[Backport to 15] Ignore UserSemantic decorations on BuiltIn variables (#2796)

UserSemantic decorations on BuiltIn variables would be added into
`llvm.global.annotations`.  During lowering of builtin variables to
function calls, `replaceUsesOfBuiltinVar` would not know how to handle
the annotation and crash.

Right now there is no clear use case for UserSemantic decorations on
BuiltIn variables, so just ignore the decoration and drop it during
translation from SPIR-V to LLVM.

Test-case-by: Ben Ashbaugh <ben.ashbaugh@intel.com>
(cherry picked from commit 0317fa8)

Author: svenvh

lib/SPIRV/SPIRVReader.cpp

@@ -3786,6 +3786,11 @@ void SPIRVToLLVM::transIntelFPGADecorations(SPIRVValue *BV, Value *V) {
       Builder.CreateCall(AnnotationFn, Args);
     }
   } else if (auto *GV = dyn_cast<GlobalVariable>(V)) {
+    // Do not add annotations for builtin variables.
+    SPIRVBuiltinVariableKind Kind;
+    if (isSPIRVBuiltinVariable(GV, &Kind))
+      return;
+
     SmallString<256> AnnotStr;
     generateIntelFPGAAnnotation(BV, AnnotStr);
 

test/OpDecorateString_UserSemantic_Builtin.spvasm

@@ -0,0 +1,45 @@
+; REQUIRES: spirv-as
+; RUN: spirv-as --target-env spv1.4 -o %t.spv %s
+; RUN: spirv-val %t.spv
+; RUN: llvm-spirv -r --spirv-target-env=CL2.0 %t.spv -o - | llvm-dis | FileCheck --check-prefix=CHECK-OCL %s
+; RUN: llvm-spirv -r --spirv-target-env=SPV-IR %t.spv -o - | llvm-dis | FileCheck --check-prefix=CHECK-SPV-IR %s
+
+; Ensure that UserSemantic decorations on BuiltIn variables do not prevent successful translation.
+
+; CHECK-OCL: call spir_func i64 @_Z13get_global_idj(i32 0)
+; CHECK-SPV-IR: call spir_func i64 @_Z33__spirv_BuiltInGlobalInvocationIdi(i32 0)
+
+               OpCapability Addresses
+               OpCapability Linkage
+               OpCapability Kernel
+               OpCapability Int64
+               OpMemoryModel Physical64 OpenCL
+               OpEntryPoint Kernel %usersemantic_test "usersemantic_test" %global_id
+               OpDecorate %global_id LinkageAttributes "global_id" Import
+               OpDecorate %global_id Constant
+               OpDecorate %global_id BuiltIn GlobalInvocationId
+               ; Basic decoration:
+               OpDecorateString %global_id UserSemantic "FOO"
+               ; Duplicate decorations are allowed as long as the string is different.
+               OpDecorateString %global_id UserSemantic "BAR"
+               ; Try one more string with punctuation.
+               OpDecorateString %global_id UserSemantic "FOO? BAR. BAZ!"
+      %ulong = OpTypeInt 64 0
+       %uint = OpTypeInt 32 0
+    %v3ulong = OpTypeVector %ulong 3
+%_ptr_Input_v3ulong = OpTypePointer Input %v3ulong
+       %void = OpTypeVoid
+%_ptr_CrossWorkgroup_uint = OpTypePointer CrossWorkgroup %uint
+          %9 = OpTypeFunction %void %_ptr_CrossWorkgroup_uint
+%global_id = OpVariable %_ptr_Input_v3ulong Input
+%usersemantic_test = OpFunction %void None %9
+        %dst = OpFunctionParameter %_ptr_CrossWorkgroup_uint
+      %entry = OpLabel
+      %index = OpLoad %v3ulong %global_id Aligned 32
+       %call = OpCompositeExtract %ulong %index 0
+       %conv = OpUConvert %uint %call
+    %idxprom = OpSConvert %ulong %conv
+   %arrayidx = OpInBoundsPtrAccessChain %_ptr_CrossWorkgroup_uint %dst %idxprom
+               OpStore %arrayidx %conv Aligned 4
+               OpReturn
+               OpFunctionEnd