Implement the `printf` HLSL Function

[farzonl]

• Implement printf clang builtin,
• Link printf clang builtin with hlsl_intrinsics.h
• Add sema checks for printf to CheckHLSLBuiltinFunctionCall in SemaChecking.cpp
• Add codegen for printf to EmitHLSLBuiltinExpr in CGBuiltin.cpp
• Add codegen tests to clang/test/CodeGenHLSL/builtins/printf.hlsl
• Add sema tests to clang/test/SemaHLSL/BuiltIns/printf-errors.hlsl
• Create the int_spv_printf intrinsic in IntrinsicsSPIRV.td
• In SPIRVInstructionSelector.cpp create the printf lowering and map it to int_spv_printf in SPIRVInstructionSelector::selectIntrinsic.
• Create SPIR-V backend test case in llvm/test/CodeGen/SPIRV/hlsl-intrinsics/printf.ll

DirectX

There is no support for printf when targeting DirectX.

SPIR-V

See "Using Debug Printf in HLSL Shaders" in https://vulkan.lunarg.com/doc/sdk/1.3.283.0/windows/debug_printf.html

Test Case(s)

Example 1

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

export void fn(string p1) {
    return printf(p1);
}

HLSL:

Submits a custom shader message to the information queue.

Syntax

void printf(
   string format,
    argument ...
);

Parameters

format

The format string.

argument ...

Optional arguments.

Return value

This function does not return a value.

Remarks

This operation does nothing on devices that do not support it.

Minimum Shader Model

This function is supported in the following shader models.

Shader Model	Supported
Shader Model 4 (DirectX HLSL) or later.	yes

 

See also

Intrinsic Functions