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Fixed hangup for loops in jump cascade

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git-svn-id: svn://svn.cc65.org/cc65/trunk@1734 b7a2c559-68d2-44c3-8de9-860c34a00d81
This commit is contained in:
cuz 2002-12-11 11:29:17 +00:00
parent 47d4d62d1f
commit 2f8c281b89
1 changed files with 32 additions and 8 deletions
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40
src/cc65/coptind.c
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@ -261,7 +261,7 @@ unsigned OptDeadJumps (CodeSeg* S)
/*****************************************************************************/
/* Remove dead code */
/* Remove dead code */
/*****************************************************************************/
@ -278,16 +278,22 @@ unsigned OptDeadCode (CodeSeg* S)
while (I < CS_GetEntryCount (S)) {
CodeEntry* N;
CodeLabel* LN;
/* Get this entry */
CodeEntry* E = CS_GetEntry (S, I);
/* Check if it's an unconditional branch, and if the next entry has
* no labels attached
* no labels attached, or if the label is just used so that the insn
* can jump to itself.
*/
if ((E->Info & OF_DEAD) != 0 &&
(N = CS_GetNextEntry (S, I)) != 0 &&
!CE_HasLabel (N)) {
if ((E->Info & OF_DEAD) != 0 && /* Dead code follows */
(N = CS_GetNextEntry (S, I)) != 0 && /* Has next entry */
(!CE_HasLabel (N) || /* Don't has a label */
((N->Info & OF_UBRA) != 0 && /* Uncond branch */
(LN = N->JumpTo) != 0 && /* Jumps to known label */
LN->Owner == N && /* Attached to insn */
CL_GetRefCount (LN) == 1))) { /* Only reference */
/* Delete the next entry */
CS_DelEntry (S, I+1);
@ -352,10 +358,28 @@ unsigned OptJumpCascades (CodeSeg* S)
((E->Info & OF_CBRA) != 0 &&
GetBranchCond (E->OPC) == GetBranchCond (N->OPC))) {
/* This is a jump cascade and we may jump to the final target.
* Insert a new instruction, then remove the old one
/* This is a jump cascade and we may jump to the final target,
* provided that the other insn does not jump to itself. If
* this is the case, we can also jump to ourselves, otherwise
* insert a jump to the new instruction and remove the old one.
*/
CodeEntry* X = NewCodeEntry (E->OPC, E->AM, N->Arg, N->JumpTo, E->LI);
CodeEntry* X;
CodeLabel* LN = N->JumpTo;
if (LN != 0 && LN->Owner == N) {
/* We found a jump to a jump to itself. Replace our jump
* by a jump to itself.
*/
CodeLabel* LE = CS_GenLabel (S, E);
X = NewCodeEntry (E->OPC, E->AM, LE->Name, LE, E->LI);
} else {
/* Jump to the final jump target */
X = NewCodeEntry (E->OPC, E->AM, N->Arg, N->JumpTo, E->LI);
}
/* Insert it behind E */
CS_InsertEntry (S, X, I+1);