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-rw-r--r--src/jsifier.js79
-rw-r--r--src/parseTools.js16
-rw-r--r--src/settings.js5
3 files changed, 68 insertions, 32 deletions
diff --git a/src/jsifier.js b/src/jsifier.js
index d6cd188c..73cc7740 100644
--- a/src/jsifier.js
+++ b/src/jsifier.js
@@ -285,42 +285,59 @@ function JSify(data, functionsOnly, givenFunctions) {
index = makeGlobalUse(item.ident); // index !== null indicates we are indexing this
allocator = 'ALLOC_NONE';
}
- if (item.external) {
- if (Runtime.isNumberType(item.type) || isPointerType(item.type)) {
- constant = zeros(Runtime.getNativeFieldSize(item.type));
- } else {
- constant = makeEmptyStruct(item.type);
+
+ if (isBSS(item)) {
+ var length = calcAllocatedSize(item.type);
+ length = Runtime.alignMemory(length);
+
+ // If not using indexed globals, go ahead and early out (it doesn't need to
+ // be explicitly allocated).
+ if (!NAMED_GLOBALS) {
+ return ret;
+ }
+ // If using named globals, shorten the call to allocate() by just passing an
+ // integer representing the length of the chunk of memory we need to alloc.
+ else {
+ constant = length;
}
} else {
- constant = parseConst(item.value, item.type, item.ident);
- }
- assert(typeof constant === 'object');//, [typeof constant, JSON.stringify(constant), item.external]);
-
- // This is a flattened object. We need to find its idents, so they can be assigned to later
- constant.forEach(function(value, i) {
- if (needsPostSet(value)) { // ident, or expression containing an ident
- ret.push({
- intertype: 'GlobalVariablePostSet',
- JS: makeSetValue(makeGlobalUse(item.ident), i, value, 'i32', false, true) + ';' // ignore=true, since e.g. rtti and statics cause lots of safe_heap errors
- });
- constant[i] = '0';
+ if (item.external) {
+ if (Runtime.isNumberType(item.type) || isPointerType(item.type)) {
+ constant = zeros(Runtime.getNativeFieldSize(item.type));
+ } else {
+ constant = makeEmptyStruct(item.type);
+ }
+ } else {
+ constant = parseConst(item.value, item.type, item.ident);
}
- });
+ assert(typeof constant === 'object');//, [typeof constant, JSON.stringify(constant), item.external]);
+
+ // This is a flattened object. We need to find its idents, so they can be assigned to later
+ constant.forEach(function(value, i) {
+ if (needsPostSet(value)) { // ident, or expression containing an ident
+ ret.push({
+ intertype: 'GlobalVariablePostSet',
+ JS: makeSetValue(makeGlobalUse(item.ident), i, value, 'i32', false, true) + ';' // ignore=true, since e.g. rtti and statics cause lots of safe_heap errors
+ });
+ constant[i] = '0';
+ }
+ });
- if (item.external) {
- // External variables in shared libraries should not be declared as
- // they would shadow similarly-named globals in the parent, so do nothing here.
- if (BUILD_AS_SHARED_LIB) return ret;
- // Library items need us to emit something, but everything else requires nothing.
- if (!LibraryManager.library[item.ident.slice(1)]) return ret;
- }
+ if (item.external) {
+ // External variables in shared libraries should not be declared as
+ // they would shadow similarly-named globals in the parent, so do nothing here.
+ if (BUILD_AS_SHARED_LIB) return ret;
+ // Library items need us to emit something, but everything else requires nothing.
+ if (!LibraryManager.library[item.ident.slice(1)]) return ret;
+ }
- // ensure alignment
- constant = constant.concat(zeros(Runtime.alignMemory(constant.length) - constant.length));
+ // ensure alignment
+ constant = constant.concat(zeros(Runtime.alignMemory(constant.length) - constant.length));
- // Special case: class vtables. We make sure they are null-terminated, to allow easy runtime operations
- if (item.ident.substr(0, 5) == '__ZTV') {
- constant = constant.concat(zeros(Runtime.alignMemory(QUANTUM_SIZE)));
+ // Special case: class vtables. We make sure they are null-terminated, to allow easy runtime operations
+ if (item.ident.substr(0, 5) == '__ZTV') {
+ constant = constant.concat(zeros(Runtime.alignMemory(QUANTUM_SIZE)));
+ }
}
// NOTE: This is the only place that could potentially create static
@@ -1568,7 +1585,7 @@ function JSify(data, functionsOnly, givenFunctions) {
print('STATICTOP = STATIC_BASE + ' + Runtime.alignMemory(Variables.nextIndexedOffset) + ';\n');
}
var generated = itemsDict.function.concat(itemsDict.type).concat(itemsDict.GlobalVariableStub).concat(itemsDict.GlobalVariable);
- print(generated.map(function(item) { return item.JS }).join('\n'));
+ print(generated.map(function(item) { return item.JS; }).join('\n'));
if (phase == 'pre') {
if (memoryInitialization.length > 0) {
diff --git a/src/parseTools.js b/src/parseTools.js
index 0b83a12b..babb2692 100644
--- a/src/parseTools.js
+++ b/src/parseTools.js
@@ -467,6 +467,17 @@ function isIndexableGlobal(ident) {
return !data.alias && !data.external;
}
+function isBSS(item) {
+ if (!USE_BSS) {
+ return false;
+ }
+
+ // return true if a global is uninitialized or initialized to 0
+ return item.external ||
+ (item.value && item.value.intertype === 'emptystruct') ||
+ (item.value && item.value.value !== undefined && item.value.value === '0');
+}
+
function makeGlobalDef(ident) {
if (!NAMED_GLOBALS && isIndexableGlobal(ident)) return '';
return 'var ' + ident + ';';
@@ -490,7 +501,10 @@ function sortGlobals(globals) {
ks.sort();
var inv = invertArray(ks);
return values(globals).sort(function(a, b) {
- return inv[b.ident] - inv[a.ident];
+ // sort globals based on if they need to be explicitly initialized or not (moving
+ // values that don't need to be to the end of the array). if equal, sort by name.
+ return (Number(isBSS(a)) - Number(isBSS(b))) ||
+ (inv[b.ident] - inv[a.ident]);
});
}
diff --git a/src/settings.js b/src/settings.js
index 3e530c52..4b6f033b 100644
--- a/src/settings.js
+++ b/src/settings.js
@@ -236,6 +236,11 @@ var FS_LOG = 0; // Log all FS operations. This is especially helpful when you'r
// a new project and want to see a list of file system operations happening
// so that you can create a virtual file system with all of the required files.
+var USE_BSS = 1; // https://en.wikipedia.org/wiki/.bss
+ // When enabled, 0-initialized globals are sorted to the end of the globals list,
+ // enabling us to not explicitly store the initialization value for each 0 byte.
+ // This significantly lowers the memory initialization array size.
+
var NAMED_GLOBALS = 0; // If 1, we use global variables for globals. Otherwise
// they are referred to by a base plus an offset (called an indexed global),
// saving global variables but adding runtime overhead.
generated by cgit v1.2.3-18-g5258 (git 2.32.0) at 2025-07-05 20:21:20 +0000