<html><head><meta http-equiv="Content-Type" content="text/html charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">Hi,<div class=""><br class=""></div><div class=""><br class=""><div><blockquote type="cite" class=""><div class="">On May 29, 2016, at 7:36 AM, Shi, Steven <<a href="mailto:steven.shi@intel.com" class="">steven.shi@intel.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div class="WordSection1" style="page: WordSection1; font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">Hi Mehdi,<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">After deeper debug, I found my firmware LTO wrong code issue is related to X64 code model (-mcmodel=large) is always overridden as small (-mcmodel=small) if LTO build. And I don't know how to correctly specific the large code model for my X64 firmware LTO build. Appreciate if you could let me know it.<span class="Apple-converted-space"> </span><o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">You know, parts of my Uefi firmware (BIOS) have to been loaded to run in high address (larger than 2 GB) at the very beginning, and I need the code makes absolutely no assumptions about the addresses and data sections. But current LLVM LTO seems stick to use the small code model and generate many code with 32-bit RIP-relative addressing, which cause CPU exceptions when run in address larger than 2GB.<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">Below, I just simply reuse the Eli's codemodel1.c example (link:<span class="Apple-converted-space"> </span><a href="http://eli.thegreenplace.net/2012/01/03/understanding-the-x64-code-models" style="color: rgb(149, 79, 114); text-decoration: underline;" class="">http://eli.thegreenplace.net/2012/01/03/understanding-the-x64-code-models</a>) to show the LLVM LTO code model issue.<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">$ clang -g -O0 codemodel1.c -mcmodel=large -o codemodel1_large.bin<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">$ clang -g -O0 codemodel1.c -mcmodel=small -o codemodel1_small.bin<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">$ clang -g -O0 -flto codemodel1.c -mcmodel=large -o codemodel1_large_lto.bin<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">$ clang -g -O0 -flto codemodel1.c -mcmodel=small -o codemodel1_small_lto.bin<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">You will see the codemodel1_large_lto.bin and codemodel1_small_lto.bin are exactly the same!<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">And if you disassemble the codemodel1_large_lto.bin, you will see it uses the small code model (32-bit RIP-relative), not large, to do addressing as below.<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">$ objdump -dS codemodel1_large_lto.bin<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">int main(int argc, const char* argv[])<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">{<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> 4004f0: 55 push %rbp<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> 4004f1: 48 89 e5 mov %rsp,%rbp<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> 4004f4: 48 83 ec 20 sub $0x20,%rsp<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> 4004f8: c7 45 fc 00 00 00 00 movl $0x0,-0x4(%rbp)<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> 4004ff: 89 7d f8 mov %edi,-0x8(%rbp)<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> 400502: 48 89 75 f0 mov %rsi,-0x10(%rbp)<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> int t = global_func(argc);<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> 400506: 8b 7d f8 mov -0x8(%rbp),%edi<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span style="color: red;" class=""> 400509: e8 d2 ff ff ff callq 4004e0 <global_func></span><o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> 40050e: 89 45 ec mov %eax,-0x14(%rbp)<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> t += global_arr[7];<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span style="color: red;" class=""> 400511: 8b 04 25 4c 10 60 00 mov 0x60104c,%eax<o:p class=""></o:p></span></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> 400518: 03 45 ec add -0x14(%rbp),%eax<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> 40051b: 89 45 ec mov %eax,-0x14(%rbp)<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> t += static_arr[7];<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span style="color: red;" class=""> 40051e: 8b 04 25 dc 11 60 00 mov 0x6011dc,%eax</span><o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> 400525: 03 45 ec add -0x14(%rbp),%eax<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> 400528: 89 45 ec mov %eax,-0x14(%rbp)<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> t += global_arr_big[7];<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span style="color: red;" class=""> 40052b: 8b 04 25 6c 13 60 00 mov 0x60136c,%eax</span><o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> 400532: 03 45 ec add -0x14(%rbp),%eax<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> 400535: 89 45 ec mov %eax,-0x14(%rbp)<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> t += static_arr_big[7];<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span style="color: red;" class=""> 400538: 8b 04 25 ac 20 63 00 mov 0x6320ac,%eax</span><o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> 40053f: 03 45 ec add -0x14(%rbp),%eax<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> 400542: 89 45 ec mov %eax,-0x14(%rbp)<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> return t;<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> 400545: 8b 45 ec mov -0x14(%rbp),%eax<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> 400548: 48 83 c4 20 add $0x20,%rsp<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> 40054c: 5d pop %rbp<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> 40054d: c3 retq<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> 40054e: 66 90 xchg %ax,%ax<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">So, does LTO support large code model? How to correctly specify the LTO code model option?</div></div></div></blockquote><div><br class=""></div><div>Same answer as before: LTO is setup by the linker, so the option for that, if it exists, will be linker specific.</div><div><br class=""></div><div>As far as I can tell, neither libLTO-based linker (ld64 on OS X for example), neither the gold plugin supports such an option and the code model is always "default". </div><div><br class=""></div><div>I don't know about lld, CC Rafael about that.</div><div><br class=""></div><div>-- </div><div>Mehdi</div><div><br class=""></div><div><br class=""></div><div><br class=""></div><br class=""><blockquote type="cite" class=""><div class=""><div class="WordSection1" style="page: WordSection1; font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">Steven Shi<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">Intel\SSG\STO\UEFI Firmware<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">Tel: +86 021-61166522<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">iNet: 821-6522<o:p class=""></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><a name="_____replyseparator" class=""></a>> -----Original Message-----</div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">> From:<span class="Apple-converted-space"> </span><a href="mailto:mehdi.amini@apple.com" style="color: rgb(149, 79, 114); text-decoration: underline;" class="">mehdi.amini@apple.com</a><span class="Apple-converted-space"> </span>[<a href="mailto:mehdi.amini@apple.com" style="color: rgb(149, 79, 114); text-decoration: underline;" class="">mailto:mehdi.amini@apple.com</a>]</div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">> Sent: Wednesday, May 18, 2016 4:02 AM</div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">> To: Umesh Kalappa <<a href="mailto:umesh.kalappa0@gmail.com" style="color: rgb(149, 79, 114); text-decoration: underline;" class="">umesh.kalappa0@gmail.com</a>></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">> Cc: Shi, Steven <<a href="mailto:steven.shi@intel.com" style="color: rgb(149, 79, 114); text-decoration: underline;" class="">steven.shi@intel.com</a>>; llvm-dev <<a href="mailto:llvm-dev@lists.llvm.org" style="color: rgb(149, 79, 114); text-decoration: underline;" class="">llvm-dev@lists.llvm.org</a>>;</div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">><span class="Apple-converted-space"> </span><a href="mailto:cfe-dev@lists.llvm.org" style="color: rgb(149, 79, 114); text-decoration: underline;" class="">cfe-dev@lists.llvm.org</a></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">> Subject: Re: [cfe-dev] [llvm-dev] How to debug if LTO generate wrong code?</div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">><span class="Apple-converted-space"> </span></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">><span class="Apple-converted-space"> </span></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">> > On May 17, 2016, at 11:21 AM, Umesh Kalappa</div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">> <<a href="mailto:umesh.kalappa0@gmail.com" style="color: rgb(149, 79, 114); text-decoration: underline;" class=""><span style="color: windowtext; text-decoration: none;" class="">umesh.kalappa0@gmail.com</span></a>> wrote:</div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">> ></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">> > Steven,</div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">> ></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">> > As mehdi stated , the optimisation level is specific to linker and it</div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">> > enables Inter-Pro opts passes ,please refer function</div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">><span class="Apple-converted-space"> </span></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">> To be very clear: the -O option may trigger *linker* optimizations as well,</div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">> independently of LTO.</div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">><span class="Apple-converted-space"> </span></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">> --</div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">> Mehdi</div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">><span class="Apple-converted-space"> </span></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">><span class="Apple-converted-space"> </span></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">><span class="Apple-converted-space"> </span></div></div></div></blockquote></div><br class=""></div></body></html>