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_INLINE, /* user's inline code */
232 PC_OPCODE, /* PORT dependent opcode */
233 PC_LABEL, /* assembly label */
234 PC_FLOW, /* flow analysis */
235 PC_FUNCTION, /* Function start or end */
236 PC_WILD /* wildcard - an opcode place holder used
237 * in the pCode peep hole optimizer */
240 /************************************************/
241 /*************** Structures ********************/
242 /************************************************/
244 struct pCodeWildBlock;
246 /*************************************************
249 The first step in optimizing pCode is determining
250 the program flow. This information is stored in
251 single-linked lists in the for of 'from' and 'to'
252 objects with in a pcode. For example, most instructions
253 don't involve any branching. So their from branch
254 points to the pCode immediately preceding them and
255 their 'to' branch points to the pcode immediately
256 following them. A skip instruction is an example of
257 a pcode that has multiple (in this case two) elements
258 in the 'to' branch. A 'label' pcode is an where there
259 may be multiple 'from' branches.
260 *************************************************/
262 typedef struct pBranch
264 struct pCode *pc; // Next pCode in a branch
265 struct pBranch *next; /* If more than one branch
266 * the next one is here */
270 /*************************************************
273 pCode Operand structure.
274 For those assembly instructions that have arguments,
275 the pCode will have a pCodeOp in which the argument
276 can be stored. For example
280 'some_register' will be stored/referenced in a pCodeOp
282 *************************************************/
284 typedef struct pCodeOp
291 typedef struct pCodeOpBit
295 unsigned int inBitSpace: 1; /* True if in bit space, else
296 just a bit of a register */
299 typedef struct pCodeOpLit
305 typedef struct pCodeOpImmd
308 int offset; /* low,med, or high byte of immediat value */
309 int index; /* add this to the immediate value */
310 unsigned _const:1; /* is in code space */
314 typedef struct pCodeOpLabel
320 typedef struct pCodeOpReg
322 pCodeOp pcop; // Can be either GPR or SFR
323 int rIdx; // Index into the register table
325 int instance; // byte # of Multi-byte registers
329 typedef struct pCodeOpRegBit
331 pCodeOpReg pcor; // The Register containing this bit
332 int bit; // 0-7 bit number.
333 PIC_OPTYPE subtype; // The type of this register.
334 unsigned int inBitSpace: 1; /* True if in bit space, else
335 just a bit of a register */
339 typedef struct pCodeOpWild
343 struct pCodeWildBlock *pcwb;
345 int id; /* index into an array of char *'s that will match
346 * the wild card. The array is in *pcp. */
347 pCodeOp *subtype; /* Pointer to the Operand type into which this wild
348 * card will be expanded */
349 pCodeOp *matched; /* When a wild matches, we'll store a pointer to the
350 * opcode we matched */
355 /*************************************************
358 Here is the basic build block of a PIC instruction.
359 Each pic instruction will get allocated a pCode.
360 A linked list of pCodes makes a program.
362 **************************************************/
368 struct pCode *prev; // The pCode objects are linked together
369 struct pCode *next; // in doubly linked lists.
371 int seq; // sequence number
373 struct pBlock *pb; // The pBlock that contains this pCode.
375 /* "virtual functions"
376 * The pCode structure is like a base class
377 * in C++. The subsequent structures that "inherit"
378 * the pCode structure will initialize these function
379 * pointers to something useful */
380 // void (*analyze) (struct pCode *_this);
381 void (*destruct)(struct pCode *_this);
382 void (*print) (FILE *of,struct pCode *_this);
387 /*************************************************
389 **************************************************/
391 typedef struct pCodeComment
400 /*************************************************
403 The Flow object is used as marker to separate
404 the assembly code into contiguous chunks. In other
405 words, everytime an instruction cause or potentially
406 causes a branch, a Flow object will be inserted into
407 the pCode chain to mark the beginning of the next
409 **************************************************/
411 typedef struct pCodeFlow
416 pCode *end; /* Last pCode in this flow. Note that
417 the first pCode is pc.next */
419 set **uses; /* map the pCode instruction inCond and outCond conditions
420 * in this array of set's. The reason we allocate an
421 * array of pointers instead of declaring each type of
422 * usage is because there are port dependent usage definitions */
423 int nuses; /* number of uses sets */
425 set *from; /* flow blocks that can send control to this flow block */
426 set *to; /* flow blocks to which this one can send control */
428 int inCond; /* Input conditions - stuff assumed defined at entry */
429 int outCond; /* Output conditions - stuff modified by flow block */
433 /*************************************************
436 Here we describe all the facets of a PIC instruction
437 (expansion for the 18cxxx is also provided).
439 **************************************************/
441 typedef struct pCodeInstruction
446 PIC_OPCODE op; // The opcode of the instruction.
448 char const * const mnemonic; // Pointer to mnemonic string
450 pBranch *from; // pCodes that execute before this one
451 pBranch *to; // pCodes that execute after
452 pBranch *label; // pCode instructions that have labels
454 pCodeOp *pcop; /* Operand, if this instruction has one */
456 pCodeFlow *pcflow; /* flow block to which this instruction belongs */
458 unsigned int num_ops; /* Number of operands (0,1,2 for mid range pics) */
459 unsigned int isModReg: 1; /* If destination is W or F, then 1==F */
460 unsigned int isBitInst: 1; /* e.g. BCF */
461 unsigned int isBranch: 1; /* True if this is a branching instruction */
462 unsigned int isSkip: 1; /* True if this is a skip instruction */
464 PIC_OPCODE inverted_op; /* Opcode of instruction that's the opposite of this one */
465 unsigned int inCond; // Input conditions for this instruction
466 unsigned int outCond; // Output conditions for this instruction
471 /*************************************************
473 **************************************************/
475 typedef struct pCodeLabel
485 /*************************************************
487 **************************************************/
489 typedef struct pCodeFunction
495 char *fname; /* If NULL, then this is the end of
496 a function. Otherwise, it's the
497 start and the name is contained
500 pBranch *from; // pCodes that execute before this one
501 pBranch *to; // pCodes that execute after
502 pBranch *label; // pCode instructions that have labels
507 /*************************************************
509 **************************************************/
511 typedef struct pCodeWild
514 pCodeInstruction pci;
516 int id; /* Index into the wild card array of a peepBlock
517 * - this wild card will get expanded into that pCode
518 * that is stored at this index */
520 /* Conditions on wild pcode instruction */
521 int mustBeBitSkipInst:1;
522 int mustNotBeBitSkipInst:1;
523 int invertBitSkipInst:1;
525 pCodeOp *operand; // Optional operand
526 pCodeOp *label; // Optional label
530 /*************************************************
533 Here are PIC program snippets. There's a strong
534 correlation between the eBBlocks and pBlocks.
535 SDCC subdivides a C program into managable chunks.
536 Each chunk becomes a eBBlock and ultimately in the
539 **************************************************/
541 typedef struct pBlock
543 memmap *cmemmap; /* The snippet is from this memmap */
544 char dbName; /* if cmemmap is NULL, then dbName will identify the block */
545 pCode *pcHead; /* A pointer to the first pCode in a link list of pCodes */
546 pCode *pcTail; /* A pointer to the last pCode in a link list of pCodes */
548 struct pBlock *next; /* The pBlocks will form a doubly linked list */
551 set *function_entries; /* dll of functions in this pblock */
556 unsigned visited:1; /* set true if traversed in call tree */
558 unsigned seq; /* sequence number of this pBlock */
562 /*************************************************
565 The collection of pBlock program snippets are
566 placed into a linked list that is implemented
567 in the pFile structure.
569 The pcode optimizer will parse the pFile.
571 **************************************************/
575 pBlock *pbHead; /* A pointer to the first pBlock */
576 pBlock *pbTail; /* A pointer to the last pBlock */
578 pBranch *functions; /* A SLL of functions in this pFile */
584 /*************************************************
587 The pCodeWildBlock object keeps track of the wild
588 variables, operands, and opcodes that exist in
590 **************************************************/
591 typedef struct pCodeWildBlock {
593 struct pCodePeep *pcp; // pointer back to ... I don't like this...
595 int nvars; // Number of wildcard registers in target.
596 char **vars; // array of pointers to them
598 int nops; // Number of wildcard operands in target.
599 pCodeOp **wildpCodeOps; // array of pointers to the pCodeOp's.
601 int nwildpCodes; // Number of wildcard pCodes in target/replace
602 pCode **wildpCodes; // array of pointers to the pCode's.
606 /*************************************************
609 The pCodePeep object mimics the peep hole optimizer
610 in the main SDCC src (e.g. SDCCpeeph.c). Essentially
611 there is a target pCode chain and a replacement
612 pCode chain. The target chain is compared to the
613 pCode that is generated by gen.c. If a match is
614 found then the pCode is replaced by the replacement
616 **************************************************/
617 typedef struct pCodePeep {
618 pCodeWildBlock target; // code we'd like to optimize
619 pCodeWildBlock replace; // and this is what we'll optimize it with.
622 //pBlock replace; // and this is what we'll optimize it with.
626 /* (Note: a wildcard register is a place holder. Any register
627 * can be replaced by the wildcard when the pcode is being
628 * compared to the target. */
630 /* Post Conditions. A post condition is a condition that
631 * must be either true or false before the peep rule is
632 * accepted. For example, a certain rule may be accepted
633 * if and only if the Z-bit is not used as an input to
634 * the subsequent instructions in a pCode chain.
636 unsigned int postFalseCond;
637 unsigned int postTrueCond;
641 /*************************************************
643 pCode peep command definitions
645 Here are some special commands that control the
646 way the peep hole optimizer behaves
648 **************************************************/
650 enum peepCommandTypes{
657 /*************************************************
658 peepCommand structure stores the peep commands.
660 **************************************************/
662 typedef struct peepCommand {
668 /*************************************************
671 **************************************************/
672 #define PCODE(x) ((pCode *)(x))
673 #define PCI(x) ((pCodeInstruction *)(x))
674 #define PCL(x) ((pCodeLabel *)(x))
675 #define PCF(x) ((pCodeFunction *)(x))
676 #define PCFL(x) ((pCodeFlow *)(x))
677 #define PCW(x) ((pCodeWild *)(x))
679 #define PCOP(x) ((pCodeOp *)(x))
680 //#define PCOB(x) ((pCodeOpBit *)(x))
681 #define PCOL(x) ((pCodeOpLit *)(x))
682 #define PCOI(x) ((pCodeOpImmd *)(x))
683 #define PCOLAB(x) ((pCodeOpLabel *)(x))
684 #define PCOR(x) ((pCodeOpReg *)(x))
685 #define PCORB(x) ((pCodeOpRegBit *)(x))
686 #define PCOW(x) ((pCodeOpWild *)(x))
688 #define PBR(x) ((pBranch *)(x))
690 #define PCWB(x) ((pCodeWildBlock *)(x))
692 /*-----------------------------------------------------------------*
694 *-----------------------------------------------------------------*/
696 pCode *newpCode (PIC_OPCODE op, pCodeOp *pcop); // Create a new pCode given an operand
697 pCode *newpCodeCharP(char *cP); // Create a new pCode given a char *
698 pCode *newpCodeInlineP(char *cP); // Create a new pCode given a char *
699 pCode *newpCodeFunction(char *g, char *f); // Create a new function
700 pCode *newpCodeLabel(char *name,int key); // Create a new label given a key
701 pBlock *newpCodeChain(memmap *cm,char c, pCode *pc); // Create a new pBlock
702 void printpBlock(FILE *of, pBlock *pb); // Write a pBlock to a file
703 void printpCode(FILE *of, pCode *pc); // Write a pCode to a file
704 void addpCode2pBlock(pBlock *pb, pCode *pc); // Add a pCode to a pBlock
705 void addpBlock(pBlock *pb); // Add a pBlock to a pFile
706 void copypCode(FILE *of, char dbName); // Write all pBlocks with dbName to *of
707 void movepBlock2Head(char dbName); // move pBlocks around
708 void AnalyzepCode(char dbName);
709 void OptimizepCode(char dbName);
710 void printCallTree(FILE *of);
711 void pCodePeepInit(void);
712 void pBlockConvert2ISR(pBlock *pb);
714 pCodeOp *newpCodeOpLabel(char *name, int key);
715 pCodeOp *newpCodeOpImmd(char *name, int offset, int index, int code_space);
716 pCodeOp *newpCodeOpLit(int lit);
717 pCodeOp *newpCodeOpBit(char *name, int bit,int inBitSpace);
718 pCodeOp *newpCodeOpRegFromStr(char *name);
719 pCodeOp *newpCodeOp(char *name, PIC_OPTYPE p);
720 pCodeOp *pCodeOpCopy(pCodeOp *pcop);
722 extern void pcode_test(void);
724 /*-----------------------------------------------------------------*
726 *-----------------------------------------------------------------*/
728 extern pCodeOpReg pc_status;
729 extern pCodeOpReg pc_intcon;
730 extern pCodeOpReg pc_indf;
731 extern pCodeOpReg pc_fsr;
732 extern pCodeOpReg pc_pcl;
733 extern pCodeOpReg pc_pclath;
734 extern pCodeOpReg pc_kzero;
735 extern pCodeOpReg pc_wsave; /* wsave and ssave are used to save W and the Status */
736 extern pCodeOpReg pc_ssave; /* registers during an interrupt */
739 #endif // __PCODE_H__