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Make penalty PRNG available for general use by compiler.

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This commit is contained in:
Mike Pall
2010-02-26 17:01:33 +01:00
parent 3c6cec0846
commit a0fbb05bf0
2 changed files with 10 additions and 10 deletions
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10
src/lj_jit.h
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@@ -278,7 +278,7 @@ typedef struct jit_State {
HotPenalty penalty[PENALTY_SLOTS]; /* Penalty slots. */
uint32_t penaltyslot; /* Round-robin index into penalty slots. */
uint32_t prngstate; /* PRNG state for penalty randomization. */
uint32_t prngstate; /* PRNG state. */
BPropEntry bpropcache[BPROP_SLOTS]; /* Backpropagation cache slots. */
uint32_t bpropslot; /* Round-robin index into bpropcache slots. */
@@ -297,6 +297,14 @@ typedef struct jit_State {
int mcprot; /* Protection of current mcode area. */
} jit_State;
/* Trivial PRNG e.g. used for penalty randomization. */
static LJ_AINLINE uint32_t LJ_PRNG_BITS(jit_State *J, int bits)
{
/* Yes, this LCG is very weak, but that doesn't matter for our use case. */
J->prngstate = J->prngstate * 1103515245 + 12345;
return J->prngstate >> (32-bits);
}
/* Exit stubs. */
#if LJ_TARGET_X86ORX64
/* Limited by the range of a short fwd jump (127): (2+2)*(32-1)-2 = 122. */