llvm-project

4d984357 - [SPIRV] Legalize byte-buffer reinterpretation ptrcasts (#192523) (#212999)

[SPIRV] Legalize byte-buffer reinterpretation ptrcasts (#192523) (#212999) Fixes #192523 by extending SPIRVLegalizePointerCast to legalize reinterpretation spv.ptrcasts on byte-addressable buffers ([0 x i8] / RWByteAddressBuffer). When Clang emits a typed load or store through such a pointer (e.g. i32, <4 x i32>), the pass now lowers it to valid logical SPIR-V instead of hitting an unreachable or producing invalid OpAccessChain into uchar storage. For HLSL/Vulkan byte-address buffers, codegen produced IR like: 1. spv.resource.getpointer → pointer tagged as i8 byte storage 2. spv.ptrcast → pointer tagged as the access type (i32, vector, etc.) 3. Typed load/store through the cast The existing legalizer only handled aggregate layout mismatches (GEP drilling, partial vector loads). When getPointerToFirstCompatibleType() found no compatible nested type—as with flat byte buffers—it hit llvm_unreachable. A naive fix (retag the original pointer to the access type and emit a single typed access) avoids the crash but produces invalid SPIR-V: OpAccessChain with a vector/scalar result type into a uchar runtime array, which spirv-val rejects. Solution is to add a reinterpretation fallback when aggregate drilling fails. The pass classifies the case and chooses one of two strategies: - ByteWise : when original layout is i8, access is multi-byte scalar/vector use per-byte i8 load/store loop - RetagDirect : other reinterpretations (e.g. single-byte access) simply retag pointer via spv_assign_ptr_type, then use typed access Co-authored-by: Cursor