From 8b776834a447f6c346130172e9d6d492b3b4e77d Mon Sep 17 00:00:00 2001
From: Piotr Czarnecki <pioczarn@gmail.com>
Date: Mon, 1 Feb 2016 11:04:49 +0100
Subject: [PATCH] Implement OwnedBuilder and BlockAndBuilder

---
 src/librustc_trans/trans/common.rs | 108 +++++++++++++++++++++++++++++
 1 file changed, 108 insertions(+)

diff --git a/src/librustc_trans/trans/common.rs b/src/librustc_trans/trans/common.rs
index 303fc17ce81b4..a23d879bba924 100644
--- a/src/librustc_trans/trans/common.rs
+++ b/src/librustc_trans/trans/common.rs
@@ -26,6 +26,7 @@ use middle::lang_items::LangItem;
 use middle::subst::{self, Substs};
 use trans::base;
 use trans::build;
+use trans::builder::Builder;
 use trans::callee;
 use trans::cleanup;
 use trans::consts;
@@ -45,6 +46,7 @@ use util::nodemap::{FnvHashMap, NodeMap};
 
 use arena::TypedArena;
 use libc::{c_uint, c_char};
+use std::ops::Deref;
 use std::ffi::CString;
 use std::cell::{Cell, RefCell};
 use std::vec::Vec;
@@ -613,6 +615,9 @@ impl<'blk, 'tcx> BlockS<'blk, 'tcx> {
     pub fn ccx(&self) -> &'blk CrateContext<'blk, 'tcx> {
         self.fcx.ccx
     }
+    pub fn fcx(&self) -> &'blk FunctionContext<'blk, 'tcx> {
+        self.fcx
+    }
     pub fn tcx(&self) -> &'blk ty::ctxt<'tcx> {
         self.fcx.ccx.tcx()
     }
@@ -659,6 +664,109 @@ impl<'blk, 'tcx> BlockS<'blk, 'tcx> {
                                          self.fcx.param_substs,
                                          value)
     }
+
+    pub fn build(&'blk self) -> BlockAndBuilder<'blk, 'tcx> {
+        BlockAndBuilder::new(self, OwnedBuilder::new_with_ccx(self.ccx()))
+    }
+}
+
+pub struct OwnedBuilder<'blk, 'tcx: 'blk> {
+    builder: Builder<'blk, 'tcx>
+}
+
+impl<'blk, 'tcx> OwnedBuilder<'blk, 'tcx> {
+    pub fn new_with_ccx(ccx: &'blk CrateContext<'blk, 'tcx>) -> Self {
+        // Create a fresh builder from the crate context.
+        let llbuilder = unsafe {
+            llvm::LLVMCreateBuilderInContext(ccx.llcx())
+        };
+        OwnedBuilder {
+            builder: Builder {
+                llbuilder: llbuilder,
+                ccx: ccx,
+            }
+        }
+    }
+}
+
+impl<'blk, 'tcx> Drop for OwnedBuilder<'blk, 'tcx> {
+    fn drop(&mut self) {
+        unsafe {
+            llvm::LLVMDisposeBuilder(self.builder.llbuilder);
+        }
+    }
+}
+
+pub struct BlockAndBuilder<'blk, 'tcx: 'blk> {
+    bcx: Block<'blk, 'tcx>,
+    owned_builder: OwnedBuilder<'blk, 'tcx>,
+}
+
+impl<'blk, 'tcx> BlockAndBuilder<'blk, 'tcx> {
+    pub fn new(bcx: Block<'blk, 'tcx>, owned_builder: OwnedBuilder<'blk, 'tcx>) -> Self {
+        // Set the builder's position to this block's end.
+        owned_builder.builder.position_at_end(bcx.llbb);
+        BlockAndBuilder {
+            bcx: bcx,
+            owned_builder: owned_builder,
+        }
+    }
+
+    pub fn with_block<F, R>(&self, f: F) -> R
+        where F: FnOnce(Block<'blk, 'tcx>) -> R
+    {
+        let result = f(self.bcx);
+        self.position_at_end(self.bcx.llbb);
+        result
+    }
+
+    pub fn map_block<F>(self, f: F) -> Self
+        where F: FnOnce(Block<'blk, 'tcx>) -> Block<'blk, 'tcx>
+    {
+        let BlockAndBuilder { bcx, owned_builder } = self;
+        let bcx = f(bcx);
+        BlockAndBuilder::new(bcx, owned_builder)
+    }
+
+    // Methods delegated to bcx
+
+    pub fn ccx(&self) -> &'blk CrateContext<'blk, 'tcx> {
+        self.bcx.ccx()
+    }
+    pub fn fcx(&self) -> &'blk FunctionContext<'blk, 'tcx> {
+        self.bcx.fcx()
+    }
+    pub fn tcx(&self) -> &'blk ty::ctxt<'tcx> {
+        self.bcx.tcx()
+    }
+    pub fn sess(&self) -> &'blk Session {
+        self.bcx.sess()
+    }
+
+    pub fn llbb(&self) -> BasicBlockRef {
+        self.bcx.llbb
+    }
+
+    pub fn mir(&self) -> &'blk Mir<'tcx> {
+        self.bcx.mir()
+    }
+
+    pub fn val_to_string(&self, val: ValueRef) -> String {
+        self.bcx.val_to_string(val)
+    }
+
+    pub fn monomorphize<T>(&self, value: &T) -> T
+        where T: TypeFoldable<'tcx>
+    {
+        self.bcx.monomorphize(value)
+    }
+}
+
+impl<'blk, 'tcx> Deref for BlockAndBuilder<'blk, 'tcx> {
+    type Target = Builder<'blk, 'tcx>;
+    fn deref(&self) -> &Self::Target {
+        &self.owned_builder.builder
+    }
 }
 
 /// A structure representing an active landing pad for the duration of a basic