[Lldb-commits] [lldb] [llvm] Add support for using foreign type units in .debug_names. (PR #87740)

[Pavel Labath via lldb-commits]

================
@@ -0,0 +1,127 @@
+// REQUIRES: lld
+
+// This test will make a type that will be compiled differently into two
+// different .dwo files in a type unit with the same type hash, but with
+// differing contents. Clang's type unit signature is based only on the mangled
+// name of the type, regardless of the contents of the type, so that will help
+// us test foreign type units in the .debug_names section of the main
+// executable. When a DWP file is made, only one type unit will be kept and the
+// type unit that is kept has the .dwo file name that it came from. When LLDB
+// loads the foreign type units, it needs to verify that any entries from
+// foreign type units come from the right .dwo file. We test this since the
+// contents of type units are not always the same even though they have the same
+// type hash. We don't want invalid accelerator table entries to come from one
+// .dwo file and be used on a type unit from another since this could cause
+// invalid lookups to happen. LLDB knows how to track down which .dwo file a
+// type unit comes from by looking at the DW_AT_dwo_name attribute in the
+// DW_TAG_type_unit.
+
+// Now test with DWARF5
+// RUN: %clang -target x86_64-pc-linux -gdwarf-5 -gsplit-dwarf \
+// RUN:   -fdebug-types-section -gpubnames -c %s -o %t.main.o
+// RUN: %clang -target x86_64-pc-linux -gdwarf-5 -gsplit-dwarf -DVARIANT \
+// RUN:   -fdebug-types-section -gpubnames -c %s -o %t.foo.o
+// RUN: ld.lld %t.main.o %t.foo.o -o %t
+
+// Check when have no .dwp file that we can find the types in both .dwo files.
+// RUN: rm -f %t.dwp
+// RUN: %lldb \
+// RUN:   -o "type lookup IntegerType" \
+// RUN:   -o "type lookup FloatType" \
+// RUN:   -o "type lookup CustomType" \
+// RUN:   -b %t | FileCheck %s --check-prefix=NODWP
+// NODWP: (lldb) type lookup IntegerType
+// NODWP-NEXT: int
+// NODWP-NEXT: unsigned int
+// NODWP: (lldb) type lookup FloatType
+// NODWP-NEXT: double
+// NODWP-NEXT: float
+// NODWP: (lldb) type lookup CustomType
+// NODWP-NEXT: struct CustomType {
+// NODWP-NEXT:     typedef int IntegerType;
+// NODWP-NEXT:     typedef double FloatType;
+// NODWP-NEXT:     CustomType::IntegerType x;
+// NODWP-NEXT:     CustomType::FloatType y;
+// NODWP-NEXT: }
+// NODWP-NEXT: struct CustomType {
+// NODWP-NEXT:     typedef unsigned int IntegerType;
+// NODWP-NEXT:     typedef float FloatType;
+// NODWP-NEXT:     CustomType::IntegerType x;
+// NODWP-NEXT:     CustomType::FloatType y;
+// NODWP-NEXT: }
+
+// Check when we make the .dwp file with %t.main.dwo first so it will
+// pick the type unit from %t.main.dwo. Verify we find only the types from
+// %t.main.dwo's type unit.
+// RUN: llvm-dwp %t.main.dwo %t.foo.dwo -o %t.dwp
+// RUN: %lldb \
+// RUN:   -o "type lookup IntegerType" \
+// RUN:   -o "type lookup FloatType" \
+// RUN:   -o "type lookup CustomType" \
+// RUN:   -b %t | FileCheck %s --check-prefix=DWPMAIN
+// DWPMAIN: (lldb) type lookup IntegerType
+// DWPMAIN-NEXT: int
+// DWPMAIN: (lldb) type lookup FloatType
+// DWPMAIN-NEXT: double
+// DWPMAIN: (lldb) type lookup CustomType
+// DWPMAIN-NEXT: struct CustomType {
+// DWPMAIN-NEXT:     typedef int IntegerType;
+// DWPMAIN-NEXT:     typedef double FloatType;
+// DWPMAIN-NEXT:     CustomType::IntegerType x;
+// DWPMAIN-NEXT:     CustomType::FloatType y;
+// DWPMAIN-NEXT: }
+
+// Next we check when we make the .dwp file with %t.foo.dwo first so it will
+// pick the type unit from %t.main.dwo. Verify we find only the types from
+// %t.main.dwo's type unit.
+// RUN: llvm-dwp %t.foo.dwo %t.main.dwo -o %t.dwp
+// RUN: %lldb \
+// RUN:   -o "type lookup IntegerType" \
+// RUN:   -o "type lookup FloatType" \
+// RUN:   -o "type lookup CustomType" \
+// RUN:   -b %t | FileCheck %s --check-prefix=DWPFOO
+
+// DWPFOO: (lldb) type lookup IntegerType
+// DWPFOO-NEXT: unsigned int
+// DWPFOO: (lldb) type lookup FloatType
+// DWPFOO-NEXT: float
+// DWPFOO: (lldb) type lookup CustomType
+// DWPFOO-NEXT: struct CustomType {
+// DWPFOO-NEXT:     typedef unsigned int IntegerType;
+// DWPFOO-NEXT:     typedef float FloatType;
+// DWPFOO-NEXT:     CustomType::IntegerType x;
+// DWPFOO-NEXT:     CustomType::FloatType y;
+// DWPFOO-NEXT: }
+
+// We need to do this so we end with a type unit in each .dwo file and that has
+// the same signature but different contents. When we make the .dwp file, then
+// one of the type units will end up in the .dwp file and we will have
+// .debug_names accelerator tables for both type units and we need to ignore
+// the type units .debug_names entries that don't match the .dwo file whose
+// copy of the type unit ends up in the final .dwp file. To do this, LLDB will
+// look at the type unit and take the DWO name attribute and make sure it
+// matches, and if it doesn't, it will ignore the accelerator table entry.
----------------
labath wrote:

This feels very repetitive. Can you merge this comment with the one at the top. (Optionally, you can also move the source code closer to the top of the file, that one will already know what to expect when one gets to the expectations, if one reads file top to bottom)

https://github.com/llvm/llvm-project/pull/87740