[X86] Update MachineLoopInfo in CMOV conversion.

[tianqing]

Summary

If a CMOV is in a loop and is converted to branches, CMOV conversion wouldn't
add newly created basic blocks to loop info. Since the candidates is collected
based on loops, instructions in these basic blocks will be ignored.

[xbolva00]

llvm/test/CodeGen/X86/x86-cmov-converter.ll

494

Full checks? Use script to generate checks

[pengfei]

llvm/lib/Target/X86/X86CmovConversion.cpp

854

Is it possible the MBB is in more than one loop, e.g. nested?

llvm/test/CodeGen/X86/x86-cmov-converter.ll

494

Maybe you can commit the test first, then show the diff in this patch.

[tianqing]

llvm/lib/Target/X86/X86CmovConversion.cpp

854

addBasicBlockToLoop() already handles nested loop.

llvm/test/CodeGen/X86/x86-cmov-converter.ll

494

See D104692.

[pengfei]

LGTM.

[tianqing]

Update test.

llvm/lib/Target/X86/X86CmovConversion.cpp

   MachineRegisterInfo *MRI = nullptr;
   const TargetInstrInfo *TII = nullptr;
   const TargetRegisterInfo *TRI = nullptr;
+  MachineLoopInfo *MLI = nullptr;
   TargetSchedModel TSchedModel;
 
   /// List of consecutive CMOV instructions.

                     << "**********\n");
 
   bool Changed = false;
-  MachineLoopInfo &MLI = getAnalysis<MachineLoopInfo>();
+  MLI = &getAnalysis<MachineLoopInfo>();
   const TargetSubtargetInfo &STI = MF.getSubtarget();
   MRI = &MF.getRegInfo();
   TII = STI.getInstrInfo();

   //===--------------------------------------------------------------------===//
 
   // Build up the loops in pre-order.
-  SmallVector<MachineLoop *, 4> Loops(MLI.begin(), MLI.end());
+  SmallVector<MachineLoop *, 4> Loops(MLI->begin(), MLI->end());
   // Note that we need to check size on each iteration as we accumulate child
   // loops.
   for (int i = 0; i < (int)Loops.size(); ++i)

 
   // Now remove the CMOV(s).
   MBB->erase(MIItBegin, MIItEnd);
+
+  // Add new basic blocks to MachineLoopInfo.
+  if (MachineLoop *L = MLI->getLoopFor(MBB)) {
+    L->addBasicBlockToLoop(FalseMBB, MLI->getBase());
+    L->addBasicBlockToLoop(SinkMBB, MLI->getBase());
+  }
 }
 
 INITIALIZE_PASS_BEGIN(X86CmovConverterPass, DEBUG_TYPE, "X86 cmov Conversion",

llvm/test/CodeGen/X86/x86-cmov-converter.ll

 ; CHECK-NEXT:    movl %edi, (%rcx)
 ; CHECK-NEXT:    addq $8, %rcx
 ; CHECK-NEXT:    cmpq %rdx, %rcx
-; CHECK-NEXT:    cmovbeq %rax, %rcx
+; CHECK-NEXT:    ja .LBB13_5
+; CHECK-NEXT:  # %bb.4: # %loop.body
+; CHECK-NEXT:    # in Loop: Header=BB13_1 Depth=1
+; CHECK-NEXT:    movq %rax, %rcx
+; CHECK-NEXT:  .LBB13_5: # %loop.body
+; CHECK-NEXT:    # in Loop: Header=BB13_1 Depth=1
 ; CHECK-NEXT:    movl %edi, (%rcx)
 ; CHECK-NEXT:    addl $1, %esi
 ; CHECK-NEXT:    cmpl $1024, %esi # imm = 0x400

   %cond = icmp slt i32 %iv.next, 1024
   br i1 %cond, label %loop.body, label %exit
 
-; CHECK-NEXT:  # %bb.4: # %exit
+; CHECK-NEXT:  # %bb.6: # %exit
 ; CHECK-NEXT:    retq
 exit:
   ret void