Odd Loop x86 CodeGen Behavior

[Edward Lee]

Some reason codegen is adding unnecessary stores that in turn cause
unnecessary loads to be added. Below is a snippet of the output of
opto assembly after some changes I've done to the nodes such as
removing the safepoint for this particular backedge. Any tips on where
I should look would be useful.

The high level code is doing HashMap.get where the object has a custom
equals method inlined that checks a long field. Kinda like..

if (entry.hash == hash_ECX && entry.key.longField == long_ESP_64)

The odd behavior is in B8 and B10, where long_ESP_64 gets loaded into
EAX,EDX in B8 and written back to the stack in B10 even though both
pair of load/stores are unnecessary. It seems that code gen is
confused by the fact that B3 loads long_ESP_64 into EAX,EDX for the
long compare and the branch from B3->B9 has a higher frequency
(0.029548) than the branch B2->B8 (0.023747).

But the really odd thing is why does B10 even exist in the first
place? There's no point in writing EAX,EDX back to the stack, and this
seems to be purely an artifact of code gen as the ideal graph doesn't
have any store nodes to that location.

080   B2: # B8 B3 <- B1 B10   Loop: B2-B10 inner  Freq: 1.01271
080     MOV    EDI,[EBX + #8] ! Field java/util/HashMap$Entry.hash
083     CMP    EDI,ECX
085     Jne,s  B8  P=0.023747 C=6443.000000
085
087   B3: # B9 B4 <- B2  Freq: 0.98866
087     MOV    ESI,[EBX + #12] ! Field java/util/HashMap$Entry.key
08a     MOV    EBP.lo,[ESI + #8]
  MOV    EBP.hi,[ESI + #8]+4 ! Field customEquals.longField
090     MOV    EAX,[ESP + #64]
  MOV    EDX,[ESP + #68]
098     CMP    EAX.lo,EBP.lo  ! Long compare; set flags for low bits
  JNE,s  skip
  CMP    EAX.hi,EBP.hi
  skip:
09e     Jne,s  B9  P=0.029548 C=6701.000000
09e
0a0   B4: # B5 <- B3 B9  Freq: 0.959448
0a0     MOV    EBX,[EBX + #16] ! Field java/util/HashMap$Entry.value
...
0d8     RET

0e0   B8: # B9 <- B2  Freq: 0.0240485
0e0     MOV    EAX,[ESP + #64]
  MOV    EDX,[ESP + #68]
0e0
0e8   B9: # B7 B10 <- B3 B8  Freq: 0.0532613
0e8     MOV    EBX,[EBX + #20] ! Field java/util/HashMap$Entry.next
0eb     TEST   EBX,EBX
0ed     Je,s  B4  P=0.038502 C=718.000000
0ed
0ef   B10: #  B2 <- B9  Freq: 0.0512106
0ef     MOV    [ESP + #64],EAX
  MOV    [ESP + #68],EDX
0f7     JMP    B2

Ed