Reland r311957 [codeview] support more DW_OPs for more complete debug info

Summary:
Some variables show up in Visual Studio as "optimized out" even in -O0
-Od builds. This change fixes two issues that would cause this to
happen. The first issue is that not all DIExpressions we generate were
recognized by the CodeView writer. This has been addressed by adding
support for DW_OP_constu, DW_OP_minus, and DW_OP_plus. The second
issue is that we had no way to encode DW_OP_deref in CodeView. We get
around that by changinge the type we encode in the debug info to be
a reference to the type in the source code.

This fixes PR34261.

The reland adds two extra checks to the original: It checks if the
DbgVariableLocation is valid before checking any of its fields, and
it only emits ranges with nonzero registers.

Reviewers: aprantl, rnk, zturner

Reviewed By: rnk

Subscribers: mgorny, llvm-commits, aprantl, hiraditya

Differential Revision: https://reviews.llvm.org/D36907

llvm-svn: 312034

1 files changed, 253 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/MIR/X86/diexpr-win32.mir b/llvm/test/CodeGen/MIR/X86/diexpr-win32.mir
new file mode 100644
index 00000000000..d5dc3e46554
--- /dev/null
+++ b/llvm/test/CodeGen/MIR/X86/diexpr-win32.mir
@@ -0,0 +1,253 @@
+# RUN: llc -filetype=obj -O0 %s -o - | llvm-readobj -codeview | FileCheck %s
+#
+# (DW_OP_plus_uconst 12)
+# CHECK: LocalSym {
+# CHECK-NEXT:   Kind: S_LOCAL (0x113E)
+# CHECK-NEXT:   Type: string* (0x
+# CHECK-NEXT:   Flags [ (0x0)
+# CHECK-NEXT:   ]
+# CHECK-NEXT:   VarName: Str
+# CHECK-NEXT: }
+# CHECK-NEXT: DefRangeRegisterRelSym {
+# CHECK-NEXT:   Kind: S_DEFRANGE_REGISTER_REL (0x1145)
+# CHECK-NEXT:   BaseRegister:
+# CHECK-NEXT:   HasSpilledUDTMember: No
+# CHECK-NEXT:   OffsetInParent: 0
+# CHECK-NEXT:   BasePointerOffset: 12
+# CHECK-NEXT:   LocalVariableAddrRange {
+# CHECK-NEXT:     OffsetStart:
+# CHECK-NEXT:     ISectStart:
+# CHECK-NEXT:     Range:
+# CHECK-NEXT:   }
+# CHECK-NEXT: }
+# (DW_OP_plus_uconst, 8, DW_OP_deref)
+# CHECK: LocalSym {
+# CHECK-NEXT:   Kind: S_LOCAL (0x113E)
+# CHECK-NEXT:   Type: string& (0x
+# CHECK-NEXT:   Flags [ (0x0)
+# CHECK-NEXT:   ]
+# CHECK-NEXT:   VarName: Result
+# CHECK-NEXT: }
+# CHECK-NEXT: DefRangeRegisterRelSym {
+# CHECK-NEXT:   Kind: S_DEFRANGE_REGISTER_REL (0x1145)
+# CHECK-NEXT:   BaseRegister:
+# CHECK-NEXT:   HasSpilledUDTMember: No
+# CHECK-NEXT:   OffsetInParent: 0
+# CHECK-NEXT:   BasePointerOffset: 8
+# CHECK-NEXT:   LocalVariableAddrRange {
+# CHECK-NEXT:     OffsetStart:
+# CHECK-NEXT:     ISectStart:
+# CHECK-NEXT:     Range:
+# CHECK-NEXT:   }
+# CHECK-NEXT: }
+# (DW_OP_constu, 4, DW_OP_minus)
+# CHECK: LocalSym {
+# CHECK-NEXT:   Kind: S_LOCAL (0x113E)
+# CHECK-NEXT:   Type: long (0x12)
+# CHECK-NEXT:   Flags [ (0x0)
+# CHECK-NEXT:   ]
+# CHECK-NEXT:   VarName: Bytes
+# CHECK-NEXT: }
+# CHECK-NEXT: DefRangeRegisterRelSym {
+# CHECK-NEXT:   Kind: S_DEFRANGE_REGISTER_REL (0x1145)
+# CHECK-NEXT:   BaseRegister:
+# CHECK-NEXT:   HasSpilledUDTMember: No
+# CHECK-NEXT:   OffsetInParent: 0
+# CHECK-NEXT:   BasePointerOffset: -4
+# CHECK-NEXT:   LocalVariableAddrRange {
+# CHECK-NEXT:     OffsetStart:
+# CHECK-NEXT:     ISectStart:
+# CHECK-NEXT:     Range:
+# CHECK-NEXT:   }
+# CHECK-NEXT: }
+--- |
+  ; ModuleID = '<stdin>'
+  source_filename = "<stdin>"
+  target datalayout = "e-m:x-p:32:32-i64:64-f80:32-n8:16:32-a:0:32-S32"
+  target triple = "i386-pc-windows-msvc19.0.24215"
+
+  %struct.string = type { i32, i32, i8* }
+
+  define void @fun(%struct.string* noalias sret %agg.result, %struct.string* noalias %str) !dbg !12 {
+  entry:
+    call void @llvm.dbg.value(metadata %struct.string* %agg.result, metadata !23, metadata !24), !dbg !25
+    call void @llvm.dbg.value(metadata %struct.string* %str, metadata !26, metadata !28), !dbg !25
+    %call = call dereferenceable(12) %struct.string* @getString(), !dbg !29
+    %0 = bitcast %struct.string* %agg.result to i8*, !dbg !29
+    %1 = bitcast %struct.string* %call to i8*, !dbg !29
+    call void @llvm.memcpy.p0i8.p0i8.i32(i8* %0, i8* %1, i32 12, i32 4, i1 false), !dbg !29
+    ret void, !dbg !30
+  }
+
+  define i32 @len(%struct.string* %s, i32 %acc) !dbg !31 {
+  entry:
+    %0 = bitcast %struct.string* %s to i32*
+    %bytes = load i32, i32* %0, !dbg !34
+    call void @llvm.dbg.declare(metadata i32 %bytes, metadata !35, metadata !28), !dbg !34
+    %1 = add i32 %bytes, %acc, !dbg !36
+    ret i32 %1, !dbg !36
+  }
+
+  ; Function Attrs: nounwind readnone speculatable
+  declare void @llvm.dbg.declare(metadata, metadata, metadata) #0
+
+  ; Function Attrs: nounwind readnone speculatable
+  declare void @llvm.dbg.value(metadata, metadata, metadata) #0
+
+  declare dereferenceable(12) %struct.string* @getString()
+
+  ; Function Attrs: argmemonly nounwind
+  declare void @llvm.memcpy.p0i8.p0i8.i32(i8* nocapture writeonly, i8* nocapture readonly, i32, i32, i1) #1
+
+  ; Function Attrs: nounwind
+  declare void @llvm.stackprotector(i8*, i8**) #2
+
+  attributes #0 = { nounwind readnone speculatable }
+  attributes #1 = { argmemonly nounwind }
+  attributes #2 = { nounwind }
+
+  !llvm.dbg.cu = !{!0}
+  !llvm.linker.options = !{!3, !4}
+  !llvm.module.flags = !{!5, !6, !7, !8}
+  !llvm.ident = !{!9}
+
+  !0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 6.0.0 ", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
+  !1 = !DIFile(filename: "diexpr.ll", directory: "C:\5Csrc", checksumkind: CSK_MD5, checksum: "c547c362c610fa79e7abaddc76e1efe7")
+  !2 = !{}
+  !3 = !{!"/DEFAULTLIB:libcmt.lib"}
+  !4 = !{!"/DEFAULTLIB:oldnames.lib"}
+  !5 = !{i32 1, !"NumRegisterParameters", i32 0}
+  !6 = !{i32 2, !"CodeView", i32 1}
+  !7 = !{i32 2, !"Debug Info Version", i32 3}
+  !8 = !{i32 1, !"wchar_size", i32 2}
+  !9 = !{!"clang version 6.0.0 "}
+  !10 = !DIExpression(DW_OP_plus_uconst, 12)
+  !11 = !DIExpression(DW_OP_plus_uconst, 8, DW_OP_deref)
+  !12 = distinct !DISubprogram(name: "fun", linkageName: "fun", scope: !1, file: !1, line: 9, type: !13, isLocal: false, isDefinition: true, scopeLine: 9, flags: DIFlagPrototyped, isOptimized: false, unit: !0, variables: !2)
+  !13 = !DISubroutineType(types: !14)
+  !14 = !{!15}
+  !15 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "string", file: !1, line: 1, size: 96, elements: !16, identifier: ".?AUstring@@")
+  !16 = !{!17, !19, !20}
+  !17 = !DIDerivedType(tag: DW_TAG_member, name: "length", scope: !15, file: !1, line: 2, baseType: !18, size: 32)
+  !18 = !DIBasicType(name: "long int", size: 32, encoding: DW_ATE_signed)
+  !19 = !DIDerivedType(tag: DW_TAG_member, name: "size", scope: !15, file: !1, line: 3, baseType: !18, size: 32, offset: 32)
+  !20 = !DIDerivedType(tag: DW_TAG_member, name: "data", scope: !15, file: !1, line: 4, baseType: !21, size: 32, offset: 64)
+  !21 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !22, size: 32)
+  !22 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char)
+  !23 = !DILocalVariable(name: "Result", scope: !12, file: !1, line: 10, type: !15)
+  !24 = !DIExpression(DW_OP_deref)
+  !25 = !DILocation(line: 10, scope: !12)
+  !26 = !DILocalVariable(name: "Str", scope: !12, file: !1, line: 10, type: !27)
+  !27 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !15, size: 32)
+  !28 = !DIExpression(DW_OP_constu, 4, DW_OP_minus)
+  !29 = !DILocation(line: 11, scope: !12)
+  !30 = !DILocation(line: 12, scope: !12)
+  !31 = distinct !DISubprogram(name: "len", linkageName: "len", scope: !1, file: !1, line: 14, type: !32, isLocal: false, isDefinition: true, scopeLine: 14, flags: DIFlagPrototyped, isOptimized: false, unit: !0, variables: !2)
+  !32 = !DISubroutineType(types: !33)
+  !33 = !{!18}
+  !34 = !DILocation(line: 15, scope: !31)
+  !35 = !DILocalVariable(name: "Bytes", scope: !31, file: !1, line: 15, type: !18)
+  !36 = !DILocation(line: 16, scope: !31)
+
+...
+---
+name:            fun
+alignment:       4
+exposesReturnsTwice: false
+legalized:       false
+regBankSelected: false
+selected:        false
+tracksRegLiveness: true
+registers:
+liveins:
+frameInfo:
+  isFrameAddressTaken: false
+  isReturnAddressTaken: false
+  hasStackMap:     false
+  hasPatchPoint:   false
+  stackSize:       4
+  offsetAdjustment: 0
+  maxAlignment:    4
+  adjustsStack:    true
+  hasCalls:        true
+  stackProtector:  ''
+  maxCallFrameSize: 0
+  hasOpaqueSPAdjustment: false
+  hasVAStart:      false
+  hasMustTailInVarArgFunc: false
+  savePoint:       ''
+  restorePoint:    ''
+fixedStack:
+  - { id: 0, type: spill-slot, offset: -8, size: 4, alignment: 4, stack-id: 0,
+      callee-saved-register: '%esi' }
+  - { id: 1, type: default, offset: 4, size: 4, alignment: 4, stack-id: 0,
+      isImmutable: true, isAliased: false, callee-saved-register: '' }
+  - { id: 2, type: default, offset: 0, size: 4, alignment: 4, stack-id: 0,
+      isImmutable: true, isAliased: false, callee-saved-register: '' }
+stack:
+constants:
+body:             |
+  bb.0.entry:
+    liveins: %esi
+
+    frame-setup PUSH32r killed %esi, implicit-def %esp, implicit %esp
+    CFI_INSTRUCTION def_cfa_offset 8
+    CFI_INSTRUCTION offset %esi, -8
+    %esi = MOV32rm %esp, 1, _, 8, _ :: (load 4 from %fixed-stack.2)
+    DBG_VALUE %esp, 0, !26, !10, debug-location !25
+    DBG_VALUE %esp, 0, !23, !11, debug-location !25
+    CALLpcrel32 @getString, csr_32, implicit %esp, implicit-def %esp, implicit-def %eax, debug-location !29
+    %ecx = MOV32rm %eax, 1, _, 0, _, debug-location !29 :: (dereferenceable load 4 from %ir.1)
+    %edx = MOV32rm %eax, 1, _, 4, _, debug-location !29 :: (dereferenceable load 4 from %ir.1 + 4)
+    MOV32mr %esi, 1, _, 0, _, killed %ecx, debug-location !29 :: (store 4 into %ir.0)
+    MOV32mr %esi, 1, _, 4, _, killed %edx, debug-location !29 :: (store 4 into %ir.0 + 4)
+    %eax = MOV32rm killed %eax, 1, _, 8, _, debug-location !29 :: (dereferenceable load 4 from %ir.1 + 8)
+    MOV32mr %esi, 1, _, 8, _, killed %eax, debug-location !29 :: (store 4 into %ir.0 + 8)
+    %eax = COPY killed %esi, debug-location !30
+    %esi = POP32r implicit-def %esp, implicit %esp, debug-location !30
+    RET 0, %eax, debug-location !30
+
+...
+---
+name:            len
+alignment:       4
+exposesReturnsTwice: false
+legalized:       false
+regBankSelected: false
+selected:        false
+tracksRegLiveness: true
+registers:
+liveins:
+frameInfo:
+  isFrameAddressTaken: false
+  isReturnAddressTaken: false
+  hasStackMap:     false
+  hasPatchPoint:   false
+  stackSize:       0
+  offsetAdjustment: 0
+  maxAlignment:    4
+  adjustsStack:    false
+  hasCalls:        false
+  stackProtector:  ''
+  maxCallFrameSize: 0
+  hasOpaqueSPAdjustment: false
+  hasVAStart:      false
+  hasMustTailInVarArgFunc: false
+  savePoint:       ''
+  restorePoint:    ''
+fixedStack:
+  - { id: 0, type: default, offset: 4, size: 4, alignment: 4, stack-id: 0,
+      isImmutable: true, isAliased: false, callee-saved-register: '' }
+  - { id: 1, type: default, offset: 0, size: 4, alignment: 4, stack-id: 0,
+      isImmutable: true, isAliased: false, callee-saved-register: '' }
+stack:
+constants:
+body:             |
+  bb.0.entry:
+    %eax = MOV32rm %esp, 1, _, 4, _ :: (load 4 from %fixed-stack.1)
+    %eax = MOV32rm killed %eax, 1, _, 0, _, debug-location !34 :: (load 4 from %ir.0)
+    DBG_VALUE debug-use %eax, 0, !35, !28, debug-location !34
+    %eax = ADD32rm killed %eax, %esp, 1, _, 8, _, implicit-def dead %eflags, debug-location !36 :: (load 4 from %fixed-stack.0)
+    RET 0, %eax, debug-location !36
+
+...