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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; *Use = REG_NONE;
} }
/* Will destroy all registers */ /* Will destroy all registers and processor flags */
*Chg = REG_ALL; *Chg = (REG_ALL | PSTATE_ALL);
/* and will destroy all processor flags */
*Chg |= PSTATE_ALL;
/* Done */ /* Done */
return FNCLS_GLOBAL; 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. ** are used mostly in inline assembly anyway.
*/ */
*Use = REG_ALL; *Use = REG_ALL;
*Chg = REG_ALL; *Chg = (REG_ALL | PSTATE_ALL);
*Chg |= PSTATE_ALL;
return FNCLS_NUMERIC; return FNCLS_NUMERIC;
} else { } 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); fprintf (stderr, "No info about internal function '%s'\n", Name);
} }
*Use = REG_ALL; *Use = REG_ALL;
*Chg = REG_ALL; *Chg = (REG_ALL | PSTATE_ALL);
*Chg |= PSTATE_ALL;
} }
return FNCLS_BUILTIN; 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 ** registers and processor flags are changed
*/ */
*Use = REG_EAXY; *Use = REG_EAXY;
*Chg = REG_ALL; *Chg = (REG_ALL | PSTATE_ALL);
*Chg |= PSTATE_ALL;
return FNCLS_UNKNOWN; 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) unsigned GetKnownReg (unsigned Use, const RegContents* RC)
/* Return the register or zero page location from the set in Use, thats /* 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 ** 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); int RegEAXUsed (struct CodeSeg* S, unsigned Index);
/* Check if any of the four bytes in EAX are used. */ /* 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); unsigned GetKnownReg (unsigned Use, const struct RegContents* RC);
/* Return the register or zero page location from the set in Use, thats /* 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 ** 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) unsigned OptUnusedLoads (CodeSeg* S)
/* Remove loads of or operations with registers where the value loaded or /* Remove loads of or operations with registers where the value loaded or
** produced is not used later. ** produced is not used later.
*/ */
{ {
unsigned Changes = 0; unsigned Changes = 0;
@@ -173,7 +173,7 @@ unsigned OptUnusedLoads (CodeSeg* S)
E->OPC == OP65_ORA; E->OPC == OP65_ORA;
/* Check for the necessary preconditions */ /* 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 */ /* Check which sort of load or transfer it is */
unsigned R; 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 ** The instruction can be removed if the flags aren't
** used later. ** used later.
*/ */
CodeEntry* N = CS_GetNextEntry (S, I); if (!LoadFlagsUsed (S, I+1)) {
if (N && !CE_UseLoadFlags (N)) {
Delete = 1; Delete = 1;
} }
} else if (Operand >= 0) { } else if (Operand >= 0) {
@@ -822,8 +821,7 @@ unsigned OptBinOps (CodeSeg* S)
** The instruction can be removed if the flags aren't ** The instruction can be removed if the flags aren't
** used later. ** used later.
*/ */
CodeEntry* N = CS_GetNextEntry (S, I); if (!LoadFlagsUsed (S, I+1)) {
if (N && !CE_UseLoadFlags (N)) {
Delete = 1; Delete = 1;
} }
} else if (Operand >= 0) { } else if (Operand >= 0) {
@@ -861,8 +859,7 @@ unsigned OptBinOps (CodeSeg* S)
** The instruction can be removed if the flags aren't ** The instruction can be removed if the flags aren't
** used later. ** used later.
*/ */
CodeEntry* N = CS_GetNextEntry (S, I); if (!LoadFlagsUsed (S, I+1)) {
if (N && !CE_UseLoadFlags (N)) {
Delete = 1; Delete = 1;
} }
} else if (Operand == 0xFF) { } else if (Operand == 0xFF) {