[GlobalISel] Lower dbg.declare into indirect DBG_VALUE

Summary:
D31439 changed the semantics of dbg.declare to take the address of a
variable as the first argument, making it indirect.  It specifically
updated FastISel for this change here:

https://reviews.llvm.org/D31439#change-WVArzi177jPl

GlobalISel needs to follow suit, or else it will be missing a level of
indirection in the generated debuginfo.  This problem was seen in a Rust
debuginfo test on aarch64, since GlobalISel is used at -O0 for aarch64.

rust-lang/rust#49807
https://bugzilla.redhat.com/show_bug.cgi?id=1611597
https://bugzilla.redhat.com/show_bug.cgi?id=1625768

Reviewers: dblaikie, aprantl, t.p.northover, javed.absar, rnk

Reviewed By: rnk

Subscribers: #debug-info, rovka, kristof.beyls, JDevlieghere, llvm-commits, tstellar

Differential Revision: https://reviews.llvm.org/D51749

llvm-svn: 341969

llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp

@@ -758,9 +758,12 @@ bool IRTranslator::translateKnownIntrinsic(const CallInst &CI, Intrinsic::ID ID,
       // instructions (in fact, they get ignored if they *do* exist).
       MF->setVariableDbgInfo(DI.getVariable(), DI.getExpression(),
                              getOrCreateFrameIndex(*AI), DI.getDebugLoc());
-    } else
-      MIRBuilder.buildDirectDbgValue(getOrCreateVReg(*Address),
-                                     DI.getVariable(), DI.getExpression());
+    } else {
+      // A dbg.declare describes the address of a source variable, so lower it
+      // into an indirect DBG_VALUE.
+      MIRBuilder.buildIndirectDbgValue(getOrCreateVReg(*Address),
+                                       DI.getVariable(), DI.getExpression());
+    }
     return true;
   }
   case Intrinsic::dbg_label: {

llvm/test/CodeGen/AArch64/GlobalISel/debug-cpp.ll

@@ -0,0 +1,67 @@
+; RUN: llc -global-isel -mtriple=aarch64 %s -stop-after=irtranslator -o - | FileCheck %s
+; RUN: llc -mtriple=aarch64 -global-isel --global-isel-abort=0 -o /dev/null
+
+; struct NTCopy {
+;   NTCopy();
+;   NTCopy(const NTCopy &);
+;   int x;
+; };
+; int foo(NTCopy o) {
+;   return o.x;
+; }
+
+; ModuleID = 'ntcopy.cpp'
+source_filename = "ntcopy.cpp"
+target datalayout = "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128"
+target triple = "aarch64-unknown-linux-gnu"
+
+%struct.NTCopy = type { i32 }
+
+; CHECK-LABEL: name: _Z3foo6NTCopy
+; CHECK: DBG_VALUE debug-use %{{[0-9]+}}(p0), 0, !23, !DIExpression(), debug-location !24
+; Function Attrs: noinline nounwind optnone
+define dso_local i32 @_Z3foo6NTCopy(%struct.NTCopy* %o) #0 !dbg !7 {
+entry:
+  call void @llvm.dbg.declare(metadata %struct.NTCopy* %o, metadata !23, metadata !DIExpression()), !dbg !24
+  %x = getelementptr inbounds %struct.NTCopy, %struct.NTCopy* %o, i32 0, i32 0, !dbg !25
+  %0 = load i32, i32* %x, align 4, !dbg !25
+  ret i32 %0, !dbg !26
+}
+
+; Function Attrs: nounwind readnone speculatable
+declare void @llvm.dbg.declare(metadata, metadata, metadata) #1
+
+attributes #0 = { noinline nounwind optnone }
+attributes #1 = { nounwind readnone speculatable }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4, !5}
+!llvm.ident = !{!6}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 8.0.0 ", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, nameTableKind: None)
+!1 = !DIFile(filename: "ntcopy.cpp", 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 = !{!"clang version 8.0.0 "}
+!7 = distinct !DISubprogram(name: "foo", linkageName: "_Z3foo6NTCopy", scope: !1, file: !1, line: 6, type: !8, isLocal: false, isDefinition: true, scopeLine: 6, flags: DIFlagPrototyped, isOptimized: false, unit: !0, retainedNodes: !2)
+!8 = !DISubroutineType(types: !9)
+!9 = !{!10, !11}
+!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!11 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "NTCopy", file: !1, line: 1, size: 32, flags: DIFlagTypePassByReference, elements: !12, identifier: "_ZTS6NTCopy")
+!12 = !{!13, !14, !18}
+!13 = !DIDerivedType(tag: DW_TAG_member, name: "x", scope: !11, file: !1, line: 4, baseType: !10, size: 32)
+!14 = !DISubprogram(name: "NTCopy", scope: !11, file: !1, line: 2, type: !15, isLocal: false, isDefinition: false, scopeLine: 2, flags: DIFlagPrototyped, isOptimized: false)
+!15 = !DISubroutineType(types: !16)
+!16 = !{null, !17}
+!17 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !11, size: 64, flags: DIFlagArtificial | DIFlagObjectPointer)
+!18 = !DISubprogram(name: "NTCopy", scope: !11, file: !1, line: 3, type: !19, isLocal: false, isDefinition: false, scopeLine: 3, flags: DIFlagPrototyped, isOptimized: false)
+!19 = !DISubroutineType(types: !20)
+!20 = !{null, !17, !21}
+!21 = !DIDerivedType(tag: DW_TAG_reference_type, baseType: !22, size: 64)
+!22 = !DIDerivedType(tag: DW_TAG_const_type, baseType: !11)
+!23 = !DILocalVariable(name: "o", arg: 1, scope: !7, file: !1, line: 6, type: !11)
+!24 = !DILocation(line: 6, column: 16, scope: !7)
+!25 = !DILocation(line: 7, column: 12, scope: !7)
+!26 = !DILocation(line: 7, column: 3, scope: !7)

llvm/test/CodeGen/AArch64/GlobalISel/debug-insts.ll

@@ -6,18 +6,16 @@
 ; CHECK:    - { id: {{.*}}, name: in.addr, type: default, offset: 0, size: {{.*}}, alignment: {{.*}},
 ; CHECK-NEXT: callee-saved-register: '', callee-saved-restored: true,
 ; CHECK-NEXT: debug-info-variable: '!11', debug-info-expression: '!DIExpression()',
-; CHECK: DBG_VALUE debug-use %0(s32), debug-use $noreg, !11, !DIExpression(), debug-location !12
 define void @debug_declare(i32 %in) #0 !dbg !7 {
 entry:
   %in.addr = alloca i32, align 4
   store i32 %in, i32* %in.addr, align 4
   call void @llvm.dbg.declare(metadata i32* %in.addr, metadata !11, metadata !DIExpression()), !dbg !12
-  call void @llvm.dbg.declare(metadata i32 %in, metadata !11, metadata !DIExpression()), !dbg !12
   ret void, !dbg !12
 }
 
 ; CHECK-LABEL: name: debug_declare_vla
-; CHECK: DBG_VALUE debug-use %{{[0-9]+}}(p0), debug-use $noreg, !14, !DIExpression(), debug-location !15
+; CHECK: DBG_VALUE debug-use %{{[0-9]+}}(p0), 0, !14, !DIExpression(), debug-location !15
 define void @debug_declare_vla(i32 %in) #0 !dbg !13 {
 entry:
   %vla.addr = alloca i32, i32 %in