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Clearly delineate load instruction "must remove" conditions from "may remove" with a new LI_MUST_REMOVE flag. A demand to remove a non-removable load is fatal.

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This commit is contained in:
Alex Volkov
2026-03-25 19:14:14 -04:00
parent c9b885b144
commit 00a1f1d447
3 changed files with 48 additions and 31 deletions
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6
src/cc65/codeoptutil.c
View File

@@ -1270,6 +1270,12 @@ void RemoveRegLoads (StackOpData* D, LoadInfo* LI)
CanRemoveX = 0;
}
/* A load removal demand which cannot be satisifed is a fatal condition */
if (((LI->A.Flags & LI_MUST_REMOVE) != 0 && !CanRemoveA) ||
((LI->X.Flags & LI_MUST_REMOVE) != 0 && !CanRemoveX)) {
Internal ("Cannot remove a load instruction which must be removed");
}
/* A request to remove a "change" insn (ChgIndex) when there is no
** corresponing load insn (LoadIndex) is never valid.
*/

1
src/cc65/codeoptutil.h
View File

@@ -70,6 +70,7 @@ typedef enum {
LI_USED_BY_Y = 0x4000, /* Content used by RegY */
LI_SP = 0x8000, /* Content on stack */
LI_LOAD_INSN = 0x010000, /* Is a load insn */
LI_MUST_REMOVE = 0x020000, /* Load must be removed */
} LI_FLAGS;
/* Structure that tells us how to load the lhs values */

72
src/cc65/coptstop.c
View File

@@ -436,9 +436,9 @@ static unsigned Opt_toseqax_tosneax (StackOpData* D, const char* BoolTransformer
X = NewCodeEntry (OP65_CMP, LoadA->AM, LoadA->Arg, 0, D->OpEntry->LI);
InsertEntry (D, X, D->IP++);
/* Rhs load entries must be removed */
D->Rhs.X.Flags |= LI_REMOVE;
D->Rhs.A.Flags |= LI_REMOVE;
/* Rhs load entries must be removed because Lhs must be in effect */
D->Rhs.X.Flags |= (LI_REMOVE | LI_MUST_REMOVE);
D->Rhs.A.Flags |= (LI_REMOVE | LI_MUST_REMOVE);
} else if (RhsIsRemovable (D)) {
@@ -454,6 +454,10 @@ static unsigned Opt_toseqax_tosneax (StackOpData* D, const char* BoolTransformer
/* Add operand for high byte */
AddOpHigh (D, OP65_CMP, &D->Rhs, 0);
/* Rhs load entries must be removed because Lhs must be in effect */
D->Rhs.X.Flags |= LI_MUST_REMOVE;
D->Rhs.A.Flags |= LI_MUST_REMOVE;
} else {
/* Implement the op via a temp ZP location */
@@ -1018,9 +1022,9 @@ static unsigned Opt_tosgeax (StackOpData* D)
X = NewCodeEntry (OP65_ROL, AM65_ACC, "a", 0, D->OpEntry->LI);
InsertEntry (D, X, D->IP++);
/* Rhs load entries must be removed */
D->Rhs.X.Flags |= LI_REMOVE;
D->Rhs.A.Flags |= LI_REMOVE;
/* Rhs load entries must be removed because Lhs must be in effect */
D->Rhs.X.Flags |= LI_MUST_REMOVE;
D->Rhs.A.Flags |= LI_MUST_REMOVE;
/* Remove the push and the call to the tosgeax function */
RemoveRemainders (D);
@@ -1075,9 +1079,9 @@ static unsigned Opt_tosltax (StackOpData* D)
X = NewCodeEntry (OP65_ROL, AM65_ACC, "a", 0, D->OpEntry->LI);
InsertEntry (D, X, D->IP++);
/* Rhs load entries must be removed */
D->Rhs.X.Flags |= LI_REMOVE;
D->Rhs.A.Flags |= LI_REMOVE;
/* Rhs load entries must be removed because Lhs must be in effect */
D->Rhs.X.Flags |= LI_MUST_REMOVE;
D->Rhs.A.Flags |= LI_MUST_REMOVE;
/* Remove the push and the call to the tosltax function */
RemoveRemainders (D);
@@ -1158,9 +1162,9 @@ static unsigned Opt_tossubax (StackOpData* D)
/* Add code for high operand */
AddOpHigh (D, OP65_SBC, &D->Rhs, 1);
/* Rhs load entries must be removed */
D->Rhs.X.Flags |= LI_REMOVE;
D->Rhs.A.Flags |= LI_REMOVE;
/* Rhs load entries must be removed because Lhs must be in effect */
D->Rhs.X.Flags |= LI_MUST_REMOVE;
D->Rhs.A.Flags |= LI_MUST_REMOVE;
/* Remove the push and the call to the tossubax function */
RemoveRemainders (D);
@@ -1200,9 +1204,9 @@ static unsigned Opt_tosugeax (StackOpData* D)
X = NewCodeEntry (OP65_ROL, AM65_ACC, "a", 0, D->OpEntry->LI);
InsertEntry (D, X, D->IP++);
/* Rhs load entries must be removed */
D->Rhs.X.Flags |= LI_REMOVE;
D->Rhs.A.Flags |= LI_REMOVE;
/* Rhs load entries must be removed because Lhs must be in effect */
D->Rhs.X.Flags |= LI_MUST_REMOVE;
D->Rhs.A.Flags |= LI_MUST_REMOVE;
/* Remove the push and the call to the tosugeax function */
RemoveRemainders (D);
@@ -1246,9 +1250,9 @@ static unsigned Opt_tosugtax (StackOpData* D)
X = NewCodeEntry (OP65_JSR, AM65_ABS, "boolugt", 0, D->OpEntry->LI);
InsertEntry (D, X, D->IP++);
/* Rhs load entries must be removed */
D->Rhs.X.Flags |= LI_REMOVE;
D->Rhs.A.Flags |= LI_REMOVE;
/* Rhs load entries must be removed because Lhs must be in effect */
D->Rhs.X.Flags |= LI_MUST_REMOVE;
D->Rhs.A.Flags |= LI_MUST_REMOVE;
/* Remove the push and the call to the operator function */
RemoveRemainders (D);
@@ -1292,9 +1296,9 @@ static unsigned Opt_tosuleax (StackOpData* D)
X = NewCodeEntry (OP65_JSR, AM65_ABS, "boolule", 0, D->OpEntry->LI);
InsertEntry (D, X, D->IP++);
/* Rhs load entries must be removed */
D->Rhs.X.Flags |= LI_REMOVE;
D->Rhs.A.Flags |= LI_REMOVE;
/* Rhs load entries must be removed because Lhs must be in effect */
D->Rhs.X.Flags |= LI_MUST_REMOVE;
D->Rhs.A.Flags |= LI_MUST_REMOVE;
/* Remove the push and the call to the operator function */
RemoveRemainders (D);
@@ -1326,9 +1330,9 @@ static unsigned Opt_tosultax (StackOpData* D)
X = NewCodeEntry (OP65_JSR, AM65_ABS, "boolult", 0, D->OpEntry->LI);
InsertEntry (D, X, D->IP++);
/* Rhs load entries must be removed */
D->Rhs.X.Flags |= LI_REMOVE;
D->Rhs.A.Flags |= LI_REMOVE;
/* Rhs load entries must be removed because Lhs must be in effect */
D->Rhs.X.Flags |= LI_MUST_REMOVE;
D->Rhs.A.Flags |= LI_MUST_REMOVE;
/* Remove the push and the call to the operator function */
RemoveRemainders (D);
@@ -1396,8 +1400,8 @@ static unsigned Opt_a_tosbitwise (StackOpData* D, opc_t OPC)
X = NewCodeEntry (OPC, D->Rhs.A.LoadEntry->AM, D->Rhs.A.LoadEntry->Arg, 0, D->OpEntry->LI);
InsertEntry (D, X, D->IP++);
/* Rhs load entries must be removed */
D->Rhs.A.Flags |= LI_REMOVE;
/* Rhs A load must be removed because Lhs must be in effect */
D->Rhs.A.Flags |= (LI_REMOVE | LI_MUST_REMOVE);
} else if (RegIsDirectNonStackLoaded (&D->Lhs.A)) {
@@ -1433,10 +1437,12 @@ static unsigned Opt_a_tosbitwise (StackOpData* D, opc_t OPC)
/* Since this is a "same X" EOR, the result is always 0. */
X = NewCodeEntry (OP65_LDX, AM65_IMM, MakeHexArg (0), 0, D->Rhs.X.ChgEntry->LI);
InsertEntry (D, X, D->IP++);
/* Rhs X load may be removed (but this is not a demand) */
D->Rhs.X.Flags |= LI_REMOVE;
}
} else {
/* Rhs load entries may be removed */
/* Rhs X load may be removed (but this is not a demand) */
D->Rhs.X.Flags |= LI_REMOVE;
}
@@ -1464,7 +1470,7 @@ static unsigned Opt_a_toscmpbool (StackOpData* D, const char* BoolTransformer)
/* Rhs low-byte load must be removed and hi-byte load may be removed */
D->Rhs.X.Flags |= LI_REMOVE;
D->Rhs.A.Flags |= LI_REMOVE;
D->Rhs.A.Flags |= LI_MUST_REMOVE;
} else if (RegIsDirectLoaded (&D->Lhs.A)) {
/* If the lhs is direct (but not stack relative), encode compares with lhs,
@@ -1604,7 +1610,9 @@ static unsigned Opt_a_tosicmp (StackOpData* D)
InsertEntry (D, X, D->IP++);
}
/* RHS may be removed */
/* RHS may be removed, but it is not a demand because Lhs was
** reloaded at Op and is in effect.
*/
D->Rhs.A.Flags |= LI_REMOVE;
D->Rhs.X.Flags |= LI_REMOVE;
}
@@ -1703,9 +1711,11 @@ static unsigned Opt_a_tossub (StackOpData* D)
InsertEntry (D, X, D->IP++);
}
/* Rhs load entries must be removed */
/* Rhs low-byte load must be removed (because Lhs must be in effect)
** and hi-byte load may be removed.
*/
D->Rhs.X.Flags |= LI_REMOVE;
D->Rhs.A.Flags |= LI_REMOVE;
D->Rhs.A.Flags |= LI_MUST_REMOVE;
/* Remove the push and the call to the tossubax function */
RemoveRemainders (D);