[PATCH, i386]: Put back __builtin_clzs and __builtin_ctzs

[Uros Bizjak]

Apparently, Qt source uses these two builtins. As the removal brings
much pain, I'd like to commit the following patch to restore
__builtin_clzs and __builtin_ctzs on gcc-6 branch.

2016-12-14  Uros Bizjak  <ubizjak@gmail.com>

    PR target/59874
    * config/i386/i386.c (enum ix86_builtins): Add IX86_BUILTIN_CLZS
    and IX86_BUILTIN_CTZS.
    (bdesc_args): Add __builtin_clzs and __builtin_ctzs.
    (ix86_fold_builtin): Handle IX86_BUILTIN_CTZS and IX86_BUILTIN_CLZS.

Bootstrapped and regression tested on x86_64-linux-gnu.

I have also checked that patched gcc emits the same code as before.

Uros.
-------------- next part --------------
Index: config/i386/i386.c
===================================================================
--- config/i386/i386.c	(revision 243649)
+++ config/i386/i386.c	(working copy)
@@ -32396,6 +32396,7 @@ enum ix86_builtins
 
   /* LZCNT */
   IX86_BUILTIN_LZCNT16,
+  IX86_BUILTIN_CLZS,
   IX86_BUILTIN_LZCNT32,
   IX86_BUILTIN_LZCNT64,
 
@@ -32422,6 +32423,7 @@ enum ix86_builtins
   IX86_BUILTIN_BEXTR32,
   IX86_BUILTIN_BEXTR64,
   IX86_BUILTIN_TZCNT16,
+  IX86_BUILTIN_CTZS,
   IX86_BUILTIN_TZCNT32,
   IX86_BUILTIN_TZCNT64,
 
@@ -33813,6 +33815,8 @@ static const struct builtin_description bdesc_args
 
   /* LZCNT */
   { OPTION_MASK_ISA_LZCNT, CODE_FOR_lzcnt_hi, "__builtin_ia32_lzcnt_u16", IX86_BUILTIN_LZCNT16, UNKNOWN, (int) UINT16_FTYPE_UINT16 },
+  /* Same as above, for backward compatibility.  */
+  { OPTION_MASK_ISA_LZCNT, CODE_FOR_lzcnt_hi, "__builtin_clzs", IX86_BUILTIN_CLZS, UNKNOWN, (int) UINT16_FTYPE_UINT16 },
   { OPTION_MASK_ISA_LZCNT, CODE_FOR_lzcnt_si, "__builtin_ia32_lzcnt_u32", IX86_BUILTIN_LZCNT32, UNKNOWN, (int) UINT_FTYPE_UINT },
   { OPTION_MASK_ISA_LZCNT | OPTION_MASK_ISA_64BIT, CODE_FOR_lzcnt_di, "__builtin_ia32_lzcnt_u64", IX86_BUILTIN_LZCNT64, UNKNOWN, (int) UINT64_FTYPE_UINT64 },
 
@@ -33821,6 +33825,8 @@ static const struct builtin_description bdesc_args
   { OPTION_MASK_ISA_BMI | OPTION_MASK_ISA_64BIT, CODE_FOR_bmi_bextr_di, "__builtin_ia32_bextr_u64", IX86_BUILTIN_BEXTR64, UNKNOWN, (int) UINT64_FTYPE_UINT64_UINT64 },
 
   { OPTION_MASK_ISA_BMI, CODE_FOR_bmi_tzcnt_hi, "__builtin_ia32_tzcnt_u16", IX86_BUILTIN_TZCNT16, UNKNOWN, (int) UINT16_FTYPE_UINT16 },
+  /* Same as above, for backward compatibility.  */
+  { OPTION_MASK_ISA_BMI, CODE_FOR_bmi_tzcnt_hi, "__builtin_ctzs", IX86_BUILTIN_CTZS, UNKNOWN, (int) UINT16_FTYPE_UINT16 },
   { OPTION_MASK_ISA_BMI, CODE_FOR_bmi_tzcnt_si, "__builtin_ia32_tzcnt_u32", IX86_BUILTIN_TZCNT32, UNKNOWN, (int) UINT_FTYPE_UINT },
   { OPTION_MASK_ISA_BMI | OPTION_MASK_ISA_64BIT, CODE_FOR_bmi_tzcnt_di, "__builtin_ia32_tzcnt_u64", IX86_BUILTIN_TZCNT64, UNKNOWN, (int) UINT64_FTYPE_UINT64 },
 
@@ -37603,6 +37609,7 @@ ix86_fold_builtin (tree fndecl, int n_args,
           return fold_builtin_cpu (fndecl, args);
 
 	case IX86_BUILTIN_TZCNT16:
+	case IX86_BUILTIN_CTZS:
 	case IX86_BUILTIN_TZCNT32:
 	case IX86_BUILTIN_TZCNT64:
 	  gcc_assert (n_args == 1);
@@ -37610,7 +37617,8 @@ ix86_fold_builtin (tree fndecl, int n_args,
 	    {
 	      tree type = TREE_TYPE (TREE_TYPE (fndecl));
 	      tree arg = args[0];
-	      if (fn_code == IX86_BUILTIN_TZCNT16)
+	      if (fn_code == IX86_BUILTIN_TZCNT16
+		  || fn_code == IX86_BUILTIN_CTZS)
 		arg = fold_convert (short_unsigned_type_node, arg);
 	      if (integer_zerop (arg))
 		return build_int_cst (type, TYPE_PRECISION (TREE_TYPE (arg)));
@@ -37620,6 +37628,7 @@ ix86_fold_builtin (tree fndecl, int n_args,
 	  break;
 
 	case IX86_BUILTIN_LZCNT16:
+	case IX86_BUILTIN_CLZS:
 	case IX86_BUILTIN_LZCNT32:
 	case IX86_BUILTIN_LZCNT64:
 	  gcc_assert (n_args == 1);
@@ -37627,7 +37636,8 @@ ix86_fold_builtin (tree fndecl, int n_args,
 	    {
 	      tree type = TREE_TYPE (TREE_TYPE (fndecl));
 	      tree arg = args[0];
-	      if (fn_code == IX86_BUILTIN_LZCNT16)
+	      if (fn_code == IX86_BUILTIN_LZCNT16
+		  || fn_code == IX86_BUILTIN_CLZS)
 		arg = fold_convert (short_unsigned_type_node, arg);
 	      if (integer_zerop (arg))
 		return build_int_cst (type, TYPE_PRECISION (TREE_TYPE (arg)));