[CodeGen/AccelTable] Add the "sizetype" synthetic type to the accelerator table

[labath]

Summary

This type is created on-demand and used as the base type for array
ranges. Since it is "special", its construction did not go through the
createTypeDIE function and so it was never inserted into the accelerator
table, although it clearly belongs there.

I add an explicit addAccelType call to insert it into the table.

[labath]

lib/CodeGen/AsmPrinter/DwarfUnit.cpp

1407 ↗

(On Diff #141669)

Another interesting question is whether we shouldn't rename this to something more unique (_Sizetype ?). As it stands now, if a user has his own sizetype defined, lldb will get confused and will not be able to differentiate the two. Gcc emits this type as "unsigned long", but doing that is a bit trickier for us as we don't want to assume a particular front-end here.

[JDevlieghere]

lib/CodeGen/AsmPrinter/DwarfUnit.cpp

1407 ↗

(On Diff #141669)

Let's use a double underscore then as that's reserved for the compilers internal use. I think both GCC and LLVM define the macro __SIZE_TYPE__, but I don't know if it's worth to repurpose that for this.

[labath]

I don't think repurpusing the SIZE_TYPE name is a good idea, because it may
give off the impression that this type *is* the compiler's SIZE_TYPE type,
but in reality, we don't even try to match it's definition. Also, right now the
compiler's SIZE_TYPE does not seem to make it into debug info, but if that
ever changes, then we will have the multiple definition problem again.

So I think this should be really unique. Right now, the best name I came up with
is ARRAY_SIZE_TYPE.

[JDevlieghere]

Sounds reasonable. LGTM!

llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp

if (auto *CV = SR->getCount().dyn_cast<DIVariable*>()) {
     addUInt(DW_Subrange, dwarf::DW_AT_count, None, Count);
 }
 
 DIE *DwarfUnit::getIndexTyDie() {
   if (IndexTyDie)
     return IndexTyDie;
   // Construct an integer type to use for indexes.
   IndexTyDie = &createAndAddDIE(dwarf::DW_TAG_base_type, getUnitDie());
-  addString(*IndexTyDie, dwarf::DW_AT_name, "sizetype");
+  StringRef Name = "__ARRAY_SIZE_TYPE__";
+  addString(*IndexTyDie, dwarf::DW_AT_name, Name);
   addUInt(*IndexTyDie, dwarf::DW_AT_byte_size, None, sizeof(int64_t));
   addUInt(*IndexTyDie, dwarf::DW_AT_encoding, dwarf::DW_FORM_data1,
           dwarf::DW_ATE_unsigned);
+  DD->addAccelType(Name, *IndexTyDie, /*Flags*/ 0);
   return IndexTyDie;
 }
 
 /// Returns true if the vector's size differs from the sum of sizes of elements
 /// the user specified.  This can occur if the vector has been rounded up to
 /// fit memory alignment constraints.
 static bool hasVectorBeenPadded(const DICompositeType *CTy) {
   assert(CTy && CTy->isVector() && "Composite type is not a vector");

llvm/trunk/test/DebugInfo/Generic/debug-names-index-type.ll

+; REQUIRES: object-emission
+; RUN: %llc_dwarf -accel-tables=Dwarf -filetype=obj -o %t < %s
+; RUN: llvm-dwarfdump -debug-names %t | FileCheck %s
+; RUN: llvm-dwarfdump -debug-names -verify %t | FileCheck --check-prefix=VERIFY %s
+
+; Check that the entry for the "__ARRAY_SIZE_TYPE__" index type is present in the
+; accelerator table.
+; CHECK: String: 0x{{[0-9a-f]*}} "__ARRAY_SIZE_TYPE__"
+; CHECK-NEXT: Entry
+; CHECK-NEXT: Abbrev
+; CHECK-NEXT: Tag: DW_TAG_base_type
+
+; VERIFY: No errors.
+
+; Generated by:
+; clang -g -x c - -o - -S -emit-llvm <<<"int a[1];"
+
+@a = common dso_local global [1 x i32] zeroinitializer, align 4, !dbg !0
+
+!llvm.dbg.cu = !{!2}
+!llvm.module.flags = !{!11, !12, !13}
+!llvm.ident = !{!14}
+
+!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
+!1 = distinct !DIGlobalVariable(name: "a", scope: !2, file: !6, line: 1, type: !7, isLocal: false, isDefinition: true)
+!2 = distinct !DICompileUnit(language: DW_LANG_C99, file: !3, producer: "clang version 7.0.0 (trunk 329543) (llvm/trunk 329575)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, globals: !5)
+!3 = !DIFile(filename: "-", directory: "/tmp")
+!4 = !{}
+!5 = !{!0}
+!6 = !DIFile(filename: "<stdin>", directory: "/tmp")
+!7 = !DICompositeType(tag: DW_TAG_array_type, baseType: !8, size: 32, elements: !9)
+!8 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!9 = !{!10}
+!10 = !DISubrange(count: 1)
+!11 = !{i32 2, !"Dwarf Version", i32 4}
+!12 = !{i32 2, !"Debug Info Version", i32 3}
+!13 = !{i32 1, !"wchar_size", i32 4}
+!14 = !{!"clang version 7.0.0 (trunk 329543) (llvm/trunk 329575)"}

llvm/trunk/test/DebugInfo/X86/nondefault-subrange-array.ll

 
 ; CHECK: DW_TAG_subrange_type
 ; CHECK-NEXT:                   DW_AT_type [DW_FORM_ref4]  (cu + 0x{{[0-9a-f]*}} => {[[BASE2:0x[0-9a-f]*]]}
 ; CHECK-NEXT:                   DW_AT_lower_bound [DW_FORM_data8]       (0xfffffffffffffffd)
 ; CHECK-NEXT:                   DW_AT_count [DW_FORM_data1]       (0x2a)
 
 ; CHECK: [[BASE]]: DW_TAG_base_type
 ; CHECK: [[BASE2]]: DW_TAG_base_type
-; CHECK-NEXT:                 DW_AT_name [DW_FORM_strp]       ( .debug_str[0x{{[0-9a-f]*}}] = "sizetype")
+; CHECK-NEXT:                 DW_AT_name [DW_FORM_strp]       ( .debug_str[0x{{[0-9a-f]*}}] = "__ARRAY_SIZE_TYPE__")
 ; CHECK-NEXT:                 DW_AT_byte_size [DW_FORM_data1] (0x08)
 ; CHECK-NEXT:                 DW_AT_encoding [DW_FORM_data1]  (DW_ATE_unsigned)
 
 !llvm.dbg.cu = !{!14}
 !llvm.module.flags = !{!17}
 
 !0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
 !1 = !DIGlobalVariable(name: "a", scope: null, file: !2, line: 1, type: !3, isLocal: false, isDefinition: true)

llvm/trunk/test/DebugInfo/X86/vla-dependencies.ll

 ; RUN: llc -mtriple=x86_64-apple-darwin %s -o - -filetype=obj | llvm-dwarfdump - | FileCheck %s
 ; CHECK:  DW_TAG_subprogram
 ; CHECK:    DW_AT_name  ("h")
 ; CHECK: 0x00000[[VLAEXPR:.*]]:     DW_TAG_variable
 ; CHECK-NEXT:    DW_AT_name ("vla_expr")
 ; CHECK:        DW_TAG_array_type
 ; CHECK-NEXT:     DW_AT_type  {{.*}}"int"
 ; CHECK-NOT: DW_TAG
 ; CHECK:        DW_TAG_subrange_type
-; CHECK-NEXT:     DW_AT_type {{.*}}"sizetype"
+; CHECK-NEXT:     DW_AT_type {{.*}}"__ARRAY_SIZE_TYPE__"
 ; CHECK-NEXT:     DW_AT_count (0x00000[[VLAEXPR]]
 ;
 ;
 ; Generated from (and then modified):
 ;
 ; #define DECLARE_ARRAY(type, var_name, size) type var_name[size]
 ;
 ; void h(void);

llvm/trunk/test/DebugInfo/X86/vla-global.ll

 ; RUN: llc -mtriple=x86_64-apple-darwin %s -o - -filetype=obj | llvm-dwarfdump - | FileCheck %s
 ; CHECK: 0x00000[[G:.*]]:     DW_TAG_variable
 ; CHECK-NEXT:                DW_AT_name ("g")
 ; CHECK: DW_TAG_array_type
 ; CHECK-NEXT:  DW_AT_type ({{.*}} "int")
 ; CHECK-NOT: DW_TAG
 ; CHECK:       DW_TAG_subrange_type
-; CHECK-NEXT:     DW_AT_type  ({{.*}} "sizetype")
+; CHECK-NEXT:     DW_AT_type  ({{.*}} "__ARRAY_SIZE_TYPE__")
 ; CHECK-NEXT:      DW_AT_count  (0x00000[[G]])
 ; Test that a VLA referring to a global variable is handled correctly.
 ; Clang doesn't generate this, but the verifier allows it.
 source_filename = "/tmp/test.c"
 target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-apple-macosx10.13.0"
 
 @g = common local_unnamed_addr global i32 0, align 4, !dbg !0

llvm/trunk/test/DebugInfo/X86/vla-multi.ll

 ; RUN: llc -mtriple=x86_64-apple-darwin %s -o - -filetype=obj | llvm-dwarfdump - | FileCheck %s
 ; Test debug info for multidimensional arrays.
 ;
 ; void f(int i, int j, int k, int r) {
 ;  int tensor1[i][j][k][r];
 ;  int tensor2[i][j][k][r];
 ;  use(tensor1, tensor2);
 ;}
 ;
 ; CHECK:        DW_TAG_array_type
 ; CHECK-NEXT:     DW_AT_type  (0x000000f8 "int")
 ; CHECK-NOT: TAG
 ; CHECK:          DW_TAG_subrange_type
-; CHECK-NEXT:       DW_AT_type  (0x{{.*}}"sizetype")
+; CHECK-NEXT:       DW_AT_type  (0x{{.*}}"__ARRAY_SIZE_TYPE__")
 ; CHECK-NEXT:       DW_AT_count (0x{{.*}})
 ; CHECK-NOT: TAG
 ; CHECK:          DW_TAG_subrange_type
-; CHECK-NEXT:       DW_AT_type  (0x{{.*}} "sizetype")
+; CHECK-NEXT:       DW_AT_type  (0x{{.*}} "__ARRAY_SIZE_TYPE__")
 ; CHECK-NEXT:       DW_AT_count (0x{{.*}})
 ; CHECK-NOT: TAG
 ; CHECK:          DW_TAG_subrange_type
-; CHECK-NEXT:       DW_AT_type  (0x{{.*}} "sizetype")
+; CHECK-NEXT:       DW_AT_type  (0x{{.*}} "__ARRAY_SIZE_TYPE__")
 ; CHECK-NEXT:       DW_AT_count (0x{{.*}})
 ; CHECK-NOT: TAG
 ; CHECK:          DW_TAG_subrange_type
-; CHECK-NEXT:       DW_AT_type  (0x{{.*}} "sizetype")
+; CHECK-NEXT:       DW_AT_type  (0x{{.*}} "__ARRAY_SIZE_TYPE__")
 ; CHECK-NEXT:       DW_AT_count (0x{{.*}})
 ; CHECK:        DW_TAG_array_type
 ; CHECK-NEXT:     DW_AT_type  (0x000000f8 "int")
 ; CHECK-NOT: TAG
 ; CHECK:          DW_TAG_subrange_type
-; CHECK-NEXT:       DW_AT_type  (0x{{.*}}"sizetype")
+; CHECK-NEXT:       DW_AT_type  (0x{{.*}}"__ARRAY_SIZE_TYPE__")
 ; CHECK-NEXT:       DW_AT_count (0x{{.*}})
 ; CHECK-NOT: TAG
 ; CHECK:          DW_TAG_subrange_type
-; CHECK-NEXT:       DW_AT_type  (0x{{.*}} "sizetype")
+; CHECK-NEXT:       DW_AT_type  (0x{{.*}} "__ARRAY_SIZE_TYPE__")
 ; CHECK-NEXT:       DW_AT_count (0x{{.*}})
 ; CHECK-NOT: TAG
 ; CHECK:          DW_TAG_subrange_type
-; CHECK-NEXT:       DW_AT_type  (0x{{.*}} "sizetype")
+; CHECK-NEXT:       DW_AT_type  (0x{{.*}} "__ARRAY_SIZE_TYPE__")
 ; CHECK-NEXT:       DW_AT_count (0x{{.*}})
 ; CHECK-NOT: TAG
 ; CHECK:          DW_TAG_subrange_type
-; CHECK-NEXT:       DW_AT_type  (0x{{.*}} "sizetype")
+; CHECK-NEXT:       DW_AT_type  (0x{{.*}} "__ARRAY_SIZE_TYPE__")
 ; CHECK-NEXT:       DW_AT_count (0x{{.*}})
 
 
 source_filename = "/tmp/test.c"
 target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-apple-macosx10.13.0"
 
 define void @f(i32 %i, i32 %j, i32 %k, i32 %r) !dbg !8 {