[compiler] Fix missing parameter attrs on sampler wrappers

This fixes a bug introduced recently, where the wrappers we create
(before LLVM 17) were losing the parameter attributes from the original
kernel. This could lead to incorrect codegen in certain cases, most
notably when we lose `byval` attributes.

modules/compiler/source/base/source/image_argument_substitution_pass.cpp

@@ -130,21 +130,38 @@ PreservedAnalyses compiler::ImageArgumentSubstitutionPass::run(
       IRBuilder<> B(BasicBlock::Create(Ctx, "entry", WrapperKernel));
 
       SmallVector<Value *, 8> Args;
+      // Our wrapper hasn't been created with any parameter attributes, as the
+      // parameter types have changed. We must copy across all attributes from
+      // the non-sampler arguments to maintain program semantics.
+      AttributeList KernelAttrs = KernelF->getAttributes();
+      SmallVector<AttributeSet, 4> WrapperParamAttrs(KernelF->arg_size());
+
       for (auto [OldArg, NewArg] :
            zip(KernelF->args(), WrapperKernel->args())) {
         // Copy parameter names across
+        unsigned ArgIdx = Args.size();
         NewArg.setName(OldArg.getName());
         if (OldArg.getType() == NewArg.getType()) {
           Args.push_back(&NewArg);
+          WrapperParamAttrs[ArgIdx] = KernelAttrs.getParamAttrs(ArgIdx);
         } else {
           // Must be a sampler: simply cast the i32 to a pointer. This mirrors
           // what we'll do down the line when changing the pointer back to an
           // i32 via the opposite operation.
           Args.push_back(B.CreateIntToPtr(&NewArg, OldArg.getType(),
                                           NewArg.getName() + ".ptrcast"));
+          // Don't copy across any parameter attributes here, as this was a
+          // pointer and is now an i32.
+          WrapperParamAttrs[ArgIdx] = AttributeSet();
         }
       }
 
+      // Set our parameter attributes, but maintain the function/return
+      // attributes the wrapper has already received.
+      WrapperKernel->setAttributes(AttributeList::get(
+          KernelF->getContext(), WrapperKernel->getAttributes().getFnAttrs(),
+          WrapperKernel->getAttributes().getRetAttrs(), WrapperParamAttrs));
+
       auto *const CI = B.CreateCall(KernelF, Args);
 
       CI->setCallingConv(KernelF->getCallingConv());

modules/compiler/test/lit/passes/image-arg-subst.ll

@@ -56,7 +56,7 @@ entry:
 }
 
 ; We've updated the old kernel to pass samplers as i32
-; CHECK: define spir_kernel void @image_sampler(ptr addrspace(1) %out, ptr addrspace(1) %img, i32 %sampler1, i32 %sampler2) [[NEW_ATTRS:#[0-9]+]] {
+; CHECK: define spir_kernel void @image_sampler(ptr addrspace(1) nocapture writeonly align 4 %out, ptr addrspace(1) %img, i32 %sampler1, i32 %sampler2) [[NEW_ATTRS:#[0-9]+]] {
 ; CHECK:   %sampler1.ptrcast = inttoptr i32 %sampler1 to ptr addrspace(2)
 ; CHECK:   %sampler2.ptrcast = inttoptr i32 %sampler2 to ptr addrspace(2)
 ; CHECK:   call spir_kernel void @image_sampler.old(