Auto merge of #103138 - nnethercote:merge-BBs, r=bjorn3

Merge basic blocks where possible when generating LLVM IR.

r? `@ghost`

compiler/rustc_codegen_gcc/src/builder.rs

@@ -755,11 +755,11 @@ impl<'a, 'gcc, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'gcc, 'tcx> {
         OperandRef { val, layout: place.layout }
     }
 
-    fn write_operand_repeatedly(mut self, cg_elem: OperandRef<'tcx, RValue<'gcc>>, count: u64, dest: PlaceRef<'tcx, RValue<'gcc>>) -> Self {
+    fn write_operand_repeatedly(&mut self, cg_elem: OperandRef<'tcx, RValue<'gcc>>, count: u64, dest: PlaceRef<'tcx, RValue<'gcc>>) {
         let zero = self.const_usize(0);
         let count = self.const_usize(count);
-        let start = dest.project_index(&mut self, zero).llval;
-        let end = dest.project_index(&mut self, count).llval;
+        let start = dest.project_index(self, zero).llval;
+        let end = dest.project_index(self, count).llval;
 
         let header_bb = self.append_sibling_block("repeat_loop_header");
         let body_bb = self.append_sibling_block("repeat_loop_body");
@@ -778,14 +778,13 @@ impl<'a, 'gcc, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'gcc, 'tcx> {
 
         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 self, PlaceRef::new_sized_aligned(current_val, cg_elem.layout, align));
+        cg_elem.val.store(self, PlaceRef::new_sized_aligned(current_val, cg_elem.layout, align));
 
         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);
 
         self.switch_to_block(next_bb);
-        self
     }
 
     fn range_metadata(&mut self, _load: RValue<'gcc>, _range: WrappingRange) {

compiler/rustc_codegen_llvm/src/builder.rs

@@ -556,15 +556,15 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
     }
 
     fn write_operand_repeatedly(
-        mut self,
+        &mut self,
         cg_elem: OperandRef<'tcx, &'ll Value>,
         count: u64,
         dest: PlaceRef<'tcx, &'ll Value>,
-    ) -> Self {
+    ) {
         let zero = self.const_usize(0);
         let count = self.const_usize(count);
-        let start = dest.project_index(&mut self, zero).llval;
-        let end = dest.project_index(&mut self, count).llval;
+        let start = dest.project_index(self, zero).llval;
+        let end = dest.project_index(self, count).llval;
 
         let header_bb = self.append_sibling_block("repeat_loop_header");
         let body_bb = self.append_sibling_block("repeat_loop_body");
@@ -592,7 +592,7 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         body_bx.br(header_bb);
         header_bx.add_incoming_to_phi(current, next, body_bb);
 
-        Self::build(self.cx, next_bb)
+        *self = Self::build(self.cx, next_bb);
     }
 
     fn range_metadata(&mut self, load: &'ll Value, range: WrappingRange) {

compiler/rustc_codegen_ssa/src/lib.rs

@@ -1,12 +1,13 @@
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
-#![feature(box_patterns)]
-#![feature(try_blocks)]
-#![feature(once_cell)]
 #![feature(associated_type_bounds)]
-#![feature(strict_provenance)]
-#![feature(int_roundings)]
+#![feature(box_patterns)]
 #![feature(if_let_guard)]
+#![feature(int_roundings)]
+#![feature(let_chains)]
 #![feature(never_type)]
+#![feature(once_cell)]
+#![feature(strict_provenance)]
+#![feature(try_blocks)]
 #![recursion_limit = "256"]
 #![allow(rustc::potential_query_instability)]