[Backport to 14] Fix incorrect translation of calls to a builtin that returns a structure (#2722) (#3032)

This PR fixes the issue with Khronos Translator incorrectly translating
calls to builtins that returns a structure and generating incorrect
extractvalue applied to a pointer. The PR is to fix the issue by
preserving equivalence of newly inserted values with prior values of
function return's type.

Author: VyacheslavLevytskyy

lib/SPIRV/SPIRVUtil.cpp

@@ -251,7 +251,7 @@ PointerType *getSPIRVOpaquePtrType(Module *M, Op OC) {
 }
 
 void getFunctionTypeParameterTypes(llvm::FunctionType *FT,
-                                   std::vector<Type *> &ArgTys) {
+                                   SmallVector<Type *> &ArgTys) {
   for (auto I = FT->param_begin(), E = FT->param_end(); I != E; ++I) {
     ArgTys.push_back(*I);
   }
@@ -2072,10 +2072,11 @@ bool postProcessBuiltinReturningStruct(Function *F) {
     if (auto *CI = dyn_cast<CallInst>(U)) {
       IRBuilder<> Builder(CI->getParent());
       Builder.SetInsertPoint(CI);
-      SmallVector<User *, 5> Users(CI->users());
+      SmallVector<User *> Users(CI->users());
       Value *A = nullptr;
+      StoreInst *SI = nullptr;
       for (auto *U : Users) {
-        if (auto *SI = dyn_cast<StoreInst>(U)) {
+        if ((SI = dyn_cast<StoreInst>(U)) != nullptr) {
           A = SI->getPointerOperand();
           InstToRemove.push_back(SI);
           break;
@@ -2084,22 +2085,29 @@ bool postProcessBuiltinReturningStruct(Function *F) {
       if (!A) {
         A = Builder.CreateAlloca(F->getReturnType());
       }
-      std::vector<Type *> ArgTys;
+      SmallVector<Type *> ArgTys;
       getFunctionTypeParameterTypes(F->getFunctionType(), ArgTys);
       ArgTys.insert(ArgTys.begin(), A->getType());
       auto *NewF =
           getOrCreateFunction(M, Type::getVoidTy(*Context), ArgTys, Name);
-      NewF->addParamAttr(0, Attribute::get(*Context,
-                                           Attribute::AttrKind::StructRet,
-                                           F->getReturnType()));
+      auto SretAttr = Attribute::get(*Context, Attribute::AttrKind::StructRet,
+                                     F->getReturnType());
+      NewF->addParamAttr(0, SretAttr);
       NewF->setCallingConv(F->getCallingConv());
       auto Args = getArguments(CI);
       Args.insert(Args.begin(), A);
-      CallInst *NewCI = Builder.CreateCall(NewF, Args, CI->getName());
+      CallInst *NewCI = Builder.CreateCall(
+          NewF, Args, NewF->getReturnType()->isVoidTy() ? "" : CI->getName());
+      NewCI->addParamAttr(0, SretAttr);
       NewCI->setCallingConv(CI->getCallingConv());
-      SmallVector<User *, 5> CIUsers(CI->users());
-      for (auto *CIUser : CIUsers) {
-        CIUser->replaceUsesOfWith(CI, A);
+      SmallVector<User *, 32> UsersToReplace;
+      for (auto *U : Users)
+        if (U != SI)
+          UsersToReplace.push_back(U);
+      if (UsersToReplace.size() > 0) {
+        auto *LI = Builder.CreateLoad(F->getReturnType(), A);
+        for (auto *U : UsersToReplace)
+          U->replaceUsesOfWith(CI, LI);
       }
       InstToRemove.push_back(CI);
     }

test/builtin_returns_struct.spvasm

@@ -0,0 +1,52 @@
+; REQUIRES: spirv-as
+; RUN: spirv-as --target-env spv1.0 -o %t.spv %s
+; RUN: spirv-val %t.spv
+; RUN: llvm-spirv -r -o - %t.spv | llvm-dis | FileCheck %s
+
+               OpCapability Kernel
+               OpCapability Addresses
+               OpCapability Int8
+               OpCapability GenericPointer
+               OpCapability Linkage
+          %1 = OpExtInstImport "OpenCL.std"
+               OpMemoryModel Physical64 OpenCL
+               OpSource OpenCL_CPP 100000
+               OpName %a "a"
+               OpName %p "p"
+               OpName %foo "foo"
+               OpName %e "e"
+               OpName %math "math"
+               OpName %ov "ov"
+               OpDecorate %foo LinkageAttributes "foo" Export
+       %uint = OpTypeInt 32 0
+      %uchar = OpTypeInt 8 0
+%_ptr_Generic_uchar = OpTypePointer Generic %uchar
+          %5 = OpTypeFunction %uint %uint %_ptr_Generic_uchar
+       %bool = OpTypeBool
+  %_struct_7 = OpTypeStruct %uint %uint
+     %uint_1 = OpConstant %uint 1
+   %uchar_42 = OpConstant %uchar 42
+         %10 = OpConstantNull %uint
+        %foo = OpFunction %uint None %5
+          %a = OpFunctionParameter %uint
+          %p = OpFunctionParameter %_ptr_Generic_uchar
+         %19 = OpLabel
+               OpBranch %20
+         %20 = OpLabel
+          %e = OpPhi %uint %a %19 %math %21
+         %16 = OpIAddCarry %_struct_7 %e %uint_1
+       %math = OpCompositeExtract %uint %16 0
+         %17 = OpCompositeExtract %uint %16 1
+         %ov = OpINotEqual %bool %17 %10
+               OpBranchConditional %ov %22 %21
+         %21 = OpLabel
+               OpStore %p %uchar_42 Aligned 1
+               OpBranch %20
+         %22 = OpLabel
+               OpReturnValue %math
+               OpFunctionEnd
+
+; CHECK: %[[#Var:]] = alloca %structtype, align 8
+; CHECK: call spir_func void @_Z17__spirv_IAddCarryii(%structtype* sret(%structtype) %[[#Var:]]
+; CHECK: %[[#Load:]] = load %structtype, %structtype* %[[#Var]], align 4
+; CHECK-2: extractvalue %structtype %[[#Load:]]