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</o:shapelayout></xml><![endif]--></head><body lang=EN-GB link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US'>Thanks for the answer. I see what you mean. Unfortunately, clang does not like if I put the attribute between the type and the pointer:<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US'>int [[vms::ptr_32]] * HiIAmA32BitPtr{ (int*)0xFFFF'FFFF };<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US'>error: 'ptr_32' attribute cannot be applied to types<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US'>int [[vms::ptr_32]] * HiIAmA32BitPtr{ (int*)0xFFFF'FFFF };<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US'>The documentation is a little unclear on how to configure these attributes. I have:<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US'>def VmsPtr32: TypeAttr<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US'>{<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US'> let Spellings = [CXX11<"vms", "ptr_32">];<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US'> let Documentation = [Undocumented];<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US'>}<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US'>What should I be doing to get clang to accept this?<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal style='margin-top:12.0pt;page-break-after:avoid'><span style='font-size:11.0pt;font-family:"Calibri Light",sans-serif;color:#A5A5A5'>Regards,</span><span lang=SV style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:black'><o:p></o:p></span></p><p class=MsoNormal style='page-break-after:avoid'><span style='font-size:11.0pt;font-family:"Calibri Light",sans-serif;color:#A5A5A5'>Patrik Eklöf</span><span lang=SV style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:black'><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><b><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri",sans-serif'>From:</span></b><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri",sans-serif'> metafoo@gmail.com [mailto:metafoo@gmail.com] <b>On Behalf Of </b>Richard Smith<br><b>Sent:</b> 03 February 2017 16:37<br><b>To:</b> Patrik EKlöf <patrik.eklof@vmssoftware.com><br><b>Cc:</b> Clang Dev <cfe-dev@lists.llvm.org><br><b>Subject:</b> Re: [cfe-dev] Implementing address space via custom C++11 attribute<o:p></o:p></span></p><p class=MsoNormal><o:p> </o:p></p><div><div><div><p class=MsoNormal>On 3 February 2017 at 12:58, Patrik EKlöf via cfe-dev <<a href="mailto:cfe-dev@lists.llvm.org" target="_blank">cfe-dev@lists.llvm.org</a>> wrote:<o:p></o:p></p><blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0cm 0cm 0cm 6.0pt;margin-left:4.8pt;margin-right:0cm'><div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>Hello dear community,<o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>I’ve been trying to implement a way to set address spaces using a custom C++11-style attribute, but I’ve been running into problems. The syntax I’m trying to use is:<o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>[[vms::ptr_32]] int* HiIAmA32BitPtr{ (int*)0xFFFF'FFFF };<o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>But apparently clang ignores those C++11-style attributes. Looking at the source, it’s because the attribute isn’t attached properly to the DeclSpec since…<o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:9.5pt;font-family:Consolas;color:#2B91AF'>DeclaratorChunk</span><span style='font-size:9.5pt;font-family:Consolas;color:black'>& DeclType = D.getTypeObject(chunkIndex);</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:9.5pt;font-family:Consolas;color:black'> </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>…returns NULL. Not sure why, or what it is doing. The alternative way of doing it that I found is doing:<o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>int* [[vms::ptr_32]] HiIAmA32BitPtr{ (int*)0xFFFF'FFFF };<o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>This attribute is detected properly, but the type passed into <span style='font-size:9.5pt;font-family:Consolas;color:black'>processTypeAttrs </span>is int* (apparently if using the __attribute((address_space)) syntax, it passes in regulator int), and attaching the address space to int* doesn’t seem to work as clang creates an llvm::type (lib/CodeGen/CodeGenTypes.cpp) using the address space of the pointee instead of the actual pointer type. That seems weird to me, but I don’t know what exactly address spaces are or how they work.<o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>So I’m a little confused on how to approach this. I would like the first syntax to work if possible,<o:p></o:p></p></div></div></blockquote><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>That would be a mistake. An attribute in that position applies to the variable HiIAmA32BitPtr itself, not to its type. You should also consider cases like:<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal> int **p;<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>What if you want p to be a 32-bit pointer to a 64-bit pointer to int, or vice versa?<o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0cm 0cm 0cm 6.0pt;margin-left:4.8pt;margin-right:0cm'><div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>but I’m not sure how one would go about implementing that without breaking anything. The second syntax seems to behave in a non-ideal way, by passing in int* instead of int. Not sure how one would go about fixing that, or if one should just make a hack to try to get the underlying type. I use address spaces since it seems like a good way to use mixed pointer sizes in the same translation unit.<o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>Any ideas or thoughts?<o:p></o:p></p></div></div></blockquote><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>It seems like what your attribute is really saying is that the 'int' lives in a 32-bit address space. So this could be written as:<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>int [[vms::ptr_32]] * HiIAmA32BitPtr{ (int*)0xFFFF'FFFF };<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>That is, HiIAmA32BitPtr is a pointer to an "int in some 32-bit address space".<o:p></o:p></p></div></div></div></div></div></body></html>