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Merged
juj merged 2 commits into from
Jun 6, 2020
Merged

Micro-optimize base64Decode #2897

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8d9a519
Micro-optimize base64Decode
juj Jun 6, 2020
0c1af21
Update test expectations
juj Jun 6, 2020
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12 changes: 5 additions & 7 deletions src/wasm2js.h
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Original file line number Diff line number Diff line change
Expand Up @@ -2258,15 +2258,13 @@ void Wasm2JSGlue::emitMemory(
base64ReverseLookup[47] = 63; // '/'
/** @noinline Inlining this function would mean expanding the base64 string 4x times in the source code, which Closure seems to be happy to do. */
function base64DecodeToExistingUint8Array(uint8Array, offset, b64) {
var b1, b2, i = 0, j = offset, bLength = b64.length, end = offset + (bLength*3>>2);
if (b64[bLength-2] == '=') --end;
if (b64[bLength-1] == '=') --end;
for (; i < bLength; i += 4, j += 3) {
var b1, b2, i = 0, j = offset, bLength = b64.length, end = offset + (bLength*3>>2) - (b64[bLength-2] == '=') - (b64[bLength-1] == '=');
for (; i < bLength; i += 4) {
b1 = base64ReverseLookup[b64.charCodeAt(i+1)];
b2 = base64ReverseLookup[b64.charCodeAt(i+2)];
uint8Array[j] = base64ReverseLookup[b64.charCodeAt(i)] << 2 | b1 >> 4;
if (j+1 < end) uint8Array[j+1] = b1 << 4 | b2 >> 2;
if (j+2 < end) uint8Array[j+2] = b2 << 6 | base64ReverseLookup[b64.charCodeAt(i+3)];
uint8Array[j++] = base64ReverseLookup[b64.charCodeAt(i)] << 2 | b1 >> 4;
if (j < end) uint8Array[j++] = b1 << 4 | b2 >> 2;
if (j < end) uint8Array[j++] = b2 << 6 | base64ReverseLookup[b64.charCodeAt(i+3)];
Comment on lines +2265 to +2267

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@juj juj Jun 6, 2020

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Hmm, that version looks like it would write

uint8Array[j] = b2 << 6 | base64ReverseLookup[b64.charCodeAt(i+3)];

on line 2267, and then not increment j, so then on the next iteration,

uint8Array[j] = base64ReverseLookup[b64.charCodeAt(i)] << 2 | b1 >> 4;

on line 2265 would end up writing on top of the same index, stomping the previous value?

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@MaxGraey MaxGraey Jun 6, 2020 •
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Ah, I didn't see this inside loop. In this case that's not relevant

}
})";
out << expr << '\n';
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12 changes: 5 additions & 7 deletions test/wasm2js/dynamicLibrary.2asm.js
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Expand Up @@ -59,15 +59,13 @@ for (var base64ReverseLookup = new Uint8Array(123/*'z'+1*/), i = 25; i >= 0; --i
base64ReverseLookup[47] = 63; // '/'
/** @noinline Inlining this function would mean expanding the base64 string 4x times in the source code, which Closure seems to be happy to do. */
function base64DecodeToExistingUint8Array(uint8Array, offset, b64) {
var b1, b2, i = 0, j = offset, bLength = b64.length, end = offset + (bLength*3>>2);
if (b64[bLength-2] == '=') --end;
if (b64[bLength-1] == '=') --end;
for (; i < bLength; i += 4, j += 3) {
var b1, b2, i = 0, j = offset, bLength = b64.length, end = offset + (bLength*3>>2) - (b64[bLength-2] == '=') - (b64[bLength-1] == '=');
for (; i < bLength; i += 4) {
b1 = base64ReverseLookup[b64.charCodeAt(i+1)];
b2 = base64ReverseLookup[b64.charCodeAt(i+2)];
uint8Array[j] = base64ReverseLookup[b64.charCodeAt(i)] << 2 | b1 >> 4;
if (j+1 < end) uint8Array[j+1] = b1 << 4 | b2 >> 2;
if (j+2 < end) uint8Array[j+2] = b2 << 6 | base64ReverseLookup[b64.charCodeAt(i+3)];
uint8Array[j++] = base64ReverseLookup[b64.charCodeAt(i)] << 2 | b1 >> 4;
if (j < end) uint8Array[j++] = b1 << 4 | b2 >> 2;
if (j < end) uint8Array[j++] = b2 << 6 | base64ReverseLookup[b64.charCodeAt(i+3)];
}
}
var bufferView = new Uint8Array(memasmFunc);
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12 changes: 5 additions & 7 deletions test/wasm2js/dynamicLibrary.2asm.js.opt
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Original file line number Diff line number Diff line change
Expand Up @@ -51,15 +51,13 @@ for (var base64ReverseLookup = new Uint8Array(123/*'z'+1*/), i = 25; i >= 0; --i
base64ReverseLookup[47] = 63; // '/'
/** @noinline Inlining this function would mean expanding the base64 string 4x times in the source code, which Closure seems to be happy to do. */
function base64DecodeToExistingUint8Array(uint8Array, offset, b64) {
var b1, b2, i = 0, j = offset, bLength = b64.length, end = offset + (bLength*3>>2);
if (b64[bLength-2] == '=') --end;
if (b64[bLength-1] == '=') --end;
for (; i < bLength; i += 4, j += 3) {
var b1, b2, i = 0, j = offset, bLength = b64.length, end = offset + (bLength*3>>2) - (b64[bLength-2] == '=') - (b64[bLength-1] == '=');
for (; i < bLength; i += 4) {
b1 = base64ReverseLookup[b64.charCodeAt(i+1)];
b2 = base64ReverseLookup[b64.charCodeAt(i+2)];
uint8Array[j] = base64ReverseLookup[b64.charCodeAt(i)] << 2 | b1 >> 4;
if (j+1 < end) uint8Array[j+1] = b1 << 4 | b2 >> 2;
if (j+2 < end) uint8Array[j+2] = b2 << 6 | base64ReverseLookup[b64.charCodeAt(i+3)];
uint8Array[j++] = base64ReverseLookup[b64.charCodeAt(i)] << 2 | b1 >> 4;
if (j < end) uint8Array[j++] = b1 << 4 | b2 >> 2;
if (j < end) uint8Array[j++] = b2 << 6 | base64ReverseLookup[b64.charCodeAt(i+3)];
}
}
var bufferView = new Uint8Array(memasmFunc);
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12 changes: 5 additions & 7 deletions test/wasm2js/emscripten-grow-no.2asm.js
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Original file line number Diff line number Diff line change
Expand Up @@ -55,15 +55,13 @@ for (var base64ReverseLookup = new Uint8Array(123/*'z'+1*/), i = 25; i >= 0; --i
base64ReverseLookup[47] = 63; // '/'
/** @noinline Inlining this function would mean expanding the base64 string 4x times in the source code, which Closure seems to be happy to do. */
function base64DecodeToExistingUint8Array(uint8Array, offset, b64) {
var b1, b2, i = 0, j = offset, bLength = b64.length, end = offset + (bLength*3>>2);
if (b64[bLength-2] == '=') --end;
if (b64[bLength-1] == '=') --end;
for (; i < bLength; i += 4, j += 3) {
var b1, b2, i = 0, j = offset, bLength = b64.length, end = offset + (bLength*3>>2) - (b64[bLength-2] == '=') - (b64[bLength-1] == '=');
for (; i < bLength; i += 4) {
b1 = base64ReverseLookup[b64.charCodeAt(i+1)];
b2 = base64ReverseLookup[b64.charCodeAt(i+2)];
uint8Array[j] = base64ReverseLookup[b64.charCodeAt(i)] << 2 | b1 >> 4;
if (j+1 < end) uint8Array[j+1] = b1 << 4 | b2 >> 2;
if (j+2 < end) uint8Array[j+2] = b2 << 6 | base64ReverseLookup[b64.charCodeAt(i+3)];
uint8Array[j++] = base64ReverseLookup[b64.charCodeAt(i)] << 2 | b1 >> 4;
if (j < end) uint8Array[j++] = b1 << 4 | b2 >> 2;
if (j < end) uint8Array[j++] = b2 << 6 | base64ReverseLookup[b64.charCodeAt(i+3)];
}
}
var bufferView = new Uint8Array(wasmMemory.buffer);
Expand Down
12 changes: 5 additions & 7 deletions test/wasm2js/emscripten-grow-no.2asm.js.opt
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Original file line number Diff line number Diff line change
Expand Up @@ -55,15 +55,13 @@ for (var base64ReverseLookup = new Uint8Array(123/*'z'+1*/), i = 25; i >= 0; --i
base64ReverseLookup[47] = 63; // '/'
/** @noinline Inlining this function would mean expanding the base64 string 4x times in the source code, which Closure seems to be happy to do. */
function base64DecodeToExistingUint8Array(uint8Array, offset, b64) {
var b1, b2, i = 0, j = offset, bLength = b64.length, end = offset + (bLength*3>>2);
if (b64[bLength-2] == '=') --end;
if (b64[bLength-1] == '=') --end;
for (; i < bLength; i += 4, j += 3) {
var b1, b2, i = 0, j = offset, bLength = b64.length, end = offset + (bLength*3>>2) - (b64[bLength-2] == '=') - (b64[bLength-1] == '=');
for (; i < bLength; i += 4) {
b1 = base64ReverseLookup[b64.charCodeAt(i+1)];
b2 = base64ReverseLookup[b64.charCodeAt(i+2)];
uint8Array[j] = base64ReverseLookup[b64.charCodeAt(i)] << 2 | b1 >> 4;
if (j+1 < end) uint8Array[j+1] = b1 << 4 | b2 >> 2;
if (j+2 < end) uint8Array[j+2] = b2 << 6 | base64ReverseLookup[b64.charCodeAt(i+3)];
uint8Array[j++] = base64ReverseLookup[b64.charCodeAt(i)] << 2 | b1 >> 4;
if (j < end) uint8Array[j++] = b1 << 4 | b2 >> 2;
if (j < end) uint8Array[j++] = b2 << 6 | base64ReverseLookup[b64.charCodeAt(i+3)];
}
}
var bufferView = new Uint8Array(wasmMemory.buffer);
Expand Down
12 changes: 5 additions & 7 deletions test/wasm2js/emscripten-grow-yes.2asm.js
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Original file line number Diff line number Diff line change
Expand Up @@ -78,15 +78,13 @@ for (var base64ReverseLookup = new Uint8Array(123/*'z'+1*/), i = 25; i >= 0; --i
base64ReverseLookup[47] = 63; // '/'
/** @noinline Inlining this function would mean expanding the base64 string 4x times in the source code, which Closure seems to be happy to do. */
function base64DecodeToExistingUint8Array(uint8Array, offset, b64) {
var b1, b2, i = 0, j = offset, bLength = b64.length, end = offset + (bLength*3>>2);
if (b64[bLength-2] == '=') --end;
if (b64[bLength-1] == '=') --end;
for (; i < bLength; i += 4, j += 3) {
var b1, b2, i = 0, j = offset, bLength = b64.length, end = offset + (bLength*3>>2) - (b64[bLength-2] == '=') - (b64[bLength-1] == '=');
for (; i < bLength; i += 4) {
b1 = base64ReverseLookup[b64.charCodeAt(i+1)];
b2 = base64ReverseLookup[b64.charCodeAt(i+2)];
uint8Array[j] = base64ReverseLookup[b64.charCodeAt(i)] << 2 | b1 >> 4;
if (j+1 < end) uint8Array[j+1] = b1 << 4 | b2 >> 2;
if (j+2 < end) uint8Array[j+2] = b2 << 6 | base64ReverseLookup[b64.charCodeAt(i+3)];
uint8Array[j++] = base64ReverseLookup[b64.charCodeAt(i)] << 2 | b1 >> 4;
if (j < end) uint8Array[j++] = b1 << 4 | b2 >> 2;
if (j < end) uint8Array[j++] = b2 << 6 | base64ReverseLookup[b64.charCodeAt(i+3)];
}
}
var bufferView = new Uint8Array(wasmMemory.buffer);
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12 changes: 5 additions & 7 deletions test/wasm2js/emscripten-grow-yes.2asm.js.opt
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Original file line number Diff line number Diff line change
Expand Up @@ -78,15 +78,13 @@ for (var base64ReverseLookup = new Uint8Array(123/*'z'+1*/), i = 25; i >= 0; --i
base64ReverseLookup[47] = 63; // '/'
/** @noinline Inlining this function would mean expanding the base64 string 4x times in the source code, which Closure seems to be happy to do. */
function base64DecodeToExistingUint8Array(uint8Array, offset, b64) {
var b1, b2, i = 0, j = offset, bLength = b64.length, end = offset + (bLength*3>>2);
if (b64[bLength-2] == '=') --end;
if (b64[bLength-1] == '=') --end;
for (; i < bLength; i += 4, j += 3) {
var b1, b2, i = 0, j = offset, bLength = b64.length, end = offset + (bLength*3>>2) - (b64[bLength-2] == '=') - (b64[bLength-1] == '=');
for (; i < bLength; i += 4) {
b1 = base64ReverseLookup[b64.charCodeAt(i+1)];
b2 = base64ReverseLookup[b64.charCodeAt(i+2)];
uint8Array[j] = base64ReverseLookup[b64.charCodeAt(i)] << 2 | b1 >> 4;
if (j+1 < end) uint8Array[j+1] = b1 << 4 | b2 >> 2;
if (j+2 < end) uint8Array[j+2] = b2 << 6 | base64ReverseLookup[b64.charCodeAt(i+3)];
uint8Array[j++] = base64ReverseLookup[b64.charCodeAt(i)] << 2 | b1 >> 4;
if (j < end) uint8Array[j++] = b1 << 4 | b2 >> 2;
if (j < end) uint8Array[j++] = b2 << 6 | base64ReverseLookup[b64.charCodeAt(i+3)];
}
}
var bufferView = new Uint8Array(wasmMemory.buffer);
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12 changes: 5 additions & 7 deletions test/wasm2js/emscripten.2asm.js
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Original file line number Diff line number Diff line change
Expand Up @@ -213,15 +213,13 @@ for (var base64ReverseLookup = new Uint8Array(123/*'z'+1*/), i = 25; i >= 0; --i
base64ReverseLookup[47] = 63; // '/'
/** @noinline Inlining this function would mean expanding the base64 string 4x times in the source code, which Closure seems to be happy to do. */
function base64DecodeToExistingUint8Array(uint8Array, offset, b64) {
var b1, b2, i = 0, j = offset, bLength = b64.length, end = offset + (bLength*3>>2);
if (b64[bLength-2] == '=') --end;
if (b64[bLength-1] == '=') --end;
for (; i < bLength; i += 4, j += 3) {
var b1, b2, i = 0, j = offset, bLength = b64.length, end = offset + (bLength*3>>2) - (b64[bLength-2] == '=') - (b64[bLength-1] == '=');
for (; i < bLength; i += 4) {
b1 = base64ReverseLookup[b64.charCodeAt(i+1)];
b2 = base64ReverseLookup[b64.charCodeAt(i+2)];
uint8Array[j] = base64ReverseLookup[b64.charCodeAt(i)] << 2 | b1 >> 4;
if (j+1 < end) uint8Array[j+1] = b1 << 4 | b2 >> 2;
if (j+2 < end) uint8Array[j+2] = b2 << 6 | base64ReverseLookup[b64.charCodeAt(i+3)];
uint8Array[j++] = base64ReverseLookup[b64.charCodeAt(i)] << 2 | b1 >> 4;
if (j < end) uint8Array[j++] = b1 << 4 | b2 >> 2;
if (j < end) uint8Array[j++] = b2 << 6 | base64ReverseLookup[b64.charCodeAt(i+3)];
}
}
var bufferView = new Uint8Array(wasmMemory.buffer);
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12 changes: 5 additions & 7 deletions test/wasm2js/emscripten.2asm.js.opt
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Original file line number Diff line number Diff line change
Expand Up @@ -194,15 +194,13 @@ for (var base64ReverseLookup = new Uint8Array(123/*'z'+1*/), i = 25; i >= 0; --i
base64ReverseLookup[47] = 63; // '/'
/** @noinline Inlining this function would mean expanding the base64 string 4x times in the source code, which Closure seems to be happy to do. */
function base64DecodeToExistingUint8Array(uint8Array, offset, b64) {
var b1, b2, i = 0, j = offset, bLength = b64.length, end = offset + (bLength*3>>2);
if (b64[bLength-2] == '=') --end;
if (b64[bLength-1] == '=') --end;
for (; i < bLength; i += 4, j += 3) {
var b1, b2, i = 0, j = offset, bLength = b64.length, end = offset + (bLength*3>>2) - (b64[bLength-2] == '=') - (b64[bLength-1] == '=');
for (; i < bLength; i += 4) {
b1 = base64ReverseLookup[b64.charCodeAt(i+1)];
b2 = base64ReverseLookup[b64.charCodeAt(i+2)];
uint8Array[j] = base64ReverseLookup[b64.charCodeAt(i)] << 2 | b1 >> 4;
if (j+1 < end) uint8Array[j+1] = b1 << 4 | b2 >> 2;
if (j+2 < end) uint8Array[j+2] = b2 << 6 | base64ReverseLookup[b64.charCodeAt(i+3)];
uint8Array[j++] = base64ReverseLookup[b64.charCodeAt(i)] << 2 | b1 >> 4;
if (j < end) uint8Array[j++] = b1 << 4 | b2 >> 2;
if (j < end) uint8Array[j++] = b2 << 6 | base64ReverseLookup[b64.charCodeAt(i+3)];
}
}
var bufferView = new Uint8Array(wasmMemory.buffer);
Expand Down