[PATCH] D44223: [ms] Emit vtordisp initializers in a deterministic order.

[Nico Weber via Phabricator via cfe-commits]

thakis updated this revision to Diff 137463.
thakis added a comment.
Herald added a subscriber: mgrang.

sort unstably


https://reviews.llvm.org/D44223

Files:
  lib/CodeGen/MicrosoftCXXABI.cpp


Index: lib/CodeGen/MicrosoftCXXABI.cpp
===================================================================
--- lib/CodeGen/MicrosoftCXXABI.cpp
+++ lib/CodeGen/MicrosoftCXXABI.cpp
@@ -1196,15 +1196,21 @@
   unsigned AS = getThisAddress(CGF).getAddressSpace();
   llvm::Value *Int8This = nullptr;  // Initialize lazily.
 
-  for (VBOffsets::const_iterator I = VBaseMap.begin(), E = VBaseMap.end();
-        I != E; ++I) {
-    if (!I->second.hasVtorDisp())
+  // Emit vtordisps in vbase offset order, to have deterministic output.
+  typedef VBOffsets::value_type VBase;
+  SmallVector<VBase, 4> VBases(VBaseMap.begin(), VBaseMap.end());
+  std::sort(VBases.begin(), VBases.end(), [](const VBase &a, const VBase &b) {
+    return a.second.VBaseOffset < b.second.VBaseOffset;
+  });
+
+  for (const VBase &V : VBases) {
+    if (!V.second.hasVtorDisp())
       continue;
 
     llvm::Value *VBaseOffset =
-        GetVirtualBaseClassOffset(CGF, getThisAddress(CGF), RD, I->first);
+        GetVirtualBaseClassOffset(CGF, getThisAddress(CGF), RD, V.first);
     uint64_t ConstantVBaseOffset =
-        Layout.getVBaseClassOffset(I->first).getQuantity();
+        Layout.getVBaseClassOffset(V.first).getQuantity();
 
     // vtorDisp_for_vbase = vbptr[vbase_idx] - offsetof(RD, vbase).
     llvm::Value *VtorDispValue = Builder.CreateSub(



Index: lib/CodeGen/MicrosoftCXXABI.cpp
===================================================================
--- lib/CodeGen/MicrosoftCXXABI.cpp
+++ lib/CodeGen/MicrosoftCXXABI.cpp
@@ -1196,15 +1196,21 @@
   unsigned AS = getThisAddress(CGF).getAddressSpace();
   llvm::Value *Int8This = nullptr;  // Initialize lazily.
 
-  for (VBOffsets::const_iterator I = VBaseMap.begin(), E = VBaseMap.end();
-        I != E; ++I) {
-    if (!I->second.hasVtorDisp())
+  // Emit vtordisps in vbase offset order, to have deterministic output.
+  typedef VBOffsets::value_type VBase;
+  SmallVector<VBase, 4> VBases(VBaseMap.begin(), VBaseMap.end());
+  std::sort(VBases.begin(), VBases.end(), [](const VBase &a, const VBase &b) {
+    return a.second.VBaseOffset < b.second.VBaseOffset;
+  });
+
+  for (const VBase &V : VBases) {
+    if (!V.second.hasVtorDisp())
       continue;
 
     llvm::Value *VBaseOffset =
-        GetVirtualBaseClassOffset(CGF, getThisAddress(CGF), RD, I->first);
+        GetVirtualBaseClassOffset(CGF, getThisAddress(CGF), RD, V.first);
     uint64_t ConstantVBaseOffset =
-        Layout.getVBaseClassOffset(I->first).getQuantity();
+        Layout.getVBaseClassOffset(V.first).getQuantity();
 
     // vtorDisp_for_vbase = vbptr[vbase_idx] - offsetof(RD, vbase).
     llvm::Value *VtorDispValue = Builder.CreateSub(

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