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Improve f64 to i32 conversion for Math.imul and Math.clz32 #779

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Merged
merged 4 commits into from
Aug 23, 2019
Merged

Improve f64 to i32 conversion for Math.imul and Math.clz32 #779

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b0ced65
Add dtoi32 with more performant path
MaxGraey Aug 20, 2019
ade66e2
don't inline
MaxGraey Aug 20, 2019
2cac895
update tests
MaxGraey Aug 21, 2019
3f758c0
remove parentesis
MaxGraey Aug 21, 2019
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42 changes: 26 additions & 16 deletions std/assembly/math.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -42,6 +42,7 @@ function R(z: f64): f64 { // Rational approximation of (asin(x)-x)/x^3
return p / q;
}

/** @internal */
// @ts-ignore: decorator
@inline
function expo2(x: f64): f64 { // exp(x)/2 for x >= log(DBL_MAX)
Expand All @@ -52,6 +53,27 @@ function expo2(x: f64): f64 { // exp(x)/2 for x >= log(DBL_MAX)
return NativeMath.exp(x - kln2) * scale * scale;
}

/** @internal */
function dtoi32(x: f64): i32 {
if (ASC_SHRINK_LEVEL > 0) {
const inv32 = 1.0 / 4294967296;
return <i32><i64>(x - 4294967296 * floor(x * inv32));
} else {
let result = 0;
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@MaxGraey MaxGraey Aug 20, 2019 •
edited
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This path on 10% faster previous one but gen much bigger code so I separate it by ASC_SHRINK_LEVEL

let u = reinterpret<u64>(x);
let e = (u >> 52) & 0x7ff;
if (e <= 1023 + 30) {
result = <i32>x;
} else if (e <= 1023 + 30 + 53) {
let v = (u & ((<u64>1 << 52) - 1)) | (<u64>1 << 52);
v = v << e - 1023 - 52 + 32;
result = <i32>(v >> 32);
result = select<i32>(-result, result, u >> 63);
}
return result;
}
}

// @ts-ignore: decorator
@lazy
var random_seeded = false;
Expand Down Expand Up @@ -398,9 +420,7 @@ export namespace NativeMath {
* For emulate JS conversion behavior and avoid trapping from wasm we should modulate by MAX_INT
* our float-point arguments before actual convertion to integers.
*/
return builtin_clz(
<i32><i64>(x - 4294967296 * builtin_floor(x * (1.0 / 4294967296)))
);
return builtin_clz(dtoi32(x));
}

export function cos(x: f64): f64 { // TODO
Expand Down Expand Up @@ -599,11 +619,7 @@ export namespace NativeMath {
* our float-point arguments before actual convertion to integers.
*/
if (!isFinite(x + y)) return 0;
const inv32 = 1.0 / 4294967296;
return (
<i32><i64>(x - 4294967296 * builtin_floor(x * inv32)) *
<i32><i64>(y - 4294967296 * builtin_floor(y * inv32))
);
return dtoi32(x) * dtoi32(y);
}

export function log(x: f64): f64 { // see: musl/src/math/log.c and SUN COPYRIGHT NOTICE above
Expand Down Expand Up @@ -1700,9 +1716,7 @@ export namespace NativeMathf {

export function clz32(x: f32): f32 {
if (!isFinite(x)) return 32;
return <f32>builtin_clz(
<i32><i64>(x - 4294967296 * builtin_floor(x * (1.0 / 4294967296)))
);
return <f32>builtin_clz(dtoi32(x));
}

export function cos(x: f32): f32 { // see: musl/src/math/cosf.c
Expand Down Expand Up @@ -1927,11 +1941,7 @@ export namespace NativeMathf {
* our float-point arguments before actual convertion to integers.
*/
if (!isFinite(x + y)) return 0;
const inv32 = 1.0 / 4294967296;
return <f32>(
<i32><i64>(x - 4294967296 * builtin_floor(x * inv32)) *
<i32><i64>(y - 4294967296 * builtin_floor(y * inv32))
);
return <f32>(dtoi32(x) * dtoi32(y));
}

export function log(x: f32): f32 { // see: musl/src/math/logf.c and SUN COPYRIGHT NOTICE above
Expand Down
4 changes: 2 additions & 2 deletions tests/compiler/std/array.optimized.wat
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Expand Up @@ -4156,7 +4156,7 @@
if
i32.const 0
i32.const 3160
i32.const 1020
i32.const 1036
i32.const 4
call $~lib/builtins/abort
unreachable
Expand Down Expand Up @@ -5709,7 +5709,7 @@
if
i32.const 3936
i32.const 3160
i32.const 1029
i32.const 1045
i32.const 24
call $~lib/builtins/abort
unreachable
Expand Down
4 changes: 2 additions & 2 deletions tests/compiler/std/array.untouched.wat
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Expand Up @@ -6534,7 +6534,7 @@
if
i32.const 0
i32.const 3160
i32.const 1020
i32.const 1036
i32.const 4
call $~lib/builtins/abort
unreachable
Expand Down Expand Up @@ -8842,7 +8842,7 @@
if
i32.const 3936
i32.const 3160
i32.const 1029
i32.const 1045
i32.const 24
call $~lib/builtins/abort
unreachable
Expand Down
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