Rework 128-bit complex multiply and divide.
This function 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
some of the changes that I plan on making, this assumption will no longer be
true in the future.
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.
We need to disable using this mapping when we are building libgcc, which is
creating the multiply and divide functions. The flag that is used when libgcc
is built (-fbuilding-libcc) is only available in the C/C++ front ends. We need
to remember that we are building libgcc in the rs6000-c.cc support to be able to
use this later to decided whether to mangle the decl assembler name or not.
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 have tested this patch on the following systems:
1) LE Power10 using --with-cpu=power10 --with-long-double-format=ieee
2) LE Power10 using --with-cpu=power9 --with-long-double-format=ibm
3) LE Power10 using --with-cpu=power8 --with-long-double-format=ibm
4) LE Power10 using --with-cpu=power10 --with-long-double-format=ibm
5) LE Power9 using --with-cpu=power9 --with-long-double-format=ibm
6) BE Power8 using --with-cpu=power8 --with-long-double-format=ibm
7) BE Power8 using --with-cpu=power5 --with-long-double-format=ibm
There were no regressions in the build or in the tests.
Can I check this patch into the trunk? Note this patch needs the first patch
in the __ibm128 patches that I posted on Thursday August 18th for the
TARGET_IBM128 declaration. If those patches are rejected, it would be fairly
simple to change the one use of TARGET_IBM128.
Did we want to backport this to earlier GCC releases?
2022-08-17 Michael Meissner
gcc/
* config/rs6000/rs6000-c.cc (rs6000_cpu_cpp_builtins): Set
building_libgcc.
* 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.
* config/rs6000/rs6000.opt (building_libgcc): New target variable.
gcc/testsuite/
* 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.
---
gcc/config/rs6000/rs6000-c.cc | 8 ++
gcc/config/rs6000/rs6000.cc | 110 +++-
gcc/config/rs6000/rs6000.opt| 4 +
gcc/testsuite/gcc.target/powerpc/divic3-1.c | 18
gcc/testsuite/gcc.target/powerpc/divic3-2.c | 17 +++
gcc/testsuite/gcc.target/powerpc/mulic3-1.c | 18
gcc/testsuite/gcc.target/powerpc/mulic3-2.c | 17 +++
7 files changed, 145 insertions(+), 47 deletions(-)
create mode 100644 gcc/testsuite/gcc.target/powerpc/divic3-1.c
create mode 100644 gcc/testsuite/gcc.target/powerpc/divic3-2.c
create mode 100644 gcc/testsuite/gcc.target/powerpc/mulic3-1.c
create mode 100644 gcc/testsuite/gcc.target/powerpc/mulic3-2.c
diff --git a/gcc/config/rs6000/rs6000-c.cc b/gcc/config/rs6000/rs6000-c.cc
index 4d051b90658..11de8389fd6 100644
--- a/gcc/config/rs6000/rs6000-c.cc
+++ b/gcc/config/rs6000/rs6000-c.cc
@@ -780,6 +780,14 @@ rs6000_cpu_cpp_builtins (cpp_reader *pfile)
|| DEFAULT_ABI == ABI_ELFv2
|| (DEFAULT_ABI == ABI_AIX && !rs6000_compat_align_parm))
builtin_define ("_
