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Add flag to rgbasm to disable LD->LDH optimization

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rgbasm tries to optimize any loads from/to $FF00-$FFFF and generate
LDH 2-byte opcodes instead of regular LD 3-byte opcodes. This is a bit
inconsistent as it only works for constant values. If a load is trying
to access a label in a HRAM floating section, or a section found in a
different object file, this optimization doesn't work.

This means that a simple refactor or code could allow rgbasm to perform
the optimzation or prevent it from doing so. For certain projects, like
disassemblies, this is a problem.

This patch adds flag -L to rgbasm to disable the optimization, and
doesn't change the behaviour of any other existing code.

Signed-off-by: Antonio Niño Díaz <antonio_nd@outlook.com>
This commit is contained in:
Antonio Niño Díaz
2018-02-24 15:43:55 +00:00
parent 2a97535e75
commit 6ad5bd2325
9 changed files with 70 additions and 29 deletions
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6
src/asm/asmy.y
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@@ -1728,7 +1728,8 @@ z80_ld_mem : T_Z80_LD op_mem_ind comma T_MODE_SP
}
| T_Z80_LD op_mem_ind comma T_MODE_A
{
if ((!rpn_isReloc(&$2)) && ($2.nVal >= 0xFF00)) {
if (CurrentOptions.optimizeloads &&
(!rpn_isReloc(&$2)) && ($2.nVal >= 0xFF00)) {
out_AbsByte(0xE0);
out_AbsByte($2.nVal & 0xFF);
} else {
@@ -1781,7 +1782,8 @@ z80_ld_a : T_Z80_LD reg_r comma T_MODE_C_IND
| T_Z80_LD reg_r comma op_mem_ind
{
if ($2 == REG_A) {
if ((!rpn_isReloc(&$4)) && ($4.nVal >= 0xFF00)) {
if (CurrentOptions.optimizeloads &&
(!rpn_isReloc(&$4)) && ($4.nVal >= 0xFF00)) {
out_AbsByte(0xF0);
out_AbsByte($4.nVal & 0xFF);
} else {