Debug info: Teach SROA how to update debug info for fragmented variables.

This allows us to generate debug info for extremely advanced code such as

  typedef struct { long int a; int b;} S;

  int foo(S s) {
    return s.b;
  }

which at -O1 on x86_64 is codegen'd into

  define i32 @foo(i64 %s.coerce0, i32 %s.coerce1) #0 {
    ret i32 %s.coerce1, !dbg !24
  }

with this patch we emit the following debug info for this

  TAG_formal_parameter [3]
    AT_location( 0x00000000
                 0x0000000000000000 - 0x0000000000000006: rdi, piece 0x00000008, rsi, piece 0x00000004
                 0x0000000000000006 - 0x0000000000000008: rdi, piece 0x00000008, rax, piece 0x00000004 )
                 AT_name( "s" )
                 AT_decl_file( "/Volumes/Data/llvm/_build.ninja.release/test.c" )

Thanks to chandlerc, dblaikie, and echristo for their feedback on all
previous iterations of this patch!

llvm-svn: 224739

1 files changed, 102 insertions, 0 deletions

diff --git a/llvm/test/DebugInfo/X86/sroasplit-2.ll b/llvm/test/DebugInfo/X86/sroasplit-2.ll
new file mode 100644
index 00000000000..4e68d0c9561
--- /dev/null
+++ b/llvm/test/DebugInfo/X86/sroasplit-2.ll
@@ -0,0 +1,102 @@
+; RUN: opt %s -sroa -verify -S -o - | FileCheck %s
+;
+; Test that we can partial emit debug info for aggregates repeatedly
+; split up by SROA.
+;
+;    // Compile with -O1
+;    typedef struct {
+;      int a;
+;      int b;
+;    } Inner;
+;
+;    typedef struct {
+;      Inner inner[2];
+;    } Outer;
+;
+;    int foo(Outer outer) {
+;      Inner i1 = outer.inner[1];
+;      return i1.a;
+;    }
+;
+
+; Verify that SROA creates a variable piece when splitting i1.
+; CHECK:  call void @llvm.dbg.value(metadata i64 %outer.coerce0, i64 0, metadata ![[O:[0-9]+]], metadata ![[PIECE1:[0-9]+]]),
+; CHECK:  call void @llvm.dbg.value(metadata i64 %outer.coerce1, i64 0, metadata ![[O]], metadata ![[PIECE2:[0-9]+]]),
+; CHECK:  call void @llvm.dbg.value({{.*}}, i64 0, metadata ![[I1:[0-9]+]], metadata ![[PIECE3:[0-9]+]]),
+; CHECK-DAG: ![[O]] = {{.*}} [ DW_TAG_arg_variable ] [outer] [line 10]
+; CHECK-DAG: ![[PIECE1]] = {{.*}} [ DW_TAG_expression ] [DW_OP_piece offset=0, size=8]
+; CHECK-DAG: ![[PIECE2]] = {{.*}} [ DW_TAG_expression ] [DW_OP_piece offset=8, size=8]
+; CHECK-DAG: ![[I1]] = {{.*}} [ DW_TAG_auto_variable ] [i1] [line 11]
+; CHECK-DAG: ![[PIECE3]] = {{.*}} [ DW_TAG_expression ] [DW_OP_piece offset=0, size=4]
+
+; ModuleID = 'sroasplit-2.c'
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.9.0"
+
+%struct.Outer = type { [2 x %struct.Inner] }
+%struct.Inner = type { i32, i32 }
+
+; Function Attrs: nounwind ssp uwtable
+define i32 @foo(i64 %outer.coerce0, i64 %outer.coerce1) #0 {
+  %outer = alloca %struct.Outer, align 8
+  %i1 = alloca %struct.Inner, align 4
+  %1 = bitcast %struct.Outer* %outer to { i64, i64 }*
+  %2 = getelementptr { i64, i64 }* %1, i32 0, i32 0
+  store i64 %outer.coerce0, i64* %2
+  %3 = getelementptr { i64, i64 }* %1, i32 0, i32 1
+  store i64 %outer.coerce1, i64* %3
+  call void @llvm.dbg.declare(metadata %struct.Outer* %outer, metadata !24, metadata !2), !dbg !25
+  call void @llvm.dbg.declare(metadata %struct.Inner* %i1, metadata !26, metadata !2), !dbg !27
+  %4 = getelementptr inbounds %struct.Outer* %outer, i32 0, i32 0, !dbg !27
+  %5 = getelementptr inbounds [2 x %struct.Inner]* %4, i32 0, i64 1, !dbg !27
+  %6 = bitcast %struct.Inner* %i1 to i8*, !dbg !27
+  %7 = bitcast %struct.Inner* %5 to i8*, !dbg !27
+  call void @llvm.memcpy.p0i8.p0i8.i64(i8* %6, i8* %7, i64 8, i32 4, i1 false), !dbg !27
+  %8 = getelementptr inbounds %struct.Inner* %i1, i32 0, i32 0, !dbg !28
+  %9 = load i32* %8, align 4, !dbg !28
+  ret i32 %9, !dbg !28
+}
+
+; Function Attrs: nounwind readnone
+declare void @llvm.dbg.declare(metadata, metadata, metadata) #1
+
+; Function Attrs: nounwind
+declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture, i8* nocapture readonly, i64, i32, i1) #2
+
+attributes #0 = { nounwind ssp uwtable "no-frame-pointer-elim"="true" }
+attributes #1 = { nounwind readnone }
+attributes #2 = { nounwind }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!21, !22}
+!llvm.ident = !{!23}
+
+!0 = !{!"0x11\0012\00clang version 3.5.0 \000\00\000\00\001", !1, !2, !2, !3, !2, !2} ; [ DW_TAG_compile_unit ] [ DW_TAG_compile_unit ] [sroasplit-2.c] [DW_LANG_C99]
+!1 = !{!"sroasplit-2.c", !""}
+!2 = !{}
+!3 = !{!4}
+!4 = !{!"0x2e\00foo\00foo\00\0010\000\001\000\006\00256\000\0010", !1, !5, !6, null, i32 (i64, i64)* @foo, null, null, !2} ; [ DW_TAG_subprogram ] [ DW_TAG_subprogram ] [line 10] [def] [foo]
+!5 = !{!"0x29", !1} ; [ DW_TAG_file_type ] [ DW_TAG_file_type ] [sroasplit-2.c]
+!6 = !{!"0x15\00\000\000\000\000\000\000", i32 0, null, null, !7, null, null, null} ; [ DW_TAG_subroutine_type ] [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
+!7 = !{!8, !9}
+!8 = !{!"0x24\00int\000\0032\0032\000\000\005", null, null} ; [ DW_TAG_base_type ] [ DW_TAG_base_type ] [int] [line 0, size 32, align 32, offset 0, enc DW_ATE_signed]
+!9 = !{!"0x16\00Outer\008\000\000\000\000", !1, null, !10} ; [ DW_TAG_typedef ] [ DW_TAG_typedef ] [Outer] [line 8, size 0, align 0, offset 0] [from ]
+!10 = !{!"0x13\00\006\00128\0032\000\000\000", !1, null, null, !11, null, null, null} ; [ DW_TAG_structure_type ] [line 6, size 128, align 32, offset 0] [def] [from ]
+!11 = !{!12}
+!12 = !{!"0xd\00inner\007\00128\0032\000\000", !1, !10, !13} ; [ DW_TAG_member ] [inner] [line 7, size 128, align 32, offset 0] [from ]
+!13 = !{!"0x1\00\000\00128\0032\000\000", null, null, !14, !19, i32 0, null, null, null} ; [ DW_TAG_array_type ] [line 0, size 128, align 32, offset 0] [from Inner]
+!14 = !{!"0x16\00Inner\004\000\000\000\000", !1, null, !15} ; [ DW_TAG_typedef ] [ DW_TAG_typedef ] [Inner] [line 4, size 0, align 0, offset 0] [from ]
+!15 = !{!"0x13\00\001\0064\0032\000\000\000", !1, null, null, !16, null, null, null} ; [ DW_TAG_structure_type ] [line 1, size 64, align 32, offset 0] [def] [from ]
+!16 = !{!17, !18}
+!17 = !{!"0xd\00a\002\0032\0032\000\000", !1, !15, !8} ; [ DW_TAG_member ] [a] [line 2, size 32, align 32, offset 0] [from int]
+!18 = !{!"0xd\00b\003\0032\0032\0032\000", !1, !15, !8} ; [ DW_TAG_member ] [b] [line 3, size 32, align 32, offset 32] [from int]
+!19 = !{!20}
+!20 = !{!"0x21\000\002"}        ; [ DW_TAG_subrange_type ] [0, 1]
+!21 = !{i32 2, !"Dwarf Version", i32 2}
+!22 = !{i32 1, !"Debug Info Version", i32 2}
+!23 = !{!"clang version 3.5.0 "}
+!24 = !{!"0x101\00outer\0016777226\000", !4, !5, !9} ; [ DW_TAG_arg_variable ] [ DW_TAG_arg_variable ] [outer] [line 10]
+!25 = !{i32 10, i32 0, !4, null}
+!26 = !{!"0x100\00i1\0011\000", !4, !5, !14} ; [ DW_TAG_auto_variable ] [ DW_TAG_auto_variable ] [i1] [line 11]
+!27 = !{i32 11, i32 0, !4, null}
+!28 = !{i32 12, i32 0, !4, null}