From fb972e9c09422f988eb278883e5bde2da58b0f04 Mon Sep 17 00:00:00 2001
From: Dehao Chen <dehao@google.com>
Date: Fri, 30 Oct 2015 04:29:05 +0000
Subject: [PATCH] Revert r251680:

Update the discriminator assignment algorithm

* If a scope has already been assigned a discriminator, do not reassign a nested discriminator for it.
* If the file and line both match, even if the column does not match, we should assign a new discriminator for the stmt.

original code:
; #1 int foo(int i) {
; #2 if (i == 3 || i == 5) return 100; else return 99;
; #3 }

; i == 3: discriminator 0
; i == 5: discriminator 2
; return 100: discriminator 1
; return 99: discriminator 3

llvm-svn: 251685
---
 lib/Transforms/Utils/AddDiscriminators.cpp   | 23 +++--
 test/Transforms/AddDiscriminators/oneline.ll | 98 --------------------
 2 files changed, 11 insertions(+), 110 deletions(-)

diff --git a/lib/Transforms/Utils/AddDiscriminators.cpp b/lib/Transforms/Utils/AddDiscriminators.cpp
index 1a101879d26..34c2f4525ea 100644
--- a/lib/Transforms/Utils/AddDiscriminators.cpp
+++ b/lib/Transforms/Utils/AddDiscriminators.cpp
@@ -180,7 +180,7 @@ bool AddDiscriminators::runOnFunction(Function &F) {
       BasicBlock *Succ = Last->getSuccessor(I);
       Instruction *First = Succ->getFirstNonPHIOrDbgOrLifetime();
       const DILocation *FirstDIL = First->getDebugLoc();
-      if (!FirstDIL || FirstDIL->getDiscriminator())
+      if (!FirstDIL)
         continue;
 
       // If the first instruction (First) of Succ is at the same file
@@ -202,22 +202,21 @@ bool AddDiscriminators::runOnFunction(Function &F) {
         unsigned Discriminator = FirstDIL->computeNewDiscriminator();
         auto *NewScope =
             Builder.createLexicalBlockFile(Scope, File, Discriminator);
+        auto *NewDIL =
+            DILocation::get(Ctx, FirstDIL->getLine(), FirstDIL->getColumn(),
+                            NewScope, FirstDIL->getInlinedAt());
+        DebugLoc newDebugLoc = NewDIL;
 
         // Attach this new debug location to First and every
         // instruction following First that shares the same location.
         for (BasicBlock::iterator I1(*First), E1 = Succ->end(); I1 != E1;
              ++I1) {
-          const DILocation *CurrentDIL = I1->getDebugLoc();
-          if (CurrentDIL && CurrentDIL->getLine() == FirstDIL->getLine() &&
-              CurrentDIL->getFilename() == FirstDIL->getFilename()) {
-            I1->setDebugLoc(DILocation::get(Ctx, CurrentDIL->getLine(),
-                                            CurrentDIL->getColumn(), NewScope,
-                                            CurrentDIL->getInlinedAt()));
-            DEBUG(dbgs() << CurrentDIL->getFilename() << ":"
-                         << CurrentDIL->getLine() << ":"
-                         << CurrentDIL->getColumn() << ":"
-                         << CurrentDIL->getDiscriminator() << *I1 << "\n");
-          }
+          if (I1->getDebugLoc().get() != FirstDIL)
+            break;
+          I1->setDebugLoc(newDebugLoc);
+          DEBUG(dbgs() << NewDIL->getFilename() << ":" << NewDIL->getLine()
+                       << ":" << NewDIL->getColumn() << ":"
+                       << NewDIL->getDiscriminator() << *I1 << "\n");
         }
         DEBUG(dbgs() << "\n");
         Changed = true;
diff --git a/test/Transforms/AddDiscriminators/oneline.ll b/test/Transforms/AddDiscriminators/oneline.ll
index dcad5ae9176..e69de29bb2d 100644
--- a/test/Transforms/AddDiscriminators/oneline.ll
+++ b/test/Transforms/AddDiscriminators/oneline.ll
@@ -1,98 +0,0 @@
-; RUN: opt < %s -add-discriminators -S | FileCheck %s
-
-; Discriminator support for code that is written in one line:
-; #1 int foo(int i) {
-; #2   if (i == 3 || i == 5) return 100; else return 99;
-; #3 }
-
-; i == 3:     discriminator 0
-; i == 5:     discriminator 2
-; return 100: discriminator 1
-; return 99:  discriminator 3
-
-define i32 @_Z3fooi(i32 %i) #0 {
-  %1 = alloca i32, align 4
-  %2 = alloca i32, align 4
-  store i32 %i, i32* %2, align 4, !tbaa !13
-  call void @llvm.dbg.declare(metadata i32* %2, metadata !9, metadata !17), !dbg !18
-  %3 = load i32, i32* %2, align 4, !dbg !19, !tbaa !13
-  %4 = icmp eq i32 %3, 3, !dbg !21
-  br i1 %4, label %8, label %5, !dbg !22
-
-; <label>:5                                       ; preds = %0
-  %6 = load i32, i32* %2, align 4, !dbg !23, !tbaa !13
-; CHECK:  %6 = load i32, i32* %2, align 4, !dbg ![[THEN1:[0-9]+]],{{.*}}
-
-  %7 = icmp eq i32 %6, 5, !dbg !24
-; CHECK:  %7 = icmp eq i32 %6, 5, !dbg ![[THEN2:[0-9]+]]
-
-  br i1 %7, label %8, label %9, !dbg !25
-; CHECK:  br i1 %7, label %8, label %9, !dbg ![[THEN3:[0-9]+]]
-
-; <label>:8                                       ; preds = %5, %0
-  store i32 100, i32* %1, align 4, !dbg !26
-; CHECK: store i32 100, i32* %1, align 4, !dbg ![[ELSE:[0-9]+]]
-
-  br label %10, !dbg !26
-; CHECK: br label %10, !dbg ![[ELSE]]
-
-; <label>:9                                       ; preds = %5
-  store i32 99, i32* %1, align 4, !dbg !27
-; CHECK: store i32 99, i32* %1, align 4, !dbg ![[COMBINE:[0-9]+]]
-
-  br label %10, !dbg !27
-; CHECK: br label %10, !dbg ![[COMBINE]]
-
-; <label>:10                                      ; preds = %9, %8
-  %11 = load i32, i32* %1, align 4, !dbg !28
-  ret i32 %11, !dbg !28
-}
-
-; Function Attrs: nounwind readnone
-declare void @llvm.dbg.declare(metadata, metadata, metadata) #1
-
-attributes #0 = { nounwind uwtable "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" "unsafe-fp-math"="false" "use-soft-float"="false" }
-attributes #1 = { nounwind readnone }
-
-!llvm.dbg.cu = !{!0}
-!llvm.module.flags = !{!10, !11}
-!llvm.ident = !{!12}
-
-!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 3.8.0 (trunk 250915)", isOptimized: true, runtimeVersion: 0, emissionKind: 1, enums: !2, subprograms: !3)
-!1 = !DIFile(filename: "a.cc", directory: "/usr/local/google/home/dehao/discr")
-!2 = !{}
-!3 = !{!4}
-!4 = distinct !DISubprogram(name: "foo", linkageName: "_Z3fooi", scope: !1, file: !1, line: 1, type: !5, isLocal: false, isDefinition: true, scopeLine: 1, flags: DIFlagPrototyped, isOptimized: true, function: i32 (i32)* @_Z3fooi, variables: !8)
-!5 = !DISubroutineType(types: !6)
-!6 = !{!7, !7}
-!7 = !DIBasicType(name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
-!8 = !{!9}
-!9 = !DILocalVariable(name: "i", arg: 1, scope: !4, file: !1, line: 1, type: !7)
-!10 = !{i32 2, !"Dwarf Version", i32 4}
-!11 = !{i32 2, !"Debug Info Version", i32 3}
-!12 = !{!"clang version 3.8.0 (trunk 250915)"}
-!13 = !{!14, !14, i64 0}
-!14 = !{!"int", !15, i64 0}
-!15 = !{!"omnipotent char", !16, i64 0}
-!16 = !{!"Simple C/C++ TBAA"}
-!17 = !DIExpression()
-!18 = !DILocation(line: 1, column: 13, scope: !4)
-!19 = !DILocation(line: 2, column: 7, scope: !20)
-!20 = distinct !DILexicalBlock(scope: !4, file: !1, line: 2, column: 7)
-!21 = !DILocation(line: 2, column: 9, scope: !20)
-!22 = !DILocation(line: 2, column: 14, scope: !20)
-!23 = !DILocation(line: 2, column: 17, scope: !20)
-!24 = !DILocation(line: 2, column: 19, scope: !20)
-!25 = !DILocation(line: 2, column: 7, scope: !4)
-!26 = !DILocation(line: 2, column: 25, scope: !20)
-!27 = !DILocation(line: 2, column: 42, scope: !20)
-!28 = !DILocation(line: 3, column: 1, scope: !4)
-
-; CHECK: ![[THEN1]] = !DILocation(line: 2, column: 17, scope: ![[THENBLOCK:[0-9]+]])
-; CHECK: ![[THENBLOCK]] = !DILexicalBlockFile({{.*}} discriminator: 2)
-; CHECK: ![[THEN2]] = !DILocation(line: 2, column: 19, scope: ![[THENBLOCK]])
-; CHECK: ![[THEN3]] = !DILocation(line: 2, column: 7, scope: ![[THENBLOCK]])
-; CHECK: ![[ELSE]] = !DILocation(line: 2, column: 25, scope: ![[ELSEBLOCK:[0-9]+]])
-; CHECK: ![[ELSEBLOCK]] = !DILexicalBlockFile({{.*}} discriminator: 1)
-; CHECK: ![[COMBINE]] = !DILocation(line: 2, column: 42, scope: ![[COMBINEBLOCK:[0-9]+]])
-; CHECK: ![[COMBINEBLOCK]] = !DILexicalBlockFile({{.*}} discriminator: 3)