Don't generate discriminators for calls to debug intrinsics

[labath]

Summary

This fails a check in Verifier.cpp, which checks for location matches between the declared
variable and the !dbg attachments.

[dnovillo]

LGTM. Thanks for the fix.

lib/Transforms/Utils/AddDiscriminators.cpp

 //===----------------------------------------------------------------------===//
 
 #include "llvm/Transforms/Scalar.h"
 #include "llvm/IR/BasicBlock.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/DIBuilder.h"
 #include "llvm/IR/DebugInfo.h"
 #include "llvm/IR/Instructions.h"
+#include "llvm/IR/IntrinsicInst.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/Module.h"
 #include "llvm/Pass.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"
 
 using namespace llvm;
bool AddDiscriminators::runOnFunction(Function &F) {
   // Traverse all instructions and assign new discriminators to call
   // instructions with the same lineno that are in the same basic block.
   // Sample base profile needs to distinguish different function calls within
   // a same source line for correct profile annotation.
   for (BasicBlock &B : F) {
     const DILocation *FirstDIL = NULL;
     for (auto &I : B.getInstList()) {
       CallInst *Current = dyn_cast<CallInst>(&I);
-      if (Current) {
-        DILocation *CurrentDIL = Current->getDebugLoc();
-        if (FirstDIL) {
-          if (CurrentDIL && CurrentDIL->getLine() == FirstDIL->getLine() &&
-              CurrentDIL->getFilename() == FirstDIL->getFilename()) {
-            auto *Scope = FirstDIL->getScope();
-            auto *File = Builder.createFile(FirstDIL->getFilename(),
-                                            Scope->getDirectory());
-            auto *NewScope = Builder.createLexicalBlockFile(
-                Scope, File, FirstDIL->computeNewDiscriminator());
-            Current->setDebugLoc(DILocation::get(
-                Ctx, CurrentDIL->getLine(), CurrentDIL->getColumn(), NewScope,
-                CurrentDIL->getInlinedAt()));
-            Changed = true;
-          } else {
-            FirstDIL = CurrentDIL;
-          }
-        } else {
-          FirstDIL = CurrentDIL;
-        }
-      }
-    }
-  }
+      if (!Current || isa<DbgInfoIntrinsic>(&I))
+        continue;
+
   return Changed;
 }

test/Transforms/AddDiscriminators/dbg-declare-discriminator.ll

+; RUN: opt -S -add-discriminators < %s | FileCheck %s
+
+declare void @llvm.dbg.declare(metadata, metadata, metadata)
+
+; This checks whether the add-discriminators pass producess valid metadata on
+; llvm.dbg.declare instructions
+;
+; CHECK-LABEL: @test_valid_metadata
+define void @test_valid_metadata() {
+  %a = alloca i8
+  call void @llvm.dbg.declare(metadata i8* %a, metadata !2, metadata !5), !dbg !6
+  %b = alloca i8
+  call void @llvm.dbg.declare(metadata i8* %b, metadata !9, metadata !5), !dbg !11
+  ret void
+}
+
+!llvm.module.flags = !{!0, !1}
+
+!0 = !{i32 2, !"Dwarf Version", i32 4}
+!1 = !{i32 2, !"Debug Info Version", i32 3}
+!2 = !DILocalVariable(scope: !3)
+!3 = distinct !DISubprogram(scope: null, file: !4, isLocal: false, isDefinition: true, isOptimized: false)
+!4 = !DIFile(filename: "a.cpp", directory: "/tmp")
+!5 = !DIExpression()
+!6 = !DILocation(line: 0, scope: !3, inlinedAt: !7)
+!7 = distinct !DILocation(line: 0, scope: !8)
+!8 = distinct !DISubprogram(linkageName: "test_valid_metadata", scope: null, isLocal: false, isDefinition: true, isOptimized: false)
+!9 = !DILocalVariable(scope: !10)
+!10 = distinct !DISubprogram(scope: null, file: !4, isLocal: false, isDefinition: true, isOptimized: false)
+!11 = !DILocation(line: 0, scope: !10)