Update discriminator assignment algorithm to handle nested call correctly.

[danielcdh]

Summary

Add discriminator for nested call correctly.

[dnovillo]

Looks much simpler. Thanks!

LGTM

lib/Transforms/Utils/AddDiscriminators.cpp

 // we can distinguish instructions at line 101 with discriminator 0 from
 // the instructions at line 101 with discriminator 1.
 //
 // For more details about DWARF discriminators, please visit
 // http://wiki.dwarfstd.org/index.php?title=Path_Discriminators
 //===----------------------------------------------------------------------===//
 
 #include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/DenseSet.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"
bool AddDiscriminators::runOnFunction(Function &F) {
   Module *M = F.getParent();
   LLVMContext &Ctx = M->getContext();
   DIBuilder Builder(*M, /*AllowUnresolved*/ false);
 
   typedef std::pair<StringRef, unsigned> Location;
   typedef DenseMap<const BasicBlock *, Metadata *> BBScopeMap;
   typedef DenseMap<Location, BBScopeMap> LocationBBMap;
   typedef DenseMap<Location, unsigned> LocationDiscriminatorMap;
+  typedef DenseSet<Location> LocationSet;
 
   LocationBBMap LBM;
   LocationDiscriminatorMap LDM;
 
   // Traverse all instructions in the function. If the source line location
   // of the instruction appears in other basic block, assign a new
   // discriminator for this instruction.
   for (BasicBlock &B : F) {
for (BasicBlock &B : 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 = nullptr;
+    LocationSet CallLocations;
     for (auto &I : B.getInstList()) {
       CallInst *Current = dyn_cast<CallInst>(&I);
       if (!Current || isa<DbgInfoIntrinsic>(&I))
         continue;
 
       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());
-          Location L =
-              std::make_pair(FirstDIL->getFilename(), FirstDIL->getLine());
-          auto *NewScope =
-              Builder.createLexicalBlockFile(Scope, File, ++LDM[L]);
-          Current->setDebugLoc(DILocation::get(
-              Ctx, CurrentDIL->getLine(), CurrentDIL->getColumn(), NewScope,
+          std::make_pair(CurrentDIL->getFilename(), CurrentDIL->getLine());
+      if (!CallLocations.insert(L).second) {
+        auto *Scope = CurrentDIL->getScope();
+        auto *File = Builder.createFile(CurrentDIL->getFilename(),
+                                        Scope->getDirectory());
+        auto *NewScope = Builder.createLexicalBlockFile(Scope, File, ++LDM[L]);
+        Current->setDebugLoc(DILocation::get(Ctx, CurrentDIL->getLine(),
+                                             CurrentDIL->getColumn(), NewScope,
                                              CurrentDIL->getInlinedAt()));
-          Changed = true;
-        } else {
-          FirstDIL = CurrentDIL;
-        }
-      } else {
-        FirstDIL = CurrentDIL;
       }
     }
   }
   return Changed;
 }

test/Transforms/AddDiscriminators/call-nested.ll

+; RUN: opt < %s -add-discriminators -S | FileCheck %s
+
+; Discriminator support for calls that are defined in one line:
+; #1 int foo(int, int);
+; #2 int bar();
+; #3 int baz() {
+; #4   return foo(bar(),
+; #5              bar());
+; #6 }
+
+; Function Attrs: uwtable
+define i32 @_Z3bazv() #0 !dbg !4 {
+  %1 = call i32 @_Z3barv(), !dbg !11
+; CHECK: %1 = call i32 @_Z3barv(), !dbg ![[CALL0:[0-9]+]]
+  %2 = call i32 @_Z3barv(), !dbg !12
+; CHECK: %2 = call i32 @_Z3barv(), !dbg ![[CALL1:[0-9]+]]
+  %3 = call i32 @_Z3fooii(i32 %1, i32 %2), !dbg !13
+; CHECK: %3 = call i32 @_Z3fooii(i32 %1, i32 %2), !dbg ![[CALL2:[0-9]+]]
+  ret i32 %3, !dbg !14
+}
+
+declare i32 @_Z3fooii(i32, i32) #1
+
+declare i32 @_Z3barv() #1
+
+attributes #0 = { uwtable "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+fxsr,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+fxsr,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!8, !9}
+!llvm.ident = !{!10}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 3.9.0 (trunk 266269)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, subprograms: !3)
+!1 = !DIFile(filename: "test.cc", directory: "")
+!2 = !{}
+!3 = !{!4}
+!4 = distinct !DISubprogram(name: "baz", linkageName: "_Z3bazv", scope: !1, file: !1, line: 3, type: !5, isLocal: false, isDefinition: true, scopeLine: 3, flags: DIFlagPrototyped, isOptimized: true, variables: !2)
+!5 = !DISubroutineType(types: !6)
+!6 = !{!7}
+!7 = !DIBasicType(name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
+!8 = !{i32 2, !"Dwarf Version", i32 4}
+!9 = !{i32 2, !"Debug Info Version", i32 3}
+!10 = !{!"clang version 3.9.0 (trunk 266269)"}
+!11 = !DILocation(line: 4, column: 14, scope: !4)
+!12 = !DILocation(line: 5, column: 14, scope: !4)
+!13 = !DILocation(line: 4, column: 10, scope: !4)
+!14 = !DILocation(line: 4, column: 3, scope: !4)
+
+; CHECK: ![[CALL2]] = !DILocation(line: 4, column: 10, scope: ![[CALL2BLOCK:[0-9]+]])
+; CHECK: ![[CALL2BLOCK]] = !DILexicalBlockFile({{.*}} discriminator: 1)