add reverse translation for OpDecorateString and OpMemberDecorateString (#2677)

This PR adds "reverse translation" (from SPIR-V to LLVM IR) support for OpDecorateString and OpMemberDecorateString, see #2460 and #2670. These instructions are currently treated as synonyms for OpDecorate and OpMemberDecorate. We'll want to tidy this up at some point, but at least for now we won't crash if we see these instructions.

I'll still need to add proper support for decorating variables in the input storage class for #2670, but I'll do that in a separate PR.

Original commit:
KhronosGroup/SPIRV-LLVM-Translator@f7057b44e20fd06

Author: bashbaug

llvm-spirv/lib/SPIRV/libSPIRV/SPIRVDecorate.h

@@ -231,6 +231,8 @@ class SPIRVDecorate : public SPIRVDecorateGeneric {
   }
 };
 
+class SPIRVDecorateString : public SPIRVDecorate {};
+
 class SPIRVDecorateId : public SPIRVDecorateGeneric {
 public:
   static const Op OC = OpDecorateId;
@@ -383,6 +385,8 @@ class SPIRVMemberDecorate : public SPIRVDecorateGeneric {
   SPIRVWord MemberNumber;
 };
 
+class SPIRVMemberDecorateString : public SPIRVMemberDecorate {};
+
 class SPIRVDecorationGroup : public SPIRVEntry {
 public:
   static const Op OC = OpDecorationGroup;

llvm-spirv/lib/SPIRV/libSPIRV/SPIRVOpCodeEnum.h

@@ -368,6 +368,8 @@ _SPIRV_OP(AtomicFMinEXT, 5614)
 _SPIRV_OP(AtomicFMaxEXT, 5615)
 _SPIRV_OP(AssumeTrueKHR, 5630)
 _SPIRV_OP(ExpectKHR, 5631)
+_SPIRV_OP(DecorateString, 5632)
+_SPIRV_OP(MemberDecorateString, 5633)
 _SPIRV_OP(VmeImageINTEL, 5699)
 _SPIRV_OP(TypeVmeImageINTEL, 5700)
 _SPIRV_OP(TypeAvcImePayloadINTEL, 5701)

llvm-spirv/test/OpDecorateString_UserSemantic.spvasm

@@ -0,0 +1,33 @@
+; REQUIRES: spirv-as
+; RUN: spirv-as --target-env spv1.4 -o %t.spv %s
+; RUN: spirv-val %t.spv
+; RUN: llvm-spirv -r -o - %t.spv | llvm-dis | FileCheck %s
+
+; SPIR-V
+; Version: 1.4
+; Generator: Khronos LLVM/SPIR-V Translator; 14
+; Bound: 40
+; Schema: 0
+               OpCapability Addresses
+               OpCapability Linkage
+               OpCapability Kernel
+               OpMemoryModel Physical64 OpenCL
+               OpEntryPoint Kernel %kernel "test"
+               ; Note: this is decorating a variable in the function storage class, which
+               ; is not actually valid according to the SPIR-V spec, but is processed by
+               ; the SPIR-V LLVM Translator and not rejected by spirv-val.
+               OpDecorateString %temp UserSemantic "foo"
+; CHECK: [[STR:@[0-9_.]+]] = {{.*}}foo
+; CHECK: call void @llvm.var.annotation.p0.p0(ptr %{{.*}}, ptr [[STR]], ptr undef, i32 undef, ptr undef)
+       %uint = OpTypeInt 32 0
+       %void = OpTypeVoid
+ %kernel_sig = OpTypeFunction %void %uint
+   %ptr_uint = OpTypePointer Function %uint
+     %kernel = OpFunction %void None %kernel_sig
+          %a = OpFunctionParameter %uint
+      %entry = OpLabel
+       %temp = OpVariable %ptr_uint Function
+        %add = OpIAdd %uint %a %a
+               OpStore %temp %add Aligned 4
+               OpReturn
+               OpFunctionEnd

llvm-spirv/test/OpMemberDecorateString_UserSemantic.spvasm

@@ -0,0 +1,37 @@
+; REQUIRES: spirv-as
+; RUN: spirv-as --target-env spv1.4 -o %t.spv %s
+; RUN: spirv-val %t.spv
+; RUN: llvm-spirv -r -o - %t.spv | llvm-dis | FileCheck %s
+
+; SPIR-V
+; Version: 1.4
+; Generator: Khronos LLVM/SPIR-V Translator; 14
+; Bound: 44
+; Schema: 0
+               OpCapability Addresses
+               OpCapability Linkage
+               OpCapability Kernel
+               OpCapability Int64
+               OpMemoryModel Physical64 OpenCL
+               OpEntryPoint Kernel %kernel "test"
+               OpMemberDecorateString %struct 0 UserSemantic "foo"
+; CHECK: [[STR:@[0-9_.]+]] = {{.*}}foo
+; Note: this is checking for an annotation on an instantiation of the structure,
+; which is different than an annotation on the structure type.
+; CHECK: call ptr @llvm.ptr.annotation.p0.p0(ptr %{{.*}}, ptr [[STR]], ptr undef, i32 undef, ptr undef)
+       %uint = OpTypeInt 32 0
+     %uint_0 = OpConstant %uint 0
+       %void = OpTypeVoid
+ %kernel_sig = OpTypeFunction %void %uint
+     %struct = OpTypeStruct %uint
+ %ptr_struct = OpTypePointer Function %struct
+   %ptr_uint = OpTypePointer Function %uint
+     %kernel = OpFunction %void None %kernel_sig
+          %a = OpFunctionParameter %uint
+      %entry = OpLabel
+          %s = OpVariable %ptr_struct Function
+        %add = OpIAdd %uint %a %a
+          %x = OpInBoundsPtrAccessChain %ptr_uint %s %uint_0 %uint_0
+               OpStore %x %add Aligned 4
+               OpReturn
+               OpFunctionEnd