[PATCH] D67256: [yaml2obj] Simplify p_filesz/p_memsz computing
Fangrui Song via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Thu Sep 5 23:35:35 PDT 2019
MaskRay created this revision.
MaskRay added reviewers: grimar, jakehehrlich, jhenderson.
Herald added a project: LLVM.
Herald added a subscriber: llvm-commits.
This fixes a bug as well. When "FileSize:" (p_filesz) is specified and
different from the actual value, the following code probably should not
use PHeader.p_filesz:
if (SHeader->sh_offset == PHeader.p_offset + PHeader.p_filesz)
PHeader.p_memsz += SHeader->sh_size;
Repository:
rL LLVM
https://reviews.llvm.org/D67256
Files:
lib/ObjectYAML/ELFEmitter.cpp
test/tools/yaml2obj/program-header-size-offset.yaml
Index: test/tools/yaml2obj/program-header-size-offset.yaml
===================================================================
--- test/tools/yaml2obj/program-header-size-offset.yaml
+++ test/tools/yaml2obj/program-header-size-offset.yaml
@@ -11,7 +11,7 @@
# CHECK: Offset: 0x2000
# CHECK: FileSize: 6
-# CHECK: MemSize: 6
+# CHECK: MemSize: 4
# CHECK: Offset: 0x2000
# CHECK: FileSize: 4
Index: lib/ObjectYAML/ELFEmitter.cpp
===================================================================
--- lib/ObjectYAML/ELFEmitter.cpp
+++ lib/ObjectYAML/ELFEmitter.cpp
@@ -624,36 +624,25 @@
PHeader.p_offset = std::min(PHeader.p_offset, SHeader->sh_offset);
}
- // Find the maximum offset of the end of a section in order to set p_filesz,
- // if not set explicitly.
- if (YamlPhdr.FileSize) {
- PHeader.p_filesz = *YamlPhdr.FileSize;
- } else {
- PHeader.p_filesz = 0;
- for (Elf_Shdr *SHeader : Sections) {
- uint64_t EndOfSection;
- if (SHeader->sh_type == llvm::ELF::SHT_NOBITS)
- EndOfSection = SHeader->sh_offset;
- else
- EndOfSection = SHeader->sh_offset + SHeader->sh_size;
- uint64_t EndOfSegment = PHeader.p_offset + PHeader.p_filesz;
- EndOfSegment = std::max(EndOfSegment, EndOfSection);
- PHeader.p_filesz = EndOfSegment - PHeader.p_offset;
- }
- }
+ // Find the maximum offset of the end of a section in order to set p_filesz
+ // and p_memsz. When setting p_filesz, sh_size is seen as 0 for SHT_NOBITS
+ // sections.
+ uint64_t FileEnd = PHeader.p_offset, MemEnd = PHeader.p_offset;
+ for (Elf_Shdr *SHeader : Sections) {
+ uint64_t End = SHeader->sh_offset + SHeader->sh_size;
+ MemEnd = std::max(MemEnd, End);
- // If not set explicitly, find the memory size by adding the size of
- // sections at the end of the segment. These should be empty (size of zero)
- // and NOBITS sections.
- if (YamlPhdr.MemSize) {
- PHeader.p_memsz = *YamlPhdr.MemSize;
- } else {
- PHeader.p_memsz = PHeader.p_filesz;
- for (Elf_Shdr *SHeader : Sections)
- if (SHeader->sh_offset == PHeader.p_offset + PHeader.p_filesz)
- PHeader.p_memsz += SHeader->sh_size;
+ if (SHeader->sh_type == llvm::ELF::SHT_NOBITS)
+ End = SHeader->sh_offset;
+ FileEnd = std::max(FileEnd, End);
}
+ // Set the file size and the memory size if not set explicitly.
+ PHeader.p_filesz = YamlPhdr.FileSize ? uint64_t(*YamlPhdr.FileSize)
+ : FileEnd - PHeader.p_offset;
+ PHeader.p_memsz = YamlPhdr.MemSize ? uint64_t(*YamlPhdr.MemSize)
+ : MemEnd - PHeader.p_offset;
+
// Set the alignment of the segment to be the same as the maximum alignment
// of the sections with the same offset so that by default the segment
// has a valid and sensible alignment.
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