Refactor matches that used to consume BranchInfo (#5734)

Explicitly borrow the instruction data, and use a mutable borrow to avoid rematch.

cranelift/codegen/src/dominator_tree.rs

@@ -351,7 +351,7 @@ impl DominatorTree {
     /// post-order except for the insertion of the new block header at the split point.
     fn push_successors(&mut self, func: &Function, block: Block) {
         if let Some(inst) = func.layout.last_inst(block) {
-            match func.dfg.insts[inst] {
+            match &func.dfg.insts[inst] {
                 ir::InstructionData::Jump {
                     destination: succ, ..
                 } => self.push_if_unseen(succ.block(&func.dfg.value_lists)),
@@ -367,10 +367,10 @@ impl DominatorTree {
                     destination: dest,
                     ..
                 } => {
-                    for succ in func.jump_tables[jt].iter() {
+                    for succ in func.jump_tables[*jt].iter() {
                         self.push_if_unseen(*succ);
                     }
-                    self.push_if_unseen(dest);
+                    self.push_if_unseen(*dest);
                 }
                 _ => {}
             }

cranelift/codegen/src/flowgraph.rs

@@ -117,7 +117,7 @@ impl ControlFlowGraph {
 
     fn compute_block(&mut self, func: &Function, block: Block) {
         if let Some(inst) = func.layout.last_inst(block) {
-            match func.dfg.insts[inst] {
+            match &func.dfg.insts[inst] {
                 ir::InstructionData::Jump {
                     destination: dest, ..
                 } => {
@@ -135,9 +135,9 @@ impl ControlFlowGraph {
                     destination: dest,
                     ..
                 } => {
-                    self.add_edge(block, inst, dest);
+                    self.add_edge(block, inst, *dest);
 
-                    for dest in func.jump_tables[jt].iter() {
+                    for dest in func.jump_tables[*jt].iter() {
                         self.add_edge(block, inst, *dest);
                     }
                 }

cranelift/codegen/src/inst_predicates.rs

@@ -175,7 +175,7 @@ pub(crate) fn visit_block_succs<F: FnMut(Inst, Block, bool)>(
     mut visit: F,
 ) {
     if let Some(inst) = f.layout.last_inst(block) {
-        match f.dfg.insts[inst] {
+        match &f.dfg.insts[inst] {
             ir::InstructionData::Jump {
                 destination: dest, ..
             } => {
@@ -197,9 +197,9 @@ pub(crate) fn visit_block_succs<F: FnMut(Inst, Block, bool)>(
             } => {
                 // The default block is reached via a direct conditional branch,
                 // so it is not part of the table.
-                visit(inst, dest, false);
+                visit(inst, *dest, false);
 
-                for &dest in f.jump_tables[table].as_slice() {
+                for &dest in f.jump_tables[*table].as_slice() {
                     visit(inst, dest, true);
                 }
             }

cranelift/codegen/src/ir/function.rs

@@ -277,14 +277,12 @@ impl FunctionStencil {
     /// Rewrite the branch destination to `new_dest` if the destination matches `old_dest`.
     /// Does nothing if called with a non-jump or non-branch instruction.
     pub fn rewrite_branch_destination(&mut self, inst: Inst, old_dest: Block, new_dest: Block) {
-        match self.dfg.insts[inst] {
+        match &mut self.dfg.insts[inst] {
             InstructionData::Jump {
                 destination: dest, ..
             } => {
                 if dest.block(&self.dfg.value_lists) == old_dest {
-                    for block in self.dfg.insts[inst].branch_destination_mut() {
+                    dest.set_block(new_dest, &mut self.dfg.value_lists)
-                        block.set_block(new_dest, &mut self.dfg.value_lists)
-                    }
                 }
             }
 
@@ -293,27 +291,11 @@ impl FunctionStencil {
                 ..
             } => {
                 if block_then.block(&self.dfg.value_lists) == old_dest {
-                    if let InstructionData::Brif {
-                        blocks: [block_then, _],
-                        ..
-                    } = &mut self.dfg.insts[inst]
-                    {
                     block_then.set_block(new_dest, &mut self.dfg.value_lists);
-                    } else {
-                        unreachable!();
-                    }
                 }
 
                 if block_else.block(&self.dfg.value_lists) == old_dest {
-                    if let InstructionData::Brif {
-                        blocks: [_, block_else],
-                        ..
-                    } = &mut self.dfg.insts[inst]
-                    {
                     block_else.set_block(new_dest, &mut self.dfg.value_lists);
-                    } else {
-                        unreachable!();
-                    }
                 }
             }
 
@@ -322,22 +304,14 @@ impl FunctionStencil {
                 destination: default_dest,
                 ..
             } => {
-                self.jump_tables[table].iter_mut().for_each(|entry| {
+                self.jump_tables[*table].iter_mut().for_each(|entry| {
                     if *entry == old_dest {
                         *entry = new_dest;
                     }
                 });
 
-                if default_dest == old_dest {
+                if *default_dest == old_dest {
-                    match &mut self.dfg.insts[inst] {
+                    *default_dest = new_dest;
-                        InstructionData::BranchTable { destination, .. } => {
-                            *destination = new_dest;
-                        }
-                        _ => panic!(
-                            "Unexpected instruction {} having default destination",
-                            self.dfg.display_inst(inst)
-                        ),
-                    }
                 }
             }
 

cranelift/codegen/src/machinst/lower.rs

@@ -943,7 +943,7 @@ impl<'func, I: VCodeInst> Lower<'func, I> {
             let (inst, succ) = self.vcode.block_order().succ_indices(block)[succ_idx];
 
             // Get branch args and convert to Regs.
-            let branch_args = match self.f.dfg.insts[inst] {
+            let branch_args = match &self.f.dfg.insts[inst] {
                 InstructionData::Jump {
                     destination: block, ..
                 } => block.args_slice(&self.f.dfg.value_lists),

cranelift/codegen/src/verifier/mod.rs

@@ -1293,7 +1293,7 @@ impl<'a> Verifier<'a> {
         inst: Inst,
         errors: &mut VerifierErrors,
     ) -> VerifierStepResult<()> {
-        match self.func.dfg.insts[inst] {
+        match &self.func.dfg.insts[inst] {
             ir::InstructionData::Jump {
                 destination: block, ..
             } => {
@@ -1333,7 +1333,7 @@ impl<'a> Verifier<'a> {
                 destination: block,
                 ..
             } => {
-                let arg_count = self.func.dfg.num_block_params(block);
+                let arg_count = self.func.dfg.num_block_params(*block);
                 if arg_count != 0 {
                     return errors.nonfatal((
                         inst,
@@ -1344,7 +1344,7 @@ impl<'a> Verifier<'a> {
                         ),
                     ));
                 }
-                for block in self.func.jump_tables[table].iter() {
+                for block in self.func.jump_tables[*table].iter() {
                     let arg_count = self.func.dfg.num_block_params(*block);
                     if arg_count != 0 {
                         return errors.nonfatal((

cranelift/frontend/src/frontend.rs

@@ -106,7 +106,7 @@ impl<'short, 'long> InstBuilderBase<'short> for FuncInstBuilder<'short, 'long> {
             self.builder.func.set_srcloc(inst, self.builder.srcloc);
         }
 
-        match self.builder.func.dfg.insts[inst] {
+        match &self.builder.func.dfg.insts[inst] {
             ir::InstructionData::Jump {
                 destination: dest, ..
             } => {
@@ -140,7 +140,7 @@ impl<'short, 'long> InstBuilderBase<'short> for FuncInstBuilder<'short, 'long> {
                     .builder
                     .func
                     .jump_tables
-                    .get(table)
+                    .get(*table)
                     .expect("you are referencing an undeclared jump table")
                     .iter()
                     .filter(|&dest_block| unique.insert(*dest_block))
@@ -152,7 +152,7 @@ impl<'short, 'long> InstBuilderBase<'short> for FuncInstBuilder<'short, 'long> {
                         .ssa
                         .declare_block_predecessor(*dest_block, inst);
                 }
-                self.builder.declare_successor(destination, inst);
+                self.builder.declare_successor(*destination, inst);
             }
 
             _ => {}

cranelift/frontend/src/ssa.rs

@@ -577,7 +577,7 @@ impl SSABuilder {
         dest_block: Block,
         val: Value,
     ) -> Option<(Block, Inst)> {
-        match func.dfg.insts[branch] {
+        match &func.dfg.insts[branch] {
             // For a single destination appending a jump argument to the instruction
             // is sufficient.
             InstructionData::Jump { .. } => {