[PATCH] D79297: [COFF] Avoid allocating temporary vectors during ICF

[Reid Kleckner via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rGfce5457a1419: [COFF] Avoid allocating temporary vectors during ICF (authored by rnk).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D79297/new/

https://reviews.llvm.org/D79297

Files:
  lld/COFF/Chunks.h
  lld/COFF/ICF.cpp


Index: lld/COFF/ICF.cpp
===================================================================
--- lld/COFF/ICF.cpp
+++ lld/COFF/ICF.cpp
@@ -127,15 +127,19 @@
 
 // Returns true if two sections' associative children are equal.
 bool ICF::assocEquals(const SectionChunk *a, const SectionChunk *b) {
-  auto childClasses = [&](const SectionChunk *sc) {
-    std::vector<uint32_t> classes;
-    for (const SectionChunk &c : sc->children())
-      if (!c.getSectionName().startswith(".debug") &&
-          c.getSectionName() != ".gfids$y" && c.getSectionName() != ".gljmp$y")
-        classes.push_back(c.eqClass[cnt % 2]);
-    return classes;
+  // Ignore associated metadata sections that don't participate in ICF, such as
+  // debug info and CFGuard metadata.
+  auto considerForICF = [](const SectionChunk &assoc) {
+    StringRef Name = assoc.getSectionName();
+    return !(Name.startswith(".debug") || Name == ".gfids$y" ||
+             Name == ".gljmp$y");
   };
-  return childClasses(a) == childClasses(b);
+  auto ra = make_filter_range(a->children(), considerForICF);
+  auto rb = make_filter_range(b->children(), considerForICF);
+  return std::equal(ra.begin(), ra.end(), rb.begin(), rb.end(),
+                    [&](const SectionChunk &ia, const SectionChunk &ib) {
+                      return ia.eqClass[cnt % 2] == ib.eqClass[cnt % 2];
+                    });
 }
 
 // Compare "non-moving" part of two sections, namely everything
Index: lld/COFF/Chunks.h
===================================================================
--- lld/COFF/Chunks.h
+++ lld/COFF/Chunks.h
@@ -269,7 +269,8 @@
     AssociatedIterator() = default;
     AssociatedIterator(SectionChunk *head) : cur(head) {}
     bool operator==(const AssociatedIterator &r) const { return cur == r.cur; }
-    const SectionChunk &operator*() const { return *cur; }
+    // FIXME: Wrong const-ness, but it makes filter ranges work.
+    SectionChunk &operator*() const { return *cur; }
     SectionChunk &operator*() { return *cur; }
     AssociatedIterator &operator++() {
       cur = cur->assocChildren;


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