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More shift optimizations.

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git-svn-id: svn://svn.cc65.org/cc65/trunk@5770 b7a2c559-68d2-44c3-8de9-860c34a00d81
This commit is contained in:
uz 2012-07-07 19:24:17 +00:00
parent ae42e3b491
commit 49905d74bd
2 changed files with 66 additions and 23 deletions
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1
src/cc65/codeopt.c
View File

@ -1086,6 +1086,7 @@ static unsigned RunOptGroup3 (CodeSeg* S)
C += RunOptFunc (S, &DOptNegAX1, 1);
C += RunOptFunc (S, &DOptNegAX2, 1);
C += RunOptFunc (S, &DOptStackOps, 3);
C += RunOptFunc (S, &DOptShift1, 1);
C += RunOptFunc (S, &DOptShift4, 1);
C += RunOptFunc (S, &DOptSub1, 1);
C += RunOptFunc (S, &DOptSub2, 1);

88
src/cc65/coptshift.c
View File

@ -128,10 +128,10 @@ enum {
/* Macros to extract values from a shift type */
#define SHIFT_COUNT(S) ((S) & SHIFT_MASK_COUNT)
#define SHIFT_DIR(S) ((S) & SHIFT_MASK_DIR)
#define SHIFT_MODE(S) ((S) & SHIFT_MASK_MODE)
#define SHIFT_TYPE(S) ((S) & SHIFT_MASK_TYPE)
#define SHIFT_COUNT(S) ((S) & SHIFT_MASK_COUNT)
#define SHIFT_DIR(S) ((S) & SHIFT_MASK_DIR)
#define SHIFT_MODE(S) ((S) & SHIFT_MASK_MODE)
#define SHIFT_TYPE(S) ((S) & SHIFT_MASK_TYPE)
@ -208,7 +208,6 @@ unsigned OptShift1 (CodeSeg* S)
while (I < CS_GetEntryCount (S)) {
unsigned Shift;
unsigned Count;
CodeEntry* N;
CodeEntry* X;
CodeLabel* L;
@ -219,23 +218,53 @@ unsigned OptShift1 (CodeSeg* S)
/* Check for the sequence */
if (E->OPC == OP65_JSR &&
(Shift = GetShift (E->Arg)) != SHIFT_NONE &&
SHIFT_DIR (Shift) == SHIFT_DIR_LEFT &&
(Count = SHIFT_COUNT (Shift)) > 0) {
SHIFT_DIR (Shift) == SHIFT_DIR_LEFT) {
unsigned Count = SHIFT_COUNT (Shift);
if (!RegXUsed (S, I+1)) {
/* Insert shift insns */
while (Count--) {
if (Count == SHIFT_COUNT_Y) {
CodeLabel* L;
if (S->CodeSizeFactor < 200) {
goto NextEntry;
}
/* Change into
*
* L1: asl a
* dey
* bpl L1
* ror a
*/
/* asl a */
X = NewCodeEntry (OP65_ASL, AM65_ACC, "a", 0, E->LI);
CS_InsertEntry (S, X, I+1);
L = CS_GenLabel (S, X);
/* dey */
X = NewCodeEntry (OP65_DEY, AM65_IMP, 0, 0, E->LI);
CS_InsertEntry (S, X, I+2);
/* bpl L1 */
X = NewCodeEntry (OP65_BPL, AM65_BRA, L->Name, L, E->LI);
CS_InsertEntry (S, X, I+3);
/* ror a */
X = NewCodeEntry (OP65_ROR, AM65_ACC, "a", 0, E->LI);
CS_InsertEntry (S, X, I+4);
} else {
/* Insert shift insns */
while (Count--) {
X = NewCodeEntry (OP65_ASL, AM65_ACC, "a", 0, E->LI);
CS_InsertEntry (S, X, I+1);
}
}
/* Delete the call to shlax */
CS_DelEntry (S, I);
/* Remember, we had changes */
++Changes;
} else if (E->RI->In.RegX == 0 &&
Count == 1 &&
(N = CS_GetNextEntry (S, I)) != 0) {
@ -253,15 +282,21 @@ unsigned OptShift1 (CodeSeg* S)
X = NewCodeEntry (OP65_INX, AM65_IMP, 0, 0, E->LI);
CS_InsertEntry (S, X, I+3);
/* Delete the call to shlax */
CS_DelEntry (S, I);
} else {
/* We won't handle this one */
goto NextEntry;
/* Remember, we had changes */
++Changes;
}
/* Delete the call to shlax */
CS_DelEntry (S, I);
/* Remember, we had changes */
++Changes;
}
NextEntry:
/* Next entry */
++I;
@ -438,19 +473,25 @@ unsigned OptShift4 (CodeSeg* S)
Count = SHIFT_COUNT (Shift);
if (Count == SHIFT_COUNT_Y) {
CodeLabel* L;
if (S->CodeSizeFactor < 200) {
/* Not acceptable */
goto NextEntry;
}
/* Generate:
*
* L1: lsr a
* dey
* bpl L1
* rol a
*
* A negative shift count or one that is greater or equal than
* the bit width of the left operand (which is promoted to
*
* A negative shift count or one that is greater or equal than
* the bit width of the left operand (which is promoted to
* integer before the operation) causes undefined behaviour, so
* above transformation is safe.
*/
CodeLabel* L;
/* lsr a */
X = NewCodeEntry (OP65_LSR, AM65_ACC, "a", 0, E->LI);
@ -486,6 +527,7 @@ unsigned OptShift4 (CodeSeg* S)
}
NextEntry:
/* Next entry */
++I;