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The main disassembly loop in llvm-objdump works by iterating through the symbols in a code section, and for each one, dumping the range of the section from that symbol to the next. If there's another symbol defined at the same location, then that range will have length 0, and llvm-objdump will skip over the symbol entirely. As a result, llvm-objdump will only show the last of the symbols defined at that address. Not only that, but the other symbols won't even be checked against the `--disassemble-symbol` list. So if you have two symbols `foo` and `bar` defined in the same place, then one of `--disassemble-symbol=foo` and `--disassemble-symbol=bar` will generate an error message and no disassembly. I think a better approach in that situation is to prioritise display of the symbol the user actually asked for. Also, if the user specifically asks for disassembly of //both// of two symbols defined at the same address, the best response I can think of is to disassemble the code once, preceded by both symbol names. This involves teaching llvm-objdump to be able to display more than one symbol name at the head of a disassembled section, which also makes it possible to implement a `--show-all-symbols` option to display //every// symbol defined in the code, not just the most preferred one at each address. This change also turns out to fix a bug in which `--disassemble-all` on a mixed Arm/Thumb ELF file would fail to switch disassembly states between Arm and Thumb functions, because the mapping symbols were accidentally ignored. Reviewed By: jhenderson Differential Revision: https://reviews.llvm.org/D131589
98 lines
4.7 KiB
ArmAsm
98 lines
4.7 KiB
ArmAsm
// This test checks the behavior of llvm-objdump's --disassemble-symbols and
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// --show-all-symbols options, in the presence of multiple symbols defined at
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// the same address in an object file.
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// The test input file contains an Arm and a Thumb function, each with two
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// function-type symbols defined at its entry point. Also, because it's Arm,
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// there's a $a mapping symbol defined at the start of the section, and a $t
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// mapping symbol at the point where Arm code stops and Thumb code begins.
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// By default, llvm-objdump will pick one of the symbols to disassemble at each
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// point where any are defined at all. The tie-break sorting criterion is
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// alphabetic, so it will be the alphabetically later symbol in each case: of
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// the names aaaa and bbbb for the Arm function it picks bbbb, and of cccc and
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// dddd for the Thumb function it picks dddd.
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// Including an Arm and a Thumb function also re-checks that these changes to
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// the display of symbols doesn't affect the recognition of mapping symbols for
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// the purpose of switching disassembly mode.
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@ REQUIRES: arm-registered-target
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@ RUN: llvm-mc -triple armv8a-unknown-linux -filetype=obj %s -o %t.o
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// All the run lines below should generate some subset of this
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// display, with different parts included:
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@ HEAD: Disassembly of section .text:
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@ HEAD-EMPTY:
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@ AMAP-NEXT: 00000000 <$a.0>:
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@ AAAA-NEXT: 00000000 <aaaa>:
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@ BBBB-NEXT: 00000000 <bbbb>:
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@ AABB-NEXT: 0: e0800080 add r0, r0, r0, lsl #1
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@ AABB-NEXT: 4: e12fff1e bx lr
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@ BOTH-EMPTY:
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@ TMAP-NEXT: 00000008 <$t.1>:
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@ CCCC-NEXT: 00000008 <cccc>:
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@ DDDD-NEXT: 00000008 <dddd>:
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@ CCDD-NEXT: 8: eb00 0080 add.w r0, r0, r0, lsl #2
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@ CCDD-NEXT: c: 4770 bx lr
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// The default disassembly chooses just the alphabetically later symbol of each
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// set, namely bbbb and dddd.
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@ RUN: llvm-objdump --triple armv8a -d %t.o | FileCheck --check-prefixes=HEAD,BBBB,AABB,BOTH,DDDD,CCDD %s
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// With the --show-all-symbols option, all the symbols are shown, including the
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// administrative mapping symbols.
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@ RUN: llvm-objdump --triple armv8a --show-all-symbols -d %t.o | FileCheck --check-prefixes=HEAD,AMAP,AAAA,BBBB,AABB,BOTH,TMAP,CCCC,DDDD,CCDD %s
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// If we use --disassemble-symbols to ask for the disassembly of aaaa or bbbb
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// or both, then we expect the second cccc/dddd function not to appear in the
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// output at all. Also, we want to see whichever symbol we asked about, or both
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// if we asked about both.
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@ RUN: llvm-objdump --triple armv8a --disassemble-symbols=aaaa -d %t.o | FileCheck --check-prefixes=HEAD,AAAA,AABB %s
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@ RUN: llvm-objdump --triple armv8a --disassemble-symbols=bbbb -d %t.o | FileCheck --check-prefixes=HEAD,BBBB,AABB %s
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@ RUN: llvm-objdump --triple armv8a --disassemble-symbols=aaaa,bbbb -d %t.o | FileCheck --check-prefixes=HEAD,AAAA,BBBB,AABB %s
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// With _any_ of those three options and also --show-all-symbols, the
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// disassembled code is still limited to just the symbol(s) you asked about,
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// but all symbols defined at the same address are mentioned, whether you asked
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// about them or not.
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@ RUN: llvm-objdump --triple armv8a --disassemble-symbols=aaaa --show-all-symbols -d %t.o | FileCheck --check-prefixes=HEAD,AMAP,AAAA,BBBB,AABB %s
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@ RUN: llvm-objdump --triple armv8a --disassemble-symbols=bbbb --show-all-symbols -d %t.o | FileCheck --check-prefixes=HEAD,AMAP,AAAA,BBBB,AABB %s
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@ RUN: llvm-objdump --triple armv8a --disassemble-symbols=aaaa,bbbb --show-all-symbols -d %t.o | FileCheck --check-prefixes=HEAD,AMAP,AAAA,BBBB,AABB %s
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// Similarly for the Thumb function and its symbols. This time we must check
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// that the aaaa/bbbb block of code was not disassembled _before_ the output
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// we're expecting.
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@ RUN: llvm-objdump --triple armv8a --disassemble-symbols=cccc -d %t.o | FileCheck --check-prefixes=HEAD,CCCC,CCDD %s
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@ RUN: llvm-objdump --triple armv8a --disassemble-symbols=dddd -d %t.o | FileCheck --check-prefixes=HEAD,DDDD,CCDD %s
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@ RUN: llvm-objdump --triple armv8a --disassemble-symbols=cccc,dddd -d %t.o | FileCheck --check-prefixes=HEAD,CCCC,DDDD,CCDD %s
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@ RUN: llvm-objdump --triple armv8a --disassemble-symbols=cccc --show-all-symbols -d %t.o | FileCheck --check-prefixes=HEAD,TMAP,CCCC,DDDD,CCDD %s
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@ RUN: llvm-objdump --triple armv8a --disassemble-symbols=dddd --show-all-symbols -d %t.o | FileCheck --check-prefixes=HEAD,TMAP,CCCC,DDDD,CCDD %s
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@ RUN: llvm-objdump --triple armv8a --disassemble-symbols=cccc,dddd --show-all-symbols -d %t.o | FileCheck --check-prefixes=HEAD,TMAP,CCCC,DDDD,CCDD %s
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.text
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.globl aaaa
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.globl bbbb
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.globl cccc
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.globl dddd
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.arm
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aaaa:
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bbbb:
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add r0, r0, r0, lsl #1
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bx lr
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.thumb
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cccc:
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dddd:
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add.w r0, r0, r0, lsl #2
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bx lr
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