Hi! This patch attempts to document some new features (without warnings, those are partially covered by Marek's patch, C++ FE (would be nice to document -faligned-new, -fnew-inheriting-ctors, -fnew-ttp-matching, -fstrong-eval-order and what from C++ is supported) and the BRIG FE).
Ok for wwwdocs? Index: changes.html =================================================================== RCS file: /cvs/gcc/wwwdocs/htdocs/gcc-7/changes.html,v retrieving revision 1.44 diff -u -p -r1.44 changes.html --- changes.html 27 Jan 2017 09:54:32 -0000 1.44 +++ changes.html 27 Jan 2017 16:23:03 -0000 @@ -45,8 +45,39 @@ a work-in-progress.</h2> <li>A new store merging pass has been added. It merges constant stores to adjacent memory locations into fewer, wider, stores. It can be enabled by using the <code>-fstore-merging</code> option and is - enabled by default at <code>-Os</code> and the <code>-O2</code> optimization - level or higher.</li> + enabled by default at the <code>-O2</code> optimization + level or higher (including <code>-Os</code>).</li> + + <li>A new code hoisting optimization has been added to the partial + redundancy elimination pass. It attempts to move evaluation of + expressions executed on all paths to the function exit as early as + possible, which helps primarily for code size, but can be useful for + speed of generated code as well. It can be enabled by using the + <code>-fcode-hoisting</code> option and is enabled by default at + the <code>-O2</code> optimization level or higher.</li> + + <li>A new interprocedural bitwise constant propagation optimization + has been added, which propagates knowledge about which bits of variables + are known to be zero (including pointer alignment information) across + the call graph. It can be enabled by using the <code>-fipa-bit-cp</code> + option if <code>-fipa-cp</code> is enabled as well, and is enabled by + default at the <code>-O2</code> optimization level and higher.</li> + + <li>A new interprocedural value range propagation optimization has been + added, which propagates integral ranges that variable values can be proven + to be within across the call graph. It can be enabled by using the + <code>-fipa-vrp</code> option and is enabled by default at the + <code>-O2</code> optimization level and higher.</li> + + <li>A new loop splitting optimization pass has been added. It splits + certain loops if they contain a condition that is always true on one + side of the iteration space and always false on the other into two + loops where each of the new two loops iterates just on one of the sides + of the iteration space and the condition does not need to be checked + inside of the loop. It can be enabled by using the + <code>-fsplit-loops</code> option and is enabled by default at the + <code>-O3</code> optimization level or higher.</li> + <li>AddressSanitizer gained a new sanitization option, <code>-fsanitize-address-use-after-scope</code>, which enables sanitization of variables whose address is taken and used after a scope where the variable is defined: @@ -64,17 +95,17 @@ main (int argc, char **argv) return *ptr; } -==28882==ERROR: AddressSanitizer: stack-use-after-scope on address 0x7fffb8dba990 at pc 0x0000004006d5 bp 0x7fffb8dba960 sp 0x7fffb8dba958 -WRITE of size 1 at 0x7fffb8dba990 thread T0 +<span class="boldred">==28882==ERROR: AddressSanitizer: stack-use-after-scope on address 0x7fffb8dba990 at pc 0x0000004006d5 bp 0x7fffb8dba960 sp 0x7fffb8dba958</span> +<span class="boldblue">WRITE of size 1 at 0x7fffb8dba990 thread T0</span> #0 0x4006d4 in main /tmp/use-after-scope-1.c:10 #1 0x7f9c71943290 in __libc_start_main (/lib64/libc.so.6+0x20290) #2 0x400739 in _start (/tmp/a.out+0x400739) -Address 0x7fffb8dba990 is located in stack of thread T0 at offset 32 in frame +<span class="boldlime">Address 0x7fffb8dba990 is located in stack of thread T0 at offset 32 in frame</span> #0 0x40067f in main /tmp/use-after-scope-1.c:3 This frame has 1 object(s): - [32, 33) 'my_char' <== Memory access at offset 32 is inside this variable + [32, 33) 'my_char' <span class="boldlime"><== Memory access at offset 32 is inside this variable</span> </pre></blockquote> The option is enabled by default with <code>-fsanitize=address</code> and disabled @@ -92,6 +123,16 @@ Address 0x7fffb8dba990 is located in sta </li> + <li>The <code>-fsanitize=signed-integer-overflow</code> suboption of the + UndefinedBehavior Sanitizer now diagnose arithmetic overflows even on + arithmetic operations with generic vectors.</li> + + <li>The upcoming version 5 of the <a + href="http://www.dwarfstd.org/Download.php">DWARF</a> debugging + information standard is supported through the <code>-gdwarf-5</code> + option. The DWARF version 4 debugging information remains the + default until debugging information consumers are adjusted.</li> + </ul> <!-- .................................................................. --> @@ -255,6 +296,14 @@ of the global declaration:</p> currently has the value of <code>UINTMAX_MAX</code> on all systems, reflecting that GCC's compile-time conversions are correctly rounded for any number of digits.</li> +<li>New <code>__builtin_add_overflow_p</code>, + <code>__builtin_sub_overflow_p</code>, + <code>__builtin_mul_overflow_p</code> built-in functions have been added. + These work similarly to earlier added built-in functions without the + <code>_p</code> suffix, but don't actually store the result of the + arithmetics anywhere, just return whether the operation would overflow. + These builtins allow easy checking for overflows e.g. in C++ + <code>constexpr</code> contexts.</li> </ul> <h3 id="c">C</h3> @@ -291,6 +340,8 @@ of the global declaration:</p> (suffixed <code>f<i>N</i></code> or <code>f<i>N</i>x</code>) for the new types: <code>__builtin_copysign</code>, <code>__builtin_fabs</code>, <code>__builtin_huge_val</code>, <code>__builtin_inf</code>, <code>__builtin_nan</code>, <code>__builtin_nans</code>.</p></li> + <li>Compilation with <code>-fopenmp</code> is now compatible with + C11 <code>_Atomic</code> keyword.</li> </ul> <h3 id="cxx">C++</h3> @@ -428,11 +479,17 @@ Fortran runtime error: Loop iterates inf </pre></blockquote> </li> + <li>Version 4.5 of the <a href="http://www.openmp.org/specifications/" + >OpenMP specification</a> is now partially supported also in the + Fortran compilers, largest missing support in the Fortran frontend + is structure element mapping .</li> </ul> <!-- <h3 id="go">Go</h3> --> -<!-- <h3 id="java">Java (GCJ)</h3> --> +<h3 id="java">Java (GCJ)</h3> +<p>The GCC Java frontend and associated libjava runtime library have been +removed from GCC.</p> <!-- .................................................................. --> <h2 id="jit">libgccjit</h2> @@ -561,7 +618,13 @@ const int* get_address (unsigned idx) <!-- <h3 id="hsa">Heterogeneous Systems Architecture</h3> --> -<!-- <h3 id="x86">IA-32/x86-64</h3> --> +<h3 id="x86">IA-32/x86-64</h3> +<ul> + <li>Support for the AVX-512 Fused Multiply Accumulation Packed Single precision + (4FMAPS), AVX-512 Vector Neural Network Instructions Word variable precision + (4VNNIW), AVX-512 Vector Population Count (VPOPCNTDQ) and Software + Guard Extensions (SGX) ISA extensions has been added.</li> +</ul> <!-- <h3 id="mips">MIPS</h3> --> @@ -571,12 +634,23 @@ const int* get_address (unsigned idx) <!-- <h3 id="nds32">NDS32</h3> --> +<h3 id="nvptx">NVPTX</h3> +<ul> + <li>OpenMP target regions can now be offloaded to NVidia PTX GPGPUs. + See https://gcc.gnu.org/wiki/Offloading on how to configure it.</li> +</ul> + <h3 id="powerpc">PowerPC / PowerPC64 / RS6000</h3> <ul> <li>The PowerPC port now uses LRA by default.</li> <li>GCC now diagnoses inline assembly that clobbers register r2. This has always been invalid code, and is no longer quietly tolerated.</li> + <li>Shrink-wrapping optimization can now separate portions of + prologues and epilogues to improve performance if some of the + work done traditionally by prologues and epilogues is not needed + on certain paths. This is controlled by the + <code>-fshrink-wrap-separate</code> option, enabled by default.</li> </ul> <!-- <h3 id="s390">S/390, System z, IBM z Systems</h3> --> Jakub