diff options
| -rw-r--r-- | src/parseTools.js | 31 |
1 files changed, 10 insertions, 21 deletions
diff --git a/src/parseTools.js b/src/parseTools.js index e6138fc1..f19eb9d5 100644 --- a/src/parseTools.js +++ b/src/parseTools.js @@ -1038,18 +1038,6 @@ function asmCoercion(value, type, signedness) { } } -var TWO_TWENTY = Math.pow(2, 20); - -function asmMultiplyI32(a, b) { - // special-case: there is no integer multiply in asm, because there is no true integer - // multiply in JS. While we wait for Math.imul, do double multiply - if ((isNumber(a) && Math.abs(a) < TWO_TWENTY) || (isNumber(b) && Math.abs(b) < TWO_TWENTY)) { - return '(((' + a + ')*(' + b + '))&-1)'; // small enough to emit directly as a multiply - } - return 'Math.imul(' + a + ',' + b + ')'; - // non-imul version: return '(~~(+((' + a + ')|0) * +((' + b + ')|0)))'; -} - function asmFloatToInt(x) { return '(~~(' + x + '))'; } @@ -1362,9 +1350,11 @@ function makeHEAPView(which, start, end) { var PLUS_MUL = set('+', '*'); var MUL_DIV = set('*', '/'); var PLUS_MINUS = set('+', '-'); +var TWO_TWENTY = Math.pow(2, 20); // Given two values and an operation, returns the result of that operation. // Tries to do as much as possible at compile time. +// Leaves overflows etc. unhandled, *except* for integer multiply, in order to be efficient with Math.imul function getFastValue(a, op, b, type) { a = a.toString(); b = b.toString(); @@ -1400,8 +1390,13 @@ function getFastValue(a, op, b, type) { return '(' + a + '<<' + shifts + ')'; } } - if (ASM_JS && !(type in Runtime.FLOAT_TYPES)) { - return asmMultiplyI32(a, b); // unoptimized multiply, do it using asm.js's special multiply operation + if (!(type in Runtime.FLOAT_TYPES)) { + // if guaranteed small enough to not overflow into a double, do a normal multiply + var bits = getBits(type); + if ((isNumber(a) && Math.abs(a) < TWO_TWENTY) || (isNumber(b) && Math.abs(b) < TWO_TWENTY) || bits < 32) { + return '(((' + a + ')*(' + b + '))&' + ((Math.pow(2, bits)-1)|0) + ')'; // keep a non-eliminatable coercion directly on this + } + return 'Math.imul(' + a + ',' + b + ')'; } } else { if (a == '0') { @@ -2128,13 +2123,7 @@ function processMathop(item) { case 'add': return handleOverflow(getFastValue(idents[0], '+', idents[1], item.type), bits); case 'sub': return handleOverflow(getFastValue(idents[0], '-', idents[1], item.type), bits); case 'sdiv': case 'udiv': return makeRounding(getFastValue(idents[0], '/', idents[1], item.type), bits, op[0] === 's'); - case 'mul': { - if (bits == 32) { - return 'Math.imul(' + idents[0] + ',' + idents[1] + ')'; - } else { - return '((' +getFastValue(idents[0], '*', idents[1], item.type) + ')&-1)'; // force a non-eliminatable coercion here, to prevent a double result from leaking - } - } + case 'mul': return getFastValue(idents[0], '*', idents[1], item.type); // overflow handling is already done in getFastValue for '*' case 'urem': case 'srem': return getFastValue(idents[0], '%', idents[1], item.type); case 'or': { if (bits > 32) { |