[PATCH] D24404: COFF: make builds more reproducible

[Rui Ueyama via llvm-commits]

ruiu added inline comments.

================
Comment at: COFF/Writer.cpp:84
@@ -83,3 +83,3 @@
   void writeTo(uint8_t *B) const override {
-    auto *R = reinterpret_cast<codeview::DebugInfo *>(B + OutputSectionOff);
+    DI = reinterpret_cast<codeview::DebugInfo *>(B + OutputSectionOff);
 
----------------
Please add a comment saying that we save DI to backfill DI->PDB70.Signature in Writer::writeBuildId.

================
Comment at: COFF/Writer.cpp:87
@@ +86,3 @@
+    DI->Signature.CVSignature = OMF::Signature::PDB70;
+    memset(DI->PDB70.Signature, 0, sizeof(DI->PDB70.Signature));
+    DI->PDB70.Age = 0;
----------------
It's a fresh file, so as long as you don't write anything, zeros are there, so this is a nop.

================
Comment at: COFF/Writer.cpp:98
@@ +97,3 @@
+public:
+  mutable codeview::DebugInfo *DI;
+
----------------
  DI = nullptr;

================
Comment at: COFF/Writer.cpp:807
@@ -798,1 +806,3 @@
 
+void Writer::writeBuildId() {
+  if (BuildId == nullptr)
----------------
Add a comment that why we have this (to fill CVSignature) and why we do this way (to get reproducible outputs.)


Repository:
  rL LLVM

https://reviews.llvm.org/D24404