[elf] AsmPrinter doesn't quote section name when necessary

[jsonn]

Bugzilla Link	9033
Resolution	FIXED
Resolved on	Mar 03, 2011 16:32
Version	trunk
OS	Linux
Attachments	Potential fix
CC	@asl

Extended Description

Consider the following input:

.section "foo bar"

With the patch from PR 8948, llvm-mc gives the following output:

.section	__TEXT,__text,regular,pure_instructions
.section	foo bar,"",@progbits

This is not equivalent to the original input and can't be parsed.

[llvmbot]

This probably blocks on 8948 being fixed first, no?

[jsonn]

This probably blocks on 8948 being fixed first, no?

If always quoting is the desired solution, fixing 8948 is important to allow round-trip from Printer -> Parser.

[llvmbot]

I think the patch is OK. We probably still fail in corner cases like

.section foo"bar"

but it is an improvement.

You will probably have to update some tests too.

[jsonn]

Revised patch (including test cases)
This patch consistently quotes the section name for all backends and uses a common function. If this is handled correctly by all platforms, it should be considered for the other elements on MachO.

The quoting routine adds \ for trailing backslash and quotes " if necessary.
This handles some cases that e.g. GCC doesn't deal with like

int test attribute((section("test"")));

[llvmbot]

I think it is fine, just ping some MachO guy to make sure that old assemblers are ok with the quotes.

[llvmbot]

I tried the Mac OS X assembler and it parses the names of the segment and section and other arguments of the .section directive via the comma separators (eating preceding white space). So the quotes around the names is likely not to do what you want there. For example if your input is:

% cat x.s
.section "foo bar", __sectname
.section foo bar, __sectname

% as x.s

You get a segment a name with the quotes:

% size -m -x -l a.out
Segment : 0x0 (vmaddr 0x0 fileoff 344)
Section (__TEXT, __text): 0x0 (addr 0x0 offset 344)
Section ("foo bar", __sectname): 0x0 (addr 0x0 offset 344)
Section (foo bar, __sectname): 0x0 (addr 0x0 offset 344)
total 0x0

And yes it is inconsistent with llvm-mc's parsing:

% llvm-mc -triple i386-apple-darwin10 x.s -filetype=obj -o a.out
x.s:2:14: error: unexpected token in '.section' directive
.section foo bar, __sectname
^

where the caret is at the beginning of the bar token.

[llvmbot]

The patch seems to apply to MCSectionELF::PrintSwitchToSection() so I don't think it would be a problem for Mach-O.

[jsonn]

The patch seems to apply to MCSectionELF::PrintSwitchToSection() so I don't
think it would be a problem for Mach-O.

The second version of the patch moved the quoting to the new MCSection::PrintQuotedSectionName. I will update the patch to apply only to ELF as to not introduce regressions for MachO.

[jsonn]

Quote section names for ELF, keep other platforms as is

[jsonn]

With a small test for the quote handling committed.