<div dir="ltr">OK, so here's the problem:<div><br></div><div>The right way to fix this seems to be to delete the assignments to LongDouble* from the MinGWX86_32TargetInfo constructor; the X86_32TargetInfo and X86TargetInfo base classes already set them to the right values. Likewise we can delete the assignments to LongDouble* from the MinGWX86_64TargetInfo constructor for the same reason.</div><div><br></div><div>But... that completely reverts Martell's r245084, which apparently fixed PR24398. So you two need to figure out what the actual problem is here, and what the right fix is. r245084 didn't provide any test cases, and had no apparent effect other than to break long double for mingw32; did it really fix PR24398 (and if so, how)?<br><div class="gmail_extra"><br><div class="gmail_quote">On Thu, Aug 20, 2015 at 2:27 PM, Yaron Keren <span dir="ltr"><<a href="mailto:yaron.keren@gmail.com" target="_blank">yaron.keren@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="rtl"><div dir="ltr">OK, based on testing, mingw i686 aligns long doubles to 4 bytes:<br></div><div dir="ltr"><br></div><div dir="ltr"><span class=""><div dir="ltr">sh-4.3$ cat < a.cpp</div><div dir="ltr">#include <iostream></div><div dir="ltr">int main() {</div></span><div dir="ltr"> struct {</div><div dir="ltr"> char c[1];</div><div dir="ltr"> long double d;</div><div dir="ltr"> } s;</div><div dir="ltr"> std::cout<<&s.c<<std::endl;</div><div dir="ltr"> std::cout<<&s.d<<std::endl;</div><div dir="ltr">}</div><div dir="ltr">sh-4.3$ g++ a.cpp&&./a.exe</div><div dir="ltr">0x28fea0</div><div dir="ltr">0x28fea4</div><div dir="ltr"><br></div><div>I'll fix that.</div><div><br></div></div></div><div class="HOEnZb"><div class="h5"><div class="gmail_extra"><div dir="ltr"><br><div class="gmail_quote">2015-08-21 0:13 GMT+03:00 Richard Smith <span dir="ltr"><<a href="mailto:richard@metafoo.co.uk" target="_blank">richard@metafoo.co.uk</a>></span>:<br><blockquote class="gmail_quote" style="margin:0 .8ex;border-left:1px #ccc solid;border-right:1px #ccc solid;padding-left:1ex;padding-right:1ex"><div class="gmail_extra"><div class="gmail_quote"><div><div>On Wed, Aug 19, 2015 at 11:42 AM, Yaron Keren <span dir="ltr"><<a href="mailto:yaron.keren@gmail.com" target="_blank">yaron.keren@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="rtl"><div dir="ltr">Yes, it looks like a legacy issue. Documentation says so:</div><div dir="ltr"><br></div><div dir="ltr"><div dir="ltr"><font color="#1155cc"><span style="font-size:12.8000001907349px"><u><a href="https://gcc.gnu.org/onlinedocs/gcc-4.8.2/gcc/i386-and-x86-64-Options.html" target="_blank">https://gcc.gnu.org/onlinedocs/gcc-4.8.2/gcc/i386-and-x86-64-Options.html</a></u></span></font><br></div><div dir="ltr" style="font-size:12.8000001907349px"><br></div><div dir="ltr" style="font-size:12.8000001907349px"><dt style="color:rgb(0,0,0);font-family:'Times New Roman';font-size:medium"><code>-m96bit-long-double</code></dt><dt style="color:rgb(0,0,0);font-family:'Times New Roman';font-size:medium"><code>-m128bit-long-double</code></dt><dd style="color:rgb(0,0,0);font-family:'Times New Roman';font-size:medium"><a name="14f4d02fe2807b01_14f4cf579915b31d_14f47455fcf8cc4c_14f4743761dc8e58_index-m96bit-long-double-1451"></a><a name="14f4d02fe2807b01_14f4cf579915b31d_14f47455fcf8cc4c_14f4743761dc8e58_index-m128bit-long-double-1452"></a>These switches control the size of <code>long double</code> type. The i386 application binary interface specifies the size to be 96 bits, so <samp><span>-m96bit-long-double</span></samp> is the default in 32-bit mode.<p>Modern architectures (Pentium and newer) prefer <code>long double</code> to be aligned to an 8- or 16-byte boundary. In arrays or structures conforming to the ABI, this is not possible. So specifying <samp><span>-m128bit-long-double</span></samp> aligns <code>long double</code> to a 16-byte boundary by padding the <code>long double</code> with an additional 32-bit zero.</p><p>In the x86-64 compiler, <samp><span>-m128bit-long-double</span></samp> is the default choice as its ABI specifies that <code>long double</code> is aligned on 16-byte boundary.</p><p>Notice that neither of these options enable any extra precision over the x87 standard of 80 bits for a <code>long double</code>.</p><p><strong>Warning:</strong> if you override the default value for your target ABI, this changes the size of structures and arrays containing <code>long double</code> variables, as well as modifying the function calling convention for functions taking <code>long double</code>. Hence they are not binary-compatible with code compiled without that switch. </p></dd></div></div><div dir="ltr"><br></div><div dir="ltr">And practical testing agrees:<br></div><div dir="ltr"><br></div><div dir="ltr"><div dir="ltr">sh-4.3$ cat < a.cpp</div><div dir="ltr">#include <iostream></div><div dir="ltr">int main() {</div><div dir="ltr"> long double a;</div><div dir="ltr"> std::cout<<sizeof(a)<<std::endl;</div><div dir="ltr">}</div><div dir="ltr">sh-4.3$ g++ -v</div><div dir="ltr">Using built-in specs.</div><div dir="ltr">COLLECT_GCC=C:\mingw32\bin\g++.exe</div><div dir="ltr">COLLECT_LTO_WRAPPER=C:/mingw32/bin/../libexec/gcc/i686-w64-mingw32/5.1.0/lto-wrapper.exe</div><div dir="ltr">Target: i686-w64-mingw32</div><div dir="ltr">Configured with: ../../../src/gcc-5.1.0/configure --host=i686-w64-mingw32 --build=i686-w64-mingw32 --target=i686-w64-mingw32 --prefix=/mingw32 --with-sysroot=/c/mingw510/i686-510-posix-dwarf-rt_v4-rev0/mingw32 --with-gxx-include-dir=/mingw32/i686-w64-mingw32/include/c++ --enable-shared --enable-static --disable-multilib --enable-languages=c,c++,fortran,objc,obj-c++,lto --enable-libstdcxx-time=yes --enable-threads=posix --enable-libgomp --enable-libatomic --enable-lto --enable-graphite --enable-checking=release --enable-fully-dynamic-string --enable-version-specific-runtime-libs --disable-sjlj-exceptions --with-dwarf2 --disable-isl-version-check --disable-libstdcxx-pch --disable-libstdcxx-debug --enable-bootstrap --disable-rpath --disable-win32-registry --disable-nls --disable-werror --disable-symvers --with-gnu-as --with-gnu-ld --with-arch=i686 --with-tune=generic --with-libiconv --with-system-zlib --with-gmp=/c/mingw510/prerequisites/i686-w64-mingw32-static --with-mpfr=/c/mingw510/prerequisites/i686-w64-mingw32-static --with-mpc=/c/mingw510/prerequisites/i686-w64-mingw32-static --with-isl=/c/mingw510/prerequisites/i686-w64-mingw32-static --with-pkgversion='i686-posix-dwarf-rev0, Built by MinGW-W64 project' --with-bugurl=<a href="http://sourceforge.net/projects/mingw-w64" target="_blank">http://sourceforge.net/projects/mingw-w64</a> CFLAGS='-O2 -pipe -I/c/mingw510/i686-510-posix-dwarf-rt_v4-rev0/mingw32/opt/include -I/c/mingw510/prerequisites/i686-zlib-static/include -I/c/mingw510/prerequisites/i686-w64-mingw32-static/include' CXXFLAGS='-O2 -pipe -I/c/mingw510/i686-510-posix-dwarf-rt_v4-rev0/mingw32/opt/include -I/c/mingw510/prerequisites/i686-zlib-static/include -I/c/mingw510/prerequisites/i686-w64-mingw32-static/include' CPPFLAGS= LDFLAGS='-pipe -L/c/mingw510/i686-510-posix-dwarf-rt_v4-rev0/mingw32/opt/lib -L/c/mingw510/prerequisites/i686-zlib-static/lib -L/c/mingw510/prerequisites/i686-w64-mingw32-static/lib -Wl,--large-address-aware'</div><div dir="ltr">Thread model: posix</div><div dir="ltr">gcc version 5.1.0 (i686-posix-dwarf-rev0, Built by MinGW-W64 project)</div><div dir="ltr"><br></div><div dir="ltr">sh-4.3$ g++ a.cpp</div><div dir="ltr">sh-4.3$ ./a.exe<br></div><div dir="ltr">12</div><div dir="ltr"><br></div><div>Without the patch clang outputs 16 and seg faults on a boost::math example.</div></div></div></blockquote><div><br></div></div></div><div>None of that answers my question. Our default GCC-compatible behavior for x86_32 long double is to give it 4-byte alignment, 12-byte size, and this matches the behavior I observe with GCC. Does MinGW /really/ deviate from this and give long double a 16-byte alignment?</div><div><div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="rtl"><div><div><div class="gmail_extra"><div dir="ltr"><div class="gmail_quote">2015-08-19 21:29 GMT+03:00 Richard Smith <span dir="ltr"><<a href="mailto:richard@metafoo.co.uk" target="_blank">richard@metafoo.co.uk</a>></span>:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div class="gmail_extra"><div class="gmail_quote"><div><div>On Wed, Aug 19, 2015 at 10:02 AM, Yaron Keren via cfe-commits <span dir="ltr"><<a href="mailto:cfe-commits@lists.llvm.org" target="_blank">cfe-commits@lists.llvm.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Author: yrnkrn<br>
Date: Wed Aug 19 12:02:32 2015<br>
New Revision: 245459<br>
<br>
URL: <a href="http://llvm.org/viewvc/llvm-project?rev=245459&view=rev" rel="noreferrer" target="_blank">http://llvm.org/viewvc/llvm-project?rev=245459&view=rev</a><br>
Log:<br>
According to i686 ABI, long double size on x86 is 12 bytes not 16 bytes.<br>
See<br>
<a href="https://gcc.gnu.org/onlinedocs/gcc-3.2/gcc/i386-and-x86-64-Options.html" rel="noreferrer" target="_blank">https://gcc.gnu.org/onlinedocs/gcc-3.2/gcc/i386-and-x86-64-Options.html</a><br>
<br>
<br>
Added:<br>
cfe/trunk/test/CodeGen/mingw-long-double-size.c<br>
Modified:<br>
cfe/trunk/lib/Basic/Targets.cpp<br>
<br>
Modified: cfe/trunk/lib/Basic/Targets.cpp<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Basic/Targets.cpp?rev=245459&r1=245458&r2=245459&view=diff" rel="noreferrer" target="_blank">http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Basic/Targets.cpp?rev=245459&r1=245458&r2=245459&view=diff</a><br>
==============================================================================<br>
--- cfe/trunk/lib/Basic/Targets.cpp (original)<br>
+++ cfe/trunk/lib/Basic/Targets.cpp Wed Aug 19 12:02:32 2015<br>
@@ -3785,7 +3785,8 @@ class MinGWX86_32TargetInfo : public Win<br>
public:<br>
MinGWX86_32TargetInfo(const llvm::Triple &Triple)<br>
: WindowsX86_32TargetInfo(Triple) {<br>
- LongDoubleWidth = LongDoubleAlign = 128;<br>
+ LongDoubleWidth = 96;<br>
+ LongDoubleAlign = 128;<br></blockquote><div><br></div></div></div><div>Is this really correct? It's deeply suspicious that the size is not a multiple of the alignment.</div><span><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
LongDoubleFormat = &llvm::APFloat::x87DoubleExtended;<br>
}<br>
void getTargetDefines(const LangOptions &Opts,<br>
<br>
Added: cfe/trunk/test/CodeGen/mingw-long-double-size.c<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/mingw-long-double-size.c?rev=245459&view=auto" rel="noreferrer" target="_blank">http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/mingw-long-double-size.c?rev=245459&view=auto</a><br>
==============================================================================<br>
--- cfe/trunk/test/CodeGen/mingw-long-double-size.c (added)<br>
+++ cfe/trunk/test/CodeGen/mingw-long-double-size.c Wed Aug 19 12:02:32 2015<br>
@@ -0,0 +1,5 @@<br>
+// RUN: %clang_cc1 -triple i686-pc-windows-gnu -S %s -o - | FileCheck %s -check-prefix=CHECK_I686<br>
+// CHECK_I686: lda,12<br>
+// RUN: %clang_cc1 -triple x86_64-pc-windows-gnu -S %s -o - | FileCheck %s -check-prefix=CHECK_X86_64<br>
+// CHECK_X86_64: lda,16<br>
+long double lda;<br>
<br>
<br>
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</blockquote></span></div><br></div></blockquote></div></div></div></div></div></div>
</blockquote></div></div></div><br></div></blockquote></div></div></div>
</div></div></blockquote></div><br></div></div></div>