6502/cc65
1
0
Fork 0
mirror of https://github.com/cc65/cc65.git synced 2025-04-04 21:33:30 +00:00
Code Issues Projects Releases Wiki Activity

Fixed Issue #784.

Browse Source
This commit is contained in:
acqn 2020-01-03 08:20:07 +08:00 committed by Oliver Schmidt
parent b2268765bf
commit 48d3578c24
1 changed files with 48 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

51
src/cc65/coptstop.c
View File

@ -60,6 +60,8 @@ typedef enum {
LI_REMOVE = 0x04, /* Load may be removed */
LI_DONT_REMOVE = 0x08, /* Load may not be removed */
LI_DUP_LOAD = 0x10, /* Duplicate load */
LI_VOLATILE_SRC = 0x20, /* Load src might be modified later */
LI_SRC_CHG = 0x40, /* Load src is possibly modified */
} LI_FLAGS;
/* Structure that tells us how to load the lhs values */
@ -71,6 +73,7 @@ struct LoadRegInfo {
int XferIndex; /* Index of transfer insn */
CodeEntry* XferEntry; /* The actual transfer entry */
int Offs; /* Stack offset if data is on stack */
const char* Arg; /* Loaded src possibly modified later */
};
/* Now combined for both registers */
@ -246,6 +249,40 @@ static void AdjustLoadInfo (LoadInfo* LI, int Index, int Change)
static int Affected (LoadRegInfo* RI, const CodeEntry* E)
/* Check if the load src is modified between the pushax and op */
{
if (RI->Flags & LI_VOLATILE_SRC) {
if (E->AM == AM65_IMM || E->AM == AM65_ACC || E->AM == AM65_IMP || E->AM == AM65_BRA) {
return 0;
}
if (E->OPC == OP65_JSR) {
if (E->Flags & CEF_USERMARK) {
/* User subs. Play it safe. */
return 1;
}
/* We could filter the non-modifing functions. */
/* But why bother optimizating for such rare cases? */
return 1;
} else if (E->OPC == OP65_DEC || E->OPC == OP65_INC ||
E->OPC == OP65_ASL || E->OPC == OP65_LSR ||
E->OPC == OP65_ROL || E->OPC == OP65_ROR ||
E->OPC == OP65_TRB || E->OPC == OP65_TSB ||
E->OPC == OP65_STA || E->OPC == OP65_STX || E->OPC == OP65_STY) {
if ((E->AM == AM65_ABS || E->AM == AM65_ZP) &&
strcmp (RI->Arg, E->Arg) != 0) {
return 0;
}
/* We could've check further for more cases where the load target isn't modified */
/* But for now let's save the trouble and just play it safe */
return 1;
}
}
return 0;
}
static void HonourUseAndChg (LoadRegInfo* RI, unsigned Reg, const CodeEntry* E)
/* Honour use and change flags for an instruction */
{
@ -254,6 +291,9 @@ static void HonourUseAndChg (LoadRegInfo* RI, unsigned Reg, const CodeEntry* E)
} else if ((E->Use & Reg) && RI->LoadIndex >= 0) {
RI->Flags |= LI_DONT_REMOVE;
}
if (Affected (RI, E)) {
RI->Flags |= LI_SRC_CHG;
}
}
@ -288,10 +328,15 @@ static void TrackLoads (LoadInfo* LI, CodeEntry* E, int I)
RI->XferIndex = -1;
/* Set load flags */
RI->Flags &= ~(LI_DIRECT | LI_RELOAD_Y);
if (E->AM == AM65_IMM || E->AM == AM65_ZP || E->AM == AM65_ABS) {
RI->Flags &= ~(LI_DIRECT | LI_RELOAD_Y | LI_VOLATILE_SRC);
if (E->AM == AM65_IMM) {
/* These insns are all ok and replaceable */
RI->Flags |= LI_DIRECT;
} else if (E->AM == AM65_ZP || E->AM == AM65_ABS) {
/* These insns are replaceable only if they are not modified later */
RI->Flags |= LI_VOLATILE_SRC;
/* Watch for any change of the load target */
RI->Arg = E->Arg;
} else if (E->AM == AM65_ZP_INDY &&
RegValIsKnown (E->RI->In.RegY) &&
strcmp (E->Arg, "sp") == 0) {
@ -333,7 +378,7 @@ static void TrackLoads (LoadInfo* LI, CodeEntry* E, int I)
Tgt->LoadIndex = Src->LoadIndex;
Tgt->XferIndex = I;
Tgt->Offs = Src->Offs;
Tgt->Flags &= ~(LI_DIRECT | LI_RELOAD_Y);
Tgt->Flags &= ~(LI_DIRECT | LI_RELOAD_Y | LI_VOLATILE_SRC);
Tgt->Flags |= Src->Flags & (LI_DIRECT | LI_RELOAD_Y);
} else if (CE_IsCallTo (E, "ldaxysp") && RegValIsKnown (E->RI->In.RegY)) {