Introduce alloc intrinsic to avoid using asm (#7499)

Improvement chart:
#7499 (comment)

---------

Co-authored-by: Igor Rončević <[email protected]>

Author: vaivaswatha

docs/book/src/reference/compiler_intrinsics.md

@@ -435,3 +435,13 @@ This number is not guaranteed to be stable on different compiler versions.
 `__encoding_mem_id` represents how the type is encoded. It returns 0 when a type does not have encoding representation.
 
 **Constraints:** None
+
+---
+
+```sway
+__alloc<T>(count: u64) -> raw_ptr
+```
+
+**Description:** Allocate `count` contiguous elements of `T` on the heap and return a pointer to the newly allocated memory.
+
+**Constraints** None

sway-ast/src/intrinsics.rs

@@ -46,6 +46,7 @@ pub enum Intrinsic {
     ElemAt, // let elem: &T = __elem_at::<T: array or ref_to_slice>(item: T, index)
     Transmute, // let dst: B = __transmute::<A, B>(src)
     Dbg,   // __dbg(value)
+    Alloc, // __alloc<T>(size: u64) -> raw_ptr
     RuntimeMemoryId, // __runtime_mem_id::<T>() -> u64
     EncodingMemoryId, // __encoding_mem_id::<T>() -> u64
 }
@@ -96,6 +97,7 @@ impl fmt::Display for Intrinsic {
             Intrinsic::ElemAt => "elem_at",
             Intrinsic::Transmute => "transmute",
             Intrinsic::Dbg => "dbg",
+            Intrinsic::Alloc => "alloc",
             Intrinsic::RuntimeMemoryId => "runtime_mem_id",
             Intrinsic::EncodingMemoryId => "encoding_mem_id",
         };
@@ -150,6 +152,7 @@ impl Intrinsic {
             "__elem_at" => ElemAt,
             "__transmute" => Transmute,
             "__dbg" => Dbg,
+            "__alloc" => Alloc,
             "__runtime_mem_id" => RuntimeMemoryId,
             "__encoding_mem_id" => EncodingMemoryId,
             _ => return None,

sway-core/src/asm_generation/evm/evm_asm_builder.rs

@@ -347,6 +347,7 @@ impl<'ir, 'eng> EvmAsmBuilder<'ir, 'eng> {
                 }
                 InstOp::IntToPtr(val, _) => self.compile_int_to_ptr(instr_val, val),
                 InstOp::Load(src_val) => self.compile_load(handler, instr_val, src_val)?,
+                InstOp::Alloc { ty, count } => self.compile_alloc(instr_val, ty, count),
                 InstOp::MemCopyBytes {
                     dst_val_ptr,
                     src_val_ptr,
@@ -501,6 +502,10 @@ impl<'ir, 'eng> EvmAsmBuilder<'ir, 'eng> {
         todo!();
     }
 
+    fn compile_alloc(&mut self, instr_val: &Value, ty: &Type, count: &Value) {
+        todo!();
+    }
+
     fn compile_log(&mut self, instr_val: &Value, log_val: &Value, log_ty: &Type, log_id: &Value) {
         todo!();
     }

sway-core/src/asm_generation/fuel/fuel_asm_builder.rs

@@ -485,6 +485,7 @@ impl<'ir, 'eng> FuelAsmBuilder<'ir, 'eng> {
                 }
                 InstOp::IntToPtr(val, _) => self.compile_no_op_move(instr_val, val),
                 InstOp::Load(src_val) => self.compile_load(instr_val, src_val),
+                InstOp::Alloc { ty, count } => self.compile_alloc(instr_val, ty, count),
                 InstOp::MemCopyBytes {
                     dst_val_ptr,
                     src_val_ptr,
@@ -1467,6 +1468,78 @@ impl<'ir, 'eng> FuelAsmBuilder<'ir, 'eng> {
         Ok(())
     }
 
+    fn compile_alloc(
+        &mut self,
+        instr_val: &Value,
+        ty: &Type,
+        count: &Value,
+    ) -> Result<(), CompileError> {
+        let owning_span = self.md_mgr.val_to_span(self.context, *instr_val);
+
+        let ty_size = ty.size(self.context).in_bytes();
+
+        let statically_known_count = count.get_constant(self.context).and_then(|count| {
+            if let ConstantValue::Uint(count_uint) = count.get_content(self.context).value {
+                Some(count_uint)
+            } else {
+                None
+            }
+        });
+
+        let size_reg = self.reg_seqr.next();
+        // If we know the count statically, multiply it by the type size to get the total size.
+        // Otherwise, just load the type size and multiply later.
+        if let Some(statically_known_count) = statically_known_count {
+            self.immediate_to_reg(
+                ty_size * statically_known_count,
+                size_reg.clone(),
+                None,
+                "get total allocation size in bytes",
+                owning_span.clone(),
+            );
+        } else {
+            self.immediate_to_reg(
+                ty_size,
+                size_reg.clone(),
+                None,
+                "get size of allocation element type",
+                owning_span.clone(),
+            );
+            let count_reg = self.value_to_register(count)?;
+            self.cur_bytecode.push(Op {
+                opcode: Either::Left(VirtualOp::MUL(
+                    size_reg.clone(),
+                    size_reg.clone(),
+                    count_reg,
+                )),
+                comment: "get total allocation size in bytes".into(),
+                owning_span: owning_span.clone(),
+            });
+        }
+
+        // Actually perform the allocation.
+        self.cur_bytecode.push(Op {
+            opcode: Either::Left(VirtualOp::ALOC(
+                VirtualRegister::Constant(ConstantRegister::HeapPointer),
+                size_reg,
+            )),
+            comment: "allocate memory".into(),
+            owning_span,
+        });
+
+        let instr_reg = self.reg_seqr.next();
+        // Move the resulting pointer from the heap pointer register to the instruction register.
+        self.cur_bytecode.push(Op::register_move(
+            instr_reg.clone(),
+            VirtualRegister::Constant(ConstantRegister::HeapPointer),
+            "save allocated memory pointer",
+            self.md_mgr.val_to_span(self.context, *instr_val),
+        ));
+
+        self.reg_map.insert(*instr_val, instr_reg);
+        Ok(())
+    }
+
     fn compile_load(&mut self, instr_val: &Value, src_val: &Value) -> Result<(), CompileError> {
         let owning_span = self.md_mgr.val_to_span(self.context, *instr_val);
         let src_ty = src_val

sway-core/src/ir_generation/const_eval.rs

@@ -1318,6 +1318,7 @@ fn const_eval_intrinsic(
             }
         },
         Intrinsic::AddrOf
+        | Intrinsic::Alloc
         | Intrinsic::PtrAdd
         | Intrinsic::PtrSub
         | Intrinsic::IsReferenceType

sway-core/src/ir_generation/function.rs

@@ -1491,6 +1491,33 @@ impl<'a> FnCompiler<'a> {
                     }
                 }
             }
+            Intrinsic::Alloc => {
+                let targ = type_arguments[0].clone();
+                let ir_type = convert_resolved_type_id(
+                    self.engines,
+                    context,
+                    md_mgr,
+                    self.module,
+                    Some(self),
+                    targ.type_id(),
+                    &targ.span(),
+                )?;
+                let count_exp = &arguments[0];
+                let count_value = return_on_termination_or_extract!(
+                    self.compile_expression_to_register(context, md_mgr, count_exp)?
+                )
+                .expect_register();
+                let span_md_idx = md_mgr.span_to_md(context, &span);
+                let val = self
+                    .current_block
+                    .append(context)
+                    .alloc(ir_type, count_value)
+                    .add_metadatum(context, span_md_idx);
+                Ok(TerminatorValue::new(
+                    CompiledValue::InRegister(val),
+                    context,
+                ))
+            }
             Intrinsic::Add
             | Intrinsic::Sub
             | Intrinsic::Mul

sway-core/src/semantic_analysis/ast_node/expression/intrinsic_function.rs

@@ -119,6 +119,9 @@ impl ty::TyIntrinsicFunctionKind {
             Intrinsic::EncodingMemoryId => {
                 type_check_encoding_memory_id(arguments, handler, kind, type_arguments, span, ctx)
             }
+            Intrinsic::Alloc => {
+                type_check_alloc(handler, ctx, kind, arguments, type_arguments, span)
+            }
         }
     }
 }
@@ -215,6 +218,65 @@ fn type_check_runtime_memory_id(
     Ok((intrinsic_function, ctx.engines.te().id_of_u64()))
 }
 
+fn type_check_alloc(
+    handler: &Handler,
+    mut ctx: TypeCheckContext,
+    kind: Intrinsic,
+    arguments: &[Expression],
+    type_arguments: &[GenericArgument],
+    span: Span,
+) -> Result<(TyIntrinsicFunctionKind, TypeId), ErrorEmitted> {
+    if arguments.len() != 1 {
+        return Err(handler.emit_err(CompileError::IntrinsicIncorrectNumArgs {
+            name: kind.to_string(),
+            expected: 1,
+            span,
+        }));
+    }
+
+    let engines = ctx.engines();
+
+    // Type argument needs to be explicitly defined
+    if type_arguments.len() != 1 {
+        return Err(handler.emit_err(CompileError::IntrinsicIncorrectNumTArgs {
+            name: kind.to_string(),
+            expected: 1,
+            span,
+        }));
+    }
+
+    let alloc_type = ctx
+        .resolve_type(
+            handler,
+            type_arguments[0].type_id(),
+            &type_arguments[0].span(),
+            EnforceTypeArguments::Yes,
+            None,
+        )
+        .unwrap_or_else(|err| engines.te().id_of_error_recovery(err));
+
+    // type check first argument, ensure that it is u64
+    let first_argument_typed_expr = {
+        let ctx = ctx
+            .by_ref()
+            .with_help_text("")
+            .with_type_annotation(engines.te().id_of_u64());
+        ty::TyExpression::type_check(handler, ctx, &arguments[0])?
+    };
+
+    let mut final_type_arguments = type_arguments.to_vec();
+    *final_type_arguments[0].type_id_mut() = alloc_type;
+    Ok((
+        TyIntrinsicFunctionKind {
+            kind,
+            arguments: vec![first_argument_typed_expr],
+            type_arguments: final_type_arguments,
+            span,
+        },
+        engines.te().id_of_raw_ptr(),
+    ))
+}
+
 fn type_check_transmute(
     arguments: &[Expression],
     handler: &Handler,

sway-core/src/semantic_analysis/cei_pattern_analysis.rs

@@ -677,6 +677,7 @@ fn effects_of_intrinsic(intr: &sway_ast::Intrinsic) -> HashSet<Effect> {
         | ElemAt
         | Transmute
         | Dbg
+        | Alloc
         | RuntimeMemoryId
         | EncodingMemoryId => HashSet::new(),
     }

sway-ir/src/analysis/memory_utils.rs

@@ -453,6 +453,7 @@ fn compute_escaped_symbols(context: &Context, function: &Function) -> EscapedSym
             InstOp::Store { stored_val, .. } => {
                 add_from_val(&mut result, stored_val, &mut is_complete)
             }
+            InstOp::Alloc { .. } => (),
         }
     }
 
@@ -519,6 +520,7 @@ pub fn get_loaded_ptr_values(context: &Context, inst: Value) -> Vec<Value> {
             ..
         }) => vec![*memopd1, *memopd2],
         InstOp::Store { dst_val_ptr: _, .. } => vec![],
+        InstOp::Alloc { .. } => vec![],
         InstOp::FuelVm(FuelVmInstruction::Gtf { .. })
         | InstOp::FuelVm(FuelVmInstruction::ReadRegister(_))
         | InstOp::FuelVm(FuelVmInstruction::Revert(_) | FuelVmInstruction::JmpMem) => vec![],
@@ -578,6 +580,7 @@ pub fn get_stored_ptr_values(context: &Context, inst: Value) -> Vec<Value> {
         | InstOp::MemClearVal { dst_val_ptr }
         | InstOp::Store { dst_val_ptr, .. } => vec![*dst_val_ptr],
         InstOp::Load(_) => vec![],
+        InstOp::Alloc { .. } => vec![],
         InstOp::FuelVm(vmop) => match vmop {
             FuelVmInstruction::Gtf { .. }
             | FuelVmInstruction::Log { .. }

sway-ir/src/error.rs

@@ -46,6 +46,7 @@ pub enum IrError {
     VerifyIntToPtrFromNonIntegerType(String),
     VerifyIntToPtrToNonPointer(String),
     VerifyIntToPtrUnknownSourceType,
+    VerifyAllocCountNotUint64,
     VerifyInvalidGtfIndexType,
     VerifyLoadFromNonPointer(String),
     VerifyLocalMissingInitializer(String, String),
@@ -280,6 +281,12 @@ impl fmt::Display for IrError {
                 f,
                 "Verification failed: int_to_ptr unable to determine source type."
             ),
+            IrError::VerifyAllocCountNotUint64 => {
+                write!(
+                    f,
+                    "Verification failed: alloc instruction count must be a u64 integer."
+                )
+            }
             IrError::VerifyLoadFromNonPointer(ty) => {
                 write!(
                     f,