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

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

diff --git a/llvm/lib/Target/BPF/BPFInstrInfo.cpp b/llvm/lib/Target/BPF/BPFInstrInfo.cpp
index d453a7d..4d47deb 100644 (file)
--- a/llvm/lib/Target/BPF/BPFInstrInfo.cpp
+++ b/llvm/lib/Target/BPF/BPFInstrInfo.cpp
@@ -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);

diff --git a/llvm/test/CodeGen/BPF/memcpy-expand-in-order.ll b/llvm/test/CodeGen/BPF/memcpy-expand-in-order.ll
index 6ee3126..988e45a 100644 (file)
--- a/llvm/test/CodeGen/BPF/memcpy-expand-in-order.ll
+++ b/llvm/test/CodeGen/BPF/memcpy-expand-in-order.ll
@@ -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
 ;