From 4eb3ce32801ddd9ad335bc82f70f245c5f3c797a Mon Sep 17 00:00:00 2001
From: Brian Anderson <banderson@mozilla.com>
Date: Wed, 7 Sep 2011 14:28:02 -0700
Subject: [PATCH] Add landing pads to invokes

Issue #236
---
 src/comp/middle/trans.rs       | 25 +++++++++++++++++++++----
 src/comp/middle/trans_build.rs |  7 +++++++
 2 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/src/comp/middle/trans.rs b/src/comp/middle/trans.rs
index 9a8b9bfaba1..df07f104270 100644
--- a/src/comp/middle/trans.rs
+++ b/src/comp/middle/trans.rs
@@ -3799,15 +3799,32 @@ fn invoke_fastcall(bcx: &@block_ctxt, llfn: ValueRef,
 
     let normal_bcx = new_sub_block_ctxt(bcx, "normal return");
     let unwind_bcx = new_sub_block_ctxt(bcx, "unwind");
-    let retval = trans_build::FastInvoke(bcx, llfn, llargs,
-                                         normal_bcx.llbb,
-                                         unwind_bcx.llbb);
+    let retval = FastInvoke(bcx, llfn, llargs,
+                            normal_bcx.llbb,
+                            unwind_bcx.llbb);
     trans_landing_pad(unwind_bcx);
     ret rslt(normal_bcx, retval);
 }
 
 fn trans_landing_pad(bcx: &@block_ctxt) {
-    Unreachable(bcx);
+    // The landing pad return type (the type being propagated). Not sure what
+    // this represents but it's determined by the personality function and
+    // this is what the EH proposal example uses.
+    let llretty = T_struct([T_ptr(T_i8()), T_i32()]);
+    // The exception handling personality function. This is the C++
+    // personality function __gxx_personality_v0, wrapped in our naming
+    // convention.
+    let personality = bcx_ccx(bcx).upcalls.rust_personality;
+    // The only landing pad clause will be 'cleanup'
+    let clauses = 1u;
+    let llpad = LandingPad(bcx, llretty, personality, clauses);
+    // The landing pad result is used both for modifying the landing pad
+    // in the C API and as the exception value
+    let llretval = llpad;
+    // The landing pad block is a cleanup
+    SetCleanup(bcx, llpad);
+    // Continue unwinding
+    Resume(bcx, llretval);
 }
 
 fn trans_tup(cx: &@block_ctxt, elts: &[@ast::expr], id: ast::node_id) ->
diff --git a/src/comp/middle/trans_build.rs b/src/comp/middle/trans_build.rs
index c869ebbb24c..6f801551d11 100644
--- a/src/comp/middle/trans_build.rs
+++ b/src/comp/middle/trans_build.rs
@@ -547,6 +547,7 @@ fn Trap(cx: &@block_ctxt) -> ValueRef {
 
 fn LandingPad(cx: &@block_ctxt, Ty: TypeRef, PersFn: ValueRef,
               NumClauses: uint) -> ValueRef {
+    assert (!cx.terminated);
     ret str::as_buf("",
                     {|buf|
                         llvm::LLVMBuildLandingPad(B(cx),
@@ -561,6 +562,12 @@ fn SetCleanup(_cx: &@block_ctxt, LandingPad: ValueRef) {
     llvm::LLVMSetCleanup(LandingPad, lib::llvm::True);
 }
 
+fn Resume(cx: &@block_ctxt, Exn: ValueRef) -> ValueRef {
+    assert (!cx.terminated);
+    cx.terminated = true;
+    ret llvm::LLVMBuildResume(B(cx), Exn);
+}
+
 //
 // Local Variables:
 // mode: rust