Fix line numbers for code inlined from __nodebug__ functions.

Instructions from __nodebug__ functions don't have file:line
information even when inlined into no-nodebug functions. As a result,
intrinsics (SSE and other) from <*intrin.h> clang headers _never_
have file:line information.

With this change, an instruction without !dbg metadata gets one from
the call instruction when inlined.

Fixes PR19001.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210459 91177308-0d34-0410-b5e6-96231b3b80d8

Author: eugenis

lib/Transforms/Utils/InlineFunction.cpp

@@ -466,7 +466,13 @@ static void fixupLineNumbers(Function *Fn, Function::iterator FI,
     for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
          BI != BE; ++BI) {
       DebugLoc DL = BI->getDebugLoc();
-      if (!DL.isUnknown()) {
+      if (DL.isUnknown()) {
+        // If the inlined instruction has no line number, make it look as if it
+        // originates from the call location. This is important for
+        // ((__always_inline__, __nodebug__)) functions which must use caller
+        // location for all instructions in their function body.
+        BI->setDebugLoc(TheCallDL);
+      } else {
         BI->setDebugLoc(updateInlinedAtInfo(DL, TheCallDL, BI->getContext()));
         if (DbgValueInst *DVI = dyn_cast<DbgValueInst>(BI)) {
           LLVMContext &Ctx = BI->getContext();

test/DebugInfo/inline-no-debug-info.ll

@@ -0,0 +1,69 @@
+; RUN: opt < %s -inline -S | FileCheck %s
+
+; This was generated from the following source:
+; int a, b;
+; __attribute__((__always_inline__)) static void callee2() { b = 2; }
+; __attribute__((__nodebug__)) void callee() { a = 1; callee2(); }
+; void caller() { callee(); }
+; by running
+;   clang -S test.c -emit-llvm -O1 -gline-tables-only -fno-strict-aliasing
+
+; CHECK-LABEL: @caller(
+
+; This instruction did not have a !dbg metadata in the callee.
+; CHECK: store i32 1, {{.*}}, !dbg [[A:!.*]]
+
+; This instruction came from callee with a !dbg metadata.
+; CHECK: store i32 2, {{.*}}, !dbg [[B:!.*]]
+
+; The remaining instruction from the caller.
+; CHECK: ret void, !dbg [[A]]
+
+; Debug location of the code in caller() and of the inlined code that did not
+; have any debug location before.
+; CHECK-DAG: [[A]] = metadata !{i32 4, i32 0, metadata !{{[01-9]+}}, null}
+
+; Debug location of the inlined code.
+; CHECK-DAG: [[B]] = metadata !{i32 2, i32 0, metadata !{{[01-9]+}}, metadata !{{[01-9]+}}}
+
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+@a = common global i32 0, align 4
+@b = common global i32 0, align 4
+
+; Function Attrs: nounwind uwtable
+define void @callee() #0 {
+entry:
+  store i32 1, i32* @a, align 4
+  store i32 2, i32* @b, align 4, !dbg !11
+  ret void
+}
+
+; Function Attrs: nounwind uwtable
+define void @caller() #0 {
+entry:
+  tail call void @callee(), !dbg !12
+  ret void, !dbg !12
+}
+
+attributes #0 = { nounwind uwtable "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!8, !9}
+!llvm.ident = !{!10}
+
+!0 = metadata !{i32 786449, metadata !1, i32 12, metadata !"clang version 3.5.0 (210174)", i1 true, metadata !"", i32 0, metadata !2, metadata !2, metadata !3, metadata !2, metadata !2, metadata !"", i32 2} ; [ DW_TAG_compile_unit ] [/code/llvm/build0/test.c] [DW_LANG_C99]
+!1 = metadata !{metadata !"test.c", metadata !"/code/llvm/build0"}
+!2 = metadata !{}
+!3 = metadata !{metadata !4, metadata !7}
+!4 = metadata !{i32 786478, metadata !1, metadata !5, metadata !"caller", metadata !"caller", metadata !"", i32 4, metadata !6, i1 false, i1 true, i32 0, i32 0, null, i32 0, i1 true, void ()* @caller, null, null, metadata !2, i32 4} ; [ DW_TAG_subprogram ] [line 4] [def] [caller]
+!5 = metadata !{i32 786473, metadata !1}          ; [ DW_TAG_file_type ] [/code/llvm/build0/test.c]
+!6 = metadata !{i32 786453, i32 0, null, metadata !"", i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !2, i32 0, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
+!7 = metadata !{i32 786478, metadata !1, metadata !5, metadata !"callee2", metadata !"callee2", metadata !"", i32 2, metadata !6, i1 true, i1 true, i32 0, i32 0, null, i32 0, i1 true, null, null, null, metadata !2, i32 2} ; [ DW_TAG_subprogram ] [line 2] [local] [def] [callee2]
+!8 = metadata !{i32 2, metadata !"Dwarf Version", i32 4}
+!9 = metadata !{i32 2, metadata !"Debug Info Version", i32 1}
+!10 = metadata !{metadata !"clang version 3.5.0 (210174)"}
+!11 = metadata !{i32 2, i32 0, metadata !7, null}
+!12 = metadata !{i32 4, i32 0, metadata !4, null}