Remove invalid assert in literal visitor (microsoft#6875)

The code has an assert when processing an OpLoad in the literal visitor
to make sure that the result of the load is not a literal type. This is
not always true. If there is a compiler-generated, temporary variable
that gets its type from a literal, then the result type of the load will
have to be decuded by the literal visitor. That is not always possible.

However, the code already handle this situation correctly. If the result
of the load is a literal type, then the function will return true
without doing anything because `canDeduceTypeFromLitType` will return
false, as it should.

Fixes microsoft#6798

Author: s-perron

tools/clang/lib/SPIRV/LiteralTypeVisitor.cpp

@@ -311,7 +311,6 @@ bool LiteralTypeVisitor::visit(SpirvLoad *inst) {
 
   assert(inst->hasAstResultType());
   QualType resultType = inst->getAstResultType();
-  assert(!isLitTypeOrVecOfLitType(resultType));
 
   if (!canDeduceTypeFromLitType(pointerType, resultType))
     return true;

tools/clang/test/CodeGenSPIRV/select.int.lit.to.bool.hlsl

@@ -0,0 +1,27 @@
+// RUN: %dxc -T ps_6_0 -HV 2021 -E main -fcgl  %s -spirv | FileCheck %s
+
+// In this case, the types for the literals in the select cannot be deduced
+// because the cast to a bool does not force the literals to be any particular
+// bitwidth. So the types should fall back to a 32-bit signed interger.
+void foo(uint x) {
+// CHECK: %temp_var_ternary = OpVariable %_ptr_Function_int Function
+// CHECK: [[x:%[0-9]+]] = OpLoad %uint %x
+// CHECK: [[cond:%[0-9]+]] = OpULessThan %bool [[x]] %uint_64
+// CHECK: OpSelectionMerge %ternary_merge None
+// CHECK: OpBranchConditional [[cond]] %ternary_lhs %ternary_rhs
+// CHECK: %ternary_lhs = OpLabel
+// CHECK: OpStore %temp_var_ternary %int_1
+// CHECK: OpBranch %ternary_merge
+// CHECK: %ternary_rhs = OpLabel
+// CHECK: OpStore %temp_var_ternary %int_0
+// CHECK: OpBranch %ternary_merge
+// CHECK: %ternary_merge = OpLabel
+// CHECK: [[ld:%[0-9]+]] = OpLoad %int %temp_var_ternary
+// CHECK: [[res:%[0-9]+]] = OpINotEqual %bool [[ld]] %int_0
+// CHECK: OpStore %value [[res]]
+  bool value = x < 64 ? 1 : 0;
+}
+
+void main() {
+  foo(2);
+}