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author | Mike Pall <mike> | 2012-08-15 16:17:34 +0200 |
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committer | Mike Pall <mike> | 2012-08-15 16:17:34 +0200 |
commit | ff0a1f3f4eedf8e43eeb5cc3d2f8d051b648e0c0 (patch) | |
tree | 344b8050d1cb8f112a8699c4d1a3a2200a196ca9 /src/lj_opt_fold.c | |
parent | 5e18c91b899f718dd371f24d5486ade1f9a9ab6d (diff) | |
download | luajit2-ff0a1f3f4eedf8e43eeb5cc3d2f8d051b648e0c0.tar.gz |
FOLD x / 2^k ==> x * 2^-k.
Diffstat (limited to 'src/lj_opt_fold.c')
-rw-r--r-- | src/lj_opt_fold.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/src/lj_opt_fold.c b/src/lj_opt_fold.c index 74cea785..461fa621 100644 --- a/src/lj_opt_fold.c +++ b/src/lj_opt_fold.c @@ -816,6 +816,15 @@ LJFOLDF(simplify_nummuldiv_k) fins->o = IR_ADD; fins->op2 = fins->op1; return RETRYFOLD; + } else if (fins->o == IR_DIV) { /* x / 2^k ==> x * 2^-k */ + uint64_t u = ir_knum(fright)->u64; + if ((u & U64x(000fffff,ffffffff)) == 0 && + (uint32_t)(u = ((u >> 52) & 0x7ff)) - 1 < 0x7fd) { + u = (u & (uint64_t)1 << 63) | ((uint64_t)(0x7fe - (uint32_t)u) << 52); + fins->o = IR_MUL; /* Multiply by exact reciprocal. */ + fins->op2 = lj_ir_knum_u64(J, u); + return RETRYFOLD; + } } return NEXTFOLD; } |