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* [gcc(refs/users/meissner/heads/dmf005)] Rework 128-bit complex multiply and divide.
@ 2022-12-03  1:10 Michael Meissner
  0 siblings, 0 replies; only message in thread
From: Michael Meissner @ 2022-12-03  1:10 UTC (permalink / raw)
  To: gcc-cvs

https://gcc.gnu.org/g:4f911506b5b78bc2d1224bfc52f811f764f5e01c

commit 4f911506b5b78bc2d1224bfc52f811f764f5e01c
Author: Michael Meissner <meissner@linux.ibm.com>
Date:   Fri Dec 2 20:04:19 2022 -0500

    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
    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?
    
    2022-12-02   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.

Diff:
---
 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(-)

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 eb7ad5e954f..5b8be7af76a 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");
@@ -28133,6 +28087,25 @@ 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
@@ -28151,11 +28124,54 @@ 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" } } */

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