[PATCH] PowerPC: Set long double size for IBM/IEEE.

[Michael Meissner]

[PATCH] PowerPC: Set long double size for IBM/IEEE.

I originally posted this patch to an internal IBM mailing list instead of
gcc-patches.

As I was working with compilers where the long double default was 64-bit, it
became annoying to have to use two options to switch to one of the 128-bit long
double types (i.e. you need both -mlong-double-128 and the
-mabi={ieee,ibm}longdouble to switch the long double type).

I did this patch so that if you explicitly set the long double ABI via the
-mabi= option, it would automatically set the long double size if that was not
set explicitly.

gcc/
2020-11-17  Michael Meissner  <meissner@linux.ibm.com>

	* config/rs6000/rs6000.c (rs6000_option_override_internal): If the
	user explicitly used -mabi=ieeelongdouble or -mabi=ibmlongdouble,
	set the long double size to 128.
	* doc/invoke.texi (PowerPC options): Document that an explicit
	-mabi=ieeelongdouble or -mabi=ibmlongdouble implicitly sets
	-mlong-double-128.
---
 gcc/config/rs6000/rs6000.c | 9 +++++++--
 gcc/doc/invoke.texi        | 7 ++++---
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index 35e9c844e17..6edd17a0b69 100644
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -4131,8 +4131,13 @@ rs6000_option_override_internal (bool global_init_p)
 
   /* Use long double size to select the appropriate long double.  We use
      TYPE_PRECISION to differentiate the 3 different long double types.  We map
-     128 into the precision used for TFmode.  */
-  int default_long_double_size = (RS6000_DEFAULT_LONG_DOUBLE_SIZE == 64
+     128 into the precision used for TFmode.
+
+     If the user explicitly used -mabi=ieeelongdouble or -mabi=ibmlongdouble,
+     but the compiler was configured for default 64-bit long doubles, set the
+     long double to be 128.  */
+  int default_long_double_size = ((RS6000_DEFAULT_LONG_DOUBLE_SIZE == 64
+				   && !global_options_set.x_rs6000_ieeequad)
 				  ? 64
 				  : FLOAT_PRECISION_TFmode);
 
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 3510a54c6c4..89d530f1d1e 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -27113,7 +27113,8 @@ Change the current ABI to use IBM extended-precision long double.
 This is not likely to work if your system defaults to using IEEE
 extended-precision long double.  If you change the long double type
 from IEEE extended-precision, the compiler will issue a warning unless
-you use the @option{-Wno-psabi} option.  Requires @option{-mlong-double-128}
+you use the @option{-Wno-psabi} option.  If this option is used, it
+will implicitly enable @option{-mlong-double-128}.
 to be enabled.
 
 @item -mabi=ieeelongdouble
@@ -27122,8 +27123,8 @@ Change the current ABI to use IEEE extended-precision long double.
 This is not likely to work if your system defaults to using IBM
 extended-precision long double.  If you change the long double type
 from IBM extended-precision, the compiler will issue a warning unless
-you use the @option{-Wno-psabi} option.  Requires @option{-mlong-double-128}
-to be enabled.
+you use the @option{-Wno-psabi} option.  If this option is used, it
+will implicitly enable @option{-mlong-double-128}.
 
 @item -mabi=elfv1
 @opindex mabi=elfv1
-- 
2.22.0


-- 
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meissner@linux.ibm.com, phone: +1 (978) 899-4797