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-rw-r--r--gdb/doc/gdb.texinfo121
1 files changed, 112 insertions, 9 deletions
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index c64c7a1..c876ed6 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -8098,11 +8098,12 @@ Variables}).
@cindex listing machine instructions
@item disassemble
@itemx disassemble /m
+@itemx disassemble /s
@itemx disassemble /r
This specialized command dumps a range of memory as machine
instructions. It can also print mixed source+disassembly by specifying
-the @code{/m} modifier and print the raw instructions in hex as well as
-in symbolic form by specifying the @code{/r}.
+the @code{/m} or @code{/s} modifier and print the raw instructions in hex
+as well as in symbolic form by specifying the @code{/r} modifier.
The default memory range is the function surrounding the
program counter of the selected frame. A single argument to this
command is a program counter value; @value{GDBN} dumps the function
@@ -8146,8 +8147,9 @@ Dump of assembler code from 0x32c4 to 0x32e4:
End of assembler dump.
@end smallexample
-Here is an example showing mixed source+assembly for Intel x86, when the
-program is stopped just after function prologue:
+Here is an example showing mixed source+assembly for Intel x86
+with @code{/m} or @code{/s}, when the program is stopped just after
+function prologue in a non-optimized function with no inline code.
@smallexample
(@value{GDBP}) disas /m main
@@ -8172,6 +8174,96 @@ Dump of assembler code for function main:
End of assembler dump.
@end smallexample
+The @code{/m} option is deprecated as its output is not useful when
+there is either inlined code or re-ordered code.
+The @code{/s} option is the preferred choice.
+Here is an example for AMD x86-64 showing the difference between
+@code{/m} output and @code{/s} output.
+This example has one inline function defined in a header file,
+and the code is compiled with @samp{-O2} optimization.
+Note how the @code{/m} output is missing the disassembly of
+several instructions that are present in the @code{/s} output.
+
+@file{foo.h}:
+
+@smallexample
+int
+foo (int a)
+@{
+ if (a < 0)
+ return a * 2;
+ if (a == 0)
+ return 1;
+ return a + 10;
+@}
+@end smallexample
+
+@file{foo.c}:
+
+@smallexample
+#include "foo.h"
+volatile int x, y;
+int
+main ()
+@{
+ x = foo (y);
+ return 0;
+@}
+@end smallexample
+
+@smallexample
+(@value{GDBP}) disas /m main
+Dump of assembler code for function main:
+5 @{
+
+6 x = foo (y);
+ 0x0000000000400400 <+0>: mov 0x200c2e(%rip),%eax # 0x601034 <y>
+ 0x0000000000400417 <+23>: mov %eax,0x200c13(%rip) # 0x601030 <x>
+
+7 return 0;
+8 @}
+ 0x000000000040041d <+29>: xor %eax,%eax
+ 0x000000000040041f <+31>: retq
+ 0x0000000000400420 <+32>: add %eax,%eax
+ 0x0000000000400422 <+34>: jmp 0x400417 <main+23>
+
+End of assembler dump.
+(@value{GDBP}) disas /s main
+Dump of assembler code for function main:
+foo.c:
+5 @{
+6 x = foo (y);
+ 0x0000000000400400 <+0>: mov 0x200c2e(%rip),%eax # 0x601034 <y>
+
+foo.h:
+4 if (a < 0)
+ 0x0000000000400406 <+6>: test %eax,%eax
+ 0x0000000000400408 <+8>: js 0x400420 <main+32>
+
+6 if (a == 0)
+7 return 1;
+8 return a + 10;
+ 0x000000000040040a <+10>: lea 0xa(%rax),%edx
+ 0x000000000040040d <+13>: test %eax,%eax
+ 0x000000000040040f <+15>: mov $0x1,%eax
+ 0x0000000000400414 <+20>: cmovne %edx,%eax
+
+foo.c:
+6 x = foo (y);
+ 0x0000000000400417 <+23>: mov %eax,0x200c13(%rip) # 0x601030 <x>
+
+7 return 0;
+8 @}
+ 0x000000000040041d <+29>: xor %eax,%eax
+ 0x000000000040041f <+31>: retq
+
+foo.h:
+5 return a * 2;
+ 0x0000000000400420 <+32>: add %eax,%eax
+ 0x0000000000400422 <+34>: jmp 0x400417 <main+23>
+End of assembler dump.
+@end smallexample
+
Here is another example showing raw instructions in hex for AMD x86-64,
@smallexample
@@ -29782,9 +29874,20 @@ displayed; if @var{lines} is higher than the number of lines between
@var{start-addr} and @var{end-addr}, only the lines up to @var{end-addr}
are displayed.
@item @var{mode}
-is either 0 (meaning only disassembly), 1 (meaning mixed source and
-disassembly), 2 (meaning disassembly with raw opcodes), or 3 (meaning
-mixed source and disassembly with raw opcodes).
+is one of:
+@itemize @bullet
+@item 0 disassembly only
+@item 1 mixed source and disassembly (deprecated)
+@item 2 disassembly with raw opcodes
+@item 3 mixed source and disassembly with raw opcodes (deprecated)
+@item 4 mixed source and disassembly
+@item 5 mixed source and disassembly with raw opcodes
+@end itemize
+
+Modes 1 and 3 are deprecated. The output is ``source centric''
+which hasn't proved useful in practice.
+@xref{Machine Code}, for a discussion of the difference between
+@code{/m} and @code{/s} output of the @code{disassemble} command.
@end table
@subsubheading Result
@@ -29810,12 +29913,12 @@ The decimal offset in bytes from the start of @samp{func-name}.
The text disassembly for this @samp{address}.
@item opcodes
-This field is only present for mode 2. This contains the raw opcode
+This field is only present for modes 2, 3 and 5. This contains the raw opcode
bytes for the @samp{inst} field.
@end table
-For modes 1 and 3 the @samp{asm_insns} list contains tuples named
+For modes 1, 3, 4 and 5 the @samp{asm_insns} list contains tuples named
@samp{src_and_asm_line}, each of which has the following fields:
@table @code