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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 | +} | |