Bug 1040955

Summary:	clang misassembles 16-bit operations
Product:	[Fedora] Fedora	Reporter:	David Woodhouse <dwmw2>
Component:	llvm	Assignee:	Nobody's working on this, feel free to take it <nobody>
Status:	CLOSED EOL	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	unspecified	Docs Contact:
Priority:	unspecified
Version:	19	CC:	ajax, bos, dmalcolm, jv+fedora, michel, petersen, scottt.tw
Target Milestone:	---
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Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2015-02-17 19:37:06 UTC	Type:	Bug
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:

Description David Woodhouse 2013-12-12 12:05:06 UTC

Steps to Reproduce:

 $ cat foo.S
movb   $0x5a,0x1234(%bp)
 $ clang -o foo.o -c -m32 foo.S
 $ objdump -d foo.o

Actual results:

00000000 <.text>:
   0:	67 c6 85 34 12 00    	movb   $0x0,0x1234(%di)
   6:	00                   	.byte 0x0
   7:	5a                   	pop    %edx


Expected results:

Well, I kind of expected it to look like more the original source. You know, with the same immediate value (0x5a) being stored, the same base register (%bp not %di) for the address, and no trailing garbage. A bit like GCC does:

00000000 <.text>:
   0:	67 c6 86 34 12 5a    	movb   $0x5a,0x1234(%bp)

Note -m32. It's differently broken in -m64 (where it should actually refuse to compile this, but doesn't and emits different garbage instead).

Additional info:

http://llvm.org/bugs/show_bug.cgi?id=18220

Comment 1 Adam Jackson 2014-11-19 16:28:35 UTC

Reassign to nobody@.  I have no time and no interest in working on clang, and the only reason it's even in the llvm package is because it can't be built any other way.

If anyone wishes to volunteer for comaintainer with a focus on clang, please let me know (preferably with direct email, if it's in bz I'll likely miss the request), I'll be happy to hook you up.

Comment 2 Fedora End Of Life 2015-01-09 20:50:34 UTC

This message is a notice that Fedora 19 is now at end of life. Fedora 
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Comment 3 Fedora End Of Life 2015-02-17 19:37:06 UTC

Fedora 19 changed to end-of-life (EOL) status on 2015-01-06. Fedora 19 is
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