Pick correct size for the constant based on the addrspace

Author: mbrkusanin

llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp

@@ -4652,14 +4652,16 @@ bool CombinerHelper::matchReassocFoldConstantsInSubTree(GPtrAdd &MI,
   if (!C2)
     return false;
 
-  // If constant widths differ pick larger one.
-  unsigned BitWidth = std::max(C1->getBitWidth(), C2->getBitWidth());
-  APInt NewConst = C1->sext(BitWidth) + C2->sext(BitWidth);
-  LLT Type =
-      MRI.getType(C1->getBitWidth() > C2->getBitWidth() ? LHSSrc2 : Src2Reg);
+  // Pick correct size for the constant based on the address space
+  const DataLayout &DL = MI.getMF()->getDataLayout();
+  Register Dst = MI.getOperand(0).getReg();
+  unsigned AS = MRI.getType(Dst).getAddressSpace();
+  unsigned NewSize = DL.getIndexSize(AS) * 8;
+  APInt ConstVal = C1->sextOrTrunc(NewSize) + C2->sextOrTrunc(NewSize);
+  LLT ConstType = MRI.getType(Src2Reg).changeElementSize(NewSize);
 
   MatchInfo = [=, &MI](MachineIRBuilder &B) {
-    auto NewCst = B.buildConstant(Type, NewConst);
+    auto NewCst = B.buildConstant(ConstType, ConstVal);
     Observer.changingInstr(MI);
     MI.getOperand(1).setReg(LHSSrc1);
     MI.getOperand(2).setReg(NewCst.getReg(0));