commit 62edcc6672cfdb4d741c56b794c902b47efb01fb
author Fangrui Song <i@maskray.me> Sun May 07 16:26:52 2023 -0700
committer Copybara-Service <copybara-worker@google.com> Sun May 07 16:31:54 2023 -0700
tree 0be433ceb1978541e85c2a634750feeffa394f3f
parent b53df630521a5fb17f0b7ba147db340363dd4e62

[MC] MCDwarfLineAddr::Encode: use SmallVectorImpl instead of raw_ostream. NFC

Similar to D145791: most call sites need a SmallString, but have to provide a
raw_svector_ostream wrapper with unneeded abstraction and overhead:

raw_ostream::write =(inlinable)=> flush_tied_then_write (unneeded TiedStream check) =(virtual function call)=> raw_svector_ostream::write_impl ==> SmallVector append(ItTy in_start, ItTy in_end) (range; less efficient then push_back).

Just use SmallVectorImpl to simplify and optimize code. Unfortunately most call
sites use SmallString, so we have to use SmallVectorImpl<char> instead of
<uint8_t> to avoid large refactoring.

GitOrigin-RevId: 49488490d195591bfc90daef111cd7293f8c80aa

lib/DWARFLinker/DWARFStreamer.cpp

diff --git a/lib/DWARFLinker/DWARFStreamer.cpp b/lib/DWARFLinker/DWARFStreamer.cpp
index 1593ea6..ebd54f7 100644
--- a/lib/DWARFLinker/DWARFStreamer.cpp
+++ b/lib/DWARFLinker/DWARFStreamer.cpp
@@ -655,9 +655,9 @@
   if (Rows.empty()) {
     // We only have the dummy entry, dsymutil emits an entry with a 0
     // address in that case.
-    MCDwarfLineAddr::Encode(*MC, Params, std::numeric_limits<int64_t>::max(), 0,
-                            EncodingOS);
-    MS->emitBytes(EncodingOS.str());
+    MCDwarfLineAddr::encode(*MC, Params, std::numeric_limits<int64_t>::max(), 0,
+                            EncodingBuffer);
+    MS->emitBytes(EncodingBuffer);
     LineSectionSize += EncodingBuffer.size();
     MS->emitLabel(LineEndSym);
     return;
@@ -735,8 +735,8 @@
 
     int64_t LineDelta = int64_t(Row.Line) - LastLine;
     if (!Row.EndSequence) {
-      MCDwarfLineAddr::Encode(*MC, Params, LineDelta, AddressDelta, EncodingOS);
-      MS->emitBytes(EncodingOS.str());
+      MCDwarfLineAddr::encode(*MC, Params, LineDelta, AddressDelta, EncodingBuffer);
+      MS->emitBytes(EncodingBuffer);
       LineSectionSize += EncodingBuffer.size();
       EncodingBuffer.resize(0);
       Address = Row.Address.Address;
@@ -753,9 +753,9 @@
         MS->emitULEB128IntValue(AddressDelta);
         LineSectionSize += 1 + getULEB128Size(AddressDelta);
       }
-      MCDwarfLineAddr::Encode(*MC, Params, std::numeric_limits<int64_t>::max(),
-                              0, EncodingOS);
-      MS->emitBytes(EncodingOS.str());
+      MCDwarfLineAddr::encode(*MC, Params, std::numeric_limits<int64_t>::max(),
+                              0, EncodingBuffer);
+      MS->emitBytes(EncodingBuffer);
       LineSectionSize += EncodingBuffer.size();
       EncodingBuffer.resize(0);
       Address = -1ULL;
@@ -765,9 +765,9 @@
   }
 
   if (RowsSinceLastSequence) {
-    MCDwarfLineAddr::Encode(*MC, Params, std::numeric_limits<int64_t>::max(), 0,
-                            EncodingOS);
-    MS->emitBytes(EncodingOS.str());
+    MCDwarfLineAddr::encode(*MC, Params, std::numeric_limits<int64_t>::max(), 0,
+                            EncodingBuffer);
+    MS->emitBytes(EncodingBuffer);
     LineSectionSize += EncodingBuffer.size();
     EncodingBuffer.resize(0);
   }