summaryrefslogtreecommitdiff
path: root/Build/source/libs/luajit/LuaJIT-src/src/lj_opt_narrow.c
diff options
context:
space:
mode:
Diffstat (limited to 'Build/source/libs/luajit/LuaJIT-src/src/lj_opt_narrow.c')
-rw-r--r--Build/source/libs/luajit/LuaJIT-src/src/lj_opt_narrow.c652
1 files changed, 652 insertions, 0 deletions
diff --git a/Build/source/libs/luajit/LuaJIT-src/src/lj_opt_narrow.c b/Build/source/libs/luajit/LuaJIT-src/src/lj_opt_narrow.c
new file mode 100644
index 00000000000..d1993452a6a
--- /dev/null
+++ b/Build/source/libs/luajit/LuaJIT-src/src/lj_opt_narrow.c
@@ -0,0 +1,652 @@
+/*
+** NARROW: Narrowing of numbers to integers (double to int32_t).
+** STRIPOV: Stripping of overflow checks.
+** Copyright (C) 2005-2015 Mike Pall. See Copyright Notice in luajit.h
+*/
+
+#define lj_opt_narrow_c
+#define LUA_CORE
+
+#include "lj_obj.h"
+
+#if LJ_HASJIT
+
+#include "lj_bc.h"
+#include "lj_ir.h"
+#include "lj_jit.h"
+#include "lj_iropt.h"
+#include "lj_trace.h"
+#include "lj_vm.h"
+#include "lj_strscan.h"
+
+/* Rationale for narrowing optimizations:
+**
+** Lua has only a single number type and this is a FP double by default.
+** Narrowing doubles to integers does not pay off for the interpreter on a
+** current-generation x86/x64 machine. Most FP operations need the same
+** amount of execution resources as their integer counterparts, except
+** with slightly longer latencies. Longer latencies are a non-issue for
+** the interpreter, since they are usually hidden by other overhead.
+**
+** The total CPU execution bandwidth is the sum of the bandwidth of the FP
+** and the integer units, because they execute in parallel. The FP units
+** have an equal or higher bandwidth than the integer units. Not using
+** them means losing execution bandwidth. Moving work away from them to
+** the already quite busy integer units is a losing proposition.
+**
+** The situation for JIT-compiled code is a bit different: the higher code
+** density makes the extra latencies much more visible. Tight loops expose
+** the latencies for updating the induction variables. Array indexing
+** requires narrowing conversions with high latencies and additional
+** guards (to check that the index is really an integer). And many common
+** optimizations only work on integers.
+**
+** One solution would be speculative, eager narrowing of all number loads.
+** This causes many problems, like losing -0 or the need to resolve type
+** mismatches between traces. It also effectively forces the integer type
+** to have overflow-checking semantics. This impedes many basic
+** optimizations and requires adding overflow checks to all integer
+** arithmetic operations (whereas FP arithmetics can do without).
+**
+** Always replacing an FP op with an integer op plus an overflow check is
+** counter-productive on a current-generation super-scalar CPU. Although
+** the overflow check branches are highly predictable, they will clog the
+** execution port for the branch unit and tie up reorder buffers. This is
+** turning a pure data-flow dependency into a different data-flow
+** dependency (with slightly lower latency) *plus* a control dependency.
+** In general, you don't want to do this since latencies due to data-flow
+** dependencies can be well hidden by out-of-order execution.
+**
+** A better solution is to keep all numbers as FP values and only narrow
+** when it's beneficial to do so. LuaJIT uses predictive narrowing for
+** induction variables and demand-driven narrowing for index expressions,
+** integer arguments and bit operations. Additionally it can eliminate or
+** hoist most of the resulting overflow checks. Regular arithmetic
+** computations are never narrowed to integers.
+**
+** The integer type in the IR has convenient wrap-around semantics and
+** ignores overflow. Extra operations have been added for
+** overflow-checking arithmetic (ADDOV/SUBOV) instead of an extra type.
+** Apart from reducing overall complexity of the compiler, this also
+** nicely solves the problem where you want to apply algebraic
+** simplifications to ADD, but not to ADDOV. And the x86/x64 assembler can
+** use lea instead of an add for integer ADD, but not for ADDOV (lea does
+** not affect the flags, but it helps to avoid register moves).
+**
+**
+** All of the above has to be reconsidered for architectures with slow FP
+** operations or without a hardware FPU. The dual-number mode of LuaJIT
+** addresses this issue. Arithmetic operations are performed on integers
+** as far as possible and overflow checks are added as needed.
+**
+** This implies that narrowing for integer arguments and bit operations
+** should also strip overflow checks, e.g. replace ADDOV with ADD. The
+** original overflow guards are weak and can be eliminated by DCE, if
+** there's no other use.
+**
+** A slight twist is that it's usually beneficial to use overflow-checked
+** integer arithmetics if all inputs are already integers. This is the only
+** change that affects the single-number mode, too.
+*/
+
+/* Some local macros to save typing. Undef'd at the end. */
+#define IR(ref) (&J->cur.ir[(ref)])
+#define fins (&J->fold.ins)
+
+/* Pass IR on to next optimization in chain (FOLD). */
+#define emitir(ot, a, b) (lj_ir_set(J, (ot), (a), (b)), lj_opt_fold(J))
+
+#define emitir_raw(ot, a, b) (lj_ir_set(J, (ot), (a), (b)), lj_ir_emit(J))
+
+/* -- Elimination of narrowing type conversions --------------------------- */
+
+/* Narrowing of index expressions and bit operations is demand-driven. The
+** trace recorder emits a narrowing type conversion (CONV.int.num or TOBIT)
+** in all of these cases (e.g. array indexing or string indexing). FOLD
+** already takes care of eliminating simple redundant conversions like
+** CONV.int.num(CONV.num.int(x)) ==> x.
+**
+** But the surrounding code is FP-heavy and arithmetic operations are
+** performed on FP numbers (for the single-number mode). Consider a common
+** example such as 'x=t[i+1]', with 'i' already an integer (due to induction
+** variable narrowing). The index expression would be recorded as
+** CONV.int.num(ADD(CONV.num.int(i), 1))
+** which is clearly suboptimal.
+**
+** One can do better by recursively backpropagating the narrowing type
+** conversion across FP arithmetic operations. This turns FP ops into
+** their corresponding integer counterparts. Depending on the semantics of
+** the conversion they also need to check for overflow. Currently only ADD
+** and SUB are supported.
+**
+** The above example can be rewritten as
+** ADDOV(CONV.int.num(CONV.num.int(i)), 1)
+** and then into ADDOV(i, 1) after folding of the conversions. The original
+** FP ops remain in the IR and are eliminated by DCE since all references to
+** them are gone.
+**
+** [In dual-number mode the trace recorder already emits ADDOV etc., but
+** this can be further reduced. See below.]
+**
+** Special care has to be taken to avoid narrowing across an operation
+** which is potentially operating on non-integral operands. One obvious
+** case is when an expression contains a non-integral constant, but ends
+** up as an integer index at runtime (like t[x+1.5] with x=0.5).
+**
+** Operations with two non-constant operands illustrate a similar problem
+** (like t[a+b] with a=1.5 and b=2.5). Backpropagation has to stop there,
+** unless it can be proven that either operand is integral (e.g. by CSEing
+** a previous conversion). As a not-so-obvious corollary this logic also
+** applies for a whole expression tree (e.g. t[(a+1)+(b+1)]).
+**
+** Correctness of the transformation is guaranteed by avoiding to expand
+** the tree by adding more conversions than the one we would need to emit
+** if not backpropagating. TOBIT employs a more optimistic rule, because
+** the conversion has special semantics, designed to make the life of the
+** compiler writer easier. ;-)
+**
+** Using on-the-fly backpropagation of an expression tree doesn't work
+** because it's unknown whether the transform is correct until the end.
+** This either requires IR rollback and cache invalidation for every
+** subtree or a two-pass algorithm. The former didn't work out too well,
+** so the code now combines a recursive collector with a stack-based
+** emitter.
+**
+** [A recursive backpropagation algorithm with backtracking, employing
+** skip-list lookup and round-robin caching, emitting stack operations
+** on-the-fly for a stack-based interpreter -- and all of that in a meager
+** kilobyte? Yep, compilers are a great treasure chest. Throw away your
+** textbooks and read the codebase of a compiler today!]
+**
+** There's another optimization opportunity for array indexing: it's
+** always accompanied by an array bounds-check. The outermost overflow
+** check may be delegated to the ABC operation. This works because ABC is
+** an unsigned comparison and wrap-around due to overflow creates negative
+** numbers.
+**
+** But this optimization is only valid for constants that cannot overflow
+** an int32_t into the range of valid array indexes [0..2^27+1). A check
+** for +-2^30 is safe since -2^31 - 2^30 wraps to 2^30 and 2^31-1 + 2^30
+** wraps to -2^30-1.
+**
+** It's also good enough in practice, since e.g. t[i+1] or t[i-10] are
+** quite common. So the above example finally ends up as ADD(i, 1)!
+**
+** Later on, the assembler is able to fuse the whole array reference and
+** the ADD into the memory operands of loads and other instructions. This
+** is why LuaJIT is able to generate very pretty (and fast) machine code
+** for array indexing. And that, my dear, concludes another story about
+** one of the hidden secrets of LuaJIT ...
+*/
+
+/* Maximum backpropagation depth and maximum stack size. */
+#define NARROW_MAX_BACKPROP 100
+#define NARROW_MAX_STACK 256
+
+/* The stack machine has a 32 bit instruction format: [IROpT | IRRef1]
+** The lower 16 bits hold a reference (or 0). The upper 16 bits hold
+** the IR opcode + type or one of the following special opcodes:
+*/
+enum {
+ NARROW_REF, /* Push ref. */
+ NARROW_CONV, /* Push conversion of ref. */
+ NARROW_SEXT, /* Push sign-extension of ref. */
+ NARROW_INT /* Push KINT ref. The next code holds an int32_t. */
+};
+
+typedef uint32_t NarrowIns;
+
+#define NARROWINS(op, ref) (((op) << 16) + (ref))
+#define narrow_op(ins) ((IROpT)((ins) >> 16))
+#define narrow_ref(ins) ((IRRef1)(ins))
+
+/* Context used for narrowing of type conversions. */
+typedef struct NarrowConv {
+ jit_State *J; /* JIT compiler state. */
+ NarrowIns *sp; /* Current stack pointer. */
+ NarrowIns *maxsp; /* Maximum stack pointer minus redzone. */
+ IRRef mode; /* Conversion mode (IRCONV_*). */
+ IRType t; /* Destination type: IRT_INT or IRT_I64. */
+ NarrowIns stack[NARROW_MAX_STACK]; /* Stack holding stack-machine code. */
+} NarrowConv;
+
+/* Lookup a reference in the backpropagation cache. */
+static BPropEntry *narrow_bpc_get(jit_State *J, IRRef1 key, IRRef mode)
+{
+ ptrdiff_t i;
+ for (i = 0; i < BPROP_SLOTS; i++) {
+ BPropEntry *bp = &J->bpropcache[i];
+ /* Stronger checks are ok, too. */
+ if (bp->key == key && bp->mode >= mode &&
+ ((bp->mode ^ mode) & IRCONV_MODEMASK) == 0)
+ return bp;
+ }
+ return NULL;
+}
+
+/* Add an entry to the backpropagation cache. */
+static void narrow_bpc_set(jit_State *J, IRRef1 key, IRRef1 val, IRRef mode)
+{
+ uint32_t slot = J->bpropslot;
+ BPropEntry *bp = &J->bpropcache[slot];
+ J->bpropslot = (slot + 1) & (BPROP_SLOTS-1);
+ bp->key = key;
+ bp->val = val;
+ bp->mode = mode;
+}
+
+/* Backpropagate overflow stripping. */
+static void narrow_stripov_backprop(NarrowConv *nc, IRRef ref, int depth)
+{
+ jit_State *J = nc->J;
+ IRIns *ir = IR(ref);
+ if (ir->o == IR_ADDOV || ir->o == IR_SUBOV ||
+ (ir->o == IR_MULOV && (nc->mode & IRCONV_CONVMASK) == IRCONV_ANY)) {
+ BPropEntry *bp = narrow_bpc_get(nc->J, ref, IRCONV_TOBIT);
+ if (bp) {
+ ref = bp->val;
+ } else if (++depth < NARROW_MAX_BACKPROP && nc->sp < nc->maxsp) {
+ NarrowIns *savesp = nc->sp;
+ narrow_stripov_backprop(nc, ir->op1, depth);
+ if (nc->sp < nc->maxsp) {
+ narrow_stripov_backprop(nc, ir->op2, depth);
+ if (nc->sp < nc->maxsp) {
+ *nc->sp++ = NARROWINS(IRT(ir->o - IR_ADDOV + IR_ADD, IRT_INT), ref);
+ return;
+ }
+ }
+ nc->sp = savesp; /* Path too deep, need to backtrack. */
+ }
+ }
+ *nc->sp++ = NARROWINS(NARROW_REF, ref);
+}
+
+/* Backpropagate narrowing conversion. Return number of needed conversions. */
+static int narrow_conv_backprop(NarrowConv *nc, IRRef ref, int depth)
+{
+ jit_State *J = nc->J;
+ IRIns *ir = IR(ref);
+ IRRef cref;
+
+ if (nc->sp >= nc->maxsp) return 10; /* Path too deep. */
+
+ /* Check the easy cases first. */
+ if (ir->o == IR_CONV && (ir->op2 & IRCONV_SRCMASK) == IRT_INT) {
+ if ((nc->mode & IRCONV_CONVMASK) <= IRCONV_ANY)
+ narrow_stripov_backprop(nc, ir->op1, depth+1);
+ else
+ *nc->sp++ = NARROWINS(NARROW_REF, ir->op1); /* Undo conversion. */
+ if (nc->t == IRT_I64)
+ *nc->sp++ = NARROWINS(NARROW_SEXT, 0); /* Sign-extend integer. */
+ return 0;
+ } else if (ir->o == IR_KNUM) { /* Narrow FP constant. */
+ lua_Number n = ir_knum(ir)->n;
+ if ((nc->mode & IRCONV_CONVMASK) == IRCONV_TOBIT) {
+ /* Allows a wider range of constants. */
+ int64_t k64 = (int64_t)n;
+ if (n == (lua_Number)k64) { /* Only if const doesn't lose precision. */
+ *nc->sp++ = NARROWINS(NARROW_INT, 0);
+ *nc->sp++ = (NarrowIns)k64; /* But always truncate to 32 bits. */
+ return 0;
+ }
+ } else {
+ int32_t k = lj_num2int(n);
+ /* Only if constant is a small integer. */
+ if (checki16(k) && n == (lua_Number)k) {
+ *nc->sp++ = NARROWINS(NARROW_INT, 0);
+ *nc->sp++ = (NarrowIns)k;
+ return 0;
+ }
+ }
+ return 10; /* Never narrow other FP constants (this is rare). */
+ }
+
+ /* Try to CSE the conversion. Stronger checks are ok, too. */
+ cref = J->chain[fins->o];
+ while (cref > ref) {
+ IRIns *cr = IR(cref);
+ if (cr->op1 == ref &&
+ (fins->o == IR_TOBIT ||
+ ((cr->op2 & IRCONV_MODEMASK) == (nc->mode & IRCONV_MODEMASK) &&
+ irt_isguard(cr->t) >= irt_isguard(fins->t)))) {
+ *nc->sp++ = NARROWINS(NARROW_REF, cref);
+ return 0; /* Already there, no additional conversion needed. */
+ }
+ cref = cr->prev;
+ }
+
+ /* Backpropagate across ADD/SUB. */
+ if (ir->o == IR_ADD || ir->o == IR_SUB) {
+ /* Try cache lookup first. */
+ IRRef mode = nc->mode;
+ BPropEntry *bp;
+ /* Inner conversions need a stronger check. */
+ if ((mode & IRCONV_CONVMASK) == IRCONV_INDEX && depth > 0)
+ mode += IRCONV_CHECK-IRCONV_INDEX;
+ bp = narrow_bpc_get(nc->J, (IRRef1)ref, mode);
+ if (bp) {
+ *nc->sp++ = NARROWINS(NARROW_REF, bp->val);
+ return 0;
+ } else if (nc->t == IRT_I64) {
+ /* Try sign-extending from an existing (checked) conversion to int. */
+ mode = (IRT_INT<<5)|IRT_NUM|IRCONV_INDEX;
+ bp = narrow_bpc_get(nc->J, (IRRef1)ref, mode);
+ if (bp) {
+ *nc->sp++ = NARROWINS(NARROW_REF, bp->val);
+ *nc->sp++ = NARROWINS(NARROW_SEXT, 0);
+ return 0;
+ }
+ }
+ if (++depth < NARROW_MAX_BACKPROP && nc->sp < nc->maxsp) {
+ NarrowIns *savesp = nc->sp;
+ int count = narrow_conv_backprop(nc, ir->op1, depth);
+ count += narrow_conv_backprop(nc, ir->op2, depth);
+ if (count <= 1) { /* Limit total number of conversions. */
+ *nc->sp++ = NARROWINS(IRT(ir->o, nc->t), ref);
+ return count;
+ }
+ nc->sp = savesp; /* Too many conversions, need to backtrack. */
+ }
+ }
+
+ /* Otherwise add a conversion. */
+ *nc->sp++ = NARROWINS(NARROW_CONV, ref);
+ return 1;
+}
+
+/* Emit the conversions collected during backpropagation. */
+static IRRef narrow_conv_emit(jit_State *J, NarrowConv *nc)
+{
+ /* The fins fields must be saved now -- emitir() overwrites them. */
+ IROpT guardot = irt_isguard(fins->t) ? IRTG(IR_ADDOV-IR_ADD, 0) : 0;
+ IROpT convot = fins->ot;
+ IRRef1 convop2 = fins->op2;
+ NarrowIns *next = nc->stack; /* List of instructions from backpropagation. */
+ NarrowIns *last = nc->sp;
+ NarrowIns *sp = nc->stack; /* Recycle the stack to store operands. */
+ while (next < last) { /* Simple stack machine to process the ins. list. */
+ NarrowIns ref = *next++;
+ IROpT op = narrow_op(ref);
+ if (op == NARROW_REF) {
+ *sp++ = ref;
+ } else if (op == NARROW_CONV) {
+ *sp++ = emitir_raw(convot, ref, convop2); /* Raw emit avoids a loop. */
+ } else if (op == NARROW_SEXT) {
+ lua_assert(sp >= nc->stack+1);
+ sp[-1] = emitir(IRT(IR_CONV, IRT_I64), sp[-1],
+ (IRT_I64<<5)|IRT_INT|IRCONV_SEXT);
+ } else if (op == NARROW_INT) {
+ lua_assert(next < last);
+ *sp++ = nc->t == IRT_I64 ?
+ lj_ir_kint64(J, (int64_t)(int32_t)*next++) :
+ lj_ir_kint(J, *next++);
+ } else { /* Regular IROpT. Pops two operands and pushes one result. */
+ IRRef mode = nc->mode;
+ lua_assert(sp >= nc->stack+2);
+ sp--;
+ /* Omit some overflow checks for array indexing. See comments above. */
+ if ((mode & IRCONV_CONVMASK) == IRCONV_INDEX) {
+ if (next == last && irref_isk(narrow_ref(sp[0])) &&
+ (uint32_t)IR(narrow_ref(sp[0]))->i + 0x40000000u < 0x80000000u)
+ guardot = 0;
+ else /* Otherwise cache a stronger check. */
+ mode += IRCONV_CHECK-IRCONV_INDEX;
+ }
+ sp[-1] = emitir(op+guardot, sp[-1], sp[0]);
+ /* Add to cache. */
+ if (narrow_ref(ref))
+ narrow_bpc_set(J, narrow_ref(ref), narrow_ref(sp[-1]), mode);
+ }
+ }
+ lua_assert(sp == nc->stack+1);
+ return nc->stack[0];
+}
+
+/* Narrow a type conversion of an arithmetic operation. */
+TRef LJ_FASTCALL lj_opt_narrow_convert(jit_State *J)
+{
+ if ((J->flags & JIT_F_OPT_NARROW)) {
+ NarrowConv nc;
+ nc.J = J;
+ nc.sp = nc.stack;
+ nc.maxsp = &nc.stack[NARROW_MAX_STACK-4];
+ nc.t = irt_type(fins->t);
+ if (fins->o == IR_TOBIT) {
+ nc.mode = IRCONV_TOBIT; /* Used only in the backpropagation cache. */
+ } else {
+ nc.mode = fins->op2;
+ }
+ if (narrow_conv_backprop(&nc, fins->op1, 0) <= 1)
+ return narrow_conv_emit(J, &nc);
+ }
+ return NEXTFOLD;
+}
+
+/* -- Narrowing of implicit conversions ----------------------------------- */
+
+/* Recursively strip overflow checks. */
+static TRef narrow_stripov(jit_State *J, TRef tr, int lastop, IRRef mode)
+{
+ IRRef ref = tref_ref(tr);
+ IRIns *ir = IR(ref);
+ int op = ir->o;
+ if (op >= IR_ADDOV && op <= lastop) {
+ BPropEntry *bp = narrow_bpc_get(J, ref, mode);
+ if (bp) {
+ return TREF(bp->val, irt_t(IR(bp->val)->t));
+ } else {
+ IRRef op1 = ir->op1, op2 = ir->op2; /* The IR may be reallocated. */
+ op1 = narrow_stripov(J, op1, lastop, mode);
+ op2 = narrow_stripov(J, op2, lastop, mode);
+ tr = emitir(IRT(op - IR_ADDOV + IR_ADD,
+ ((mode & IRCONV_DSTMASK) >> IRCONV_DSH)), op1, op2);
+ narrow_bpc_set(J, ref, tref_ref(tr), mode);
+ }
+ } else if (LJ_64 && (mode & IRCONV_SEXT) && !irt_is64(ir->t)) {
+ tr = emitir(IRT(IR_CONV, IRT_INTP), tr, mode);
+ }
+ return tr;
+}
+
+/* Narrow array index. */
+TRef LJ_FASTCALL lj_opt_narrow_index(jit_State *J, TRef tr)
+{
+ IRIns *ir;
+ lua_assert(tref_isnumber(tr));
+ if (tref_isnum(tr)) /* Conversion may be narrowed, too. See above. */
+ return emitir(IRTGI(IR_CONV), tr, IRCONV_INT_NUM|IRCONV_INDEX);
+ /* Omit some overflow checks for array indexing. See comments above. */
+ ir = IR(tref_ref(tr));
+ if ((ir->o == IR_ADDOV || ir->o == IR_SUBOV) && irref_isk(ir->op2) &&
+ (uint32_t)IR(ir->op2)->i + 0x40000000u < 0x80000000u)
+ return emitir(IRTI(ir->o - IR_ADDOV + IR_ADD), ir->op1, ir->op2);
+ return tr;
+}
+
+/* Narrow conversion to integer operand (overflow undefined). */
+TRef LJ_FASTCALL lj_opt_narrow_toint(jit_State *J, TRef tr)
+{
+ if (tref_isstr(tr))
+ tr = emitir(IRTG(IR_STRTO, IRT_NUM), tr, 0);
+ if (tref_isnum(tr)) /* Conversion may be narrowed, too. See above. */
+ return emitir(IRTI(IR_CONV), tr, IRCONV_INT_NUM|IRCONV_ANY);
+ if (!tref_isinteger(tr))
+ lj_trace_err(J, LJ_TRERR_BADTYPE);
+ /*
+ ** Undefined overflow semantics allow stripping of ADDOV, SUBOV and MULOV.
+ ** Use IRCONV_TOBIT for the cache entries, since the semantics are the same.
+ */
+ return narrow_stripov(J, tr, IR_MULOV, (IRT_INT<<5)|IRT_INT|IRCONV_TOBIT);
+}
+
+/* Narrow conversion to bitop operand (overflow wrapped). */
+TRef LJ_FASTCALL lj_opt_narrow_tobit(jit_State *J, TRef tr)
+{
+ if (tref_isstr(tr))
+ tr = emitir(IRTG(IR_STRTO, IRT_NUM), tr, 0);
+ if (tref_isnum(tr)) /* Conversion may be narrowed, too. See above. */
+ return emitir(IRTI(IR_TOBIT), tr, lj_ir_knum_tobit(J));
+ if (!tref_isinteger(tr))
+ lj_trace_err(J, LJ_TRERR_BADTYPE);
+ /*
+ ** Wrapped overflow semantics allow stripping of ADDOV and SUBOV.
+ ** MULOV cannot be stripped due to precision widening.
+ */
+ return narrow_stripov(J, tr, IR_SUBOV, (IRT_INT<<5)|IRT_INT|IRCONV_TOBIT);
+}
+
+#if LJ_HASFFI
+/* Narrow C array index (overflow undefined). */
+TRef LJ_FASTCALL lj_opt_narrow_cindex(jit_State *J, TRef tr)
+{
+ lua_assert(tref_isnumber(tr));
+ if (tref_isnum(tr))
+ return emitir(IRT(IR_CONV, IRT_INTP), tr, (IRT_INTP<<5)|IRT_NUM|IRCONV_ANY);
+ /* Undefined overflow semantics allow stripping of ADDOV, SUBOV and MULOV. */
+ return narrow_stripov(J, tr, IR_MULOV,
+ LJ_64 ? ((IRT_INTP<<5)|IRT_INT|IRCONV_SEXT) :
+ ((IRT_INTP<<5)|IRT_INT|IRCONV_TOBIT));
+}
+#endif
+
+/* -- Narrowing of arithmetic operators ----------------------------------- */
+
+/* Check whether a number fits into an int32_t (-0 is ok, too). */
+static int numisint(lua_Number n)
+{
+ return (n == (lua_Number)lj_num2int(n));
+}
+
+/* Narrowing of arithmetic operations. */
+TRef lj_opt_narrow_arith(jit_State *J, TRef rb, TRef rc,
+ TValue *vb, TValue *vc, IROp op)
+{
+ if (tref_isstr(rb)) {
+ rb = emitir(IRTG(IR_STRTO, IRT_NUM), rb, 0);
+ lj_strscan_num(strV(vb), vb);
+ }
+ if (tref_isstr(rc)) {
+ rc = emitir(IRTG(IR_STRTO, IRT_NUM), rc, 0);
+ lj_strscan_num(strV(vc), vc);
+ }
+ /* Must not narrow MUL in non-DUALNUM variant, because it loses -0. */
+ if ((op >= IR_ADD && op <= (LJ_DUALNUM ? IR_MUL : IR_SUB)) &&
+ tref_isinteger(rb) && tref_isinteger(rc) &&
+ numisint(lj_vm_foldarith(numberVnum(vb), numberVnum(vc),
+ (int)op - (int)IR_ADD)))
+ return emitir(IRTGI((int)op - (int)IR_ADD + (int)IR_ADDOV), rb, rc);
+ if (!tref_isnum(rb)) rb = emitir(IRTN(IR_CONV), rb, IRCONV_NUM_INT);
+ if (!tref_isnum(rc)) rc = emitir(IRTN(IR_CONV), rc, IRCONV_NUM_INT);
+ return emitir(IRTN(op), rb, rc);
+}
+
+/* Narrowing of unary minus operator. */
+TRef lj_opt_narrow_unm(jit_State *J, TRef rc, TValue *vc)
+{
+ if (tref_isstr(rc)) {
+ rc = emitir(IRTG(IR_STRTO, IRT_NUM), rc, 0);
+ lj_strscan_num(strV(vc), vc);
+ }
+ if (tref_isinteger(rc)) {
+ if ((uint32_t)numberVint(vc) != 0x80000000u)
+ return emitir(IRTGI(IR_SUBOV), lj_ir_kint(J, 0), rc);
+ rc = emitir(IRTN(IR_CONV), rc, IRCONV_NUM_INT);
+ }
+ return emitir(IRTN(IR_NEG), rc, lj_ir_knum_neg(J));
+}
+
+/* Narrowing of modulo operator. */
+TRef lj_opt_narrow_mod(jit_State *J, TRef rb, TRef rc, TValue *vc)
+{
+ TRef tmp;
+ if (tvisstr(vc) && !lj_strscan_num(strV(vc), vc))
+ lj_trace_err(J, LJ_TRERR_BADTYPE);
+ if ((LJ_DUALNUM || (J->flags & JIT_F_OPT_NARROW)) &&
+ tref_isinteger(rb) && tref_isinteger(rc) &&
+ (tvisint(vc) ? intV(vc) != 0 : !tviszero(vc))) {
+ emitir(IRTGI(IR_NE), rc, lj_ir_kint(J, 0));
+ return emitir(IRTI(IR_MOD), rb, rc);
+ }
+ /* b % c ==> b - floor(b/c)*c */
+ rb = lj_ir_tonum(J, rb);
+ rc = lj_ir_tonum(J, rc);
+ tmp = emitir(IRTN(IR_DIV), rb, rc);
+ tmp = emitir(IRTN(IR_FPMATH), tmp, IRFPM_FLOOR);
+ tmp = emitir(IRTN(IR_MUL), tmp, rc);
+ return emitir(IRTN(IR_SUB), rb, tmp);
+}
+
+/* Narrowing of power operator or math.pow. */
+TRef lj_opt_narrow_pow(jit_State *J, TRef rb, TRef rc, TValue *vc)
+{
+ if (tvisstr(vc) && !lj_strscan_num(strV(vc), vc))
+ lj_trace_err(J, LJ_TRERR_BADTYPE);
+ /* Narrowing must be unconditional to preserve (-x)^i semantics. */
+ if (tvisint(vc) || numisint(numV(vc))) {
+ int checkrange = 0;
+ /* Split pow is faster for bigger exponents. But do this only for (+k)^i. */
+ if (tref_isk(rb) && (int32_t)ir_knum(IR(tref_ref(rb)))->u32.hi >= 0) {
+ int32_t k = numberVint(vc);
+ if (!(k >= -65536 && k <= 65536)) goto split_pow;
+ checkrange = 1;
+ }
+ if (!tref_isinteger(rc)) {
+ if (tref_isstr(rc))
+ rc = emitir(IRTG(IR_STRTO, IRT_NUM), rc, 0);
+ /* Guarded conversion to integer! */
+ rc = emitir(IRTGI(IR_CONV), rc, IRCONV_INT_NUM|IRCONV_CHECK);
+ }
+ if (checkrange && !tref_isk(rc)) { /* Range guard: -65536 <= i <= 65536 */
+ TRef tmp = emitir(IRTI(IR_ADD), rc, lj_ir_kint(J, 65536));
+ emitir(IRTGI(IR_ULE), tmp, lj_ir_kint(J, 2*65536));
+ }
+ return emitir(IRTN(IR_POW), rb, rc);
+ }
+split_pow:
+ /* FOLD covers most cases, but some are easier to do here. */
+ if (tref_isk(rb) && tvispone(ir_knum(IR(tref_ref(rb)))))
+ return rb; /* 1 ^ x ==> 1 */
+ rc = lj_ir_tonum(J, rc);
+ if (tref_isk(rc) && ir_knum(IR(tref_ref(rc)))->n == 0.5)
+ return emitir(IRTN(IR_FPMATH), rb, IRFPM_SQRT); /* x ^ 0.5 ==> sqrt(x) */
+ /* Split up b^c into exp2(c*log2(b)). Assembler may rejoin later. */
+ rb = emitir(IRTN(IR_FPMATH), rb, IRFPM_LOG2);
+ rc = emitir(IRTN(IR_MUL), rb, rc);
+ return emitir(IRTN(IR_FPMATH), rc, IRFPM_EXP2);
+}
+
+/* -- Predictive narrowing of induction variables ------------------------- */
+
+/* Narrow a single runtime value. */
+static int narrow_forl(jit_State *J, cTValue *o)
+{
+ if (tvisint(o)) return 1;
+ if (LJ_DUALNUM || (J->flags & JIT_F_OPT_NARROW)) return numisint(numV(o));
+ return 0;
+}
+
+/* Narrow the FORL index type by looking at the runtime values. */
+IRType lj_opt_narrow_forl(jit_State *J, cTValue *tv)
+{
+ lua_assert(tvisnumber(&tv[FORL_IDX]) &&
+ tvisnumber(&tv[FORL_STOP]) &&
+ tvisnumber(&tv[FORL_STEP]));
+ /* Narrow only if the runtime values of start/stop/step are all integers. */
+ if (narrow_forl(J, &tv[FORL_IDX]) &&
+ narrow_forl(J, &tv[FORL_STOP]) &&
+ narrow_forl(J, &tv[FORL_STEP])) {
+ /* And if the loop index can't possibly overflow. */
+ lua_Number step = numberVnum(&tv[FORL_STEP]);
+ lua_Number sum = numberVnum(&tv[FORL_STOP]) + step;
+ if (0 <= step ? (sum <= 2147483647.0) : (sum >= -2147483648.0))
+ return IRT_INT;
+ }
+ return IRT_NUM;
+}
+
+#undef IR
+#undef fins
+#undef emitir
+#undef emitir_raw
+
+#endif