From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 1005) id 940183858404; Mon, 23 Jan 2023 21:18:27 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 940183858404 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1674508707; bh=Wy2uopfadu4URnnDm3SSMJSZDSRmOLFo1gK9qEpCW+8=; h=From:To:Subject:Date:From; b=n87KzdIPpFljr/aZvomAdZsHbu8SSvWYM84cBthOOqdXllxmZKGrhM+uNP8ZP4FhT d33sLOBkUP/LpD1Ngq0f6kHREk40Kk2ZpRcjRF9vcyJDg3Hw3bOGrdvpH8hdO9L4yO 7CvaLMnck6KQJ5JJn+YYORu3IIy1ngCOdkjkFlC4= Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit From: Michael Meissner To: gcc-cvs@gcc.gnu.org Subject: [gcc(refs/users/meissner/heads/dmf007)] Update ChangeLog.meissner X-Act-Checkin: gcc X-Git-Author: Michael Meissner X-Git-Refname: refs/users/meissner/heads/dmf007 X-Git-Oldrev: 2e79c25662ef183d083f46f9ea387119ed820546 X-Git-Newrev: 121b1d3e9608a575e6c6d4c7ba6e6ed49b93340c Message-Id: <20230123211827.940183858404@sourceware.org> Date: Mon, 23 Jan 2023 21:18:27 +0000 (GMT) List-Id: https://gcc.gnu.org/g:121b1d3e9608a575e6c6d4c7ba6e6ed49b93340c commit 121b1d3e9608a575e6c6d4c7ba6e6ed49b93340c Author: Michael Meissner Date: Fri Jan 20 17:22:47 2023 -0500 Update ChangeLog.meissner Diff: --- gcc/ChangeLog.meissner | 141 ++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 140 insertions(+), 1 deletion(-) diff --git a/gcc/ChangeLog.meissner b/gcc/ChangeLog.meissner index fda09a48c25..83e9ee06ffc 100644 --- a/gcc/ChangeLog.meissner +++ b/gcc/ChangeLog.meissner @@ -1,4 +1,143 @@ +==================== dmf007, patch #2 ==================== + +Rework 128-bit complex multiply and divide. + +This patch reworks how the complex multiply and divide built-in functions are +done. Previously we created built-in declarations for doing long double complex +multiply and divide when long double is IEEE 128-bit. The old code also did not +support __ibm128 complex multiply and divide if long double is IEEE 128-bit. + +In terms of history, I wrote the original code just as I was starting to test +GCC on systems where IEEE 128-bit long double was the default. At the time, we +had not yet started mangling the built-in function names as a way to bridge +going from a system with 128-bit IBM long double to 128-bin IEEE long double. + +The original code depends on there only being two 128-bit types invovled. With +the next patch in this series, this assumption will no longer be true. When +long double is IEEE 128-bit, there will be 2 IEEE 128-bit types (one for the +explicit __float128/_Float128 type and one for long double). + +The problem is we cannot create two separate built-in functions that resolve to +the same name. This is a requirement of add_builtin_function and the C front +end. That means for the 3 possible modes (IFmode, KFmode, and TFmode), you can +only use 2 of them. + +This code does not create the built-in declaration with the changed name. +Instead, it uses the TARGET_MANGLE_DECL_ASSEMBLER_NAME hook to change the name +before it is written out to the assembler file like it now does for all of the +other long double built-in functions. + +When I wrote these patches, I discovered that __ibm128 complex multiply and +divide had originally not been supported if long double is IEEE 128-bit as it +would generate calls to __mulic3 and __divic3. I added tests in the testsuite +to verify that the correct name (i.e. __multc3 and __divtc3) is used in this +case. + +I had previously sent this patch out on November 1st. Compared to that version, +this version no longer disables the special mapping when you are building +libgcc, as it turns out we don't need it. + +I tested all 3 patchs for PR target/107299 on: + + 1) LE Power10 using --with-cpu=power10 --with-long-double-format=ieee + 2) LE Power10 using --with-cpu=power10 --with-long-double-format=ibm + 3) LE Power9 using --with-cpu=power9 --with-long-double-format=ibm + 4) BE Power8 using --with-cpu=power8 --with-long-double-format=ibm + +Once all 3 patches have been applied, we can once again build GCC when long +double is IEEE 128-bit. There were no other regressions with these patches. +Can I check these patches into the trunk? + 2023-01-20 Michael Meissner - Clone branch +gcc/ + + PR target/107299 + * config/rs6000/rs6000.cc (create_complex_muldiv): Delete. + (init_float128_ieee): Delete code to switch complex multiply and divide + for long double. + (complex_multiply_builtin_code): New helper function. + (complex_divide_builtin_code): Likewise. + (rs6000_mangle_decl_assembler_name): Add support for mangling the name + of complex 128-bit multiply and divide built-in functions. + +gcc/testsuite/ + + PR target/107299 + * gcc.target/powerpc/divic3-1.c: New test. + * gcc.target/powerpc/divic3-2.c: Likewise. + * gcc.target/powerpc/mulic3-1.c: Likewise. + * gcc.target/powerpc/mulic3-2.c: Likewise. + +==================== dmf007, patch #1 ==================== + +PR target/107299: Fix build issue when long double is IEEE 128-bit + +This patch updates the IEEE 128-bit types used in libgcc. +At the moment, we cannot build GCC when the target uses IEEE 128-bit long +doubles, such as building the compiler for a native Fedora 36 system. The +build dies when it is trying to build the _mulkc3.c and _divkc3 modules. + +This patch changes libgcc to use long double for the IEEE 128-bit base type if +long double is IEEE 128-bit, and it uses _Float128 otherwise. The built-in +functions are adjusted to be the correct version based on the IEEE 128-bit base +type used. + +While it is desirable to ultimately have __float128 and _Float128 use the same +internal type and mode within GCC, at present if you use the option +-mabi=ieeelongdouble, the __float128 type will use the long double type and not +the _Float128 type. We get an internal compiler error if we combine the +signbitf128 built-in with a long double type. + +I've gone through several iterations of trying to fix this within GCC, and +there are various problems that have come up. I developed this alternative +patch that changes libgcc so that it does not tickle the issue. I hope we can +fix the compiler at some point, but right now, this is preventing people on +Fedora 36 systems from building compilers where the default long double is IEEE +128-bit. + +I have built a GCC compiler tool chain on the following platforms and there +were no regressions caused by these patches. + + * Power10 little endian, IBM long double, --with-cpu=power10 + + * Power9 little endian, IBM long double, --with-cpu=power9 + + * Power8 big endian, IBM long double, --with-cpu=power8, both + 32-bit/64-bit tests. + +In addition, I have built a GCC compiler tool chain on the following systems +with IEEE 128-bit long double as the default. Comparing the test suite runs to +the runs for the toolchain with IBM long double as the default, I only get the +expected differences (C++ modules test fail on IEEE long double, 3 Fortran +tests pass on IEEE long double that fail on IBM long double, C test pr105334.c +fails, and C test fp128_conversions.c fails on power10): + + * Power10 little endian, IEEE long double, --with-cpu=power10 + + * Power9 little endian, IEEE long double, --with-cpu=power9 + +Can I check this change into the master branch? + +2023-01-20 Michael Meissner + + PR target/107299 + * config/rs6000/_divkc3.c (COPYSIGN): Use the correct built-in based on + whether long double is IBM or IEEE. + (INFINITY): Likewise. + (FABS): Likewise. + * config/rs6000/_mulkc3.c (COPYSIGN): Likewise. + (INFINITY): Likewise. + * config/rs6000/quad-float128.h (TF): Remove definition. + (TFtype): Define to be long double or _Float128. + (TCtype): Define to be _Complex long double or _Complex _Float128. + * libgcc2.h (TFtype): Allow machine config files to override this. + (TCtype): Likewise. + * soft-fp/quad.h (TFtype): Likewise. + +==================== dmf007, branch head ==================== + +2023-01-20 Michael Meissner + + Clone branch