Implement the `CheckAccessFullyMapped` HLSL Function

[farzonl]

Implement the CheckAccessFullyMapped HLSL function in hlsl_intrinsics.h.

To match DXC when targeting DirectX, this operation can essentially just be a cast from uint to bool - the backend already handles inserting the DXIL op where necessary when the status of a load, gather, or sample is used, as per https://llvm.org/docs/DirectX/DXILResources.html#loads-samples-and-gathers.

For SPIR-V DXC maps this to OpImageSparseTexelsResident (See https://github.com/microsoft/DirectXShaderCompiler/blob/main/docs/SPIR-V.rst). In this case it does not appear to behave simply as a cast to bool and might need more work.

DirectX

DXIL Opcode	DXIL OpName	Shader Model	Shader Stages
71	CheckAccessFullyMapped	6.0	()

SPIR-V

OpImageSparseTexelsResident:

Description:

Translates a Resident Code into a Boolean. Result is false if any
of the texels were in uncommitted texture memory, and true
otherwise.

Result Type must be a Boolean type scalar.

Resident Code is a value from an OpImageSparse…​ instruction that
results in a resident code.

Capability:
SparseResidency

Word Count	Opcode	Results	Operands
4	316	<id> Result Type	Result <id>	<id> Resident Code

Test Case(s)

Example 1

//dxc CheckAccessFullyMapped_test.hlsl -T lib_6_8 -enable-16bit-types -O0

RWBuffer<float4> g_buffer;

[numthreads(1, 1, 1)]
[shader("pixel")]
bool fn( ) : SV_Target {
	uint p1;
	float4 data = g_buffer.Load(0, p1);
	return CheckAccessFullyMapped(p1);
}

HLSL:

Determines whether all values from a Sample, Gather, or Load operation accessed mapped tiles in a tiled resource.

Syntax

bool CheckAccessFullyMapped(
  in uint_only status
);

Parameters

status [in]

Type: uint_only

The status value that is returned from a Sample, Gather, or Load operation. Because you can't access this status value directly, you need to pass it to CheckAccessFullyMapped.

Return value

Type: bool

Returns a Boolean value that indicates whether all values from a Sample, Gather, or Load operation accessed mapped tiles in a tiled resource. Returns TRUE if all values from the operation accessed mapped tiles; otherwise, returns FALSE if any values were taken from an unmapped tile.

Remarks

Minimum Shader Model

This function is supported in the following shader models.

Shader Model	Supported
Shader Model 5 and higher shader models	yes

 

This function is supported in the following types of shaders:

Vertex	Hull	Domain	Geometry	Pixel	Compute
				x	x

 

See also

Intrinsic Functions

[damyanp]

This needs more planning work to figure out what we'll be doing for SPIR-V. Once that's done and the issue is updated we can take it back to refinement.