[PATCH] D84120: [Debuginfo] (8/N) Support for DW_OP_implicit_pointer for named and unnamed variables (second strategy).

[Jeremy Morse via Phabricator via llvm-commits]

jmorse added a comment.

I see what seem to be changes to codegen here (see inline comments), is that intentional? And if so, why is that needed for DW_OP_LLVM_explicit_pointer to work?



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Comment at: llvm/lib/IR/Metadata.cpp:395
   assert(From != To && "Expected changed value");
-  assert(From->getType() == To->getType() && "Unexpected type change");
 
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Why is this now permitted behaviour?


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Comment at: llvm/lib/Transforms/Scalar/EarlyCSE.cpp:1438-1443
+    auto Changed = CSE.run();
+    if (Changed) {
+      for (BasicBlock &BB : F)
+        RemoveRedundantDbgInstrs(&BB);
+    }
+    return Changed;
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Is this necessary for the implicit pointer work?


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Comment at: llvm/lib/Transforms/Scalar/SROA.cpp:4366
 }
 
+void SROA::salvageInstruction(Instruction *Ins) {
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Again, this block of code will need comments about its purpose adding.


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Comment at: llvm/lib/Transforms/Scalar/SROA.cpp:4396-4400
+      const uint64_t *Valptr = Offset.getRawData();
+      if ((AI = findFragmentAlloca(*Valptr))) {
+        Ins->replaceAllUsesWith(AI);
+        DeadInsts.insert(Ins);
+      }
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This part looks like it's changing the code generated, replacing a GEP with an alloca. If that's the case, IMO this should be split out into a different patch (one for codegen, one for debuginfo), as any codegen change will need an independent argument as to why it's a good idea.

Plus, this would only be a codegen change for people building with dwarf-5, which would mean you get different code with and without the -g option to clang.


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Comment at: llvm/lib/Transforms/Utils/PromoteMemoryToRegister.cpp:424
     SmallVector<DbgVariableIntrinsic *, 1> DbgUsers;
-    findDbgUsers(DbgUsers, AI);
+    AI->findDbgUsers(DbgUsers);
     for (auto *DII : DbgUsers) {
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This should be folded into the previous patch (7?)


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  https://reviews.llvm.org/D84120/new/

https://reviews.llvm.org/D84120