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some simplifications/optimizations in returns from Lua functions

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Roberto Ierusalimschy
2018-02-15 13:34:29 -02:00
parent b1379936cf
commit 0682fe8169
7 changed files with 80 additions and 77 deletions
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22
lopcodes.h
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@@ -1,5 +1,5 @@
/*
** $Id: lopcodes.h,v 1.186 2018/02/07 15:18:04 roberto Exp roberto $
** $Id: lopcodes.h,v 1.187 2018/02/09 15:16:06 roberto Exp roberto $
** Opcodes for Lua virtual machine
** See Copyright Notice in lua.h
*/
@@ -267,8 +267,7 @@ OP_TESTSET,/* A B if (not R(B) == k) then R(A) := R(B) else pc++ */
OP_CALL,/* A B C R(A), ... ,R(A+C-2) := R(A)(R(A+1), ... ,R(A+B-1)) */
OP_TAILCALL,/* A B C return R(A)(R(A+1), ... ,R(A+B-1)) */
OP_RETURN,/* A B return R(A), ... ,R(A+B-2) (see note) */
OP_RETVARARG,/* A B return R(A), ... ,R(A+B-2) (see note) */
OP_RETURN,/* A B C return R(A), ... ,R(A+B-2) (see note) */
OP_RETURN0,/* return */
OP_RETURN1,/* A return R(A) */
@@ -302,14 +301,13 @@ OP_EXTRAARG/* Ax extra (larger) argument for previous opcode */
/*===========================================================================
Notes:
(*) In OP_CALL, if (B == 0) then B = top. If (C == 0), then 'top' is
set to last_result+1, so next open instruction (OP_CALL, OP_RETURN,
set to last_result+1, so next open instruction (OP_CALL, OP_RETURN*,
OP_SETLIST) may use 'top'.
(*) In OP_VARARG, if (C == 0) then use actual number of varargs and
set top (like in OP_CALL with C == 0).
(*) In OP_RETURN/OP_RETVARARG, if (B == 0) then return up to 'top'.
(OP_RETVARARG is the return instruction for vararg functions.)
(*) In OP_RETURN, if (B == 0) then return up to 'top'.
(*) In OP_SETLIST, if (B == 0) then real B = 'top'; if (C == 0) then
next 'instruction' is EXTRAARG(real C).
@@ -326,9 +324,11 @@ OP_EXTRAARG/* Ax extra (larger) argument for previous opcode */
(*) All 'skips' (pc++) assume that next instruction is a jump.
(*) In instructions ending a function (OP_RETURN*, OP_TAILCALL), k
specifies that the function builds upvalues, which may need to be
closed.
(*) In instructions OP_RETURN/OP_TAILCALL, 'k' specifies that the
function either builds upvalues, which may need to be closed, or is
vararg, which must be corrected before returning. When 'k' is true,
C > 0 means the function is vararg and (C - 1) is its number of
fixed parameters.
===========================================================================*/
@@ -351,7 +351,9 @@ LUAI_DDEC const lu_byte luaP_opmodes[NUM_OPCODES];
#define testOTMode(m) (luaP_opmodes[m] & (1 << 6))
/* "out top" (set top for next instruction) */
#define isOT(i) (testOTMode(GET_OPCODE(i)) && GETARG_C(i) == 0)
#define isOT(i) \
((testOTMode(GET_OPCODE(i)) && GETARG_C(i) == 0) || \
GET_OPCODE(i) == OP_TAILCALL)
/* "in top" (uses top from previous instruction) */
#define isIT(i) (testITMode(GET_OPCODE(i)) && GETARG_B(i) == 0)