[llvm] [SPIRV] Legalize byte-buffer reinterpretation ptrcasts (#192523) (PR #212999)

[Tim Corringham via llvm-commits]

================
@@ -76,3 +76,288 @@ entry:
 }
 
 attributes #0 = { "hlsl.numthreads"="1,1,1" "hlsl.shader"="compute" }
+
+ at .str = private unnamed_addr constant [4 x i8] c"Buf\00", align 1
+
+declare target("spirv.VulkanBuffer", [0 x i8], 12, 0) @llvm.spv.resource.handlefrombinding(i32, i32, i32, i32, ptr)
+declare ptr addrspace(11) @llvm.spv.resource.getpointer(target("spirv.VulkanBuffer", [0 x i8], 12, 0), i32)
+
+; Byte-addressable buffer tests model Clang's SPIR-V resource layout for HLSL
+; ByteAddressBuffer/RWByteAddressBuffer: the handle carries [0 x i8] as the
+; OpTypeRuntimeArray element type for storage-buffer blocks. That i8 names
+; byte-addressable layout in LLVM IR; it is not an HLSL surface type. Typed
+; HLSL accesses (e.g. Store(offset, uint)) lower to i32 load/store at a byte
+; offset in getpointer's index operand. emit-intrinsics tags getpointer as i8
+; from the layout, then inserts i8->T spv_ptrcast for the typed access;
+; legalize-pointer-cast removes the ptrcast and keeps the typed access.
----------------
tcorringham wrote:

done

https://github.com/llvm/llvm-project/pull/212999