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Small optimization of some cc65-generated loops.

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"bne" means also branch-on-not-zero.  Therefore, this optimization doesn't put a compare-to-zero between an increment and a "bne".
This commit is contained in:
Greg King 2016-05-24 15:52:12 -04:00
parent b0e929420b
commit 8d5717b57a
3 changed files with 32 additions and 15 deletions
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7
src/cc65/codegen.c
View File

@ -55,6 +55,7 @@
#include "global.h"
#include "segments.h"
#include "stackptr.h"
#include "stdfunc.h"
#include "textseg.h"
#include "util.h"
#include "codegen.h"
@ -4241,7 +4242,7 @@ void g_initauto (unsigned Label, unsigned Size)
AddCodeLine ("lda %s,y", GetLabelName (CF_STATIC, Label, 0));
AddCodeLine ("sta (sp),y");
AddCodeLine ("iny");
AddCodeLine ("cpy #$%02X", (unsigned char) Size);
AddCmpCodeIfSizeNot256 ("cpy #$%02X", Size);
AddCodeLine ("bne %s", LocalLabelName (CodeLabel));
}
}
@ -4266,10 +4267,10 @@ void g_initstatic (unsigned InitLabel, unsigned VarLabel, unsigned Size)
AddCodeLine ("lda %s,y", GetLabelName (CF_STATIC, InitLabel, 0));
AddCodeLine ("sta %s,y", GetLabelName (CF_STATIC, VarLabel, 0));
AddCodeLine ("iny");
AddCodeLine ("cpy #$%02X", (unsigned char) Size);
AddCmpCodeIfSizeNot256 ("cpy #$%02X", Size);
AddCodeLine ("bne %s", LocalLabelName (CodeLabel));
} else {
/* Use the easy way here: memcpy */
/* Use the easy way here: memcpy() */
g_getimmed (CF_STATIC, VarLabel, 0);
AddCodeLine ("jsr pushax");
g_getimmed (CF_STATIC, InitLabel, 0);

33
src/cc65/stdfunc.c
View File

@ -185,6 +185,19 @@ static void ParseArg (ArgDesc* Arg, Type* Type)
void AddCmpCodeIfSizeNot256 (const char* Code, long Size)
/* Add a line of Assembly code that compares an index register
** only if it isn't comparing to #<256. (If the next line
** is "bne", then this will avoid a redundant line.)
*/
{
if (Size != 256) {
AddCodeLine (Code, (unsigned int)Size);
}
}
/*****************************************************************************/
/* memcpy */
/*****************************************************************************/
@ -272,7 +285,6 @@ static void StdFunc_memcpy (FuncDesc* F attribute ((unused)), ExprDesc* Expr)
if (Arg3.Expr.IVal <= 127) {
AddCodeLine ("ldy #$%02X", (unsigned char) (Arg3.Expr.IVal-1));
AddCodeLine ("lda #$%02X", (unsigned char) Arg2.Expr.IVal);
g_defcodelabel (Label);
if (Reg2) {
AddCodeLine ("lda (%s),y", ED_GetLabelName (&Arg2.Expr, 0));
@ -290,7 +302,6 @@ static void StdFunc_memcpy (FuncDesc* F attribute ((unused)), ExprDesc* Expr)
} else {
AddCodeLine ("ldy #$00");
AddCodeLine ("lda #$%02X", (unsigned char) Arg2.Expr.IVal);
g_defcodelabel (Label);
if (Reg2) {
AddCodeLine ("lda (%s),y", ED_GetLabelName (&Arg2.Expr, 0));
@ -303,7 +314,7 @@ static void StdFunc_memcpy (FuncDesc* F attribute ((unused)), ExprDesc* Expr)
AddCodeLine ("sta %s,y", ED_GetLabelName (&Arg1.Expr, 0));
}
AddCodeLine ("iny");
AddCodeLine ("cpy #$%02X", (unsigned char) Arg3.Expr.IVal);
AddCmpCodeIfSizeNot256 ("cpy #$%02X", Arg3.Expr.IVal);
AddCodeLine ("bne %s", LocalLabelName (Label));
}
@ -366,7 +377,7 @@ static void StdFunc_memcpy (FuncDesc* F attribute ((unused)), ExprDesc* Expr)
AddCodeLine ("lda %s,y", ED_GetLabelName (&Arg2.Expr, -Offs));
AddCodeLine ("sta (sp),y");
AddCodeLine ("iny");
AddCodeLine ("cpy #$%02X", (unsigned char) (Offs + Arg3.Expr.IVal));
AddCmpCodeIfSizeNot256 ("cpy #$%02X", Offs + Arg3.Expr.IVal);
AddCodeLine ("bne %s", LocalLabelName (Label));
} else {
AddCodeLine ("ldx #$00");
@ -376,7 +387,7 @@ static void StdFunc_memcpy (FuncDesc* F attribute ((unused)), ExprDesc* Expr)
AddCodeLine ("sta (sp),y");
AddCodeLine ("iny");
AddCodeLine ("inx");
AddCodeLine ("cpx #$%02X", (unsigned char) Arg3.Expr.IVal);
AddCmpCodeIfSizeNot256 ("cpx #$%02X", Arg3.Expr.IVal);
AddCodeLine ("bne %s", LocalLabelName (Label));
}
@ -440,7 +451,7 @@ static void StdFunc_memcpy (FuncDesc* F attribute ((unused)), ExprDesc* Expr)
AddCodeLine ("lda (sp),y");
AddCodeLine ("sta %s,y", ED_GetLabelName (&Arg1.Expr, -Offs));
AddCodeLine ("iny");
AddCodeLine ("cpy #$%02X", (unsigned char) (Offs + Arg3.Expr.IVal));
AddCmpCodeIfSizeNot256 ("cpy #$%02X", Offs + Arg3.Expr.IVal);
AddCodeLine ("bne %s", LocalLabelName (Label));
} else {
AddCodeLine ("ldx #$00");
@ -450,7 +461,7 @@ static void StdFunc_memcpy (FuncDesc* F attribute ((unused)), ExprDesc* Expr)
AddCodeLine ("sta %s,x", ED_GetLabelName (&Arg1.Expr, 0));
AddCodeLine ("iny");
AddCodeLine ("inx");
AddCodeLine ("cpx #$%02X", (unsigned char) Arg3.Expr.IVal);
AddCmpCodeIfSizeNot256 ("cpx #$%02X", Arg3.Expr.IVal);
AddCodeLine ("bne %s", LocalLabelName (Label));
}
@ -487,7 +498,7 @@ static void StdFunc_memcpy (FuncDesc* F attribute ((unused)), ExprDesc* Expr)
AddCodeLine ("lda (sp),y");
AddCodeLine ("sta (ptr1),y");
AddCodeLine ("iny");
AddCodeLine ("cpy #$%02X", (unsigned char) Arg3.Expr.IVal);
AddCmpCodeIfSizeNot256 ("cpy #$%02X", Arg3.Expr.IVal);
AddCodeLine ("bne %s", LocalLabelName (Label));
}
@ -631,7 +642,7 @@ static void StdFunc_memset (FuncDesc* F attribute ((unused)), ExprDesc* Expr)
AddCodeLine ("sta %s,y", ED_GetLabelName (&Arg1.Expr, 0));
}
AddCodeLine ("iny");
AddCodeLine ("cpy #$%02X", (unsigned char) Arg3.Expr.IVal);
AddCmpCodeIfSizeNot256 ("cpy #$%02X", Arg3.Expr.IVal);
AddCodeLine ("bne %s", LocalLabelName (Label));
}
@ -661,7 +672,7 @@ static void StdFunc_memset (FuncDesc* F attribute ((unused)), ExprDesc* Expr)
g_defcodelabel (Label);
AddCodeLine ("sta (sp),y");
AddCodeLine ("iny");
AddCodeLine ("cpy #$%02X", (unsigned char) (Offs + Arg3.Expr.IVal));
AddCmpCodeIfSizeNot256 ("cpy #$%02X", Offs + Arg3.Expr.IVal);
AddCodeLine ("bne %s", LocalLabelName (Label));
/* memset returns the address, so the result is actually identical
@ -697,7 +708,7 @@ static void StdFunc_memset (FuncDesc* F attribute ((unused)), ExprDesc* Expr)
g_defcodelabel (Label);
AddCodeLine ("sta (ptr1),y");
AddCodeLine ("iny");
AddCodeLine ("cpy #$%02X", (unsigned char) Arg3.Expr.IVal);
AddCmpCodeIfSizeNot256 ("cpy #$%02X", Arg3.Expr.IVal);
AddCodeLine ("bne %s", LocalLabelName (Label));
}

7
src/cc65/stdfunc.h
View File

@ -50,6 +50,12 @@
void AddCmpCodeIfSizeNot256 (const char* Code, long Size);
/* Add a line of Assembly code that compares an index register
** only if it isn't comparing to #<256. (If the next line
** is "bne", then this will avoid a redundant line.)
*/
int FindStdFunc (const char* Name);
/* Determine if the given function is a known standard function that may be
** called in a special way. If so, return the index, otherwise return -1.
@ -61,5 +67,4 @@ void HandleStdFunc (int Index, struct FuncDesc* F, ExprDesc* lval);
/* End of stdfunc.h */
#endif