d: vector float comparison doesn't result in 0 or -1 [PR108945]

When comparing two vectors, the type of vector was used as the result of
the condition result.  This meant that for floating point comparisons,
each value would either be `0.0' or `-1.0' reinterpreted as an integer,
not the expected integral bitmask values `0' and `-1'.

Instead, use the comparison type determined by truth_type_for as the
result of the comparison.  If a reinterpret is later required by the
final conversion for generating CmpExp, it is still only going to
reinterpret one integer kind as another.

	PR d/108945

gcc/d/ChangeLog:

	* d-codegen.cc (build_boolop): Evaluate vector comparison as
	the truth_type_for vector type.

gcc/testsuite/ChangeLog:

	* gdc.dg/pr108945.d: New test.

gcc/d/d-codegen.cc

@@ -1453,13 +1453,12 @@ build_boolop (tree_code code, tree arg0, tree arg1)
     {
       /* Build a vector comparison.
 	 VEC_COND_EXPR <e1 op e2, { -1, -1, -1, -1 }, { 0, 0, 0, 0 }>; */
-      tree type = TREE_TYPE (arg0);
-      tree cmptype = truth_type_for (type);
+      tree cmptype = truth_type_for (TREE_TYPE (arg0));
       tree cmp = fold_build2_loc (input_location, code, cmptype, arg0, arg1);
 
-      return fold_build3_loc (input_location, VEC_COND_EXPR, type, cmp,
-			      build_minus_one_cst (type),
-			      build_zero_cst (type));
+      return fold_build3_loc (input_location, VEC_COND_EXPR, cmptype, cmp,
+			      build_minus_one_cst (cmptype),
+			      build_zero_cst (cmptype));
     }
 
   if (code == EQ_EXPR || code == NE_EXPR)

gcc/testsuite/gdc.dg/pr108945.d

@@ -0,0 +1,12 @@
+// { dg-options "-fdump-tree-gimple" }
+// { dg-additional-options "-mavx" { target avx_runtime } }
+// { dg-do compile { target { avx_runtime || vect_sizes_16B_8B } } }
+
+alias f4 = __vector(float[4]);
+
+auto pr108945(f4 a, f4 b)
+{
+    return a < b;
+}
+
+// { dg-final { scan-tree-dump-not "VEC_COND_EXPR" "gimple" } }