[CodeExtractor] Add debug locations for new call and branch instrs.

Summary:
If a partially inlined function has debug info, we have to add debug
locations to the call instruction calling the outlined function.
We use the debug location of the first instruction in the outlined
function, as the introduced call transfers control to this statement and
there is no other equivalent line in the source code.

We also use the same debug location for the branch instruction added
to jump from artificial entry block for the outlined function, which just
jumps to the first actual basic block of the outlined function.

Reviewers: davide, aprantl, rriddle, dblaikie, danielcdh, wmi

Reviewed By: aprantl, rriddle, danielcdh

Subscribers: eraman, JDevlieghere, llvm-commits

Differential Revision: https://reviews.llvm.org/D40413

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@320199 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/Utils/CodeExtractor.cpp

@@ -746,6 +746,14 @@ emitCallAndSwitchStatement(Function *newFunction, BasicBlock *codeReplacer,
   // Emit the call to the function
   CallInst *call = CallInst::Create(newFunction, params,
                                     NumExitBlocks > 1 ? "targetBlock" : "");
+  // Add debug location to the new call, if the original function has debug
+  // info. In that case, the terminator of the entry block of the extracted
+  // function contains the first debug location of the extracted function,
+  // set in extractCodeRegion.
+  if (codeReplacer->getParent()->getSubprogram()) {
+    if (auto DL = newFunction->getEntryBlock().getTerminator()->getDebugLoc())
+      call->setDebugLoc(DL);
+  }
   codeReplacer->getInstList().push_back(call);
 
   Function::arg_iterator OutputArgBegin = newFunction->arg_begin();
@@ -1023,7 +1031,22 @@ Function *CodeExtractor::extractCodeRegion() {
   // head of the region, but the entry node of a function cannot have preds.
   BasicBlock *newFuncRoot = BasicBlock::Create(header->getContext(), 
                                                "newFuncRoot");
-  newFuncRoot->getInstList().push_back(BranchInst::Create(header));
+  auto *BranchI = BranchInst::Create(header);
+  // If the original function has debug info, we have to add a debug location
+  // to the new branch instruction from the artificial entry block.
+  // We use the debug location of the first instruction in the extracted
+  // blocks, as there is no other equivalent line in the source code.
+  if (oldFunction->getSubprogram()) {
+    any_of(Blocks, [&BranchI](const BasicBlock *BB) {
+      return any_of(*BB, [&BranchI](const Instruction &I) {
+        if (!I.getDebugLoc())
+          return false;
+        BranchI->setDebugLoc(I.getDebugLoc());
+        return true;
+      });
+    });
+  }
+  newFuncRoot->getInstList().push_back(BranchI);
 
   findAllocas(SinkingCands, HoistingCands, CommonExit);
   assert(HoistingCands.empty() || CommonExit);

test/Transforms/CodeExtractor/PartialInlineDebug.ll

@@ -0,0 +1,104 @@
+; RUN: opt < %s -S -partial-inliner -skip-partial-inlining-cost-analysis=true | FileCheck %s
+
+; CHECK-LABEL: @callee
+; CHECK: %mul = mul nsw i32 %v, 10, !dbg ![[DBG1:[0-9]+]]
+define i32 @callee(i32 %v) !dbg !16 {
+entry:
+  %cmp = icmp sgt i32 %v, 2000
+  br i1 %cmp, label %if.then, label %if.end
+
+if.then:                                          ; preds = %entry
+  %mul = mul nsw i32 %v, 10, !dbg !17
+  br label %if.then2
+
+if.then2:
+  %sub = sub i32 %v, 10, !dbg !23
+  br label %if.end
+
+if.end:                                           ; preds = %if.then, %entry
+  %v2 = phi i32 [ %v, %entry ], [ %mul, %if.then2 ]
+  %add = add nsw i32 %v2, 200
+  ret i32 %add
+}
+
+; CHECK-LABEL: @caller
+; CHECK: codeRepl.i:
+; CHECK-NEXT: call void @callee.2_if.then(i32 %v, i32* %mul.loc.i), !dbg ![[DBG2:[0-9]+]]
+define i32 @caller(i32 %v) !dbg !8 {
+entry:
+  %call = call i32 @callee(i32 %v), !dbg !14
+  ret i32 %call
+}
+
+
+; CHECK-LABEL: @callee2
+; CHECK: %sub = sub i32 %v, 10, !dbg ![[DBG3:[0-9]+]]
+define i32 @callee2(i32 %v) !dbg !18 {
+entry:
+  %cmp = icmp sgt i32 %v, 2000
+  br i1 %cmp, label %if.then, label %if.end
+
+if.then:
+  br label %if.then2
+
+if.then2:
+  %sub = sub i32 %v, 10, !dbg !20
+  br label %if.end
+
+if.end:
+  %v2 = phi i32 [ %v, %entry ], [ %sub, %if.then2 ]
+  %add = add nsw i32 %v2, 200
+  ret i32 %add
+}
+
+; CHECK-LABEL: @caller2
+; CHECK: codeRepl.i:
+; CHECK-NEXT: call void @callee2.1_if.then(i32 %v, i32* %sub.loc.i), !dbg ![[DBG4:[0-9]+]]
+define i32 @caller2(i32 %v) !dbg !21 {
+entry:
+  %call = call i32 @callee2(i32 %v), !dbg !22
+  ret i32 %call
+}
+
+; CHECK-LABEL: define internal void @callee2.1_if.then
+; CHECK: br label %if.then, !dbg ![[DBG5:[0-9]+]]
+
+; CHECK-LABEL: define internal void @callee.2_if.then
+; CHECK: br label %if.then, !dbg ![[DBG6:[0-9]+]]
+
+; CHECK: ![[DBG1]] = !DILocation(line: 10, column: 7,
+; CHECK: ![[DBG2]] = !DILocation(line: 10, column: 7,
+; CHECK: ![[DBG3]] = !DILocation(line: 110, column: 17,
+; CHECK: ![[DBG4]] = !DILocation(line: 110, column: 17,
+; CHECK: ![[DBG5]] = !DILocation(line: 110, column: 17,
+; CHECK: ![[DBG6]] = !DILocation(line: 10, column: 7,
+
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4, !5, !6}
+!llvm.ident = !{!7}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 6.0.0 (trunk 177881)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
+!1 = !DIFile(filename: "test.c", directory: "/tmp")
+!2 = !{}
+!3 = !{i32 2, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{i32 1, !"wchar_size", i32 4}
+!6 = !{i32 1, !"min_enum_size", i32 4}
+!7 = !{!"clang version 6.0.0"}
+!8 = distinct !DISubprogram(name: "caller", scope: !1, file: !1, line: 3, type: !9, isLocal: false, isDefinition: true, scopeLine: 3, flags: DIFlagPrototyped, isOptimized: true, unit: !0, variables: !12)
+!9 = !DISubroutineType(types: !10)
+!10 = !{!11, !11}
+!11 = !DIBasicType(name: "int", size: 19, encoding: DW_ATE_signed)
+!12 = !{!13}
+!13 = !DILocalVariable(name: "v", arg: 1, scope: !8, file: !1, line: 3, type: !11)
+!14 = !DILocation(line: 5, column: 10, scope: !8)
+!15 = distinct !DILexicalBlock(scope: !16, file: !1, line: 9, column: 7)
+!16 = distinct !DISubprogram(name: "callee", scope: !1, file: !1, line: 8, type: !9, isLocal: false, isDefinition: true, scopeLine: 8, flags: DIFlagPrototyped, isOptimized: true, unit: !0, variables: !12)
+!17 = !DILocation(line: 10, column: 7, scope: !15)
+!18 = distinct !DISubprogram(name: "callee2", scope: !1, file: !1, line: 8, type: !9, isLocal: false, isDefinition: true, scopeLine: 8, flags: DIFlagPrototyped, isOptimized: true, unit: !0, variables: !12)
+!19 = distinct !DILexicalBlock(scope: !18, file: !1, line: 100, column: 1)
+!20 = !DILocation(line: 110, column: 17, scope: !19)
+!21 = distinct !DISubprogram(name: "caller2", scope: !1, file: !1, line: 8, type: !9, isLocal: false, isDefinition: true, scopeLine: 8, flags: DIFlagPrototyped, isOptimized: true, unit: !0, variables: !12)
+!22 = !DILocation(line: 110, column: 17, scope: !21)
+!23 = !DILocation(line: 15, column: 7, scope: !15)