[llvm] a484e02 - [Object] Add ELF section type SHT_LLVM_BITCODE for LLVM bitcode
Fangrui Song via llvm-commits
llvm-commits at lists.llvm.org
Wed Jun 28 14:01:12 PDT 2023
Author: Fangrui Song
Date: 2023-06-28T14:01:08-07:00
New Revision: a484e020d75d398049e1fcbeb0157d57011714b3
URL: https://github.com/llvm/llvm-project/commit/a484e020d75d398049e1fcbeb0157d57011714b3
DIFF: https://github.com/llvm/llvm-project/commit/a484e020d75d398049e1fcbeb0157d57011714b3.diff
LOG: [Object] Add ELF section type SHT_LLVM_BITCODE for LLVM bitcode
clang -ffat-lto-objects can use this new ELF section type for the .llvm.lto
section for fat LTO support (D146776).
Original RFC: https://discourse.llvm.org/t/rfc-ffat-lto-objects-support/63977
Reviewed By: jhenderson
Differential Revision: https://reviews.llvm.org/D153215
Added:
llvm/test/ObjectYAML/ELF/llvm-section-types.yaml
Modified:
llvm/docs/Extensions.rst
llvm/include/llvm/BinaryFormat/ELF.h
llvm/lib/MC/MCParser/ELFAsmParser.cpp
llvm/lib/MC/MCSectionELF.cpp
llvm/lib/Object/ELF.cpp
llvm/lib/ObjectYAML/ELFYAML.cpp
llvm/test/MC/AsmParser/llvm_section_types.s
llvm/test/MC/ELF/section.s
llvm/test/tools/llvm-readobj/ELF/section-types.test
Removed:
llvm/test/ObjectYAML/ELF/sht-offloading.yaml
################################################################################
diff --git a/llvm/docs/Extensions.rst b/llvm/docs/Extensions.rst
index b4ea741fdfe7b..6e94840897832 100644
--- a/llvm/docs/Extensions.rst
+++ b/llvm/docs/Extensions.rst
@@ -463,6 +463,13 @@ The binary data stored in this section conforms to a custom binary format used
for storing offloading metadata. This format is effectively a string table
containing metadata accompanied by a device image.
+``SHT_LLVM_LTO`` Section (LLVM bitcode for fat LTO)
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+This section stores LLVM bitcode used to perform regular LTO or ThinLTO at link
+time. This section is generated when the compiler enables fat LTO. This section
+has the ``SHF_EXCLUDE`` flag so that it is stripped from the final executable
+or shared library.
+
CodeView-Dependent
------------------
diff --git a/llvm/include/llvm/BinaryFormat/ELF.h b/llvm/include/llvm/BinaryFormat/ELF.h
index 2cb2d8fe63ec0..a303d404f9be4 100644
--- a/llvm/include/llvm/BinaryFormat/ELF.h
+++ b/llvm/include/llvm/BinaryFormat/ELF.h
@@ -1036,6 +1036,7 @@ enum : unsigned {
SHT_LLVM_CALL_GRAPH_PROFILE = 0x6fff4c09, // LLVM Call Graph Profile.
SHT_LLVM_BB_ADDR_MAP = 0x6fff4c0a, // LLVM Basic Block Address Map.
SHT_LLVM_OFFLOADING = 0x6fff4c0b, // LLVM device offloading data.
+ SHT_LLVM_LTO = 0x6fff4c0c, // .llvm.lto for fat LTO.
// Android's experimental support for SHT_RELR sections.
// https://android.googlesource.com/platform/bionic/+/b7feec74547f84559a1467aca02708ff61346d2a/libc/include/elf.h#512
SHT_ANDROID_RELR = 0x6fffff00, // Relocation entries; only offsets.
diff --git a/llvm/lib/MC/MCParser/ELFAsmParser.cpp b/llvm/lib/MC/MCParser/ELFAsmParser.cpp
index f1bd2528eaeeb..dbfe0d83e1b29 100644
--- a/llvm/lib/MC/MCParser/ELFAsmParser.cpp
+++ b/llvm/lib/MC/MCParser/ELFAsmParser.cpp
@@ -675,6 +675,8 @@ bool ELFAsmParser::ParseSectionArguments(bool IsPush, SMLoc loc) {
Type = ELF::SHT_LLVM_BB_ADDR_MAP;
else if (TypeName == "llvm_offloading")
Type = ELF::SHT_LLVM_OFFLOADING;
+ else if (TypeName == "llvm_lto")
+ Type = ELF::SHT_LLVM_LTO;
else if (TypeName.getAsInteger(0, Type))
return TokError("unknown section type");
}
diff --git a/llvm/lib/MC/MCSectionELF.cpp b/llvm/lib/MC/MCSectionELF.cpp
index ce828cb4799f7..666252ffcb74e 100644
--- a/llvm/lib/MC/MCSectionELF.cpp
+++ b/llvm/lib/MC/MCSectionELF.cpp
@@ -169,6 +169,8 @@ void MCSectionELF::printSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
OS << "llvm_bb_addr_map_v0";
else if (Type == ELF::SHT_LLVM_OFFLOADING)
OS << "llvm_offloading";
+ else if (Type == ELF::SHT_LLVM_LTO)
+ OS << "llvm_lto";
else
report_fatal_error("unsupported type 0x" + Twine::utohexstr(Type) +
" for section " + getName());
diff --git a/llvm/lib/Object/ELF.cpp b/llvm/lib/Object/ELF.cpp
index cc4bcb89255a8..0d1862e573712 100644
--- a/llvm/lib/Object/ELF.cpp
+++ b/llvm/lib/Object/ELF.cpp
@@ -313,6 +313,7 @@ StringRef llvm::object::getELFSectionTypeName(uint32_t Machine, unsigned Type) {
STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_BB_ADDR_MAP_V0);
STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_BB_ADDR_MAP);
STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_OFFLOADING);
+ STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_LTO);
STRINGIFY_ENUM_CASE(ELF, SHT_GNU_ATTRIBUTES);
STRINGIFY_ENUM_CASE(ELF, SHT_GNU_HASH);
STRINGIFY_ENUM_CASE(ELF, SHT_GNU_verdef);
diff --git a/llvm/lib/ObjectYAML/ELFYAML.cpp b/llvm/lib/ObjectYAML/ELFYAML.cpp
index 1ec480f86ad64..32282ae31a980 100644
--- a/llvm/lib/ObjectYAML/ELFYAML.cpp
+++ b/llvm/lib/ObjectYAML/ELFYAML.cpp
@@ -681,6 +681,7 @@ void ScalarEnumerationTraits<ELFYAML::ELF_SHT>::enumeration(
ECase(SHT_LLVM_BB_ADDR_MAP_V0);
ECase(SHT_LLVM_BB_ADDR_MAP);
ECase(SHT_LLVM_OFFLOADING);
+ ECase(SHT_LLVM_LTO);
ECase(SHT_GNU_ATTRIBUTES);
ECase(SHT_GNU_HASH);
ECase(SHT_GNU_verdef);
diff --git a/llvm/test/MC/AsmParser/llvm_section_types.s b/llvm/test/MC/AsmParser/llvm_section_types.s
index 91cee6c7ec8f6..147b1499d2b88 100644
--- a/llvm/test/MC/AsmParser/llvm_section_types.s
+++ b/llvm/test/MC/AsmParser/llvm_section_types.s
@@ -15,6 +15,8 @@
.byte 1
.section .section7,"", at llvm_offloading
.byte 1
+.section .section8,"", at llvm_lto
+.byte 1
# CHECK: Name: .section1
# CHECK-NEXT: Type: SHT_LLVM_BB_ADDR_MAP
@@ -30,3 +32,5 @@
# CHECK-NEXT: Type: SHT_LLVM_DEPENDENT_LIBRARIES
# CHECK: Name: .section7
# CHECK-NEXT: Type: SHT_LLVM_OFFLOADING
+# CHECK: Name: .section8
+# CHECK-NEXT: Type: SHT_LLVM_LTO
diff --git a/llvm/test/MC/ELF/section.s b/llvm/test/MC/ELF/section.s
index fb0aaadef1013..3a6d046821f4a 100644
--- a/llvm/test/MC/ELF/section.s
+++ b/llvm/test/MC/ELF/section.s
@@ -326,3 +326,14 @@ bar:
// CHECK-NEXT: Flags [
// CHECK-NEXT: ]
// CHECK: }
+
+.section .llvm.lto,"e", at llvm_lto
+// ASM: .section .llvm.lto,"e", at llvm_lto
+
+// CHECK: Section {
+// CHECK: Name: .llvm.lto
+// CHECK-NEXT: Type: SHT_LLVM_LTO
+// CHECK-NEXT: Flags [
+// CHECK-NEXT: SHF_EXCLUDE
+// CHECK-NEXT: ]
+// CHECK: }
diff --git a/llvm/test/ObjectYAML/ELF/sht-offloading.yaml b/llvm/test/ObjectYAML/ELF/llvm-section-types.yaml
similarity index 60%
rename from llvm/test/ObjectYAML/ELF/sht-offloading.yaml
rename to llvm/test/ObjectYAML/ELF/llvm-section-types.yaml
index b234b967517b7..efa283930d073 100644
--- a/llvm/test/ObjectYAML/ELF/sht-offloading.yaml
+++ b/llvm/test/ObjectYAML/ELF/llvm-section-types.yaml
@@ -11,18 +11,31 @@ Sections:
- Name: .llvm.offloading
Type: SHT_LLVM_OFFLOADING
Flags: [ SHF_EXCLUDE ]
+ - Name: .llvm.lto
+ Type: SHT_LLVM_LTO
+ Flags: [ SHF_EXCLUDE ]
# OBJ: Sections [
# OBJ: Section {
# OBJ: Index: 1
-# OBJ-NEXT: Name: .llvm.offloading (1)
+# OBJ-NEXT: Name: .llvm.offloading
# OBJ-NEXT: Type: SHT_LLVM_OFFLOADING (0x6FFF4C0B)
# OBJ-NEXT: Flags [ (0x80000000)
# OBJ-NEXT: SHF_EXCLUDE (0x80000000)
# OBJ-NEXT: ]
+# OBJ: Section {
+# OBJ: Index: 2
+# OBJ-NEXT: Name: .llvm.lto
+# OBJ-NEXT: Type: SHT_LLVM_LTO (0x6FFF4C0C)
+# OBJ-NEXT: Flags [ (0x80000000)
+# OBJ-NEXT: SHF_EXCLUDE (0x80000000)
+# OBJ-NEXT: ]
# YAML: Sections:
# YAML-NEXT: - Name: .llvm.offloading
# YAML-NEXT: Type: SHT_LLVM_OFFLOADING
# YAML-NEXT: Flags: [ SHF_EXCLUDE ]
+# YAML: - Name: .llvm.lto
+# YAML-NEXT: Type: SHT_LLVM_LTO
+# YAML-NEXT: Flags: [ SHF_EXCLUDE ]
diff --git a/llvm/test/tools/llvm-readobj/ELF/section-types.test b/llvm/test/tools/llvm-readobj/ELF/section-types.test
index ee220982eeefb..071ca80575849 100644
--- a/llvm/test/tools/llvm-readobj/ELF/section-types.test
+++ b/llvm/test/tools/llvm-readobj/ELF/section-types.test
@@ -59,6 +59,8 @@
# LLVM: Type: SHT_LLVM_PART_EHDR
# LLVM: Name: .phdrs
# LLVM: Type: SHT_LLVM_PART_PHDR
+# LLVM: Name: .llvm.lto
+# LLVM: Type: SHT_LLVM_LTO
# LLVM: Name: gnu_attributes
# LLVM: Type: SHT_GNU_ATTRIBUTES
# LLVM: Name: gnu_hash
@@ -119,6 +121,7 @@
# GNU-NEXT: .llvm_sympart.f LLVM_SYMPART
# GNU-NEXT: part1 LLVM_PART_EHDR
# GNU-NEXT: .phdrs LLVM_PART_PHDR
+# GNU-NEXT: .llvm.lto LLVM_LTO
# GNU-NEXT: gnu_attributes ATTRIBUTES
# GNU-NEXT: gnu_hash GNU_HASH
# GNU-NEXT: gnu_verdef VERDEF
@@ -205,6 +208,8 @@ Sections:
Type: SHT_LLVM_PART_EHDR
- Name: .phdrs
Type: SHT_LLVM_PART_PHDR
+ - Name: .llvm.lto
+ Type: SHT_LLVM_LTO
- Name: gnu_attributes
Type: SHT_GNU_ATTRIBUTES
- Name: gnu_hash
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