machinst: Avoid a lot of short-lived allocations in ABICall;

cranelift/codegen/src/isa/aarch64/abi.rs

@@ -1179,44 +1179,40 @@ impl AArch64ABICall {
     }
 }
 
-fn adjust_stack(amount: u64, is_sub: bool) -> Vec<Inst> {
+fn adjust_stack<C: LowerCtx<I = Inst>>(ctx: &mut C, amount: u64, is_sub: bool) {
-    if amount > 0 {
+    if amount == 0 {
+        return;
+    }
+
     let sp_adjustment = if is_sub {
         amount as i64
     } else {
         -(amount as i64)
     };
-        let adj_meta_insn = Inst::VirtualSPOffsetAdj {
+    ctx.emit(Inst::VirtualSPOffsetAdj {
         offset: sp_adjustment,
-        };
+    });
 
     let alu_op = if is_sub { ALUOp::Sub64 } else { ALUOp::Add64 };
     if let Some(imm12) = Imm12::maybe_from_u64(amount) {
-            vec![
+        ctx.emit(Inst::AluRRImm12 {
-                adj_meta_insn,
-                Inst::AluRRImm12 {
             alu_op,
             rd: writable_stack_reg(),
             rn: stack_reg(),
             imm12,
-                },
+        })
-            ]
     } else {
-            let const_load = Inst::LoadConst64 {
+        ctx.emit(Inst::LoadConst64 {
             rd: writable_spilltmp_reg(),
             const_data: amount,
-            };
+        });
-            let adj = Inst::AluRRRExtend {
+        ctx.emit(Inst::AluRRRExtend {
             alu_op,
             rd: writable_stack_reg(),
             rn: stack_reg(),
             rm: spilltmp_reg(),
             extendop: ExtendOp::UXTX,
-            };
+        });
-            vec![adj_meta_insn, const_load, adj]
-        }
-    } else {
-        vec![]
     }
 }
 
@@ -1227,64 +1223,82 @@ impl ABICall for AArch64ABICall {
         self.sig.args.len()
     }
 
-    fn gen_stack_pre_adjust(&self) -> Vec<Inst> {
+    fn emit_stack_pre_adjust<C: LowerCtx<I = Self::I>>(&self, ctx: &mut C) {
-        adjust_stack(self.sig.stack_arg_space as u64, /* is_sub = */ true)
+        adjust_stack(
+            ctx,
+            self.sig.stack_arg_space as u64,
+            /* is_sub = */ true,
+        )
     }
 
-    fn gen_stack_post_adjust(&self) -> Vec<Inst> {
+    fn emit_stack_post_adjust<C: LowerCtx<I = Self::I>>(&self, ctx: &mut C) {
-        adjust_stack(self.sig.stack_arg_space as u64, /* is_sub = */ false)
+        adjust_stack(
+            ctx,
+            self.sig.stack_arg_space as u64,
+            /* is_sub = */ false,
+        )
     }
 
-    fn gen_copy_reg_to_arg(&self, idx: usize, from_reg: Reg) -> Vec<Inst> {
+    fn emit_copy_reg_to_arg<C: LowerCtx<I = Self::I>>(
+        &self,
+        ctx: &mut C,
+        idx: usize,
+        from_reg: Reg,
+    ) {
         match &self.sig.args[idx] {
-            &ABIArg::Reg(reg, ty) => vec![Inst::gen_move(
+            &ABIArg::Reg(reg, ty) => ctx.emit(Inst::gen_move(
                 Writable::from_reg(reg.to_reg()),
                 from_reg,
                 ty,
-            )],
+            )),
-            &ABIArg::Stack(off, ty) => vec![store_stack(MemArg::SPOffset(off), from_reg, ty)],
+            &ABIArg::Stack(off, ty) => ctx.emit(store_stack(MemArg::SPOffset(off), from_reg, ty)),
         }
     }
 
-    fn gen_copy_retval_to_reg(&self, idx: usize, into_reg: Writable<Reg>) -> Inst {
+    fn emit_copy_retval_to_reg<C: LowerCtx<I = Self::I>>(
+        &self,
+        ctx: &mut C,
+        idx: usize,
+        into_reg: Writable<Reg>,
+    ) {
         match &self.sig.rets[idx] {
-            &ABIArg::Reg(reg, ty) => Inst::gen_move(into_reg, reg.to_reg(), ty),
+            &ABIArg::Reg(reg, ty) => ctx.emit(Inst::gen_move(into_reg, reg.to_reg(), ty)),
             _ => unimplemented!(),
         }
     }
 
-    fn gen_call(&self) -> Vec<Inst> {
+    fn emit_call<C: LowerCtx<I = Self::I>>(&self, ctx: &mut C) {
         let (uses, defs) = (self.uses.clone(), self.defs.clone());
         match &self.dest {
-            &CallDest::ExtName(ref name, RelocDistance::Near) => vec![Inst::Call {
+            &CallDest::ExtName(ref name, RelocDistance::Near) => ctx.emit(Inst::Call {
                 dest: name.clone(),
                 uses,
                 defs,
                 loc: self.loc,
                 opcode: self.opcode,
-            }],
+            }),
-            &CallDest::ExtName(ref name, RelocDistance::Far) => vec![
+            &CallDest::ExtName(ref name, RelocDistance::Far) => {
-                Inst::LoadExtName {
+                ctx.emit(Inst::LoadExtName {
                     rd: writable_spilltmp_reg(),
                     name: name.clone(),
                     offset: 0,
                     srcloc: self.loc,
-                },
+                });
-                Inst::CallInd {
+                ctx.emit(Inst::CallInd {
                     rn: spilltmp_reg(),
                     uses,
                     defs,
                     loc: self.loc,
                     opcode: self.opcode,
-                },
+                });
-            ],
+            }
-            &CallDest::Reg(reg) => vec![Inst::CallInd {
+            &CallDest::Reg(reg) => ctx.emit(Inst::CallInd {
                 rn: reg,
                 uses,
                 defs,
                 loc: self.loc,
                 opcode: self.opcode,
-            }],
+            }),
         }
     }
 }

cranelift/codegen/src/isa/aarch64/lower_inst.rs

@@ -1285,26 +1285,18 @@ pub(crate) fn lower_insn_to_regs<C: LowerCtx<I = Inst>>(ctx: &mut C, insn: IRIns
                 _ => unreachable!(),
             };
 
-            for inst in abi.gen_stack_pre_adjust().into_iter() {
+            abi.emit_stack_pre_adjust(ctx);
-                ctx.emit(inst);
-            }
             assert!(inputs.len() == abi.num_args());
             for (i, input) in inputs.iter().enumerate() {
                 let arg_reg = input_to_reg(ctx, *input, NarrowValueMode::None);
-                for inst in abi.gen_copy_reg_to_arg(i, arg_reg) {
+                abi.emit_copy_reg_to_arg(ctx, i, arg_reg);
-                    ctx.emit(inst);
-                }
-            }
-            for inst in abi.gen_call().into_iter() {
-                ctx.emit(inst);
             }
+            abi.emit_call(ctx);
             for (i, output) in outputs.iter().enumerate() {
                 let retval_reg = output_to_reg(ctx, *output);
-                ctx.emit(abi.gen_copy_retval_to_reg(i, retval_reg));
+                abi.emit_copy_retval_to_reg(ctx, i, retval_reg);
-            }
-            for inst in abi.gen_stack_post_adjust().into_iter() {
-                ctx.emit(inst);
             }
+            abi.emit_stack_post_adjust(ctx);
         }
 
         Opcode::GetPinnedReg => {

cranelift/codegen/src/machinst/abi.rs

@@ -135,19 +135,29 @@ pub trait ABICall {
     /// Get the number of arguments expected.
     fn num_args(&self) -> usize;
 
-    /// Copy an argument value from a source register, prior to the call.
+    /// Emit a copy of an argument value from a source register, prior to the call.
-    fn gen_copy_reg_to_arg(&self, idx: usize, from_reg: Reg) -> Vec<Self::I>;
+    fn emit_copy_reg_to_arg<C: LowerCtx<I = Self::I>>(
+        &self,
+        ctx: &mut C,
+        idx: usize,
+        from_reg: Reg,
+    );
 
-    /// Copy a return value into a destination register, after the call returns.
+    /// Emit a copy a return value into a destination register, after the call returns.
-    fn gen_copy_retval_to_reg(&self, idx: usize, into_reg: Writable<Reg>) -> Self::I;
+    fn emit_copy_retval_to_reg<C: LowerCtx<I = Self::I>>(
+        &self,
+        ctx: &mut C,
+        idx: usize,
+        into_reg: Writable<Reg>,
+    );
 
-    /// Pre-adjust the stack, prior to argument copies and call.
+    /// Emit code to pre-adjust the stack, prior to argument copies and call.
-    fn gen_stack_pre_adjust(&self) -> Vec<Self::I>;
+    fn emit_stack_pre_adjust<C: LowerCtx<I = Self::I>>(&self, ctx: &mut C);
 
-    /// Post-adjust the satck, after call return and return-value copies.
+    /// Emit code to post-adjust the satck, after call return and return-value copies.
-    fn gen_stack_post_adjust(&self) -> Vec<Self::I>;
+    fn emit_stack_post_adjust<C: LowerCtx<I = Self::I>>(&self, ctx: &mut C);
 
-    /// Generate the call itself.
+    /// Emit the call itself.
     ///
     /// The returned instruction should have proper use- and def-sets according
     /// to the argument registers, return-value registers, and clobbered
@@ -157,5 +167,5 @@ pub trait ABICall {
     /// registers are also logically defs, but should never be read; their
     /// values are "defined" (to the regalloc) but "undefined" in every other
     /// sense.)
-    fn gen_call(&self) -> Vec<Self::I>;
+    fn emit_call<C: LowerCtx<I = Self::I>>(&self, ctx: &mut C);
 }