[SPIR-V] Add -fvk-bind-*-heap flag to DXC

[Keenuts]

Those flags allow the user to hardcode the binding ID for the heaps. This allow the user to either force heap aliasing, or simply have more control over the heaps.

Fixes #6913

[s-perron]

The only part that seems missing that other resources that are automatically assigned resources bindings should not use the fixed binding for the descriptor heaps:

// RUN: %dxc -T cs_6_6 -E main -fcgl %s -spirv -fvk-bind-resource-heap 0 0 -fvk-bind-counter-heap 1 0 | FileCheck %s

// CHECK-DAG: OpDecorate %a DescriptorSet 0
// CHECK-DAG: OpDecorate %a Binding 2
// CHECK-DAG: OpDecorate %counter_var_a DescriptorSet 0
// CHECK-DAG: OpDecorate %counter_var_a Binding 3
RWStructuredBuffer<uint> a; 

[numthreads(1, 1, 1)]
void main() {  
// CHECK-DAG: OpDecorate %ResourceDescriptorHeap DescriptorSet 0
// CHECK-DAG: OpDecorate %ResourceDescriptorHeap Binding 0
// CHECK-DAG: OpDecorate %counter_var_ResourceDescriptorHeap DescriptorSet 0
// CHECK-DAG: OpDecorate %counter_var_ResourceDescriptorHeap Binding 1
  RWStructuredBuffer<uint> b = ResourceDescriptorHeap[1];
  
  a.IncrementCounter();
  b.IncrementCounter();
}

[Keenuts]

resources

You mean a test checking only resources related to the flag are fixed, and the others are still keeping the automatic behavior?

[Keenuts]

Oh got it

[Keenuts]

thanks for the finding! pre-reserved the IDs.
If you use the flags, but not the heaps, then the IDs are still reserved. This allow for a much simpler solution (otherwise I'd need to go over resources once to pre-reserve, and then to the normal allocation)