr is used in place where
register usage information matters even though the memcpy expanding is not
in such case as it happens at the last stage of IR optimization pipeline.

We should always specify those register usage information which compiler
couldn't deduct automatically whenever we add a hardware register manually.

Reported-by: Builder llvm-clang-x86_64-expensive-checks-win Build #11261
Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
Reviewed-by: Yonghong Song <yhs@fb.com>
llvm-svn: 338134
This commit is contained in:
Yonghong Song 2018-07-27 16:58:52 +00:00
parent d359ef098c
commit 90ca961862
2 changed files with 12 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
lib/Target/BPF/BPFInstrInfo.cpp
View File

@ -77,9 +77,11 @@ void BPFInstrInfo::expandMEMCPY(MachineBasicBlock::iterator MI) const {
unsigned IterationNum = CopyLen >> Log2_64(Alignment);
for(unsigned I = 0; I < IterationNum; ++I) {
BuildMI(*BB, MI, dl, get(LdOpc))
.addReg(ScratchReg).addReg(SrcReg).addImm(I * Alignment);
.addReg(ScratchReg, RegState::Define).addReg(SrcReg)
.addImm(I * Alignment);
BuildMI(*BB, MI, dl, get(StOpc))
.addReg(ScratchReg).addReg(DstReg).addImm(I * Alignment);
.addReg(ScratchReg, RegState::Kill).addReg(DstReg)
.addImm(I * Alignment);
}
unsigned BytesLeft = CopyLen & (Alignment - 1);
@ -89,23 +91,23 @@ void BPFInstrInfo::expandMEMCPY(MachineBasicBlock::iterator MI) const {
bool Hanging1Byte = BytesLeft & 0x1;
if (Hanging4Byte) {
BuildMI(*BB, MI, dl, get(BPF::LDW))
.addReg(ScratchReg).addReg(SrcReg).addImm(Offset);
.addReg(ScratchReg, RegState::Define).addReg(SrcReg).addImm(Offset);
BuildMI(*BB, MI, dl, get(BPF::STW))
.addReg(ScratchReg).addReg(DstReg).addImm(Offset);
.addReg(ScratchReg, RegState::Kill).addReg(DstReg).addImm(Offset);
Offset += 4;
}
if (Hanging2Byte) {
BuildMI(*BB, MI, dl, get(BPF::LDH))
.addReg(ScratchReg).addReg(SrcReg).addImm(Offset);
.addReg(ScratchReg, RegState::Define).addReg(SrcReg).addImm(Offset);
BuildMI(*BB, MI, dl, get(BPF::STH))
.addReg(ScratchReg).addReg(DstReg).addImm(Offset);
.addReg(ScratchReg, RegState::Kill).addReg(DstReg).addImm(Offset);
Offset += 2;
}
if (Hanging1Byte) {
BuildMI(*BB, MI, dl, get(BPF::LDB))
.addReg(ScratchReg).addReg(SrcReg).addImm(Offset);
.addReg(ScratchReg, RegState::Define).addReg(SrcReg).addImm(Offset);
BuildMI(*BB, MI, dl, get(BPF::STB))
.addReg(ScratchReg).addReg(DstReg).addImm(Offset);
.addReg(ScratchReg, RegState::Kill).addReg(DstReg).addImm(Offset);
}
BB->erase(MI);

4
test/CodeGen/BPF/memcpy-expand-in-order.ll
View File

@ -1,5 +1,5 @@
; RUN: llc < %s -march=bpfel -bpf-expand-memcpy-in-order | FileCheck %s
; RUN: llc < %s -march=bpfeb -bpf-expand-memcpy-in-order | FileCheck %s
; RUN: llc < %s -march=bpfel -verify-machineinstrs -bpf-expand-memcpy-in-order | FileCheck %s
; RUN: llc < %s -march=bpfeb -verify-machineinstrs -bpf-expand-memcpy-in-order | FileCheck %s
;
; #define COPY_LEN 9
;