[llvm] r333866 - [Debugify] Add debug intrinsics before terminating musttail calls

[Vedant Kumar via llvm-commits]

Author: vedantk
Date: Sun Jun  3 20:33:01 2018
New Revision: 333866

URL: http://llvm.org/viewvc/llvm-project?rev=333866&view=rev
Log:
[Debugify] Add debug intrinsics before terminating musttail calls

After r333856, opt -debugify would just stop emitting debug value
intrinsics after encountering a musttail call. This wasn't sufficient to
avoid verifier failures.

Debug value intrinicss for all instructions preceding a musttail call
must also be emitted before the musttail call.

Modified:
    llvm/trunk/test/Transforms/InstCombine/musttail-thunk.ll
    llvm/trunk/tools/opt/Debugify.cpp

Modified: llvm/trunk/test/Transforms/InstCombine/musttail-thunk.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/musttail-thunk.ll?rev=333866&r1=333865&r2=333866&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/musttail-thunk.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/musttail-thunk.ll Sun Jun  3 20:33:01 2018
@@ -1,4 +1,5 @@
 ; RUN: opt -instcombine -S < %s | FileCheck %s
+; RUN: opt -debugify-each -instcombine -S < %s | FileCheck %s
 
 ; These are both direct calls, but make sure instcombine leaves the casts
 ; alone.

Modified: llvm/trunk/tools/opt/Debugify.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/opt/Debugify.cpp?rev=333866&r1=333865&r2=333866&view=diff
==============================================================================
--- llvm/trunk/tools/opt/Debugify.cpp (original)
+++ llvm/trunk/tools/opt/Debugify.cpp Sun Jun  3 20:33:01 2018
@@ -91,28 +91,32 @@ bool applyDebugifyMetadata(Module &M,
       if (BB.isEHPad())
         continue;
 
+      // Debug values must be inserted before a musttail call (if one is
+      // present), or before the block terminator otherwise.
+      Instruction *LastInst = BB.getTerminatingMustTailCall();
+      if (!LastInst)
+        LastInst = BB.getTerminator();
+
       // Attach debug values.
-      for (Instruction &I : BB) {
+      for (auto It = BB.begin(), End = LastInst->getIterator(); It != End;
+           ++It) {
+        Instruction &I = *It;
+
         // Skip void-valued instructions.
         if (I.getType()->isVoidTy())
           continue;
 
-        // Skip the terminator instruction and any just-inserted intrinsics.
-        if (isa<TerminatorInst>(&I) || isa<DbgValueInst>(&I))
+        // Skip any just-inserted intrinsics.
+        if (isa<DbgValueInst>(&I))
           break;
 
-        // Don't insert instructions after a musttail call.
-        if (auto *Call = dyn_cast<CallInst>(&I))
-          if (Call->isMustTailCall())
-            break;
-
         std::string Name = utostr(NextVar++);
         const DILocation *Loc = I.getDebugLoc().get();
         auto LocalVar = DIB.createAutoVariable(SP, Name, File, Loc->getLine(),
                                                getCachedDIType(I.getType()),
                                                /*AlwaysPreserve=*/true);
         DIB.insertDbgValueIntrinsic(&I, LocalVar, DIB.createExpression(), Loc,
-                                    BB.getTerminator());
+                                    LastInst);
       }
     }
     DIB.finalizeSubprogram(SP);