<HTML><BODY style="word-wrap: break-word; -khtml-nbsp-mode: space; -khtml-line-break: after-white-space; "><BR><DIV><DIV>On Dec 6, 2006, at 1:58 PM, Andrew Lenharth wrote:</DIV><BR class="Apple-interchange-newline"><BLOCKQUOTE type="cite"><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">The attached patch (gcc.patch) implements the gcc portion of packed</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">types.<SPAN class="Apple-converted-space"> </SPAN>I have only tested this on a few examples, so I may be missing</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">some type conversions somewhere.</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><BR></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">The gcc patch requires llvm_extra.patch, not included in the previous emails.</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><BR></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Andrew<SPAN><DIV><llvm_extra.patch></DIV></SPAN></DIV></BLOCKQUOTE><DIV><BR class="khtml-block-placeholder"></DIV><DIV>llvm_extra.patch is fine, it can go in with the rest.</DIV><BR><BLOCKQUOTE type="cite"><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><SPAN><DIV><gcc.patch></DIV></SPAN></DIV></BLOCKQUOTE><DIV><BR class="khtml-block-placeholder"></DIV><DIV>This patch isn't sufficient for two reasons: 1) it will turn structs that don't need to be packed into packed llvm structs. 2) it won't turn some that should be packed llvm structs into packed structs (e.g. strange ABI considerations force a field to be unaligned, not an attribute at the source level).</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>Here's an example of #1:</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "> extern struct { int x; int y; int z; } __attribute((packed)) foos;;</DIV><DIV>This should just be {int,int,int}, not <{int,int,int}>.</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>The approach I'd like to see is:</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">StructTypeConversionInfo should have a bool field "Packed" that is initialized to false.</SPAN></FONT></DIV><DIV><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;"><BR class="khtml-block-placeholder"></SPAN></FONT></DIV><DIV><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">As fields are added to StructTypeConversionInfo, there are three cases:</SPAN></FONT></DIV><DIV><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;"><BR class="khtml-block-placeholder"></SPAN></FONT></DIV><DIV><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">1. GCC wants the field to be at an offset equal to where LLVM would place it. Just add the field.</SPAN></FONT></DIV><DIV><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">2. GCC wants to place the field at an offset further from where llvm would place it. Just add enough dummy fields to pad it over to where it needs to be.</SPAN></FONT></DIV><DIV><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">3. GCC wants to place the field at an offset closer to where LLVM would place it. When this happens, the current struct is marked packed and the existing fields have 'spacers' put in between them if necessary.</SPAN></FONT></DIV><DIV><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;"><BR class="khtml-block-placeholder"></SPAN></FONT></DIV><DIV><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">This ensures we only make things 'llvm packed' if needed, and should allow the logic to be significantly simplified.</SPAN></FONT></DIV><DIV><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;"><BR class="khtml-block-placeholder"></SPAN></FONT></DIV><DIV><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">Seem reasonable?</SPAN></FONT></DIV><DIV><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;"><BR class="khtml-block-placeholder"></SPAN></FONT></DIV><DIV><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">-Chris</SPAN></FONT></DIV><BR></DIV><BR></BODY></HTML>