1 /*-------------------------------------------------------------------------
3 pcode.h - post code generation
4 Written By - Scott Dattalo scott@dattalo.com
6 This program is free software; you can redistribute it and/or modify it
7 under the terms of the GNU General Public License as published by the
8 Free Software Foundation; either version 2, or (at your option) any
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program; if not, write to the Free Software
18 Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
20 -------------------------------------------------------------------------*/
28 The post code generation is an assembler optimizer. The assembly code
29 produced by all of the previous steps is fully functional. This step
30 will attempt to analyze the flow of the assembly code and agressively
31 optimize it. The peep hole optimizer attempts to do the same thing.
32 As you may recall, the peep hole optimizer replaces blocks of assembly
33 with more optimal blocks (e.g. removing redundant register loads).
34 However, the peep hole optimizer has to be somewhat conservative since
35 an assembly program has implicit state information that's unavailable
36 when only a few instructions are examined.
37 Consider this example:
43 The movf seems redundant since we know that the W register already
44 contains the same value of t1. So a peep hole optimizer is tempted to
45 remove the "movf". However, this is dangerous since the movf affects
46 the flags in the status register (specifically the Z flag) and subsequent
47 code may depend upon this. Look at these two examples:
51 movf t1,w ; Can't remove this movf
57 movf t1,w ; This movf can be removed
58 xorwf t2,w ; since xorwf will over write Z
68 /***********************************************************************
71 * The DFPRINTF macro will call fprintf if PCODE_DEBUG is defined.
72 * The macro is used like:
74 * DPRINTF(("%s #%d\n","test", 1));
76 * The double parenthesis (()) are necessary
78 ***********************************************************************/
82 #define DFPRINTF(args) (fprintf args)
84 #define DFPRINTF(args) ;
88 /***********************************************************************
89 * PIC status bits - this will move into device dependent headers
90 ***********************************************************************/
94 #define PIC_RP0_BIT 5 /* Register Bank select bits RP1:0 : */
95 #define PIC_RP1_BIT 6 /* 00 - bank 0, 01 - bank 1, 10 - bank 2, 11 - bank 3 */
96 #define PIC_IRP_BIT 7 /* Indirect register page select */
98 /***********************************************************************
99 * PIC INTCON bits - this will move into device dependent headers
100 ***********************************************************************/
101 #define PIC_RBIF_BIT 0 /* Port B level has changed flag */
102 #define PIC_INTF_BIT 1 /* Port B bit 0 interrupt on edge flag */
103 #define PIC_T0IF_BIT 2 /* TMR0 has overflowed flag */
104 #define PIC_RBIE_BIT 3 /* Port B level has changed - Interrupt Enable */
105 #define PIC_INTE_BIT 4 /* Port B bit 0 interrupt on edge - Int Enable */
106 #define PIC_T0IE_BIT 5 /* TMR0 overflow Interrupt Enable */
107 #define PIC_PIE_BIT 6 /* Peripheral Interrupt Enable */
108 #define PIC_GIE_BIT 7 /* Global Interrupt Enable */
110 /***********************************************************************
112 ***********************************************************************/
118 /***********************************************************************
120 * PIC_OPTYPE - Operand types that are specific to the PIC architecture
122 * If a PIC assembly instruction has an operand then here is where we
123 * associate a type to it. For example,
127 * The movf has two operands: 'reg' and the W register. 'reg' is some
128 * arbitrary general purpose register, hence it has the type PO_GPR_REGISTER.
129 * The W register, which is the PIC's accumulator, has the type PO_W.
131 ***********************************************************************/
137 PO_NONE=0, // No operand e.g. NOP
138 PO_W, // The 'W' register
139 PO_STATUS, // The 'STATUS' register
140 PO_FSR, // The "file select register" (in 18c it's one of three)
141 PO_INDF, // The Indirect register
142 PO_INTCON, // Interrupt Control register
143 PO_GPR_REGISTER, // A general purpose register
144 PO_GPR_BIT, // A bit of a general purpose register
145 PO_GPR_TEMP, // A general purpose temporary register
146 PO_SFR_REGISTER, // A special function register (e.g. PORTA)
147 PO_PCL, // Program counter Low register
148 PO_PCLATH, // Program counter Latch high register
149 PO_LITERAL, // A constant
150 PO_IMMEDIATE, // (8051 legacy)
151 PO_DIR, // Direct memory (8051 legacy)
152 PO_CRY, // bit memory (8051 legacy)
153 PO_BIT, // bit operand.
154 PO_STR, // (8051 legacy)
156 PO_WILD // Wild card operand in peep optimizer
160 /***********************************************************************
164 * This is not a list of the PIC's opcodes per se, but instead
165 * an enumeration of all of the different types of pic opcodes.
167 ***********************************************************************/
171 POC_WILD=-1, /* Wild card - used in the pCode peep hole optimizer
172 * to represent ANY pic opcode */
224 /***********************************************************************
225 * PC_TYPE - pCode Types
226 ***********************************************************************/
230 PC_COMMENT=0, /* pCode is a comment */
231 PC_OPCODE, /* PORT dependent opcode */
232 PC_LABEL, /* assembly label */
233 PC_FLOW, /* flow analysis */
234 PC_FUNCTION, /* Function start or end */
235 PC_WILD /* wildcard - an opcode place holder used
236 * in the pCode peep hole optimizer */
239 /************************************************/
240 /*************** Structures ********************/
241 /************************************************/
243 struct pCodeWildBlock;
245 /*************************************************
248 The first step in optimizing pCode is determining
249 the program flow. This information is stored in
250 single-linked lists in the for of 'from' and 'to'
251 objects with in a pcode. For example, most instructions
252 don't involve any branching. So their from branch
253 points to the pCode immediately preceding them and
254 their 'to' branch points to the pcode immediately
255 following them. A skip instruction is an example of
256 a pcode that has multiple (in this case two) elements
257 in the 'to' branch. A 'label' pcode is an where there
258 may be multiple 'from' branches.
259 *************************************************/
261 typedef struct pBranch
263 struct pCode *pc; // Next pCode in a branch
264 struct pBranch *next; /* If more than one branch
265 * the next one is here */
269 /*************************************************
272 pCode Operand structure.
273 For those assembly instructions that have arguments,
274 the pCode will have a pCodeOp in which the argument
275 can be stored. For example
279 'some_register' will be stored/referenced in a pCodeOp
281 *************************************************/
283 typedef struct pCodeOp
290 typedef struct pCodeOpBit
294 unsigned int inBitSpace: 1; /* True if in bit space, else
295 just a bit of a register */
298 typedef struct pCodeOpLit
304 typedef struct pCodeOpImmd
310 typedef struct pCodeOpLabel
316 typedef struct pCodeOpReg
318 pCodeOp pcop; // Can be either GPR or SFR
319 int rIdx; // Index into the register table
321 int instance; // byte # of Multi-byte registers
325 typedef struct pCodeOpRegBit
327 pCodeOpReg pcor; // The Register containing this bit
328 int bit; // 0-7 bit number.
329 PIC_OPTYPE subtype; // The type of this register.
330 unsigned int inBitSpace: 1; /* True if in bit space, else
331 just a bit of a register */
335 typedef struct pCodeOpWild
339 struct pCodeWildBlock *pcwb;
341 int id; /* index into an array of char *'s that will match
342 * the wild card. The array is in *pcp. */
343 pCodeOp *subtype; /* Pointer to the Operand type into which this wild
344 * card will be expanded */
345 pCodeOp *matched; /* When a wild matches, we'll store a pointer to the
346 * opcode we matched */
351 /*************************************************
354 Here is the basic build block of a PIC instruction.
355 Each pic instruction will get allocated a pCode.
356 A linked list of pCodes makes a program.
358 **************************************************/
364 struct pCode *prev; // The pCode objects are linked together
365 struct pCode *next; // in doubly linked lists.
367 int seq; // sequence number
369 struct pBlock *pb; // The pBlock that contains this pCode.
371 /* "virtual functions"
372 * The pCode structure is like a base class
373 * in C++. The subsequent structures that "inherit"
374 * the pCode structure will initialize these function
375 * pointers to something useful */
376 // void (*analyze) (struct pCode *_this);
377 void (*destruct)(struct pCode *_this);
378 void (*print) (FILE *of,struct pCode *_this);
383 /*************************************************
385 **************************************************/
387 typedef struct pCodeComment
396 /*************************************************
399 The Flow object is used as marker to separate
400 the assembly code into contiguous chunks. In other
401 words, everytime an instruction cause or potentially
402 causes a branch, a Flow object will be inserted into
403 the pCode chain to mark the beginning of the next
405 **************************************************/
407 typedef struct pCodeFlow
412 pCode *end; /* Last pCode in this flow. Note that
413 the first pCode is pc.next */
415 set **uses; /* map the pCode instruction inCond and outCond conditions
416 * in this array of set's. The reason we allocate an
417 * array of pointers instead of declaring each type of
418 * usage is because there are port dependent usage definitions */
419 int nuses; /* number of uses sets */
421 set *from; /* flow blocks that can send control to this flow block */
422 set *to; /* flow blocks to which this one can send control */
424 int inCond; /* Input conditions - stuff assumed defined at entry */
425 int outCond; /* Output conditions - stuff modified by flow block */
429 /*************************************************
432 Here we describe all the facets of a PIC instruction
433 (expansion for the 18cxxx is also provided).
435 **************************************************/
437 typedef struct pCodeInstruction
442 PIC_OPCODE op; // The opcode of the instruction.
444 char const * const mnemonic; // Pointer to mnemonic string
446 pBranch *from; // pCodes that execute before this one
447 pBranch *to; // pCodes that execute after
448 pBranch *label; // pCode instructions that have labels
450 pCodeOp *pcop; /* Operand, if this instruction has one */
452 pCodeFlow *pcflow; /* flow block to which this instruction belongs */
454 unsigned int num_ops; /* Number of operands (0,1,2 for mid range pics) */
455 unsigned int isModReg: 1; /* If destination is W or F, then 1==F */
456 unsigned int isBitInst: 1; /* e.g. BCF */
457 unsigned int isBranch: 1; /* True if this is a branching instruction */
458 unsigned int isSkip: 1; /* True if this is a skip instruction */
460 PIC_OPCODE inverted_op; /* Opcode of instruction that's the opposite of this one */
461 unsigned int inCond; // Input conditions for this instruction
462 unsigned int outCond; // Output conditions for this instruction
467 /*************************************************
469 **************************************************/
471 typedef struct pCodeLabel
481 /*************************************************
483 **************************************************/
485 typedef struct pCodeFunction
491 char *fname; /* If NULL, then this is the end of
492 a function. Otherwise, it's the
493 start and the name is contained
496 pBranch *from; // pCodes that execute before this one
497 pBranch *to; // pCodes that execute after
498 pBranch *label; // pCode instructions that have labels
503 /*************************************************
505 **************************************************/
507 typedef struct pCodeWild
510 pCodeInstruction pci;
512 int id; /* Index into the wild card array of a peepBlock
513 * - this wild card will get expanded into that pCode
514 * that is stored at this index */
516 /* Conditions on wild pcode instruction */
517 int mustBeBitSkipInst:1;
518 int mustNotBeBitSkipInst:1;
519 int invertBitSkipInst:1;
521 pCodeOp *operand; // Optional operand
522 pCodeOp *label; // Optional label
526 /*************************************************
529 Here are PIC program snippets. There's a strong
530 correlation between the eBBlocks and pBlocks.
531 SDCC subdivides a C program into managable chunks.
532 Each chunk becomes a eBBlock and ultimately in the
535 **************************************************/
537 typedef struct pBlock
539 memmap *cmemmap; /* The snippet is from this memmap */
540 char dbName; /* if cmemmap is NULL, then dbName will identify the block */
541 pCode *pcHead; /* A pointer to the first pCode in a link list of pCodes */
542 pCode *pcTail; /* A pointer to the last pCode in a link list of pCodes */
544 struct pBlock *next; /* The pBlocks will form a doubly linked list */
547 set *function_entries; /* dll of functions in this pblock */
552 unsigned visited:1; /* set true if traversed in call tree */
554 unsigned seq; /* sequence number of this pBlock */
558 /*************************************************
561 The collection of pBlock program snippets are
562 placed into a linked list that is implemented
563 in the pFile structure.
565 The pcode optimizer will parse the pFile.
567 **************************************************/
571 pBlock *pbHead; /* A pointer to the first pBlock */
572 pBlock *pbTail; /* A pointer to the last pBlock */
574 pBranch *functions; /* A SLL of functions in this pFile */
580 /*************************************************
583 The pCodeWildBlock object keeps track of the wild
584 variables, operands, and opcodes that exist in
586 **************************************************/
587 typedef struct pCodeWildBlock {
589 struct pCodePeep *pcp; // pointer back to ... I don't like this...
591 int nvars; // Number of wildcard registers in target.
592 char **vars; // array of pointers to them
594 int nops; // Number of wildcard operands in target.
595 pCodeOp **wildpCodeOps; // array of pointers to the pCodeOp's.
597 int nwildpCodes; // Number of wildcard pCodes in target/replace
598 pCode **wildpCodes; // array of pointers to the pCode's.
602 /*************************************************
605 The pCodePeep object mimics the peep hole optimizer
606 in the main SDCC src (e.g. SDCCpeeph.c). Essentially
607 there is a target pCode chain and a replacement
608 pCode chain. The target chain is compared to the
609 pCode that is generated by gen.c. If a match is
610 found then the pCode is replaced by the replacement
612 **************************************************/
613 typedef struct pCodePeep {
614 pCodeWildBlock target; // code we'd like to optimize
615 pCodeWildBlock replace; // and this is what we'll optimize it with.
618 //pBlock replace; // and this is what we'll optimize it with.
622 /* (Note: a wildcard register is a place holder. Any register
623 * can be replaced by the wildcard when the pcode is being
624 * compared to the target. */
626 /* Post Conditions. A post condition is a condition that
627 * must be either true or false before the peep rule is
628 * accepted. For example, a certain rule may be accepted
629 * if and only if the Z-bit is not used as an input to
630 * the subsequent instructions in a pCode chain.
632 unsigned int postFalseCond;
633 unsigned int postTrueCond;
637 /*************************************************
639 pCode peep command definitions
641 Here are some special commands that control the
642 way the peep hole optimizer behaves
644 **************************************************/
646 enum peepCommandTypes{
653 /*************************************************
654 peepCommand structure stores the peep commands.
656 **************************************************/
658 typedef struct peepCommand {
664 /*************************************************
667 **************************************************/
668 #define PCODE(x) ((pCode *)(x))
669 #define PCI(x) ((pCodeInstruction *)(x))
670 #define PCL(x) ((pCodeLabel *)(x))
671 #define PCF(x) ((pCodeFunction *)(x))
672 #define PCFL(x) ((pCodeFlow *)(x))
673 #define PCW(x) ((pCodeWild *)(x))
675 #define PCOP(x) ((pCodeOp *)(x))
676 //#define PCOB(x) ((pCodeOpBit *)(x))
677 #define PCOL(x) ((pCodeOpLit *)(x))
678 #define PCOI(x) ((pCodeOpImmd *)(x))
679 #define PCOLAB(x) ((pCodeOpLabel *)(x))
680 #define PCOR(x) ((pCodeOpReg *)(x))
681 #define PCORB(x) ((pCodeOpRegBit *)(x))
682 #define PCOW(x) ((pCodeOpWild *)(x))
684 #define PBR(x) ((pBranch *)(x))
686 #define PCWB(x) ((pCodeWildBlock *)(x))
688 /*-----------------------------------------------------------------*
690 *-----------------------------------------------------------------*/
692 pCode *newpCode (PIC_OPCODE op, pCodeOp *pcop); // Create a new pCode given an operand
693 pCode *newpCodeCharP(char *cP); // Create a new pCode given a char *
694 pCode *newpCodeFunction(char *g, char *f); // Create a new function
695 pCode *newpCodeLabel(char *name,int key); // Create a new label given a key
696 pBlock *newpCodeChain(memmap *cm,char c, pCode *pc); // Create a new pBlock
697 void printpBlock(FILE *of, pBlock *pb); // Write a pBlock to a file
698 void printpCode(FILE *of, pCode *pc); // Write a pCode to a file
699 void addpCode2pBlock(pBlock *pb, pCode *pc); // Add a pCode to a pBlock
700 void addpBlock(pBlock *pb); // Add a pBlock to a pFile
701 void copypCode(FILE *of, char dbName); // Write all pBlocks with dbName to *of
702 void movepBlock2Head(char dbName); // move pBlocks around
703 void AnalyzepCode(char dbName);
704 void OptimizepCode(char dbName);
705 void printCallTree(FILE *of);
706 void pCodePeepInit(void);
707 void pBlockConvert2ISR(pBlock *pb);
709 pCodeOp *newpCodeOpLabel(char *name, int key);
710 pCodeOp *newpCodeOpImmd(char *name, int offset);
711 pCodeOp *newpCodeOpLit(int lit);
712 pCodeOp *newpCodeOpBit(char *name, int bit,int inBitSpace);
713 pCodeOp *newpCodeOpRegFromStr(char *name);
714 pCodeOp *newpCodeOp(char *name, PIC_OPTYPE p);
715 pCodeOp *pCodeOpCopy(pCodeOp *pcop);
717 extern void pcode_test(void);
719 /*-----------------------------------------------------------------*
721 *-----------------------------------------------------------------*/
723 extern pCodeOpReg pc_status;
724 extern pCodeOpReg pc_intcon;
725 extern pCodeOpReg pc_indf;
726 extern pCodeOpReg pc_fsr;
727 extern pCodeOpReg pc_pcl;
728 extern pCodeOpReg pc_pclath;
729 extern pCodeOpReg pc_kzero;
730 extern pCodeOpReg pc_wsave; /* wsave and ssave are used to save W and the Status */
731 extern pCodeOpReg pc_ssave; /* registers during an interrupt */
734 #endif // __PCODE_H__