| Key: |
RVM-387
|
| Type: |
Improvement
|
| Status: |
Closed
|
| Resolution: |
Fixed
|
| Priority: |
Major
|
| Assignee: |
Unassigned
|
| Reporter: |
Ian Rogers
|
| Votes: |
0
|
| Watchers: |
0
|
|
If you were logged in you would be able to see more operations.
|
|
|
|
In some situations we generate a displacement of 0 in the baseline compiler. For example, if we have 1 local then iload0 becomes "push [ESP+0]" when the operand stack is empty. Encoding this is RegDisp form creates an instruction of
opcode = 0xFF
modrm = 01b || 110b || 100b
(include /6 of the extended part of the opcode)
sib = 00100100b
imm8 = 0
ie. 4 bytes long. If this were RegInd form then the instruction could be:
opcode = 0xFF
modrm = 00b || 110b || 100b
sib = 00100100b
ie. 3 bytes long. We probably don't want to clutter up the assembler with "if (disp == 0) ..." so we should fix the baseline compiler.
|
|
Description
|
In some situations we generate a displacement of 0 in the baseline compiler. For example, if we have 1 local then iload0 becomes "push [ESP+0]" when the operand stack is empty. Encoding this is RegDisp form creates an instruction of
opcode = 0xFF
modrm = 01b || 110b || 100b
(include /6 of the extended part of the opcode)
sib = 00100100b
imm8 = 0
ie. 4 bytes long. If this were RegInd form then the instruction could be:
opcode = 0xFF
modrm = 00b || 110b || 100b
sib = 00100100b
ie. 3 bytes long. We probably don't want to clutter up the assembler with "if (disp == 0) ..." so we should fix the baseline compiler. |
Show » |
|
Baseline compiler emits RegDisp instructions when the Disp is 0