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| 1 | #include "java.h" | ||
| 2 | |||
| 3 | /* | ||
| 4 | * Patch operands, etc. that reference pc offsets. | ||
| 5 | */ | ||
| 6 | |||
| 7 | enum { | ||
| 8 | P_CASE = 1, | ||
| 9 | P_OTHER | ||
| 10 | }; | ||
| 11 | |||
| 12 | typedef struct Patch Patch; | ||
| 13 | |||
| 14 | struct Patch { | ||
| 15 | uchar kind; /* P_xxx */ | ||
| 16 | Inst *i; | ||
| 17 | int n; /* number of cases in ... */ | ||
| 18 | int *jmptbl; /* ... case jump table */ | ||
| 19 | Patch *next; | ||
| 20 | }; | ||
| 21 | |||
| 22 | static Patch *plist; | ||
| 23 | |||
| 24 | /* | ||
| 25 | * Allocate a Patch structure. | ||
| 26 | */ | ||
| 27 | |||
| 28 | static Patch* | ||
| 29 | newPatch(uchar kind, Inst *i) | ||
| 30 | { | ||
| 31 | Patch *p; | ||
| 32 | |||
| 33 | p = Malloc(sizeof(Patch)); | ||
| 34 | p->kind = kind; | ||
| 35 | p->i = i; | ||
| 36 | p->next = plist; | ||
| 37 | plist = p; | ||
| 38 | return p; | ||
| 39 | } | ||
| 40 | |||
| 41 | /* | ||
| 42 | * Record non-case branch instruction for later patching. | ||
| 43 | */ | ||
| 44 | |||
| 45 | void | ||
| 46 | patchop(Inst *i) | ||
| 47 | { | ||
| 48 | newPatch(P_OTHER, i); | ||
| 49 | } | ||
| 50 | |||
| 51 | /* | ||
| 52 | * Record case jump table for later patching. | ||
| 53 | */ | ||
| 54 | |||
| 55 | void | ||
| 56 | patchcase(Inst *i, int n, int *jmptbl) | ||
| 57 | { | ||
| 58 | Patch *p; | ||
| 59 | |||
| 60 | p = newPatch(P_CASE, i); | ||
| 61 | p->n = n; | ||
| 62 | p->jmptbl = jmptbl; | ||
| 63 | } | ||
| 64 | |||
| 65 | /* | ||
| 66 | * Calculate patch address; Java branches are relative. | ||
| 67 | */ | ||
| 68 | |||
| 69 | static int | ||
| 70 | patchaddr(Inst *i, int pc) | ||
| 71 | { | ||
| 72 | Jinst *j; | ||
| 73 | int span, srcjpc, dstjpc; | ||
| 74 | |||
| 75 | span = pc; | ||
| 76 | srcjpc = i->j->pc; | ||
| 77 | dstjpc = srcjpc + span; | ||
| 78 | j = &code->j[dstjpc]; | ||
| 79 | |||
| 80 | /* account for no-op's (dup, swap, pop, etc.), elided loads/stores */ | ||
| 81 | while(j->dis == nil) | ||
| 82 | j += j->size; | ||
| 83 | |||
| 84 | return j->dis->pc; | ||
| 85 | } | ||
| 86 | |||
| 87 | /* | ||
| 88 | * Patch branch instructions and case jump tables of a method. | ||
| 89 | */ | ||
| 90 | |||
| 91 | void | ||
| 92 | patchmethod(int startpc) | ||
| 93 | { | ||
| 94 | Patch *p; | ||
| 95 | Inst *i; | ||
| 96 | int *jt; | ||
| 97 | int n; | ||
| 98 | |||
| 99 | for(p = plist; p; p = p->next) { | ||
| 100 | i = p->i; | ||
| 101 | if(p->kind == P_CASE) { | ||
| 102 | jt = p->jmptbl; | ||
| 103 | for(n = 0; n < p->n; n++) | ||
| 104 | jt[n*3+2] = patchaddr(i, jt[n*3+2]); | ||
| 105 | jt[p->n*3] = patchaddr(i, jt[p->n*3]); | ||
| 106 | } else { /* P_OTHER */ | ||
| 107 | i->d.u.ival = patchaddr(i, i->d.u.ival); | ||
| 108 | /* | ||
| 109 | * jmp $start_of_method -> jmp $start_of_method+1 | ||
| 110 | * skip (re-)allocation of Sys->Exception object | ||
| 111 | */ | ||
| 112 | if(i->d.u.ival == startpc && i->op == IJMP && code->nex != 0) | ||
| 113 | i->d.u.ival += 1; | ||
| 114 | } | ||
| 115 | } | ||
| 116 | } | ||
| 117 | |||
| 118 | /* | ||
| 119 | * Clear the patch list after each method. | ||
| 120 | */ | ||
| 121 | |||
| 122 | void | ||
| 123 | patchfree(void) | ||
| 124 | { | ||
| 125 | Patch *p, *p2; | ||
| 126 | |||
| 127 | for(p = plist; p; p = p2) { | ||
| 128 | p2 = p->next; | ||
| 129 | free(p); | ||
| 130 | } | ||
| 131 | plist = nil; | ||
| 132 | } | ||