[LLVMbugs] [Bug 5503] New: __attribute__ aligned does not work as expected on mingw32

[bugzilla-daemon at cs.uiuc.edu]

http://llvm.org/bugs/show_bug.cgi?id=5503

           Summary: __attribute__ aligned does not work as expected on
                    mingw32
           Product: tools
           Version: 2.6
          Platform: PC
        OS/Version: Windows XP
            Status: NEW
          Severity: normal
          Priority: P2
         Component: llvm-gcc
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: sherpya at gmail.com
                CC: llvmbugs at cs.uiuc.edu


Created an attachment (id=3822)
 --> (http://llvm.org/bugs/attachment.cgi?id=3822)
test case

There is a bug on gcc/binutils, resolved on latest svn revisions

__attribute__ aligned does not work well with commons
since the info about alignment is lost when producing coff objects

this can be a problem when vectorizing (dunno on llvm) with -O3 and cpu with
sse, or simply using some inline sse code that expects 16-byte aligned
data

there are 2 kind of aligned, global or local
by using -fno-common on gcc the problem is workarounded

on llvm, with -fno-common only global declarations are aligned

I'm attaching a test case

here my outputs:

llvm-gcc:
Local Aligned 16: 8
Local Aligned 32: 8
Global Aligned 16: 8
Global Aligned 32: 8

llvm-gcc with -fno-common:
Local Aligned 16: 8
Local Aligned 32: 8
Global Aligned 16: 0
Global Aligned 32: 0

gcc with -fno-common:
Local Aligned 16: 0
Local Aligned 32: 0
Global Aligned 16: 0
Global Aligned 32: 0

link to gcc bug:
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37216


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