Fix incorrect redundant expression in target AMDGPU.

[etienneb]

Summary

The expression is detected as a redundant expression.
Turn out, this is probably a bug.

/home/etienneb/llvm/llvm/lib/Target/AMDGPU/SIInstrInfo.cpp:306:26: warning: both side of operator are equivalent [misc-redundant-expression]
  if (isSMRD(*FirstLdSt) && isSMRD(*FirstLdSt)) {

[• tstellarAMD]

Thanks for catching this.

lib/Target/AMDGPU/SIInstrInfo.cpp

bool SIInstrInfo::shouldClusterMemOps(MachineInstr *FirstLdSt,
   const MachineOperand *FirstDst = nullptr;
   const MachineOperand *SecondDst = nullptr;
 
   if (isDS(*FirstLdSt) && isDS(*SecondLdSt)) {
     FirstDst = getNamedOperand(*FirstLdSt, AMDGPU::OpName::vdst);
     SecondDst = getNamedOperand(*SecondLdSt, AMDGPU::OpName::vdst);
   }
 
-  if (isSMRD(*FirstLdSt) && isSMRD(*FirstLdSt)) {
+  if (isSMRD(*FirstLdSt) && isSMRD(*SecondLdSt)) {
     FirstDst = getNamedOperand(*FirstLdSt, AMDGPU::OpName::sdst);
     SecondDst = getNamedOperand(*SecondLdSt, AMDGPU::OpName::sdst);
   }
 
   if ((isMUBUF(*FirstLdSt) && isMUBUF(*SecondLdSt)) ||
       (isMTBUF(*FirstLdSt) && isMTBUF(*SecondLdSt))) {
     FirstDst = getNamedOperand(*FirstLdSt, AMDGPU::OpName::vdata);
     SecondDst = getNamedOperand(*SecondLdSt, AMDGPU::OpName::vdata);