DWARF type hashing: Handle multiple (including recursive) references to the same type
This uses a map, keeping the type DIE numbering separate from the DIEs
themselves - alternatively we could do things the way GCC does if we
want to add an integer to the DIE type to record the numbering there.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193105 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/AsmPrinter/DIEHash.cpp b/lib/CodeGen/AsmPrinter/DIEHash.cpp
index 13238f3..aa54db0 100644
--- a/lib/CodeGen/AsmPrinter/DIEHash.cpp
+++ b/lib/CodeGen/AsmPrinter/DIEHash.cpp
@@ -196,22 +196,30 @@
// 7.27s3
// ... An attribute that refers to another type entry T is processed as
// follows:
- // a) If T is in the list of [previously hashed types], use the letter 'R' as
- // the marker and use the unsigned LEB128 encoding of [the index of T in the
- // list] as the attribute value; otherwise,
-
- // [TODO: implement clause (a)]
-
if (const DIEEntry *EntryAttr = dyn_cast<DIEEntry>(Value)) {
DIE *Entry = EntryAttr->getEntry();
+ unsigned &DieNumber = Numbering[Entry];
+ if (DieNumber) {
+ // a) If T is in the list of [previously hashed types], use the letter
+ // 'R' as the marker
+ addULEB128('R');
- // b) use the letter 'T' as a the marker, ...
+ addULEB128(Desc->getAttribute());
+
+ // and use the unsigned LEB128 encoding of [the index of T in the
+ // list] as the attribute value;
+ addULEB128(DieNumber);
+ return;
+ }
+
+ // otherwise, b) use the letter 'T' as a the marker, ...
addULEB128('T');
addULEB128(Desc->getAttribute());
// ... process the type T recursively by performing Steps 2 through 7, and
// use the result as the attribute value.
+ DieNumber = Numbering.size();
computeHash(Entry);
return;
}
@@ -321,7 +329,6 @@
// given in section 7.27 of the DWARF4 standard. It is the md5 hash of a
// flattened description of the DIE.
void DIEHash::computeHash(DIE *Die) {
-
// Append the letter 'D', followed by the DWARF tag of the DIE.
addULEB128('D');
addULEB128(Die->getTag());
@@ -377,6 +384,8 @@
/// with the inclusion of the full CU and all top level CU entities.
// TODO: Initialize the type chain at 0 instead of 1 for CU signatures.
uint64_t DIEHash::computeCUSignature(DIE *Die) {
+ Numbering.clear();
+ Numbering[Die] = 1;
// Hash the DIE.
computeHash(Die);
@@ -396,6 +405,8 @@
/// with the inclusion of additional forms not specifically called out in the
/// standard.
uint64_t DIEHash::computeTypeSignature(DIE *Die) {
+ Numbering.clear();
+ Numbering[Die] = 1;
if (DIE *Parent = Die->getParent())
addParentContext(Parent);