commit 6ef366644f7c3c21cfb17434835edf4ebf970d6d
parent 03cde80b58ea7f112f1b7a35c037893093b59f2e
Author: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Tue, 24 Sep 2019 14:34:25 -0300
Subtraction of small constant integers optimized with OP_ADDI
Diffstat:
4 files changed, 46 insertions(+), 31 deletions(-)
diff --git a/lcode.c b/lcode.c
@@ -1213,6 +1213,15 @@ static int isSCint (expdesc *e) {
/*
+** Check whether expression 'e' and its negation are literal integers
+** in proper range to fit in register sC
+*/
+static int isSCintN (expdesc *e) {
+ return luaK_isKint(e) && fitsC(e->u.ival) && fitsC(-e->u.ival);
+}
+
+
+/*
** Check whether expression 'e' is a literal integer or float in
** proper range to fit in a register (sB or sC).
*/
@@ -1373,6 +1382,18 @@ static void codebini (FuncState *fs, OpCode op,
}
+/* Code binary operators negating the immediate operand for the
+** opcode. For the metamethod, 'v2' must keep its original value.
+*/
+static void finishbinexpneg (FuncState *fs, expdesc *e1, expdesc *e2,
+ OpCode op, int line, TMS event) {
+ int v2 = cast_int(e2->u.ival);
+ finishbinexpval(fs, e1, e2, op, int2sC(-v2), 0, line, OP_MMBINI, event);
+ /* correct metamethod argument */
+ SETARG_B(fs->f->code[fs->pc - 1], int2sC(v2));
+}
+
+
static void swapexps (expdesc *e1, expdesc *e2) {
expdesc temp = *e1; *e1 = *e2; *e2 = temp; /* swap 'e1' and 'e2' */
}
@@ -1445,27 +1466,6 @@ static void codebitwise (FuncState *fs, BinOpr opr,
/*
-** Code shift operators. If second operand is constant, use immediate
-** operand (negating it if shift is in the other direction).
-*/
-static void codeshift (FuncState *fs, OpCode op,
- expdesc *e1, expdesc *e2, int line) {
- if (isSCint(e2)) {
- if (op == OP_SHR)
- codebini(fs, OP_SHRI, e1, e2, 0, line, TM_SHR);
- else {
- int offset = cast_int(e2->u.ival);
- finishbinexpval(fs, e1, e2, OP_SHRI, int2sC(offset),
- 0, line, OP_MMBINI, TM_SHL);
- SETARG_C(fs->f->code[fs->pc - 2], int2sC(-offset));
- }
- }
- else
- codebinexpval(fs, op, e1, e2, line);
-}
-
-
-/*
** Emit code for order comparisons. When using an immediate operand,
** 'isfloat' tells whether the original value was a float.
*/
@@ -1646,8 +1646,15 @@ void luaK_posfix (FuncState *fs, BinOpr opr,
codecommutative(fs, opr, e1, e2, line);
break;
}
- case OPR_SUB: case OPR_DIV:
- case OPR_IDIV: case OPR_MOD: case OPR_POW: {
+ case OPR_SUB: {
+ if (isSCintN(e2)) { /* subtracting a small integer constant? */
+ /* code it as (r1 + -I) */
+ finishbinexpneg(fs, e1, e2, OP_ADDI, line, TM_SUB);
+ break;
+ }
+ /* ELSE *//* FALLTHROUGH */
+ }
+ case OPR_DIV: case OPR_IDIV: case OPR_MOD: case OPR_POW: {
codearith(fs, opr, e1, e2, 0, line);
break;
}
@@ -1658,14 +1665,21 @@ void luaK_posfix (FuncState *fs, BinOpr opr,
case OPR_SHL: {
if (isSCint(e1)) {
swapexps(e1, e2);
- codebini(fs, OP_SHLI, e1, e2, 1, line, TM_SHL);
+ codebini(fs, OP_SHLI, e1, e2, 1, line, TM_SHL); /* I << r2 */
+ }
+ else if (isSCintN(e2)) { /* shifting by a small integer constant? */
+ /* code it as (r1 >> -I) */
+ finishbinexpneg(fs, e1, e2, OP_SHRI, line, TM_SHL);
}
- else
- codeshift(fs, OP_SHL, e1, e2, line);
+ else /* regular case (two registers) */
+ codebinexpval(fs, OP_SHL, e1, e2, line);
break;
}
case OPR_SHR: {
- codeshift(fs, OP_SHR, e1, e2, line);
+ if (isSCintN(e2))
+ codebini(fs, OP_SHRI, e1, e2, 0, line, TM_SHR); /* r1 >> I */
+ else /* regular case (two registers) */
+ codebinexpval(fs, OP_SHR, e1, e2, line);
break;
}
case OPR_EQ: case OPR_NE: {
diff --git a/testes/bitwise.lua b/testes/bitwise.lua
@@ -60,9 +60,9 @@ assert("1234.0" << "5.0" == 1234 * 32)
assert("0xffff.0" ~ "0xAAAA" == 0x5555)
assert(~"0x0.000p4" == -1)
-assert("7" .. 3 << 1 == 146)
-assert(10 >> 1 .. "9" == 0)
-assert(10 | 1 .. "9" == 27)
+assert(("7" .. 3) << 1 == 146)
+assert(0xffffffff >> (1 .. "9") == 0x1fff)
+assert(10 | (1 .. "9") == 27)
do
local st, msg = pcall(function () return 4 & "a" end)
diff --git a/testes/code.lua b/testes/code.lua
@@ -293,6 +293,7 @@ checkK(function () return -(border + 1) end, -(sbx + 1.0))
-- immediate operands
checkR(function (x) return x + k1 end, 10, 11, 'ADDI', 'MMBINI', 'RETURN1')
+checkR(function (x) return x - 127 end, 10, -117, 'ADDI', 'MMBINI', 'RETURN1')
checkR(function (x) return 128 + x end, 0.0, 128.0,
'ADDI', 'MMBINI', 'RETURN1')
checkR(function (x) return x * -127 end, -1.0, 127.0,
diff --git a/testes/locals.lua b/testes/locals.lua
@@ -82,7 +82,7 @@ assert(c.a == nil)
f()
assert(c.a == 3)
--- old test for limits for special instructions (now just a generic test)
+-- old test for limits for special instructions
do
local i = 2
local p = 4 -- p == 2^i
