Merge add_handler into catch_switch

Some codegen backends may require all handlers to be immediately known

compiler/rustc_codegen_gcc/src/builder.rs

@@ -1291,11 +1291,12 @@ impl<'a, 'gcc, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'gcc, 'tcx> {
         unimplemented!();
     }
 
-    fn catch_switch(&mut self, _parent: Option<RValue<'gcc>>, _unwind: Option<Block<'gcc>>, _num_handlers: usize) -> RValue<'gcc> {
-        unimplemented!();
-    }
-
-    fn add_handler(&mut self, _catch_switch: RValue<'gcc>, _handler: Block<'gcc>) {
+    fn catch_switch(
+        &mut self,
+        _parent: Option<RValue<'gcc>>,
+        _unwind: Option<Block<'gcc>>,
+        _handlers: &[Block<'gcc>],
+    ) -> RValue<'gcc> {
         unimplemented!();
     }
 

compiler/rustc_codegen_llvm/src/builder.rs

@@ -1028,7 +1028,7 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         &mut self,
         parent: Option<&'ll Value>,
         unwind: Option<&'ll BasicBlock>,
-        num_handlers: usize,
+        handlers: &[&'ll BasicBlock],
     ) -> &'ll Value {
         let name = cstr!("catchswitch");
         let ret = unsafe {
@@ -1036,17 +1036,17 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
                 self.llbuilder,
                 parent,
                 unwind,
-                num_handlers as c_uint,
+                handlers.len() as c_uint,
                 name.as_ptr(),
             )
         };
-        ret.expect("LLVM does not have support for catchswitch")
-    }
-
-    fn add_handler(&mut self, catch_switch: &'ll Value, handler: &'ll BasicBlock) {
-        unsafe {
-            llvm::LLVMRustAddHandler(catch_switch, handler);
+        let ret = ret.expect("LLVM does not have support for catchswitch");
+        for handler in handlers {
+            unsafe {
+                llvm::LLVMRustAddHandler(ret, handler);
+            }
         }
+        ret
     }
 
     // Atomic Operations

compiler/rustc_codegen_llvm/src/intrinsic.rs

@@ -525,9 +525,8 @@ fn codegen_msvc_try<'ll>(
 
         normal.ret(bx.const_i32(0));
 
-        let cs = catchswitch.catch_switch(None, None, 2);
-        catchswitch.add_handler(cs, catchpad_rust.llbb());
-        catchswitch.add_handler(cs, catchpad_foreign.llbb());
+        let cs =
+            catchswitch.catch_switch(None, None, &[catchpad_rust.llbb(), catchpad_foreign.llbb()]);
 
         // We can't use the TypeDescriptor defined in libpanic_unwind because it
         // might be in another DLL and the SEH encoding only supports specifying

compiler/rustc_codegen_ssa/src/mir/block.rs

@@ -1346,8 +1346,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                     let mut cp_bx = self.new_block(&format!("cp_funclet{:?}", bb));
                     ret_llbb = cs_bx.llbb();
 
-                    let cs = cs_bx.catch_switch(None, None, 1);
-                    cs_bx.add_handler(cs, cp_bx.llbb());
+                    let cs = cs_bx.catch_switch(None, None, &[cp_bx.llbb()]);
 
                     // The "null" here is actually a RTTI type descriptor for the
                     // C++ personality function, but `catch (...)` has no type so

compiler/rustc_codegen_ssa/src/traits/builder.rs

@@ -441,9 +441,8 @@ pub trait BuilderMethods<'a, 'tcx>:
         &mut self,
         parent: Option<Self::Value>,
         unwind: Option<Self::BasicBlock>,
-        num_handlers: usize,
+        handlers: &[Self::BasicBlock],
     ) -> Self::Value;
-    fn add_handler(&mut self, catch_switch: Self::Value, handler: Self::BasicBlock);
 
     fn atomic_cmpxchg(
         &mut self,