[llvm] [SPIRV] Add support for `bfloat16` atomics via the `SPV_INTEL_16bit_atomics` extension (PR #166257)

[Matt Arsenault via llvm-commits]

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@@ -0,0 +1,28 @@
+; RUN: not llc -O0 -mtriple=spirv64-unknown-unknown --spirv-ext=+SPV_EXT_shader_atomic_float_min_max,+SPV_KHR_bfloat16 %s -o %t.spvt 2>&1 | FileCheck %s --check-prefix=CHECK-ERROR
+; RUN: llc -verify-machineinstrs -O0 -mtriple=spirv64-unknown-unknown --spirv-ext=+SPV_EXT_shader_atomic_float_min_max,+SPV_INTEL_16bit_atomics,+SPV_KHR_bfloat16 %s -o - | FileCheck %s
+
+; CHECK-ERROR: LLVM ERROR: The atomic bfloat16 instruction requires the following SPIR-V extension: SPV_INTEL_16bit_atomics
+
+; CHECK: Capability AtomicBFloat16MinMaxINTEL
+; CHECK: Extension "SPV_KHR_bfloat16"
+; CHECK: Extension "SPV_EXT_shader_atomic_float_min_max"
+; CHECK: Extension "SPV_INTEL_16bit_atomics"
+; CHECK-DAG: %[[TyBF16:[0-9]+]] = OpTypeFloat 16 0
+; CHECK-DAG: %[[TyBF16Ptr:[0-9]+]] = OpTypePointer {{[a-zA-Z]+}} %[[TyBF16]]
+; CHECK-DAG: %[[TyInt32:[0-9]+]] = OpTypeInt 32 0
+; CHECK-DAG: %[[ConstBF16:[0-9]+]] = OpConstant %[[TyBF16]] 16936{{$}}
+; CHECK-DAG: %[[Const0:[0-9]+]] = OpConstantNull %[[TyBF16]]
+; CHECK-DAG: %[[BF16Ptr:[0-9]+]] = OpVariable %[[TyBF16Ptr]] CrossWorkgroup %[[Const0]]
+; CHECK-DAG: %[[ScopeAllSvmDevices:[0-9]+]] = OpConstantNull %[[TyInt32]]
+; CHECK-DAG: %[[MemSeqCst:[0-9]+]] = OpConstant %[[TyInt32]] 16{{$}}
+; CHECK: OpAtomicFMinEXT %[[TyBF16]] %[[BF16Ptr]] %[[ScopeAllSvmDevices]] %[[MemSeqCst]] %[[ConstBF16]]
+; CHECK: OpAtomicFMaxEXT %[[TyBF16]] %[[BF16Ptr]] %[[ScopeAllSvmDevices]] %[[MemSeqCst]] %[[ConstBF16]]
+
+ at f = common dso_local local_unnamed_addr addrspace(1) global bfloat 0.000000e+00, align 8
+
+define dso_local spir_func void @test1() local_unnamed_addr {
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arsenm wrote:

```suggestion
define spir_func void @test1() {
```

https://github.com/llvm/llvm-project/pull/166257