Return accurate size of addressing mode dsp/dsp+cnst instr descriptor

[kunalspathak]

During spmi asmdiffs with cross compiled jit, I noticed we hit the following assert

runtime/src/coreclr/jit/emit.cpp

Line 1270 in 035821a

assert(id->idDebugOnlyInfo()->idSize == sz);

It happens because for ID_OP_AMD and ID_OP_AMD_CNS format, we create instrDescCnsAmd but then in emitSizeOfInsDsc(), when we try to calculate the size, we calculate the size of instrDescCnsDsp instead. They don't match for cross compilation scenario like running superpmi asmdiffs for cross target. E.g. While running with clrjit_win_x86_x64.dll, sizeof(instrDescCnsAmd) == 40 but sizeof(instrDescCnsDsp) == 32. The is because instrDescCnsDsp contains a field of type target_ssize_t which is different for x64 vs. x86.

runtime/src/coreclr/jit/emit.h

Line 1401 in 035821a

struct instrDescCnsDsp : instrDesc // large cons + disp

The fix is to return the size of right struct for these formats.

[kunalspathak]

@dotnet/jit-contrib

[echesakov]

@kunalspathak Have you confirmed our hypothesis that size of the instructions descriptors are the same with crossgen (x86) as we discussed yesterday?

[BruceForstall]

Based on emitNewInstrAmdCns, I would expect it to be:

            if (id->idIsLargeCns())
            {
                if (id->idIsLargeDsp())
                {
                    return sizeof(instrDescCnsAmd);
                }
                else
                {
                    return sizeof(instrDescCns);
                }
            }
            else
            {
                if (id->idIsLargeDsp())
                {
                    return sizeof(instrDescAmd);
                }
                else
                {
                    return sizeof(instrDesc);
                }
            }

[kunalspathak]

Actually yes.

[kunalspathak]

@kunalspathak Have you confirmed our hypothesis that size of the instructions descriptors are the same with crossgen (x86) as we discussed yesterday?

Yes @echesakovMSFT - they are same. I also crossgen stind_i1.ilproj project which reproed the issue and used R2RDump.exe to see if things work.