[PATCH 1/3] Rework 128-bit complex multiply and divide, PR target/107299

[Michael Meissner <meissner@linux.ibm.com>]

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
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.

We need to disable using this mapping when we are building libgcc, specifically
when it is building the floating point 128-bit 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 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?

2022-11-01   Michael Meissner  <meissner@linux.ibm.com>

gcc/

	PR target/107299
	* 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/

	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.
---
 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 56609462629..5c2f3bcee9f 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 ("__STRUCT_PARM_ALIGN__=16");
+
+  /* Store whether or not we are building libgcc.  This is needed to disable
+     generating the alternate names for 128-bit complex multiply and divide.
+     We need to disable generating __multc3, __divtc3, __mulkc3, and __divkc3
+     when we are building those functions in libgcc.  The variable
+     flag_building_libgcc is only available for the C family of front-ends.
+     We set this variable here to disable generating the alternate names.  */
+  building_libgcc = flag_building_libgcc;
 }
 
 \f
diff --git a/gcc/config/rs6000/rs6000.cc b/gcc/config/rs6000/rs6000.cc
index a85d7630b41..cfb6227e27b 100644
--- a/gcc/config/rs6000/rs6000.cc
+++ b/gcc/config/rs6000/rs6000.cc
@@ -11123,26 +11123,6 @@ init_float128_ibm (machine_mode mode)
     }
 }
 
-/* Create a decl for either complex long double multiply or complex long double
-   divide when long double is IEEE 128-bit floating point.  We can't use
-   __multc3 and __divtc3 because the original long double using IBM extended
-   double used those names.  The complex multiply/divide functions are encoded
-   as builtin functions with a complex result and 4 scalar inputs.  */
-
-static void
-create_complex_muldiv (const char *name, built_in_function fncode, tree fntype)
-{
-  tree fndecl = add_builtin_function (name, fntype, fncode, BUILT_IN_NORMAL,
-				      name, NULL_TREE);
-
-  set_builtin_decl (fncode, fndecl, true);
-
-  if (TARGET_DEBUG_BUILTIN)
-    fprintf (stderr, "create complex %s, fncode: %d\n", name, (int) fncode);
-
-  return;
-}
-
 /* Set up IEEE 128-bit floating point routines.  Use different names if the
    arguments can be passed in a vector register.  The historical PowerPC
    implementation of IEEE 128-bit floating point used _q_<op> for the names, so
@@ -11154,32 +11134,6 @@ init_float128_ieee (machine_mode mode)
 {
   if (FLOAT128_VECTOR_P (mode))
     {
-      static bool complex_muldiv_init_p = false;
-
-      /* Set up to call __mulkc3 and __divkc3 under -mabi=ieeelongdouble.  If
-	 we have clone or target attributes, this will be called a second
-	 time.  We want to create the built-in function only once.  */
-     if (mode == TFmode && TARGET_IEEEQUAD && !complex_muldiv_init_p)
-       {
-	 complex_muldiv_init_p = true;
-	 built_in_function fncode_mul =
-	   (built_in_function) (BUILT_IN_COMPLEX_MUL_MIN + TCmode
-				- MIN_MODE_COMPLEX_FLOAT);
-	 built_in_function fncode_div =
-	   (built_in_function) (BUILT_IN_COMPLEX_DIV_MIN + TCmode
-				- MIN_MODE_COMPLEX_FLOAT);
-
-	 tree fntype = build_function_type_list (complex_long_double_type_node,
-						 long_double_type_node,
-						 long_double_type_node,
-						 long_double_type_node,
-						 long_double_type_node,
-						 NULL_TREE);
-
-	 create_complex_muldiv ("__mulkc3", fncode_mul, fntype);
-	 create_complex_muldiv ("__divkc3", fncode_div, fntype);
-       }
-
       set_optab_libfunc (add_optab, mode, "__addkf3");
       set_optab_libfunc (sub_optab, mode, "__subkf3");
       set_optab_libfunc (neg_optab, mode, "__negkf2");
@@ -28142,6 +28096,25 @@ rs6000_starting_frame_offset (void)
   return RS6000_STARTING_FRAME_OFFSET;
 }
 \f
+/* Internal function to return the built-in function id for the complex
+   multiply operation for a given mode.  */
+
+static inline built_in_function
+complex_multiply_builtin_code (machine_mode mode)
+{
+  return (built_in_function) (BUILT_IN_COMPLEX_MUL_MIN + mode
+			      - MIN_MODE_COMPLEX_FLOAT);
+}
+
+/* Internal function to return the built-in function id for the complex divide
+   operation for a given mode.  */
+
+static inline built_in_function
+complex_divide_builtin_code (machine_mode mode)
+{
+  return (built_in_function) (BUILT_IN_COMPLEX_DIV_MIN + mode
+			      - MIN_MODE_COMPLEX_FLOAT);
+}
 
 /* On 64-bit Linux and Freebsd systems, possibly switch the long double library
    function names from <foo>l to <foo>f128 if the default long double type is
@@ -28160,11 +28133,54 @@ rs6000_starting_frame_offset (void)
    only do this transformation if the __float128 type is enabled.  This
    prevents us from doing the transformation on older 32-bit ports that might
    have enabled using IEEE 128-bit floating point as the default long double
-   type.  */
+   type.
+
+   We also use the TARGET_MANGLE_DECL_ASSEMBLER_NAME hook to change the
+   function names used for complex multiply and divide to the appropriate
+   names.  */
 
 static tree
 rs6000_mangle_decl_assembler_name (tree decl, tree id)
 {
+  /* Handle complex multiply/divide.  For IEEE 128-bit, use __mulkc3 or
+     __divkc3 and for IBM 128-bit use __multc3 and __divtc3.  */
+  if (TARGET_FLOAT128_TYPE
+      && !building_libgcc
+      && TREE_CODE (decl) == FUNCTION_DECL
+      && DECL_IS_UNDECLARED_BUILTIN (decl)
+      && DECL_BUILT_IN_CLASS (decl) == BUILT_IN_NORMAL)
+    {
+      built_in_function id = DECL_FUNCTION_CODE (decl);
+      const char *newname = NULL;
+
+      if (id == complex_multiply_builtin_code (KCmode))
+	newname = "__mulkc3";
+
+      else if (id == complex_multiply_builtin_code (ICmode))
+	newname = "__multc3";
+
+      else if (id == complex_multiply_builtin_code (TCmode))
+	newname = (TARGET_IEEEQUAD) ? "__mulkc3" : "__multc3";
+
+      else if (id == complex_divide_builtin_code (KCmode))
+	newname = "__divkc3";
+
+      else if (id == complex_divide_builtin_code (ICmode))
+	newname = "__divtc3";
+
+      else if (id == complex_divide_builtin_code (TCmode))
+	newname = (TARGET_IEEEQUAD) ? "__divkc3" : "__divtc3";
+
+      if (newname)
+	{
+	  if (TARGET_DEBUG_BUILTIN)
+	    fprintf (stderr, "Map complex mul/div => %s\n", newname);
+
+	  return get_identifier (newname);
+	}
+    }
+
+  /* Map long double built-in functions if long double is IEEE 128-bit.  */
   if (TARGET_FLOAT128_TYPE && TARGET_IEEEQUAD && TARGET_LONG_DOUBLE_128
       && TREE_CODE (decl) == FUNCTION_DECL
       && DECL_IS_UNDECLARED_BUILTIN (decl)
diff --git a/gcc/config/rs6000/rs6000.opt b/gcc/config/rs6000/rs6000.opt
index b63a5d443af..e2de03dda92 100644
--- a/gcc/config/rs6000/rs6000.opt
+++ b/gcc/config/rs6000/rs6000.opt
@@ -100,6 +100,10 @@ unsigned int rs6000_recip_control
 TargetVariable
 unsigned int rs6000_debug
 
+;; Whether we are building libgcc or not.
+TargetVariable
+bool building_libgcc = false
+
 ;; Whether to enable the -mfloat128 stuff without necessarily enabling the
 ;; __float128 keyword.
 TargetSave
diff --git a/gcc/testsuite/gcc.target/powerpc/divic3-1.c b/gcc/testsuite/gcc.target/powerpc/divic3-1.c
new file mode 100644
index 00000000000..1cc6b1be904
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/divic3-1.c
@@ -0,0 +1,18 @@
+/* { dg-do compile { target { powerpc*-*-* } } } */
+/* { dg-require-effective-target powerpc_p8vector_ok } */
+/* { dg-require-effective-target longdouble128 } */
+/* { dg-require-effective-target ppc_float128_sw } */
+/* { dg-options "-O2 -mpower8-vector -mabi=ieeelongdouble -Wno-psabi" } */
+
+/* Check that complex divide generates the right call for __ibm128 when long
+   double is IEEE 128-bit floating point.  */
+
+typedef _Complex long double c_ibm128_t __attribute__((mode(__IC__)));
+
+void
+divide (c_ibm128_t *p, c_ibm128_t *q, c_ibm128_t *r)
+{
+  *p = *q / *r;
+}
+
+/* { dg-final { scan-assembler "bl __divtc3" } } */
diff --git a/gcc/testsuite/gcc.target/powerpc/divic3-2.c b/gcc/testsuite/gcc.target/powerpc/divic3-2.c
new file mode 100644
index 00000000000..8ff342e0116
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/divic3-2.c
@@ -0,0 +1,17 @@
+/* { dg-do compile { target { powerpc*-*-* } } } */
+/* { dg-require-effective-target powerpc_p8vector_ok } */
+/* { dg-require-effective-target longdouble128 } */
+/* { dg-options "-O2 -mpower8-vector -mabi=ibmlongdouble -Wno-psabi" } */
+
+/* Check that complex divide generates the right call for __ibm128 when long
+   double is IBM 128-bit floating point.  */
+
+typedef _Complex long double c_ibm128_t __attribute__((mode(__TC__)));
+
+void
+divide (c_ibm128_t *p, c_ibm128_t *q, c_ibm128_t *r)
+{
+  *p = *q / *r;
+}
+
+/* { dg-final { scan-assembler "bl __divtc3" } } */
diff --git a/gcc/testsuite/gcc.target/powerpc/mulic3-1.c b/gcc/testsuite/gcc.target/powerpc/mulic3-1.c
new file mode 100644
index 00000000000..4cd773c4b06
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/mulic3-1.c
@@ -0,0 +1,18 @@
+/* { dg-do compile { target { powerpc*-*-* } } } */
+/* { dg-require-effective-target powerpc_p8vector_ok } */
+/* { dg-require-effective-target longdouble128 } */
+/* { dg-require-effective-target ppc_float128_sw } */
+/* { dg-options "-O2 -mpower8-vector -mabi=ieeelongdouble -Wno-psabi" } */
+
+/* Check that complex multiply generates the right call for __ibm128 when long
+   double is IEEE 128-bit floating point.  */
+
+typedef _Complex long double c_ibm128_t __attribute__((mode(__IC__)));
+
+void
+multiply (c_ibm128_t *p, c_ibm128_t *q, c_ibm128_t *r)
+{
+  *p = *q * *r;
+}
+
+/* { dg-final { scan-assembler "bl __multc3" } } */
diff --git a/gcc/testsuite/gcc.target/powerpc/mulic3-2.c b/gcc/testsuite/gcc.target/powerpc/mulic3-2.c
new file mode 100644
index 00000000000..36fe8bc3061
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/mulic3-2.c
@@ -0,0 +1,17 @@
+/* { dg-do compile { target { powerpc*-*-* } } } */
+/* { dg-require-effective-target powerpc_p8vector_ok } */
+/* { dg-require-effective-target longdouble128 } */
+/* { dg-options "-O2 -mpower8-vector -mabi=ibmlongdouble -Wno-psabi" } */
+
+/* Check that complex multiply generates the right call for __ibm128 when long
+   double is IBM 128-bit floating point.  */
+
+typedef _Complex long double c_ibm128_t __attribute__((mode(__TC__)));
+
+void
+multiply (c_ibm128_t *p, c_ibm128_t *q, c_ibm128_t *r)
+{
+  *p = *q * *r;
+}
+
+/* { dg-final { scan-assembler "bl __multc3" } } */
-- 
2.37.3


-- 
Michael Meissner, IBM
PO Box 98, Ayer, Massachusetts, USA, 01432
email: meissner@linux.ibm.com