[DebugInfo] GlobalOpt DW_OP_deref_size instead of DW_OP_deref.

[markus]

Summary

Optimization pass lib/Transforms/IPO/GlobalOpt.cpp needs to insert DW_OP_deref_size instead of DW_OP_deref to be compatible with big-endian targets for same reasons as in https://reviews.llvm.org/D59687.

lib/Transforms/IPO/GlobalOpt.cpp

if (ConstantInt *CI = dyn_cast<ConstantInt>(OtherVal)){
     if (ConstantInt *CIInit = dyn_cast<ConstantInt>(GV->getInitializer())){
       uint64_t ValInit = CIInit->getZExtValue();
       uint64_t ValOther = CI->getZExtValue();
       uint64_t ValMinus = ValOther - ValInit;
 
       for(auto *GVe : GVs){
         DIGlobalVariable *DGV = GVe->getVariable();
         DIExpression *E = GVe->getExpression();
+        const DataLayout &DL = GV->getParent()->getDataLayout();
+        unsigned SizeInOctets =
+          DL.getTypeAllocSizeInBits(NewGV->getType()->getElementType()) / 8;
 
         // It is expected that the address of global optimized variable is on
         // top of the stack. After optimization, value of that variable will
         // be ether 0 for initial value or 1 for other value. The following
         // expression should return constant integer value depending on the
         // value at global object address:
         // val * (ValOther - ValInit) + ValInit:
         // DW_OP_deref DW_OP_constu <ValMinus>
         // DW_OP_mul DW_OP_constu <ValInit> DW_OP_plus DW_OP_stack_value
         SmallVector<uint64_t, 12> Ops = {
-            dwarf::DW_OP_deref, dwarf::DW_OP_constu, ValMinus,
-            dwarf::DW_OP_mul,   dwarf::DW_OP_constu, ValInit,
+            dwarf::DW_OP_deref_size, SizeInOctets,
+            dwarf::DW_OP_constu, ValMinus,
+            dwarf::DW_OP_mul, dwarf::DW_OP_constu, ValInit,
             dwarf::DW_OP_plus};
         E = DIExpression::prependOpcodes(E, Ops, DIExpression::WithStackValue);
         DIGlobalVariableExpression *DGVE =
           DIGlobalVariableExpression::get(NewGV->getContext(), DGV, E);
         NewGV->addDebugInfo(DGVE);
      }
      EmitOneOrZero = false;
     }

test/Transforms/GlobalOpt/integer-bool-dwarf.ll

 ;RUN: opt -S -globalopt -f %s | FileCheck %s
 
 ;CHECK: @foo = internal unnamed_addr global i1 false, align 4, !dbg ![[VAR:.*]]
 ;CHECK: ![[VAR]] = !DIGlobalVariableExpression(var: !1, expr:
-;CHECK-SAME: !DIExpression(DW_OP_deref, DW_OP_constu, 111, DW_OP_mul,
+;CHECK-SAME: !DIExpression(DW_OP_deref_size, 1, DW_OP_constu, 111, DW_OP_mul,
 ;CHECK-SAME:               DW_OP_constu, 0, DW_OP_plus, DW_OP_stack_value,
 ;CHECK-SAME:               DW_OP_LLVM_fragment, 0, 1)) 
 
 @foo = internal global i32 0, align 4, !dbg !0
 
 ; Function Attrs: noinline nounwind optnone uwtable
 define void @set1() #0 !dbg !11 {
 entry: