<html><head><meta http-equiv="Content-Type" content="text/html; charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">I think I ran into this trying to build FFI to libclang.<div class=""><br class=""></div><div class="">It passes a lot of structs by value and some calls came back with nothing. </div><div class=""><br class=""></div><div class="">My message to <a href="mailto:vm-dev@lists.squeakfoundation.org" class="">vm-dev@lists.squeakfoundation.org</a> on Nov 21, 2017 follows;</div><div class=""><br class=""></div><div class="">Apologies if this isn't relevant. </div><div class=""><br class=""></div><div class=""><blockquote type="cite" class="">I've been trying to track this down for a couple weeks now.<div class=""><br class=""></div><div class="">I have concluded that structs passed by value to functions on the 64 bit VM are not properly populated. The struct's memory is all zero'd.</div><div class=""><br class=""></div><div class="">I found this while trying to work with LibClang and found that functions that fetched code locations from code ranges always returned invalid zero'd locations. After spending some time with lldb I have traced the problem into the native code and found that the argument is not correct.</div><div class=""><br class=""></div><div class="">I've carved out the wee bit of clang to reproduce this in a tiny library.</div><div class=""><br class=""></div><div class="">The gist of it is below and the entire file is included. Basically the struct passed to the function clang_getRangeStart is zero'd memory regardless of the data I send from the image side.</div><div class=""><br class=""></div><div class="">The build command I used on sierra is <span class="" style="font-family: Menlo; font-size: 11px; background-color: rgb(255, 255, 255);">clang -shared -undefined dynamic_lookup -o microclang.dylib microclang.c</span></div><div class=""><br class=""></div><div class="">I'm stuck. The FFI64 plugin is way beyond my comprehension.</div><div class=""><br class=""></div><div class="">// microclang.c</div><div class=""><br class=""></div><div class=""><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"><span class="" style="font-variant-ligatures: no-common-ligatures;">typedef struct {</span></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"><span class="" style="font-variant-ligatures: no-common-ligatures;"> const void *ptr_data[2];</span></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"><span class="" style="font-variant-ligatures: no-common-ligatures;"> unsigned int_data;</span></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"><span class="" style="font-variant-ligatures: no-common-ligatures;">} CXSourceLocation;</span></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255); min-height: 13px;"><span class="" style="font-variant-ligatures: no-common-ligatures;"></span><br class=""></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"><span class="" style="font-variant-ligatures: no-common-ligatures;">/**</span></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"><span class="" style="font-variant-ligatures: no-common-ligatures;"> * \brief Identifies a half-open character range in the source code.</span></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"><span class="" style="font-variant-ligatures: no-common-ligatures;"> *</span></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"><span class="" style="font-variant-ligatures: no-common-ligatures;"> * Use clang_getRangeStart() and clang_getRangeEnd() to retrieve the</span></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"><span class="" style="font-variant-ligatures: no-common-ligatures;"> * starting and end locations from a source range, respectively.</span></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"><span class="" style="font-variant-ligatures: no-common-ligatures;"> */</span></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"><span class="" style="font-variant-ligatures: no-common-ligatures;">typedef struct {</span></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"><span class="" style="font-variant-ligatures: no-common-ligatures;"> const void *ptr_data[2];</span></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"><span class="" style="font-variant-ligatures: no-common-ligatures;"> unsigned begin_int_data;</span></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"><span class="" style="font-variant-ligatures: no-common-ligatures;"> unsigned end_int_data;</span></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"><span class="" style="font-variant-ligatures: no-common-ligatures;">} CXSourceRange;</span></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255); min-height: 13px;"><span class="" style="font-variant-ligatures: no-common-ligatures;"></span><br class=""></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"><span class="" style="font-variant-ligatures: no-common-ligatures;">const char* first = "first_pointer";</span></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"><span class="" style="font-variant-ligatures: no-common-ligatures;">const char* second = "second_pointer";</span></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255); min-height: 13px;"><span class="" style="font-variant-ligatures: no-common-ligatures;"></span><br class=""></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255); min-height: 13px;"><span class="" style="font-variant-ligatures: no-common-ligatures;"></span>// return a fake range with non zero data</div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"><span class="" style="font-variant-ligatures: no-common-ligatures;">CXSourceRange clang_getArbitraryRange()</span></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"><span class="" style="font-variant-ligatures: no-common-ligatures;">{</span></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"><span class="" style="font-variant-ligatures: no-common-ligatures;"> CXSourceRange range = {0};</span></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"><span class="" style="font-variant-ligatures: no-common-ligatures;"> range.ptr_data[0] = (void*)first;</span></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"><span class="" style="font-variant-ligatures: no-common-ligatures;"> range.ptr_data[1] = (void*)second;</span></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"><span class="" style="font-variant-ligatures: no-common-ligatures;"> range.begin_int_data = 17;</span></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"><span class="" style="font-variant-ligatures: no-common-ligatures;"> range.end_int_data = 24;</span></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"><span class="" style="font-variant-ligatures: no-common-ligatures;"> return range;</span></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"><span class="" style="font-variant-ligatures: no-common-ligatures;">}</span></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255); min-height: 13px;"><span class="" style="font-variant-ligatures: no-common-ligatures;"></span><br class=""></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255); min-height: 13px;"><span class="" style="font-variant-ligatures: no-common-ligatures;"></span>// Actual clang function - range is always zero'd here despite having values in the image</div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"><span class="" style="font-variant-ligatures: no-common-ligatures;">CXSourceLocation clang_getRangeStart(CXSourceRange range) {</span></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"><span class="" style="font-variant-ligatures: no-common-ligatures;"> // Special decoding for CXSourceLocations for CXLoadedDiagnostics.</span></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"><span class="" style="font-variant-ligatures: no-common-ligatures;"> if ((uintptr_t)range.ptr_data[0] & 0x1) {</span></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"><span class="" style="font-variant-ligatures: no-common-ligatures;"> CXSourceLocation Result = { { range.ptr_data[0], nullptr }, 0 };</span></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"><span class="" style="font-variant-ligatures: no-common-ligatures;"> return Result; </span></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"><span class="" style="font-variant-ligatures: no-common-ligatures;"> }</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255); min-height: 13px;" class=""><span class="" style="font-variant-ligatures: no-common-ligatures;"> </span><br class="webkit-block-placeholder"></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"><span class="" style="font-variant-ligatures: no-common-ligatures;"> CXSourceLocation Result = { { range.ptr_data[0], range.ptr_data[1] },</span></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"><span class="" style="font-variant-ligatures: no-common-ligatures;"> range.begin_int_data };</span></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"><span class="" style="font-variant-ligatures: no-common-ligatures;"> return Result;</span></div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"><span class="" style="font-variant-ligatures: no-common-ligatures;">}</span></div></div><div class=""><span class="" style="font-variant-ligatures: no-common-ligatures;"><br class=""></span></div><div class=""></div></blockquote></div></body></html>