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llvm-project/llvm/test/MC/ELF/many-sections.s

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Create .symtab_shndxr only when needed. We need .symtab_shndxr if and only if a symbol references a section with an index >= 0xff00. The old code was trying to figure out if the section was needed ahead of time, making it a fairly dependent on the code actually writing the table. It was also somewhat conservative and would create the section in cases where it was not needed. If I remember correctly, the old structure was there so that the sections were created in the same order gas creates them. That was valuable when MC's support for ELF was new and we tested with elf-dump.py. This patch refactors the symbol table creation to another class and makes it obvious that .symtab_shndxr is really only created when we are about to output a reference to a section index >= 0xff00. While here, also improve the tests to use macros. One file is one section short of needing .symtab_shndxr, the second one has just the right number. llvm-svn: 204769
2014-03-26 07:44:25 +08:00
// RUN: llvm-mc -filetype=obj -triple x86_64-pc-linux-gnu %s -o %t
// RUN: llvm-readobj -s %t | FileCheck --check-prefix=SECTIONS %s
// RUN: llvm-readobj -t %t | FileCheck --check-prefix=SYMBOLS %s
// Test that we don't create a .symtab_shndx since we are one section short of
// SHN_LORESERVE (0xFF00).
// SECTIONS-NOT: Name: .symtab_shndx
// Check the last referenced section.
Fix the interpretation of a 0 st_name. The ELF spec is very clear: ----------------------------------------------------------------------------- If the value is non-zero, it represents a string table index that gives the symbol name. Otherwise, the symbol table entry has no name. -------------------------------------------------------------------------- In particular, a st_name of 0 most certainly doesn't mean that the symbol has the same name as the section. llvm-svn: 238899
2015-06-03 13:14:22 +08:00
// SYMBOLS: Name: (0)
// SYMBOLS: Value: 0x0
// SYMBOLS: Size: 0
// SYMBOLS: Binding: Local (0x0)
// SYMBOLS: Type: Section (0x3)
// SYMBOLS: Other: 0
// SYMBOLS: Section: zed (0xFEFF)
Create .symtab_shndxr only when needed. We need .symtab_shndxr if and only if a symbol references a section with an index >= 0xff00. The old code was trying to figure out if the section was needed ahead of time, making it a fairly dependent on the code actually writing the table. It was also somewhat conservative and would create the section in cases where it was not needed. If I remember correctly, the old structure was there so that the sections were created in the same order gas creates them. That was valuable when MC's support for ELF was new and we tested with elf-dump.py. This patch refactors the symbol table creation to another class and makes it obvious that .symtab_shndxr is really only created when we are about to output a reference to a section index >= 0xff00. While here, also improve the tests to use macros. One file is one section short of needing .symtab_shndxr, the second one has just the right number. llvm-svn: 204769
2014-03-26 07:44:25 +08:00
// SYMBOLS-NEXT: }
// SYMBOLS-NEXT:]
.macro gen_sections4 x
.section a\x
.section b\x
.section c\x
.section d\x
.endm
.macro gen_sections8 x
gen_sections4 a\x
gen_sections4 b\x
.endm
.macro gen_sections16 x
gen_sections8 a\x
gen_sections8 b\x
.endm
.macro gen_sections32 x
gen_sections16 a\x
gen_sections16 b\x
.endm
.macro gen_sections64 x
gen_sections32 a\x
gen_sections32 b\x
.endm
.macro gen_sections128 x
gen_sections64 a\x
gen_sections64 b\x
.endm
.macro gen_sections256 x
gen_sections128 a\x
gen_sections128 b\x
.endm
.macro gen_sections512 x
gen_sections256 a\x
gen_sections256 b\x
.endm
.macro gen_sections1024 x
gen_sections512 a\x
gen_sections512 b\x
.endm
.macro gen_sections2048 x
gen_sections1024 a\x
gen_sections1024 b\x
.endm
.macro gen_sections4096 x
gen_sections2048 a\x
gen_sections2048 b\x
.endm
.macro gen_sections8192 x
gen_sections4096 a\x
gen_sections4096 b\x
.endm
.macro gen_sections16384 x
gen_sections8192 a\x
gen_sections8192 b\x
.endm
.macro gen_sections32768 x
gen_sections16384 a\x
gen_sections16384 b\x
.endm
gen_sections32768 a
gen_sections16384 b
gen_sections8192 c
gen_sections4096 d
gen_sections2048 e
gen_sections1024 f
gen_sections512 g
gen_sections128 h
gen_sections64 i
gen_sections32 j
gen_sections16 k
gen_sections8 l
Don't create empty sections just to look like gas. We are long past the time when this much bug for bug compatibility was useful. llvm-svn: 251970
2015-11-04 04:02:22 +08:00
gen_sections4 m
Write the section header string table directly to the output stream. Instead of accumulating the content in a fragment first, just write it to the output stream. Also put it first in the section table, so that we never have to worry about its index being >= SHN_LORESERVE. llvm-svn: 236145
2015-04-30 04:25:24 +08:00
.section zed
Omit unused section symbols from the symbol table. Section symbols exist as an optimization: instead of having multiple relocations point to different symbols, many of them can point to a single section symbol. When that optimization is unused, a section symbol is also unused and adds no extra information to the object file. This saves a bit of space on the object files and makes the output of llvm-objdump -t easier to read and consequently some tests get quite a bit simpler. llvm-svn: 239045
2015-06-04 23:33:30 +08:00
.long zed