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Fix the check for CPU flags being used after an instruction that gets removed.

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Previously only the next instruction was checked for usage of the CPU flags
but this fails for certain code.
This commit is contained in:
Kugel Fuhr 2024-09-07 17:19:13 +02:00
parent 6e18e0880a
commit f43cfd1ad0
4 changed files with 22 additions and 20 deletions
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24
src/cc65/codeinfo.c
View File

@ -560,11 +560,8 @@ fncls_t GetFuncInfo (const char* Name, unsigned int* Use, unsigned int* Chg)
*Use = REG_NONE;
}
/* Will destroy all registers */
*Chg = REG_ALL;
/* and will destroy all processor flags */
*Chg |= PSTATE_ALL;
/* Will destroy all registers and processor flags */
*Chg = (REG_ALL | PSTATE_ALL);
/* Done */
return FNCLS_GLOBAL;
@ -577,8 +574,7 @@ fncls_t GetFuncInfo (const char* Name, unsigned int* Use, unsigned int* Chg)
** are used mostly in inline assembly anyway.
*/
*Use = REG_ALL;
*Chg = REG_ALL;
*Chg |= PSTATE_ALL;
*Chg = (REG_ALL | PSTATE_ALL);
return FNCLS_NUMERIC;
} else {
@ -605,8 +601,7 @@ fncls_t GetFuncInfo (const char* Name, unsigned int* Use, unsigned int* Chg)
fprintf (stderr, "No info about internal function '%s'\n", Name);
}
*Use = REG_ALL;
*Chg = REG_ALL;
*Chg |= PSTATE_ALL;
*Chg = (REG_ALL | PSTATE_ALL);
}
return FNCLS_BUILTIN;
}
@ -615,8 +610,7 @@ fncls_t GetFuncInfo (const char* Name, unsigned int* Use, unsigned int* Chg)
** registers and processor flags are changed
*/
*Use = REG_EAXY;
*Chg = REG_ALL;
*Chg |= PSTATE_ALL;
*Chg = (REG_ALL | PSTATE_ALL);
return FNCLS_UNKNOWN;
}
@ -899,6 +893,14 @@ int RegEAXUsed (struct CodeSeg* S, unsigned Index)
int LoadFlagsUsed (struct CodeSeg* S, unsigned Index)
/* Check if one of the flags set by a register load (Z and N) are used. */
{
return (GetRegInfo (S, Index, PSTATE_ZN) & PSTATE_ZN) != 0;
}
unsigned GetKnownReg (unsigned Use, const RegContents* RC)
/* Return the register or zero page location from the set in Use, thats
** contents are known. If Use does not contain any register, or if the

3
src/cc65/codeinfo.h
View File

@ -201,6 +201,9 @@ int RegAXUsed (struct CodeSeg* S, unsigned Index);
int RegEAXUsed (struct CodeSeg* S, unsigned Index);
/* Check if any of the four bytes in EAX are used. */
int LoadFlagsUsed (struct CodeSeg* S, unsigned Index);
/* Check if one of the flags set by a register load (Z and N) are used. */
unsigned GetKnownReg (unsigned Use, const struct RegContents* RC);
/* Return the register or zero page location from the set in Use, thats
** contents are known. If Use does not contain any register, or if the

6
src/cc65/coptind.c
View File

@ -151,8 +151,8 @@ static short ZPRegVal (unsigned short Use, const RegContents* RC)
unsigned OptUnusedLoads (CodeSeg* S)
/* Remove loads of or operations with registers where the value loaded or
** produced is not used later.
/* Remove loads of or operations with registers where the value loaded or
** produced is not used later.
*/
{
unsigned Changes = 0;
@ -173,7 +173,7 @@ unsigned OptUnusedLoads (CodeSeg* S)
E->OPC == OP65_ORA;
/* Check for the necessary preconditions */
if (IsOp && (N = CS_GetNextEntry (S, I)) != 0 && !CE_UseLoadFlags (N)) {
if (IsOp && (N = CS_GetNextEntry (S, I)) != 0 && !LoadFlagsUsed (S, I+1)) {
/* Check which sort of load or transfer it is */
unsigned R;

9
src/cc65/coptmisc.c
View File

@ -788,8 +788,7 @@ unsigned OptBinOps (CodeSeg* S)
** The instruction can be removed if the flags aren't
** used later.
*/
CodeEntry* N = CS_GetNextEntry (S, I);
if (N && !CE_UseLoadFlags (N)) {
if (!LoadFlagsUsed (S, I+1)) {
Delete = 1;
}
} else if (Operand >= 0) {
@ -822,8 +821,7 @@ unsigned OptBinOps (CodeSeg* S)
** The instruction can be removed if the flags aren't
** used later.
*/
CodeEntry* N = CS_GetNextEntry (S, I);
if (N && !CE_UseLoadFlags (N)) {
if (!LoadFlagsUsed (S, I+1)) {
Delete = 1;
}
} else if (Operand >= 0) {
@ -861,8 +859,7 @@ unsigned OptBinOps (CodeSeg* S)
** The instruction can be removed if the flags aren't
** used later.
*/
CodeEntry* N = CS_GetNextEntry (S, I);
if (N && !CE_UseLoadFlags (N)) {
if (!LoadFlagsUsed (S, I+1)) {
Delete = 1;
}
} else if (Operand == 0xFF) {