Re: [PATCH] vect: more oversized bitmask fixups

[Andrew Stubbs <ams@baylibre.com>]

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On 22/03/2024 08:43, Richard Biener wrote:

>>>   I'll note that we don't pass 'val' there and
>>> 'val' is unfortunately
>>> not documented - what's it supposed to be?  I think I placed the original fix in
>>> do_compare_and_jump because we have the full into available there.  So
>>> what's the
>>> do_compare_rtx_and_jump caller that needs fixing as well?  (IMHO keying on 'val'
>>> looks fragile)
>>
>> "val" is the tree expression from which the rtx op0 was expanded. It's
>> optional, but it's used in emit_cmp_and_jump_insns to determine whether
>> the target supports tbranch (according to a comment).
>>
>> I think it would be safe to remove your code as that path does path
>> "treeop0" to "val".
>>
>> WDYT?
> 
> Looks like a bit of a mess, but yes, I think that sounds good.

Thanks, here's what I pushed.

Andrew

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vect: more oversized bitmask fixups

These patches fix up a failure in testcase vect/tsvc/vect-tsvc-s278.c when
configured to use V32 instead of V64 (I plan to do this for RDNA devices).

The problem was that a "not" operation on the mask inadvertently enabled
inactive lanes 31-63 and corrupted the output.  The fix is to adjust the mask
when calling internal functions (in this case COND_MINUS), when doing masked
loads and stores, and when doing conditional jumps (some cases were already
handled).

gcc/ChangeLog:

	* dojump.cc (do_compare_rtx_and_jump): Clear excess bits in vector
	bitmasks.
	(do_compare_and_jump): Remove now-redundant similar code.
	* internal-fn.cc (expand_fn_using_insn): Clear excess bits in vector
	bitmasks.
	(add_mask_and_len_args): Likewise.

diff --git a/gcc/dojump.cc b/gcc/dojump.cc
index 88600cb42d3..5f74b696b41 100644
--- a/gcc/dojump.cc
+++ b/gcc/dojump.cc
@@ -1235,6 +1235,24 @@ do_compare_rtx_and_jump (rtx op0, rtx op1, enum rtx_code code, int unsignedp,
 	    }
 	}
 
+      /* For boolean vectors with less than mode precision
+	 make sure to fill padding with consistent values.  */
+      if (val
+	  && VECTOR_BOOLEAN_TYPE_P (TREE_TYPE (val))
+	  && SCALAR_INT_MODE_P (mode))
+	{
+	  auto nunits = TYPE_VECTOR_SUBPARTS (TREE_TYPE (val)).to_constant ();
+	  if (maybe_ne (GET_MODE_PRECISION (mode), nunits))
+	    {
+	      op0 = expand_binop (mode, and_optab, op0,
+				  GEN_INT ((HOST_WIDE_INT_1U << nunits) - 1),
+				  NULL_RTX, true, OPTAB_WIDEN);
+	      op1 = expand_binop (mode, and_optab, op1,
+				  GEN_INT ((HOST_WIDE_INT_1U << nunits) - 1),
+				  NULL_RTX, true, OPTAB_WIDEN);
+	    }
+	}
+
       emit_cmp_and_jump_insns (op0, op1, code, size, mode, unsignedp, val,
 			       if_true_label, prob);
     }
@@ -1266,7 +1284,6 @@ do_compare_and_jump (tree treeop0, tree treeop1, enum rtx_code signed_code,
   machine_mode mode;
   int unsignedp;
   enum rtx_code code;
-  unsigned HOST_WIDE_INT nunits;
 
   /* Don't crash if the comparison was erroneous.  */
   op0 = expand_normal (treeop0);
@@ -1309,21 +1326,6 @@ do_compare_and_jump (tree treeop0, tree treeop1, enum rtx_code signed_code,
       emit_insn (targetm.gen_canonicalize_funcptr_for_compare (new_op1, op1));
       op1 = new_op1;
     }
-  /* For boolean vectors with less than mode precision
-     make sure to fill padding with consistent values.  */
-  else if (VECTOR_BOOLEAN_TYPE_P (type)
-	   && SCALAR_INT_MODE_P (mode)
-	   && TYPE_VECTOR_SUBPARTS (type).is_constant (&nunits)
-	   && maybe_ne (GET_MODE_PRECISION (mode), nunits))
-    {
-      gcc_assert (code == EQ || code == NE);
-      op0 = expand_binop (mode, and_optab, op0,
-			  GEN_INT ((HOST_WIDE_INT_1U << nunits) - 1), NULL_RTX,
-			  true, OPTAB_WIDEN);
-      op1 = expand_binop (mode, and_optab, op1,
-			  GEN_INT ((HOST_WIDE_INT_1U << nunits) - 1), NULL_RTX,
-			  true, OPTAB_WIDEN);
-    }
 
   do_compare_rtx_and_jump (op0, op1, code, unsignedp, treeop0, mode,
 			   ((mode == BLKmode)
diff --git a/gcc/internal-fn.cc b/gcc/internal-fn.cc
index fcf47c7fa12..5269f0ac528 100644
--- a/gcc/internal-fn.cc
+++ b/gcc/internal-fn.cc
@@ -245,6 +245,18 @@ expand_fn_using_insn (gcall *stmt, insn_code icode, unsigned int noutputs,
 	       && SSA_NAME_IS_DEFAULT_DEF (rhs)
 	       && VAR_P (SSA_NAME_VAR (rhs)))
 	create_undefined_input_operand (&ops[opno], TYPE_MODE (rhs_type));
+      else if (VECTOR_BOOLEAN_TYPE_P (rhs_type)
+	       && SCALAR_INT_MODE_P (TYPE_MODE (rhs_type))
+	       && maybe_ne (GET_MODE_PRECISION (TYPE_MODE (rhs_type)),
+			    TYPE_VECTOR_SUBPARTS (rhs_type).to_constant ()))
+	{
+	  /* Ensure that the vector bitmasks do not have excess bits.  */
+	  int nunits = TYPE_VECTOR_SUBPARTS (rhs_type).to_constant ();
+	  rtx tmp = expand_binop (TYPE_MODE (rhs_type), and_optab, rhs_rtx,
+				  GEN_INT ((HOST_WIDE_INT_1U << nunits) - 1),
+				  NULL_RTX, true, OPTAB_WIDEN);
+	  create_input_operand (&ops[opno], tmp, TYPE_MODE (rhs_type));
+	}
       else
 	create_input_operand (&ops[opno], rhs_rtx, TYPE_MODE (rhs_type));
       opno += 1;
@@ -312,6 +324,20 @@ add_mask_and_len_args (expand_operand *ops, unsigned int opno, gcall *stmt)
     {
       tree mask = gimple_call_arg (stmt, mask_index);
       rtx mask_rtx = expand_normal (mask);
+
+      tree mask_type = TREE_TYPE (mask);
+      if (VECTOR_BOOLEAN_TYPE_P (mask_type)
+	  && SCALAR_INT_MODE_P (TYPE_MODE (mask_type))
+	  && maybe_ne (GET_MODE_PRECISION (TYPE_MODE (mask_type)),
+		       TYPE_VECTOR_SUBPARTS (mask_type).to_constant ()))
+	{
+	  /* Ensure that the vector bitmasks do not have excess bits.  */
+	  int nunits = TYPE_VECTOR_SUBPARTS (mask_type).to_constant ();
+	  mask_rtx = expand_binop (TYPE_MODE (mask_type), and_optab, mask_rtx,
+				   GEN_INT ((HOST_WIDE_INT_1U << nunits) - 1),
+				   NULL_RTX, true, OPTAB_WIDEN);
+	}
+
       create_input_operand (&ops[opno++], mask_rtx,
 			    TYPE_MODE (TREE_TYPE (mask)));
     }