use middle::trans::tvec;
use middle::trans::type_of;
use middle::trans::type_of::*;
+use middle::trans::value::Value;
use middle::ty;
use util::common::indenter;
use util::ppaux::{Repr, ty_to_str};
// Builds the return block for a function.
pub fn build_return_block(fcx: &FunctionContext, ret_cx: @mut Block) {
// Return the value if this function immediate; otherwise, return void.
- if fcx.llretptr.is_some() && fcx.has_immediate_return_value {
- Ret(ret_cx, Load(ret_cx, fcx.llretptr.unwrap()))
- } else {
- RetVoid(ret_cx)
+ if fcx.llretptr.is_none() || !fcx.has_immediate_return_value {
+ return RetVoid(ret_cx);
}
+
+ let retptr = Value(fcx.llretptr.unwrap());
+ let retval = match retptr.get_dominating_store(ret_cx) {
+ // If there's only a single store to the ret slot, we can directly return
+ // the value that was stored and omit the store and the alloca
+ Some(s) => {
+ let retval = *s.get_operand(0).unwrap();
+ s.erase_from_parent();
+
+ if retptr.has_no_uses() {
+ retptr.erase_from_parent();
+ }
+
+ retval
+ }
+ // Otherwise, load the return value from the ret slot
+ None => Load(ret_cx, fcx.llretptr.unwrap())
+ };
+
+
+ Ret(ret_cx, retval);
}
pub enum self_arg { impl_self(ty::t, ty::SelfMode), no_self, }
--- /dev/null
+// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use lib::llvm::{llvm, BasicBlockRef};
+use middle::trans::value::{UserIterator, Value};
+use std::iterator::{Filter, Map};
+
+pub struct BasicBlock(BasicBlockRef);
+
+pub type PredIterator<'self> = Map<'self, Value, BasicBlock, Filter<'self, Value, UserIterator>>;
+
+/**
+ * Wrapper for LLVM BasicBlockRef
+ */
+impl BasicBlock {
+ pub fn as_value(self) -> Value {
+ unsafe {
+ Value(llvm::LLVMBasicBlockAsValue(*self))
+ }
+ }
+
+ pub fn pred_iter(self) -> PredIterator {
+ self.as_value().user_iter()
+ .filter(|user| user.is_a_terminator_inst())
+ .transform(|user| user.get_parent().unwrap())
+ }
+
+ pub fn get_single_predecessor(self) -> Option<BasicBlock> {
+ let mut iter = self.pred_iter();
+ match (iter.next(), iter.next()) {
+ (Some(first), None) => Some(first),
+ _ => None
+ }
+ }
+}
--- /dev/null
+// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use lib::llvm::{llvm, UseRef, ValueRef};
+use middle::trans::basic_block::BasicBlock;
+use middle::trans::common::Block;
+use std::libc::c_uint;
+
+pub struct Value(ValueRef);
+
+macro_rules! opt_val ( ($e:expr) => (
+ unsafe {
+ match $e {
+ p if p.is_not_null() => Some(Value(p)),
+ _ => None
+ }
+ }
+))
+
+/**
+ * Wrapper for LLVM ValueRef
+ */
+impl Value {
+ /// Returns the BasicBlock that contains this value
+ pub fn get_parent(self) -> Option<BasicBlock> {
+ unsafe {
+ match llvm::LLVMGetInstructionParent(*self) {
+ p if p.is_not_null() => Some(BasicBlock(p)),
+ _ => None
+ }
+ }
+ }
+
+ /// Removes this value from its containing BasicBlock
+ pub fn erase_from_parent(self) {
+ unsafe {
+ llvm::LLVMInstructionEraseFromParent(*self);
+ }
+ }
+
+ /// Returns the single dominating store to this value, if any
+ /// This only performs a search for a trivially dominating store. The store
+ /// must be the only user of this value, and there must not be any conditional
+ /// branches between the store and the given block.
+ pub fn get_dominating_store(self, bcx: @mut Block) -> Option<Value> {
+ match self.get_single_user().chain(|user| user.as_store_inst()) {
+ Some(store) => {
+ do store.get_parent().chain |store_bb| {
+ let mut bb = BasicBlock(bcx.llbb);
+ let mut ret = Some(store);
+ while *bb != *store_bb {
+ match bb.get_single_predecessor() {
+ Some(pred) => bb = pred,
+ None => { ret = None; break }
+ }
+ }
+ ret
+ }
+ }
+ _ => None
+ }
+ }
+
+ /// Returns the first use of this value, if any
+ pub fn get_first_use(self) -> Option<Use> {
+ unsafe {
+ match llvm::LLVMGetFirstUse(*self) {
+ u if u.is_not_null() => Some(Use(u)),
+ _ => None
+ }
+ }
+ }
+
+ /// Tests if there are no uses of this value
+ pub fn has_no_uses(self) -> bool {
+ self.get_first_use().is_none()
+ }
+
+ /// Returns the single user of this value
+ /// If there are no users or multiple users, this returns None
+ pub fn get_single_user(self) -> Option<Value> {
+ let mut iter = self.user_iter();
+ match (iter.next(), iter.next()) {
+ (Some(first), None) => Some(first),
+ _ => None
+ }
+ }
+
+ /// Returns an iterator for the users of this value
+ pub fn user_iter(self) -> UserIterator {
+ UserIterator {
+ next: self.get_first_use()
+ }
+ }
+
+ /// Returns the requested operand of this instruction
+ /// Returns None, if there's no operand at the given index
+ pub fn get_operand(self, i: uint) -> Option<Value> {
+ opt_val!(llvm::LLVMGetOperand(*self, i as c_uint))
+ }
+
+ /// Returns the Store represent by this value, if any
+ pub fn as_store_inst(self) -> Option<Value> {
+ opt_val!(llvm::LLVMIsAStoreInst(*self))
+ }
+
+ /// Tests if this value is a terminator instruction
+ pub fn is_a_terminator_inst(self) -> bool {
+ unsafe {
+ llvm::LLVMIsATerminatorInst(*self).is_not_null()
+ }
+ }
+}
+
+pub struct Use(UseRef);
+
+/**
+ * Wrapper for LLVM UseRef
+ */
+impl Use {
+ pub fn get_user(self) -> Value {
+ unsafe {
+ Value(llvm::LLVMGetUser(*self))
+ }
+ }
+
+ pub fn get_next_use(self) -> Option<Use> {
+ unsafe {
+ match llvm::LLVMGetNextUse(*self) {
+ u if u.is_not_null() => Some(Use(u)),
+ _ => None
+ }
+ }
+ }
+}
+
+/// Iterator for the users of a value
+pub struct UserIterator {
+ priv next: Option<Use>
+}
+
+impl Iterator<Value> for UserIterator {
+ fn next(&mut self) -> Option<Value> {
+ let current = self.next;
+
+ self.next = do current.chain |u| { u.get_next_use() };
+
+ do current.map |u| { u.get_user() }
+ }
+}
projects / rust.git / commitdiff