From 62a07cb59b432f9539eb2bb34b9a1c5e44016b7c Mon Sep 17 00:00:00 2001
From: Rafael Espindola <rafael.espindola@gmail.com>
Date: Fri, 22 May 2015 15:43:00 +0000
Subject: Stop inventing symbol sizes.

MachO and COFF quite reasonably only define the size for common symbols.

We used to try to figure out the "size" by computing the gap from one symbol to
the next.

This would not be correct in general, since a part of a section can belong to no
visible symbol (padding, private globals).

It was also really expensive, since we would walk every symbol to find the size
of one.

If a caller really wants this, it can sort all the symbols once and get all the
gaps ("size") in O(n log n) instead of O(n^2).

On MachO this also has the advantage of centralizing all the checks for an
invalid n_sect.

llvm-svn: 238028
---
 llvm/lib/Object/MachOObjectFile.cpp | 52 +++++--------------------------------
 1 file changed, 6 insertions(+), 46 deletions(-)

(limited to 'llvm/lib/Object/MachOObjectFile.cpp')

diff --git a/llvm/lib/Object/MachOObjectFile.cpp b/llvm/lib/Object/MachOObjectFile.cpp
index 504b317..79f8100 100644
--- a/llvm/lib/Object/MachOObjectFile.cpp
+++ b/llvm/lib/Object/MachOObjectFile.cpp
@@ -415,49 +415,13 @@ std::error_code MachOObjectFile::getSymbolAlignment(DataRefImpl DRI,
 
 std::error_code MachOObjectFile::getSymbolSize(DataRefImpl DRI,
                                                uint64_t &Result) const {
-  uint64_t BeginOffset;
-  uint64_t EndOffset = 0;
-  uint8_t SectionIndex;
-
-  MachO::nlist_base Entry = getSymbolTableEntryBase(this, DRI);
   uint64_t Value;
   getSymbolAddress(DRI, Value);
-  if (Value == UnknownAddressOrSize) {
+  uint32_t flags = getSymbolFlags(DRI);
+  if (flags & SymbolRef::SF_Common)
+    Result = Value;
+  else
     Result = UnknownAddressOrSize;
-    return object_error::success;
-  }
-
-  BeginOffset = Value;
-
-  SectionIndex = Entry.n_sect;
-  if (!SectionIndex) {
-    uint32_t flags = getSymbolFlags(DRI);
-    if (flags & SymbolRef::SF_Common)
-      Result = Value;
-    else
-      Result = UnknownAddressOrSize;
-    return object_error::success;
-  }
-  // Unfortunately symbols are unsorted so we need to touch all
-  // symbols from load command
-  for (const SymbolRef &Symbol : symbols()) {
-    DataRefImpl DRI = Symbol.getRawDataRefImpl();
-    Entry = getSymbolTableEntryBase(this, DRI);
-    getSymbolAddress(DRI, Value);
-    if (Value == UnknownAddressOrSize)
-      continue;
-    if (Entry.n_sect == SectionIndex && Value > BeginOffset)
-      if (!EndOffset || Value < EndOffset)
-        EndOffset = Value;
-  }
-  if (!EndOffset) {
-    DataRefImpl Sec;
-    Sec.d.a = SectionIndex-1;
-    uint64_t Size = getSectionSize(Sec);
-    EndOffset = getSectionAddress(Sec);
-    EndOffset += Size;
-  }
-  Result = EndOffset - BeginOffset;
   return object_error::success;
 }
 
@@ -2263,16 +2227,12 @@ MachOObjectFile::getNextLoadCommandInfo(const LoadCommandInfo &L) const {
 }
 
 MachO::section MachOObjectFile::getSection(DataRefImpl DRI) const {
-  // TODO: What if Sections.size() == 0?
-  if (DRI.d.a >= Sections.size())
-    report_fatal_error("getSection: Invalid section index.");
+  assert(DRI.d.a < Sections.size() && "Should have detected this earlier");
   return getStruct<MachO::section>(this, Sections[DRI.d.a]);
 }
 
 MachO::section_64 MachOObjectFile::getSection64(DataRefImpl DRI) const {
-  // TODO: What if Sections.size() == 0?
-  if (DRI.d.a >= Sections.size())
-    report_fatal_error("getSection64: Invalid section index.");
+  assert(DRI.d.a < Sections.size() && "Should have detected this earlier");
   return getStruct<MachO::section_64>(this, Sections[DRI.d.a]);
 }
 
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