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Emit DeferredDeclsToEmit in a DFS order.

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Currently we emit DeferredDeclsToEmit in reverse order. This patch changes that.

The advantages of the change are that

* The output order is a bit closer to the source order. The change to
test/CodeGenCXX/pod-member-memcpys.cpp is a good example.

* If we decide to deffer more, it will not cause as large changes in the
estcases as it would without this patch.

llvm-svn: 226751
This commit is contained in:
Rafael Espindola
2015-01-22 00:24:57 +00:00
parent 343e496473
commit e5df59ff78
46 changed files with 379 additions and 356 deletions
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38
clang/lib/CodeGen/CodeGenModule.cpp
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@@ -1084,24 +1084,28 @@ void CodeGenModule::EmitDeferred() {
// previously unused static decl may become used during the generation of code
// for a static function, iterate until no changes are made.
while (true) {
if (!DeferredVTables.empty()) {
EmitDeferredVTables();
if (!DeferredVTables.empty()) {
EmitDeferredVTables();
// Emitting a v-table doesn't directly cause more v-tables to
// become deferred, although it can cause functions to be
// emitted that then need those v-tables.
assert(DeferredVTables.empty());
}
// Emitting a v-table doesn't directly cause more v-tables to
// become deferred, although it can cause functions to be
// emitted that then need those v-tables.
assert(DeferredVTables.empty());
}
// Stop if we're out of both deferred v-tables and deferred declarations.
if (DeferredDeclsToEmit.empty())
break;
// Stop if we're out of both deferred v-tables and deferred declarations.
if (DeferredDeclsToEmit.empty())
return;
DeferredGlobal &G = DeferredDeclsToEmit.back();
// Grab the list of decls to emit. If EmitGlobalDefinition schedules more
// work, it will not interfere with this.
std::vector<DeferredGlobal> CurDeclsToEmit;
CurDeclsToEmit.swap(DeferredDeclsToEmit);
for (DeferredGlobal &G : CurDeclsToEmit) {
GlobalDecl D = G.GD;
llvm::GlobalValue *GV = G.GV;
DeferredDeclsToEmit.pop_back();
G.GV = nullptr;
assert(!GV || GV == GetGlobalValue(getMangledName(D)));
if (!GV)
@@ -1118,6 +1122,14 @@ void CodeGenModule::EmitDeferred() {
// Otherwise, emit the definition and move on to the next one.
EmitGlobalDefinition(D, GV);
// If we found out that we need to emit more decls, do that recursively.
// This has the advantage that the decls are emitted in a DFS and related
// ones are close together, which is convenient for testing.
if (!DeferredVTables.empty() || !DeferredDeclsToEmit.empty()) {
EmitDeferred();
assert(DeferredVTables.empty() && DeferredDeclsToEmit.empty());
}
}
}