[PATCH] D56986: COFF, ELF: ICF: Perform 2 rounds of relocation hash propagation.

[Peter Collingbourne via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rL351899: COFF, ELF: ICF: Perform 2 rounds of relocation hash propagation. (authored by pcc, committed by ).

Changed prior to commit:
  https://reviews.llvm.org/D56986?vs=182716&id=182993#toc

Repository:
  rL LLVM

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D56986/new/

https://reviews.llvm.org/D56986

Files:
  lld/trunk/COFF/ICF.cpp
  lld/trunk/ELF/ICF.cpp


Index: lld/trunk/COFF/ICF.cpp
===================================================================
--- lld/trunk/COFF/ICF.cpp
+++ lld/trunk/COFF/ICF.cpp
@@ -262,19 +262,21 @@
 
   // Initially, we use hash values to partition sections.
   parallelForEach(Chunks, [&](SectionChunk *SC) {
-    SC->Class[1] = xxHash64(SC->getContents());
+    SC->Class[0] = xxHash64(SC->getContents());
   });
 
   // Combine the hashes of the sections referenced by each section into its
   // hash.
-  parallelForEach(Chunks, [&](SectionChunk *SC) {
-    uint32_t Hash = SC->Class[1];
-    for (Symbol *B : SC->symbols())
-      if (auto *Sym = dyn_cast_or_null<DefinedRegular>(B))
-        Hash += Sym->getChunk()->Class[1];
-    // Set MSB to 1 to avoid collisions with non-hash classs.
-    SC->Class[0] = Hash | (1U << 31);
-  });
+  for (unsigned Cnt = 0; Cnt != 2; ++Cnt) {
+    parallelForEach(Chunks, [&](SectionChunk *SC) {
+      uint32_t Hash = SC->Class[Cnt % 2];
+      for (Symbol *B : SC->symbols())
+        if (auto *Sym = dyn_cast_or_null<DefinedRegular>(B))
+          Hash += Sym->getChunk()->Class[Cnt % 2];
+      // Set MSB to 1 to avoid collisions with non-hash classs.
+      SC->Class[(Cnt + 1) % 2] = Hash | (1U << 31);
+    });
+  }
 
   // From now on, sections in Chunks are ordered so that sections in
   // the same group are consecutive in the vector.
Index: lld/trunk/ELF/ICF.cpp
===================================================================
--- lld/trunk/ELF/ICF.cpp
+++ lld/trunk/ELF/ICF.cpp
@@ -425,16 +425,17 @@
 // Combine the hashes of the sections referenced by the given section into its
 // hash.
 template <class ELFT, class RelTy>
-static void combineRelocHashes(InputSection *IS, ArrayRef<RelTy> Rels) {
-  uint32_t Hash = IS->Class[1];
+static void combineRelocHashes(unsigned Cnt, InputSection *IS,
+                               ArrayRef<RelTy> Rels) {
+  uint32_t Hash = IS->Class[Cnt % 2];
   for (RelTy Rel : Rels) {
     Symbol &S = IS->template getFile<ELFT>()->getRelocTargetSym(Rel);
     if (auto *D = dyn_cast<Defined>(&S))
       if (auto *RelSec = dyn_cast_or_null<InputSection>(D->Section))
-        Hash += RelSec->Class[1];
+        Hash += RelSec->Class[Cnt % 2];
   }
   // Set MSB to 1 to avoid collisions with non-hash IDs.
-  IS->Class[0] = Hash | (1U << 31);
+  IS->Class[(Cnt + 1) % 2] = Hash | (1U << 31);
 }
 
 static void print(const Twine &S) {
@@ -452,15 +453,17 @@
 
   // Initially, we use hash values to partition sections.
   parallelForEach(Sections, [&](InputSection *S) {
-    S->Class[1] = xxHash64(S->data());
+    S->Class[0] = xxHash64(S->data());
   });
 
-  parallelForEach(Sections, [&](InputSection *S) {
-    if (S->AreRelocsRela)
-      combineRelocHashes<ELFT>(S, S->template relas<ELFT>());
-    else
-      combineRelocHashes<ELFT>(S, S->template rels<ELFT>());
-  });
+  for (unsigned Cnt = 0; Cnt != 2; ++Cnt) {
+    parallelForEach(Sections, [&](InputSection *S) {
+      if (S->AreRelocsRela)
+        combineRelocHashes<ELFT>(Cnt, S, S->template relas<ELFT>());
+      else
+        combineRelocHashes<ELFT>(Cnt, S, S->template rels<ELFT>());
+    });
+  }
 
   // From now on, sections in Sections vector are ordered so that sections
   // in the same equivalence class are consecutive in the vector.


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D56986.182993.patch
Type: text/x-patch
Size: 3292 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20190122/3d34eba6/attachment.bin>