[gcc(refs/users/meissner/heads/work043)] Add long double target-supports on PowerPC.

[Michael Meissner <meissner@gcc.gnu.org>]

https://gcc.gnu.org/g:2c91f8d4b3bceaf82d0f8b3174c2f5b11fdbce86

commit 2c91f8d4b3bceaf82d0f8b3174c2f5b11fdbce86
Author: Michael Meissner <meissner@linux.ibm.com>
Date:   Tue Mar 30 14:20:50 2021 -0400

    Add long double target-supports on PowerPC.
    
    This patch add several more selections to target-supports.exp:
    
        *   3 selections for the current long double format;
        *   3 selections if we can change the long double format to a particular
            value.
        *   3 functions to return the options needed to switch the long double
            format for use with dg-add-options.
    
    I have run tests on a little endian power9 system with 3 compilers.  There
    were no regressions with these patches, and the two tests in the following
    patches now work if the default long double is not IBM 128-bit:
    
        *   One compiler using the default IBM 128-bit format;
        *   One compiler using the IEEE 128-bit format; (and)
        *   One compiler using 64-bit long doubles.
    
    I have also tested compilers on a big endian power8 system with a compiler
    defaulting to power8 code generation and another with the default cpu
    set.  There were no regressions.
    
    Can I check this patch into the master branch?
    
    gcc/testsuite/
    2021-03-30  Michael Meissner  <meissner@linux.ibm.com>
    
            * lib/target-supports.exp
            (check_effective_target_ppc_long_double_ibm128): New function.
            (check_effective_target_ppc_long_double_ieee128): New function.
            (check_effective_target_ppc_long_double_64bit): New function.
            (add_options_for_ppc_long_double_override_ibm128): New function.
            (check_effective_target_ppc_long_double_override_ibm128): New
            function.
            (add_options_for_ppc_long_double_override_ieee128): New function.
            (check_effective_target_ppc_long_double_override_ieee128): New
            function.
            (add_options_for_ppc_long_double_override_64bit): New function.
            (check_effective_target_ppc_long_double_override_64bit): New
            function.

Diff:
---
 gcc/testsuite/lib/target-supports.exp | 155 ++++++++++++++++++++++++++++++++++
 1 file changed, 155 insertions(+)

diff --git a/gcc/testsuite/lib/target-supports.exp b/gcc/testsuite/lib/target-supports.exp
index 1230d194215..7c54301403b 100644
--- a/gcc/testsuite/lib/target-supports.exp
+++ b/gcc/testsuite/lib/target-supports.exp
@@ -2360,6 +2360,161 @@ proc check_effective_target_ppc_ieee128_ok { } {
     }]
 }
 
+# See if the target is a powerpc with the long double format that uses the IBM
+# extended double format.
+
+proc check_effective_target_ppc_long_double_ibm128 { } {
+    return [check_cached_effective_target ppc_long_double_ibm {
+	int main()
+	{
+	  #if !defined(_ARCH_PPC) || !defined(__LONG_DOUBLE_IBM128__)
+	    return 1;
+	  #else
+	    return 0;
+	  #endif
+	}
+    }]
+}
+
+# See if the target is a powerpc with the long double format that uses the IEEE
+# 128-bit format.
+
+proc check_effective_target_ppc_long_double_ieee128 { } {
+    return [check_cached_effective_target ppc_long_double_ieee {
+	int main()
+	{
+	  #if !defined(_ARCH_PPC) || !defined(__LONG_DOUBLE_IEEE128__)
+	    return 1;
+	  #else
+	    return 0;
+	  #endif
+	}
+    }]
+}
+
+# See if the target is a powerpc with the long double format that is 64-bit.
+
+proc check_effective_target_ppc_long_double_64bit { } {
+    return [check_cached_effective_target ppc_long_double_64bit {
+	int main()
+	{
+	  #ifndef _ARCH_PPC
+	    return 1;
+	  #else
+	    return sizeof (long double) != 8;
+	  #endif
+	}
+    }]
+}
+
+# Like check_effective_target_ppc_long_double_ibm128, but check if we can
+# explicitly override the long double format to use the IBM 128-bit extended
+# double format, and GLIBC supports doing this override by switching the
+# sprintf to handle long double.
+
+proc add_options_for_ppc_long_double_override_ibm128 { flags } {
+    if { [istarget powerpc*-*-*] } {
+	return "$flags -mlong-double-128 -Wno-psabi -mabi=ibmlongdouble"
+    }
+    return "$flags"
+}
+
+proc check_effective_target_ppc_long_double_override_ibm128 { } {
+    return [check_runtime_nocache ppc_long_double_override_ibm128 {
+	#include <string.h>
+	#include <stdio.h>
+	volatile __ibm128 a = (__ibm128) 3.0;
+	volatile long double one = 1.0L;
+	volatile long double two = 2.0L;
+	volatile long double b;
+	char buffer[20];
+	int main()
+	{
+	  #if !defined(_ARCH_PPC) || !defined(__LONG_DOUBLE_IBM128__)
+	    return 1;
+	  #else
+	    b = one + two;
+	    if (memcmp ((void *)&a, (void *)&b, sizeof (long double)) != 0)
+	      return 1;
+	    sprintf (buffer, "%lg", b);
+	    return strcmp (buffer, "3") != 0;
+	  #endif
+	}
+    } [add_options_for_ppc_long_double_override_ibm128 ""]]
+}
+
+# Like check_effective_target_ppc_long_double_ieee, but check if we can
+# explicitly override the long double format to use the IEEE 128-bit format,
+# and GLIBC supports doing this override by switching the sprintf to handle
+# long double.
+
+proc add_options_for_ppc_long_double_override_ieee128 { flags } {
+    if { [istarget powerpc*-*-*] } {
+	return "$flags -mlong-double-128 -Wno-psabi -mabi=ieeelongdouble"
+    }
+    return "$flags"
+}
+
+proc check_effective_target_ppc_long_double_override_ieee128 { } {
+    return [check_runtime_nocache ppc_long_double_override_ieee128 {
+	#include <string.h>
+	#include <stdio.h>
+	volatile _Float128 a = 3.0f128;
+	volatile long double one = 1.0L;
+	volatile long double two = 2.0L;
+	volatile long double b;
+	char buffer[20];
+	int main()
+	{
+	  #if !defined(_ARCH_PPC) || !defined(__LONG_DOUBLE_IEEE128__)
+	    return 1;
+	  #else
+	    b = one + two;
+	    if (memcmp ((void *)&a, (void *)&b, sizeof (long double)) != 0)
+	      return 1;
+	    sprintf (buffer, "%lg", b);
+	    return strcmp (buffer, "3") != 0;
+	  #endif
+	}
+    }  [add_options_for_ppc_long_double_override_ieee128 ""]]
+}
+
+# Like check_effective_target_ppc_long_double_64bit, but override the long
+# double format to be 64-bit explicitly.
+
+proc add_options_for_ppc_long_double_override_64bit { flags } {
+    if { [istarget powerpc*-*-*] } {
+	return "$flags -mlong-double-64"
+    }
+    return "$flags"
+}
+
+proc check_effective_target_ppc_long_double_override_64bit { } {
+    return [check_runtime_nocache ppc_long_double_override_64bit {
+	#include <string.h>
+	#include <stdio.h>
+	volatile double a = 3.0;
+	volatile long double one = 1.0L;
+	volatile long double two = 2.0L;
+	volatile long double b;
+	char buffer[20];
+	int main()
+	{
+	  #if !defined(_ARCH_PPC) || defined(__LONG_DOUBLE_128__)
+	    return 1;
+	  #else
+	    if (sizeof (long double) != sizeof (double))
+	      return 1;
+	    b = one + two;
+	    if (memcmp ((void *)&a, (void *)&b, sizeof (long double)) != 0)
+	      return 1;
+	    sprintf (buffer, "%lg", b);
+	    return strcmp (buffer, "3") != 0;
+	  #endif
+	}
+    }  [add_options_for_ppc_long_double_override_64bit ""]]
+}
+
 # Return 1 if the target supports executing VSX instructions, 0
 # otherwise.  Cache the result.