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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal>Hi,<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I’m planning to implement “execute only” support in the ARM code generator. This basically means that the compiler will not generate data access to the generated code sections (e.g. data and code are strictly separated into different sections). Outline:<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoListParagraph style='text-indent:-18.0pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='mso-list:Ignore'>-<span style='font:7.0pt "Times New Roman"'> </span></span><![endif]>Add the subtarget feature/attribute "execute-only” to the ARM code generator to enable the feature.<o:p></o:p></p><p class=MsoListParagraph style='text-indent:-18.0pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='mso-list:Ignore'>-<span style='font:7.0pt "Times New Roman"'> </span></span><![endif]>Add a clang option “-mexecute-only” that passes said attribute to LLVM.<o:p></o:p></p><p class=MsoNormal>If execute only is enabled:<o:p></o:p></p><p class=MsoListParagraph style='text-indent:-18.0pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='mso-list:Ignore'>-<span style='font:7.0pt "Times New Roman"'> </span></span><![endif]>Instead of using integer literal pools, use movw/movt to construct the literals. This means this feature is only available for sub-targets that support these instructions.<o:p></o:p></p><p class=MsoListParagraph style='text-indent:-18.0pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='mso-list:Ignore'>-<span style='font:7.0pt "Times New Roman"'> </span></span><![endif]>For floating point literals, use movw/movt/vmov instead of a literal pool.<o:p></o:p></p><p class=MsoListParagraph style='text-indent:-18.0pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='mso-list:Ignore'>-<span style='font:7.0pt "Times New Roman"'> </span></span><![endif]>Move jump tables to data sections.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>This is basically a re-implementation of a feature that is found in the ARM Compiler (<a href="http://infocenter.arm.com/help/topic/com.arm.doc.dui0471l/chr1368698593511.html">http://infocenter.arm.com/help/topic/com.arm.doc.dui0471l/chr1368698593511.html</a>).<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Would such a feature be accepted upstream?<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Thanks,<o:p></o:p></p><p class=MsoNormal>Christof<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>