Cycles: Kernel address space changes for MSL

This is the first of a sequence of changes to support compiling Cycles kernels as MSL (Metal Shading Language) in preparation for a Metal GPU device implementation.

MSL requires that all pointer types be declared with explicit address space attributes (device, thread, etc...). There is already precedent for this with Cycles' address space macros (ccl_global, ccl_private, etc...), therefore the first step of MSL-enablement is to apply these consistently. Line-for-line this represents the largest change required to enable MSL. Applying this change first will simplify future patches as well as offering the emergent benefit of enhanced descriptiveness.

The vast majority of deltas in this patch fall into one of two cases:

- Ensuring ccl_private is specified for thread-local pointer types
- Ensuring ccl_global is specified for device-wide pointer types

Additionally, the ccl_addr_space qualifier can be removed. Prior to Cycles X, ccl_addr_space was used as a context-dependent address space qualifier, but now it is either redundant (e.g. in struct typedefs), or can be replaced by ccl_global in the case of pointer types. Associated function variants (e.g. lcg_step_float_addrspace) are also redundant.

In cases where address space qualifiers are chained with "const", this patch places the address space qualifier first. The rationale for this is that the choice of address space is likely to have the greater impact on runtime performance and overall architecture.

The final part of this patch is the addition of a metal/compat.h header. This is partially complete and will be extended in future patches, paving the way for the full Metal implementation.

Ref T92212

Reviewed By: brecht

Maniphest Tasks: T92212

Differential Revision: https://developer.blender.org/D12864

1 files changed, 9 insertions, 12 deletions

diff --git a/intern/cycles/kernel/kernel_random.h b/intern/cycles/kernel/kernel_random.h
index 240c92bf9d0..7db4289acec 100644
--- a/intern/cycles/kernel/kernel_random.h
+++ b/intern/cycles/kernel/kernel_random.h
@@ -38,7 +38,7 @@ CCL_NAMESPACE_BEGIN
  */
 #  define SOBOL_SKIP 64
 
-ccl_device uint sobol_dimension(const KernelGlobals *kg, int index, int dimension)
+ccl_device uint sobol_dimension(ccl_global const KernelGlobals *kg, int index, int dimension)
 {
   uint result = 0;
   uint i = index + SOBOL_SKIP;
@@ -51,7 +51,7 @@ ccl_device uint sobol_dimension(const KernelGlobals *kg, int index, int dimensio
 
 #endif /* __SOBOL__ */
 
-ccl_device_forceinline float path_rng_1D(const KernelGlobals *kg,
+ccl_device_forceinline float path_rng_1D(ccl_global const KernelGlobals *kg,
                                          uint rng_hash,
                                          int sample,
                                          int dimension)
@@ -85,8 +85,12 @@ ccl_device_forceinline float path_rng_1D(const KernelGlobals *kg,
 #endif
 }
 
-ccl_device_forceinline void path_rng_2D(
-    const KernelGlobals *kg, uint rng_hash, int sample, int dimension, float *fx, float *fy)
+ccl_device_forceinline void path_rng_2D(ccl_global const KernelGlobals *kg,
+                                        uint rng_hash,
+                                        int sample,
+                                        int dimension,
+                                        ccl_private float *fx,
+                                        ccl_private float *fy)
 {
 #ifdef __DEBUG_CORRELATION__
   *fx = (float)drand48();
@@ -137,7 +141,7 @@ ccl_device_inline uint hash_iqnt2d(const uint x, const uint y)
   return n;
 }
 
-ccl_device_inline uint path_rng_hash_init(const KernelGlobals *ccl_restrict kg,
+ccl_device_inline uint path_rng_hash_init(ccl_global const KernelGlobals *ccl_restrict kg,
                                           const int sample,
                                           const int x,
                                           const int y)
@@ -184,13 +188,6 @@ ccl_device_inline uint lcg_state_init(const uint rng_hash,
   return lcg_init(rng_hash + rng_offset + sample * scramble);
 }
 
-ccl_device float lcg_step_float_addrspace(ccl_addr_space uint *rng)
-{
-  /* Implicit mod 2^32 */
-  *rng = (1103515245 * (*rng) + 12345);
-  return (float)*rng * (1.0f / (float)0xFFFFFFFF);
-}
-
 ccl_device_inline bool sample_is_even(int pattern, int sample)
 {
   if (pattern == SAMPLING_PATTERN_PMJ) {