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BUGFIX: Fix the "same X value" and "same A value" evaluations issue in OptStackOps(), where the values compared come from the wrong instruction when a runtime call has an asm label.

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This commit is contained in:
Alex Volkov
2026-03-10 20:08:35 -04:00
parent 505698c450
commit bf5d8c44e4
1 changed files with 23 additions and 65 deletions
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84
src/cc65/coptstop.c
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@@ -94,68 +94,34 @@ struct OptFuncDesc {
static int SameRegAValue (StackOpData* D) static int SameRegAValueAtOp (const StackOpData* D, CodeEntry* OpEntry)
/* Check if Rhs Reg A == Lhs Reg A */ /* Check if Rhs Reg A at OpIndex == Lhs Reg A at PushIndex */
{ {
RegInfo* LRI = GetLastChangedRegInfo (D, &D->Lhs.A); CodeEntry* PushEntry;
RegInfo* RRI = GetLastChangedRegInfo (D, &D->Rhs.A);
/* ### Bug: The Rhs Reg A value used in the logic here can be from a return CHECK (D->PushIndex >= 0);
** value of the runtime call being optimized away (e.g. "jsr tosgtax"), PushEntry = CS_GetEntry (D->Code, D->PushIndex);
** and *not* its operand. That happens when the call insn (JSR) has a label.
** Then the RRI is that of the runtime call JSR, and the RRI->Out.RegA
** compares here are not valid.
** See OptStackOps(), case FoundPush: if (CE_HasLabel (E)) { ...
** and usage in Opt_a_tosicmp().
*/
/* RHS can have a -1 ChgIndex only if it is carried over from LHS */
if (RRI == 0 ||
(D->Rhs.A.ChgIndex >= 0 &&
D->Rhs.A.ChgIndex == D->Lhs.A.ChgIndex) ||
(LRI != 0 &&
RegValIsKnown (LRI->Out.RegA) &&
RegValIsKnown (RRI->Out.RegA) &&
(LRI->Out.RegA & 0xFF) == (RRI->Out.RegA & 0xFF))) {
return 1;
}
return 0;
return
RegValIsKnown (PushEntry->RI->In.RegA) &&
RegValIsKnown (OpEntry->RI->In.RegA) &&
PushEntry->RI->In.RegA == OpEntry->RI->In.RegA;
} }
static int SameRegXValue (StackOpData* D) static int SameRegXValueAtOp (const StackOpData* D, CodeEntry* OpEntry)
/* Check if Rhs Reg X == Lhs Reg X */ /* Check if Rhs Reg X at OpIndex == Lhs Reg X at PushIndex */
{ {
RegInfo* LRI = GetLastChangedRegInfo (D, &D->Lhs.X); CodeEntry* PushEntry;
RegInfo* RRI = GetLastChangedRegInfo (D, &D->Rhs.X);
/* ### Bug: The Rhs Reg X value used in the logic here can be from a return CHECK (D->PushIndex >= 0);
** value of the runtime call being optimized away (e.g. "jsr tosgtax"), PushEntry = CS_GetEntry (D->Code, D->PushIndex);
** and *not* its operand. That happens when the call insn (JSR) has a label.
** Then the RRI is that of the runtime call JSR, and the RRI->Out.RegX
** compares here are not valid.
** See OptStackOps(), case FoundPush: if (CE_HasLabel (E)) { ...
** RegAPreCondOk() has special armour code for this issue:
** if (LhsHiVal != RhsHiVal) { /Cannot optimize/ break; }
*/
if (RRI == 0 ||
(D->Rhs.X.ChgIndex >= 0 &&
D->Rhs.X.ChgIndex == D->Lhs.X.ChgIndex) ||
(LRI != 0 &&
RegValIsKnown (LRI->Out.RegX) &&
RegValIsKnown (RRI->Out.RegX) &&
(LRI->Out.RegX & 0xFF) == (RRI->Out.RegX & 0xFF))) {
return 1;
}
return 0;
return
RegValIsKnown (PushEntry->RI->In.RegX) &&
RegValIsKnown (OpEntry->RI->In.RegX) &&
PushEntry->RI->In.RegX == OpEntry->RI->In.RegX;
} }
@@ -1398,13 +1364,8 @@ static unsigned Opt_a_tosicmp (StackOpData* D)
RegInfo* RI; RegInfo* RI;
const char* Arg; const char* Arg;
/* ### Bug to come: The Reg A value used in SameRegAValue() call here if (!SameRegAValueAtOp (D, D->OpEntry)) {
** can be from the wrong instruction in some cases, producing invalid /* Because of SameRegAValueAtOp */
** result. Any effects of this issue are currently suppressed because
** other subopts eliminate this subopt's use cases.
*/
if (!SameRegAValue (D)) {
/* Because of SameRegAValue */
CHECK (D->Rhs.A.ChgIndex >= 0); CHECK (D->Rhs.A.ChgIndex >= 0);
/* HaveUnusedTempZPLoc precondition must have been met */ /* HaveUnusedTempZPLoc precondition must have been met */
@@ -2079,9 +2040,6 @@ unsigned OptStackOps (CodeSeg* S)
** Treat this as a change to all regs. ** Treat this as a change to all regs.
*/ */
ClearLoadInfo (&Data.Rhs); ClearLoadInfo (&Data.Rhs);
/* ### Note: this causes the below SameRegXValue() to not
** work correctly in some cases.
*/
Data.Rhs.A.ChgIndex = I; Data.Rhs.A.ChgIndex = I;
Data.Rhs.X.ChgIndex = I; Data.Rhs.X.ChgIndex = I;
Data.Rhs.Y.ChgIndex = I; Data.Rhs.Y.ChgIndex = I;
@@ -2096,7 +2054,7 @@ unsigned OptStackOps (CodeSeg* S)
** When the A-only preconditions fail, good A/X cases are ** When the A-only preconditions fail, good A/X cases are
** left unoptimized. ** left unoptimized.
*/ */
if (SameRegXValue (&Data)) { if (SameRegXValueAtOp (&Data, E)) {
Data.OptFunc = FindFunc (FuncRegATable, FUNC_COUNT (FuncRegATable), E->Arg); Data.OptFunc = FindFunc (FuncRegATable, FUNC_COUNT (FuncRegATable), E->Arg);
IsRegAOptFunc = 1; IsRegAOptFunc = 1;
} }