Introduce Bx::switch_to_block

compiler/rustc_codegen_gcc/src/builder.rs

@@ -404,6 +404,11 @@ impl<'a, 'gcc, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'gcc, 'tcx> {
         func.new_block(name)
     }
 
+    fn switch_to_block(&mut self, block: Self::BasicBlock) {
+        *self.cx.current_block.borrow_mut() = Some(block);
+        self.block = Some(block);
+    }
+
     fn ret_void(&mut self) {
         self.llbb().end_with_void_return(None)
     }
@@ -886,19 +891,20 @@ impl<'a, 'gcc, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'gcc, 'tcx> {
 
         self.br(header_bb);
 
-        let mut header_bx = Builder::build(self.cx, header_bb);
-        let keep_going = header_bx.icmp(IntPredicate::IntNE, current_val, end);
-        header_bx.cond_br(keep_going, body_bb, next_bb);
+        self.switch_to_block(header_bb);
+        let keep_going = self.icmp(IntPredicate::IntNE, current_val, end);
+        self.cond_br(keep_going, body_bb, next_bb);
 
-        let mut body_bx = Builder::build(self.cx, body_bb);
+        self.switch_to_block(body_bb);
         let align = dest.align.restrict_for_offset(dest.layout.field(self.cx(), 0).size);
-        cg_elem.val.store(&mut body_bx, PlaceRef::new_sized_aligned(current_val, cg_elem.layout, align));
+        cg_elem.val.store(&mut self, PlaceRef::new_sized_aligned(current_val, cg_elem.layout, align));
 
-        let next = body_bx.inbounds_gep(self.backend_type(cg_elem.layout), current.to_rvalue(), &[self.const_usize(1)]);
-        body_bx.llbb().add_assignment(None, current, next);
-        body_bx.br(header_bb);
+        let next = self.inbounds_gep(self.backend_type(cg_elem.layout), current.to_rvalue(), &[self.const_usize(1)]);
+        self.llbb().add_assignment(None, current, next);
+        self.br(header_bb);
 
-        Builder::build(self.cx, next_bb)
+        self.switch_to_block(next_bb);
+        self
     }
 
     fn range_metadata(&mut self, _load: RValue<'gcc>, _range: WrappingRange) {

compiler/rustc_codegen_llvm/src/builder.rs

@@ -166,6 +166,10 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         Self::append_block(self.cx, self.llfn(), name)
     }
 
+    fn switch_to_block(&mut self, llbb: Self::BasicBlock) {
+        *self = Self::build(self.cx, llbb)
+    }
+
     fn ret_void(&mut self) {
         unsafe {
             llvm::LLVMBuildRetVoid(self.llbuilder);

compiler/rustc_codegen_llvm/src/intrinsic.rs

@@ -522,11 +522,11 @@ fn codegen_msvc_try<'ll>(
         let try_func_ty = bx.type_func(&[bx.type_i8p()], bx.type_void());
         bx.invoke(try_func_ty, try_func, &[data], normal, catchswitch, None);
 
-        let mut normal = Builder::build(bx.cx, normal);
-        normal.ret(bx.const_i32(0));
+        bx.switch_to_block(normal);
+        bx.ret(bx.const_i32(0));
 
-        let mut catchswitch = Builder::build(bx.cx, catchswitch);
-        let cs = catchswitch.catch_switch(None, None, &[catchpad_rust, catchpad_foreign]);
+        bx.switch_to_block(catchswitch);
+        let cs = bx.catch_switch(None, None, &[catchpad_rust, catchpad_foreign]);
 
         // We can't use the TypeDescriptor defined in libpanic_unwind because it
         // might be in another DLL and the SEH encoding only supports specifying
@@ -559,24 +559,24 @@ fn codegen_msvc_try<'ll>(
         // since our exception object effectively contains a Box.
         //
         // Source: MicrosoftCXXABI::getAddrOfCXXCatchHandlerType in clang
-        let mut catchpad_rust = Builder::build(bx.cx, catchpad_rust);
+        bx.switch_to_block(catchpad_rust);
         let flags = bx.const_i32(8);
-        let funclet = catchpad_rust.catch_pad(cs, &[tydesc, flags, slot]);
-        let ptr = catchpad_rust.load(bx.type_i8p(), slot, ptr_align);
+        let funclet = bx.catch_pad(cs, &[tydesc, flags, slot]);
+        let ptr = bx.load(bx.type_i8p(), slot, ptr_align);
         let catch_ty = bx.type_func(&[bx.type_i8p(), bx.type_i8p()], bx.type_void());
-        catchpad_rust.call(catch_ty, catch_func, &[data, ptr], Some(&funclet));
-        catchpad_rust.catch_ret(&funclet, caught);
+        bx.call(catch_ty, catch_func, &[data, ptr], Some(&funclet));
+        bx.catch_ret(&funclet, caught);
 
         // The flag value of 64 indicates a "catch-all".
-        let mut catchpad_foreign = Builder::build(bx.cx, catchpad_foreign);
+        bx.switch_to_block(catchpad_foreign);
         let flags = bx.const_i32(64);
         let null = bx.const_null(bx.type_i8p());
-        let funclet = catchpad_foreign.catch_pad(cs, &[null, flags, null]);
-        catchpad_foreign.call(catch_ty, catch_func, &[data, null], Some(&funclet));
-        catchpad_foreign.catch_ret(&funclet, caught);
+        let funclet = bx.catch_pad(cs, &[null, flags, null]);
+        bx.call(catch_ty, catch_func, &[data, null], Some(&funclet));
+        bx.catch_ret(&funclet, caught);
 
-        let mut caught = Builder::build(bx.cx, caught);
-        caught.ret(bx.const_i32(1));
+        bx.switch_to_block(caught);
+        bx.ret(bx.const_i32(1));
     });
 
     // Note that no invoke is used here because by definition this function
@@ -626,24 +626,24 @@ fn codegen_gnu_try<'ll>(
         let try_func_ty = bx.type_func(&[bx.type_i8p()], bx.type_void());
         bx.invoke(try_func_ty, try_func, &[data], then, catch, None);
 
-        let mut then = Builder::build(bx.cx, then);
-        then.ret(bx.const_i32(0));
+        bx.switch_to_block(then);
+        bx.ret(bx.const_i32(0));
 
         // Type indicator for the exception being thrown.
         //
         // The first value in this tuple is a pointer to the exception object
         // being thrown.  The second value is a "selector" indicating which of
         // the landing pad clauses the exception's type had been matched to.
         // rust_try ignores the selector.
-        let mut catch = Builder::build(bx.cx, catch);
+        bx.switch_to_block(catch);
         let lpad_ty = bx.type_struct(&[bx.type_i8p(), bx.type_i32()], false);
-        let vals = catch.landing_pad(lpad_ty, bx.eh_personality(), 1);
+        let vals = bx.landing_pad(lpad_ty, bx.eh_personality(), 1);
         let tydesc = bx.const_null(bx.type_i8p());
-        catch.add_clause(vals, tydesc);
-        let ptr = catch.extract_value(vals, 0);
+        bx.add_clause(vals, tydesc);
+        let ptr = bx.extract_value(vals, 0);
         let catch_ty = bx.type_func(&[bx.type_i8p(), bx.type_i8p()], bx.type_void());
-        catch.call(catch_ty, catch_func, &[data, ptr], None);
-        catch.ret(bx.const_i32(1));
+        bx.call(catch_ty, catch_func, &[data, ptr], None);
+        bx.ret(bx.const_i32(1));
     });
 
     // Note that no invoke is used here because by definition this function
@@ -690,51 +690,45 @@ fn codegen_emcc_try<'ll>(
         let try_func_ty = bx.type_func(&[bx.type_i8p()], bx.type_void());
         bx.invoke(try_func_ty, try_func, &[data], then, catch, None);
 
-        let mut then = Builder::build(bx.cx, then);
-        then.ret(bx.const_i32(0));
+        bx.switch_to_block(then);
+        bx.ret(bx.const_i32(0));
 
         // Type indicator for the exception being thrown.
         //
         // The first value in this tuple is a pointer to the exception object
         // being thrown.  The second value is a "selector" indicating which of
         // the landing pad clauses the exception's type had been matched to.
-        let mut catch = Builder::build(bx.cx, catch);
+        bx.switch_to_block(catch);
         let tydesc = bx.eh_catch_typeinfo();
         let lpad_ty = bx.type_struct(&[bx.type_i8p(), bx.type_i32()], false);
-        let vals = catch.landing_pad(lpad_ty, bx.eh_personality(), 2);
-        catch.add_clause(vals, tydesc);
-        catch.add_clause(vals, bx.const_null(bx.type_i8p()));
-        let ptr = catch.extract_value(vals, 0);
-        let selector = catch.extract_value(vals, 1);
+        let vals = bx.landing_pad(lpad_ty, bx.eh_personality(), 2);
+        bx.add_clause(vals, tydesc);
+        bx.add_clause(vals, bx.const_null(bx.type_i8p()));
+        let ptr = bx.extract_value(vals, 0);
+        let selector = bx.extract_value(vals, 1);
 
         // Check if the typeid we got is the one for a Rust panic.
-        let rust_typeid = catch.call_intrinsic("llvm.eh.typeid.for", &[tydesc]);
-        let is_rust_panic = catch.icmp(IntPredicate::IntEQ, selector, rust_typeid);
-        let is_rust_panic = catch.zext(is_rust_panic, bx.type_bool());
+        let rust_typeid = bx.call_intrinsic("llvm.eh.typeid.for", &[tydesc]);
+        let is_rust_panic = bx.icmp(IntPredicate::IntEQ, selector, rust_typeid);
+        let is_rust_panic = bx.zext(is_rust_panic, bx.type_bool());
 
         // We need to pass two values to catch_func (ptr and is_rust_panic), so
         // create an alloca and pass a pointer to that.
         let ptr_align = bx.tcx().data_layout.pointer_align.abi;
         let i8_align = bx.tcx().data_layout.i8_align.abi;
         let catch_data_type = bx.type_struct(&[bx.type_i8p(), bx.type_bool()], false);
-        let catch_data = catch.alloca(catch_data_type, ptr_align);
-        let catch_data_0 = catch.inbounds_gep(
-            catch_data_type,
-            catch_data,
-            &[bx.const_usize(0), bx.const_usize(0)],
-        );
-        catch.store(ptr, catch_data_0, ptr_align);
-        let catch_data_1 = catch.inbounds_gep(
-            catch_data_type,
-            catch_data,
-            &[bx.const_usize(0), bx.const_usize(1)],
-        );
-        catch.store(is_rust_panic, catch_data_1, i8_align);
-        let catch_data = catch.bitcast(catch_data, bx.type_i8p());
+        let catch_data = bx.alloca(catch_data_type, ptr_align);
+        let catch_data_0 =
+            bx.inbounds_gep(catch_data_type, catch_data, &[bx.const_usize(0), bx.const_usize(0)]);
+        bx.store(ptr, catch_data_0, ptr_align);
+        let catch_data_1 =
+            bx.inbounds_gep(catch_data_type, catch_data, &[bx.const_usize(0), bx.const_usize(1)]);
+        bx.store(is_rust_panic, catch_data_1, i8_align);
+        let catch_data = bx.bitcast(catch_data, bx.type_i8p());
 
         let catch_ty = bx.type_func(&[bx.type_i8p(), bx.type_i8p()], bx.type_void());
-        catch.call(catch_ty, catch_func, &[data, catch_data], None);
-        catch.ret(bx.const_i32(1));
+        bx.call(catch_ty, catch_func, &[data, catch_data], None);
+        bx.ret(bx.const_i32(1));
     });
 
     // Note that no invoke is used here because by definition this function

compiler/rustc_codegen_llvm/src/va_arg.rs

@@ -131,51 +131,47 @@ fn emit_aapcs_va_arg<'ll, 'tcx>(
     // it could be on the stack so we have to update the offset and then check
     // the offset again.
 
-    let mut maybe_reg = Builder::build(bx.cx, maybe_reg);
+    bx.switch_to_block(maybe_reg);
     if gr_type && layout.align.abi.bytes() > 8 {
-        reg_off_v = maybe_reg.add(reg_off_v, bx.const_i32(15));
-        reg_off_v = maybe_reg.and(reg_off_v, bx.const_i32(-16));
+        reg_off_v = bx.add(reg_off_v, bx.const_i32(15));
+        reg_off_v = bx.and(reg_off_v, bx.const_i32(-16));
     }
-    let new_reg_off_v = maybe_reg.add(reg_off_v, bx.const_i32(slot_size as i32));
+    let new_reg_off_v = bx.add(reg_off_v, bx.const_i32(slot_size as i32));
 
-    maybe_reg.store(new_reg_off_v, reg_off, offset_align);
+    bx.store(new_reg_off_v, reg_off, offset_align);
 
     // Check to see if we have overflowed the registers as a result of this.
     // If we have then we need to use the stack for this value
-    let use_stack = maybe_reg.icmp(IntPredicate::IntSGT, new_reg_off_v, zero);
-    maybe_reg.cond_br(use_stack, on_stack, in_reg);
+    let use_stack = bx.icmp(IntPredicate::IntSGT, new_reg_off_v, zero);
+    bx.cond_br(use_stack, on_stack, in_reg);
 
-    let mut in_reg = Builder::build(bx.cx, in_reg);
+    bx.switch_to_block(in_reg);
     let top_type = bx.type_i8p();
-    let top = in_reg.struct_gep(va_list_ty, va_list_addr, reg_top_index);
-    let top = in_reg.load(top_type, top, bx.tcx().data_layout.pointer_align.abi);
+    let top = bx.struct_gep(va_list_ty, va_list_addr, reg_top_index);
+    let top = bx.load(top_type, top, bx.tcx().data_layout.pointer_align.abi);
 
     // reg_value = *(@top + reg_off_v);
-    let mut reg_addr = in_reg.gep(bx.type_i8(), top, &[reg_off_v]);
+    let mut reg_addr = bx.gep(bx.type_i8(), top, &[reg_off_v]);
     if bx.tcx().sess.target.endian == Endian::Big && layout.size.bytes() != slot_size {
         // On big-endian systems the value is right-aligned in its slot.
         let offset = bx.const_i32((slot_size - layout.size.bytes()) as i32);
-        reg_addr = in_reg.gep(bx.type_i8(), reg_addr, &[offset]);
+        reg_addr = bx.gep(bx.type_i8(), reg_addr, &[offset]);
     }
     let reg_type = layout.llvm_type(bx);
-    let reg_addr = in_reg.bitcast(reg_addr, bx.cx.type_ptr_to(reg_type));
-    let reg_value = in_reg.load(reg_type, reg_addr, layout.align.abi);
-    in_reg.br(end);
+    let reg_addr = bx.bitcast(reg_addr, bx.cx.type_ptr_to(reg_type));
+    let reg_value = bx.load(reg_type, reg_addr, layout.align.abi);
+    bx.br(end);
 
     // On Stack block
-    let mut on_stack = Builder::build(bx.cx, on_stack);
+    bx.switch_to_block(on_stack);
     let stack_value =
-        emit_ptr_va_arg(&mut on_stack, list, target_ty, false, Align::from_bytes(8).unwrap(), true);
-    on_stack.br(end);
+        emit_ptr_va_arg(bx, list, target_ty, false, Align::from_bytes(8).unwrap(), true);
+    bx.br(end);
 
-    let mut end = Builder::build(bx.cx, end);
-    let val = end.phi(
-        layout.immediate_llvm_type(bx),
-        &[reg_value, stack_value],
-        &[in_reg.llbb(), on_stack.llbb()],
-    );
+    bx.switch_to_block(end);
+    let val =
+        bx.phi(layout.immediate_llvm_type(bx), &[reg_value, stack_value], &[in_reg, on_stack]);
 
-    *bx = end;
     val
 }
 

compiler/rustc_codegen_ssa/src/mir/block.rs

@@ -170,10 +170,9 @@ impl<'a, 'tcx> TerminatorCodegenHelper<'tcx> {
             }
 
             if let Some((ret_dest, target)) = destination {
-                let target_llbb = fx.llbb(target);
-                let mut ret_bx = Bx::build(fx.cx, target_llbb);
-                fx.set_debug_loc(&mut ret_bx, self.terminator.source_info);
-                fx.store_return(&mut ret_bx, ret_dest, &fn_abi.ret, invokeret);
+                bx.switch_to_block(fx.llbb(target));
+                fx.set_debug_loc(bx, self.terminator.source_info);
+                fx.store_return(bx, ret_dest, &fn_abi.ret, invokeret);
             }
         } else {
             let llret = bx.call(fn_ty, fn_ptr, &llargs, self.funclet(fx));
@@ -462,7 +461,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
         }
 
         // After this point, bx is the block for the call to panic.
-        bx = Bx::build(self.cx, panic_block);
+        bx.switch_to_block(panic_block);
         self.set_debug_loc(&mut bx, terminator.source_info);
 
         // Get the location information.
@@ -914,20 +913,20 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
             let bb_fail = bx.append_sibling_block("type_test.fail");
             bx.cond_br(cond, bb_pass, bb_fail);
 
-            let mut bx_pass = Bx::build(self.cx, bb_pass);
+            bx.switch_to_block(bb_pass);
             helper.do_call(
                 self,
-                &mut bx_pass,
+                &mut bx,
                 fn_abi,
                 fn_ptr,
                 &llargs,
                 destination.as_ref().map(|&(_, target)| (ret_dest, target)),
                 cleanup,
             );
 
-            let mut bx_fail = Bx::build(self.cx, bb_fail);
-            bx_fail.abort();
-            bx_fail.unreachable();
+            bx.switch_to_block(bb_fail);
+            bx.abort();
+            bx.unreachable();
 
             return;
         }

compiler/rustc_codegen_ssa/src/traits/builder.rs

@@ -53,6 +53,8 @@ pub trait BuilderMethods<'a, 'tcx>:
 
     fn append_sibling_block(&mut self, name: &str) -> Self::BasicBlock;
 
+    fn switch_to_block(&mut self, llbb: Self::BasicBlock);
+
     fn ret_void(&mut self);
     fn ret(&mut self, v: Self::Value);
     fn br(&mut self, dest: Self::BasicBlock);