rs6000: Change optab for ibm128 and ieee128 conversion

Currently for 128 bit floating-point ibm128 and ieee128
formats conversion, the corresponding libcalls are:
  ibm128 -> ieee128 "__trunctfkf2"
  ieee128 -> ibm128 "__extendkftf2"
, and generic code handling (like convert_mode_scalar) also
adopts sext_optab for ieee128 -> ibm128 while trunc_optab
for ibm128 -> ieee128.  But in rs6000 port as function
rs6000_expand_float128_convert and init_float128_ieee show,
we adopt sext_optab for ibm128 -> ieee128 with "__trunctfkf2"
while trunc_optab for ieee128 -> ibm128 with "__extendkftf2".

To make them consistent and avoid some surprises, this patch
is to adjust rs6000 internal handlings by adopting trunc_optab
for ibm128 -> ieee128 with "__trunctfkf2" while sext_optab for
ieee128 -> ibm128 with "__extendkftf2".

gcc/ChangeLog:

	* config/rs6000/rs6000.cc (init_float128_ieee): Use trunc_optab rather
	than sext_optab for converting FLOAT128_IBM_P mode to FLOAT128_IEEE_P
	mode, and use sext_optab rather than trunc_optab for converting
	FLOAT128_IEEE_P mode to FLOAT128_IBM_P mode.
	(rs6000_expand_float128_convert): Likewise.

diff --git a/gcc/config/rs6000/rs6000.cc b/gcc/config/rs6000/rs6000.cc
index 905e6cb6a942c4ddaf5d0d3bd75fcad8c4d68491..2c0a7fc8cefa728e85effe943e6de2010c2abb02 100644 (file)
--- a/gcc/config/rs6000/rs6000.cc
+++ b/gcc/config/rs6000/rs6000.cc
@@ -11476,13 +11476,13 @@ init_float128_ieee (machine_mode mode)
       set_conv_libfunc (trunc_optab, SFmode, mode, "__trunckfsf2");
       set_conv_libfunc (trunc_optab, DFmode, mode, "__trunckfdf2");
 
-      set_conv_libfunc (sext_optab, mode, IFmode, "__trunctfkf2");
+      set_conv_libfunc (trunc_optab, mode, IFmode, "__trunctfkf2");
       if (mode != TFmode && FLOAT128_IBM_P (TFmode))
-       set_conv_libfunc (sext_optab, mode, TFmode, "__trunctfkf2");
+       set_conv_libfunc (trunc_optab, mode, TFmode, "__trunctfkf2");
 
-      set_conv_libfunc (trunc_optab, IFmode, mode, "__extendkftf2");
+      set_conv_libfunc (sext_optab, IFmode, mode, "__extendkftf2");
       if (mode != TFmode && FLOAT128_IBM_P (TFmode))
-       set_conv_libfunc (trunc_optab, TFmode, mode, "__extendkftf2");
+       set_conv_libfunc (sext_optab, TFmode, mode, "__extendkftf2");
 
       set_conv_libfunc (sext_optab, mode, SDmode, "__dpd_extendsdkf");
       set_conv_libfunc (sext_optab, mode, DDmode, "__dpd_extendddkf");
@@ -15640,7 +15640,7 @@ rs6000_expand_float128_convert (rtx dest, rtx src, bool unsigned_p)
        case E_IFmode:
        case E_TFmode:
          if (FLOAT128_IBM_P (src_mode))
-           cvt = sext_optab;
+           cvt = trunc_optab;
          else
            do_move = true;
          break;
@@ -15702,7 +15702,7 @@ rs6000_expand_float128_convert (rtx dest, rtx src, bool unsigned_p)
        case E_IFmode:
        case E_TFmode:
          if (FLOAT128_IBM_P (dest_mode))
-           cvt = trunc_optab;
+           cvt = sext_optab;
          else
            do_move = true;
          break;