Auto merge of #100999 - nnethercote:shrink-FnAbi, r=bjorn3

Shrink `FnAbi`

Because they can take up a lot of memory in debug and release builds.

r? `@bjorn3`

compiler/rustc_target/src/abi/call/aarch64.rs

@@ -77,7 +77,7 @@ where
         classify_ret(cx, &mut fn_abi.ret);
     }
 
-    for arg in &mut fn_abi.args {
+    for arg in fn_abi.args.iter_mut() {
         if arg.is_ignore() {
             continue;
         }

compiler/rustc_target/src/abi/call/amdgpu.rs

@@ -26,7 +26,7 @@ where
         classify_ret(cx, &mut fn_abi.ret);
     }
 
-    for arg in &mut fn_abi.args {
+    for arg in fn_abi.args.iter_mut() {
         if arg.is_ignore() {
             continue;
         }

compiler/rustc_target/src/abi/call/arm.rs

@@ -88,7 +88,7 @@ where
         classify_ret(cx, &mut fn_abi.ret, vfp);
     }
 
-    for arg in &mut fn_abi.args {
+    for arg in fn_abi.args.iter_mut() {
         if arg.is_ignore() {
             continue;
         }

compiler/rustc_target/src/abi/call/avr.rs

@@ -49,7 +49,7 @@ pub fn compute_abi_info<Ty>(fty: &mut FnAbi<'_, Ty>) {
         classify_ret_ty(&mut fty.ret);
     }
 
-    for arg in &mut fty.args {
+    for arg in fty.args.iter_mut() {
         if arg.is_ignore() {
             continue;
         }

compiler/rustc_target/src/abi/call/bpf.rs

@@ -22,7 +22,7 @@ pub fn compute_abi_info<Ty>(fn_abi: &mut FnAbi<'_, Ty>) {
         classify_ret(&mut fn_abi.ret);
     }
 
-    for arg in &mut fn_abi.args {
+    for arg in fn_abi.args.iter_mut() {
         if arg.is_ignore() {
             continue;
         }

compiler/rustc_target/src/abi/call/hexagon.rs

@@ -21,7 +21,7 @@ pub fn compute_abi_info<Ty>(fn_abi: &mut FnAbi<'_, Ty>) {
         classify_ret(&mut fn_abi.ret);
     }
 
-    for arg in &mut fn_abi.args {
+    for arg in fn_abi.args.iter_mut() {
         if arg.is_ignore() {
             continue;
         }

compiler/rustc_target/src/abi/call/m68k.rs

@@ -21,7 +21,7 @@ pub fn compute_abi_info<Ty>(fn_abi: &mut FnAbi<'_, Ty>) {
         classify_ret(&mut fn_abi.ret);
     }
 
-    for arg in &mut fn_abi.args {
+    for arg in fn_abi.args.iter_mut() {
         if arg.is_ignore() {
             continue;
         }

compiler/rustc_target/src/abi/call/mips.rs

@@ -22,10 +22,8 @@ where
     let align = arg.layout.align.max(dl.i32_align).min(dl.i64_align).abi;
 
     if arg.layout.is_aggregate() {
-        arg.cast_to(Uniform { unit: Reg::i32(), total: size });
-        if !offset.is_aligned(align) {
-            arg.pad_with(Reg::i32());
-        }
+        let pad_i32 = !offset.is_aligned(align);
+        arg.cast_to_and_pad_i32(Uniform { unit: Reg::i32(), total: size }, pad_i32);
     } else {
         arg.extend_integer_width_to(32);
     }
@@ -42,7 +40,7 @@ where
         classify_ret(cx, &mut fn_abi.ret, &mut offset);
     }
 
-    for arg in &mut fn_abi.args {
+    for arg in fn_abi.args.iter_mut() {
         if arg.is_ignore() {
             continue;
         }

compiler/rustc_target/src/abi/call/mips64.rs

@@ -158,7 +158,7 @@ where
         classify_ret(cx, &mut fn_abi.ret);
     }
 
-    for arg in &mut fn_abi.args {
+    for arg in fn_abi.args.iter_mut() {
         if arg.is_ignore() {
             continue;
         }

compiler/rustc_target/src/abi/call/mod.rs

@@ -26,7 +26,7 @@ mod x86;
 mod x86_64;
 mod x86_win64;
 
-#[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, HashStable_Generic)]
+#[derive(PartialEq, Eq, Hash, Debug, HashStable_Generic)]
 pub enum PassMode {
     /// Ignore the argument.
     ///
@@ -40,9 +40,10 @@ pub enum PassMode {
     ///
     /// The argument has a layout abi of `ScalarPair`.
     Pair(ArgAttributes, ArgAttributes),
-    /// Pass the argument after casting it, to either
-    /// a single uniform or a pair of registers.
-    Cast(CastTarget),
+    /// Pass the argument after casting it, to either a single uniform or a
+    /// pair of registers. The bool indicates if a `Reg::i32()` dummy argument
+    /// is emitted before the real argument.
+    Cast(Box<CastTarget>, bool),
     /// Pass the argument indirectly via a hidden pointer.
     /// The `extra_attrs` value, if any, is for the extra data (vtable or length)
     /// which indicates that it refers to an unsized rvalue.
@@ -463,10 +464,6 @@ impl<'a, Ty> TyAndLayout<'a, Ty> {
 #[derive(PartialEq, Eq, Hash, Debug, HashStable_Generic)]
 pub struct ArgAbi<'a, Ty> {
     pub layout: TyAndLayout<'a, Ty>,
-
-    /// Dummy argument, which is emitted before the real argument.
-    pub pad: Option<Reg>,
-
     pub mode: PassMode,
 }
 
@@ -486,7 +483,7 @@ impl<'a, Ty> ArgAbi<'a, Ty> {
             Abi::Vector { .. } => PassMode::Direct(ArgAttributes::new()),
             Abi::Aggregate { .. } => PassMode::Direct(ArgAttributes::new()),
         };
-        ArgAbi { layout, pad: None, mode }
+        ArgAbi { layout, mode }
     }
 
     fn indirect_pass_mode(layout: &TyAndLayout<'a, Ty>) -> PassMode {
@@ -548,11 +545,11 @@ impl<'a, Ty> ArgAbi<'a, Ty> {
     }
 
     pub fn cast_to<T: Into<CastTarget>>(&mut self, target: T) {
-        self.mode = PassMode::Cast(target.into());
+        self.mode = PassMode::Cast(Box::new(target.into()), false);
     }
 
-    pub fn pad_with(&mut self, reg: Reg) {
-        self.pad = Some(reg);
+    pub fn cast_to_and_pad_i32<T: Into<CastTarget>>(&mut self, target: T, pad_i32: bool) {
+        self.mode = PassMode::Cast(Box::new(target.into()), pad_i32);
     }
 
     pub fn is_indirect(&self) -> bool {
@@ -614,7 +611,7 @@ pub enum Conv {
 #[derive(PartialEq, Eq, Hash, Debug, HashStable_Generic)]
 pub struct FnAbi<'a, Ty> {
     /// The LLVM types of each argument.
-    pub args: Vec<ArgAbi<'a, Ty>>,
+    pub args: Box<[ArgAbi<'a, Ty>]>,
 
     /// LLVM return type.
     pub ret: ArgAbi<'a, Ty>,
@@ -625,7 +622,7 @@ pub struct FnAbi<'a, Ty> {
     ///
     /// Should only be different from args.len() when c_variadic is true.
     /// This can be used to know whether an argument is variadic or not.
-    pub fixed_count: usize,
+    pub fixed_count: u32,
 
     pub conv: Conv,
 
@@ -730,3 +727,13 @@ impl<'a, Ty> FnAbi<'a, Ty> {
         Ok(())
     }
 }
+
+// Some types are used a lot. Make sure they don't unintentionally get bigger.
+#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
+mod size_asserts {
+    use super::*;
+    use rustc_data_structures::static_assert_size;
+    // These are in alphabetical order, which is easy to maintain.
+    static_assert_size!(ArgAbi<'_, usize>, 56);
+    static_assert_size!(FnAbi<'_, usize>, 80);
+}

compiler/rustc_target/src/abi/call/msp430.rs

@@ -30,7 +30,7 @@ pub fn compute_abi_info<Ty>(fn_abi: &mut FnAbi<'_, Ty>) {
         classify_ret(&mut fn_abi.ret);
     }
 
-    for arg in &mut fn_abi.args {
+    for arg in fn_abi.args.iter_mut() {
         if arg.is_ignore() {
             continue;
         }

compiler/rustc_target/src/abi/call/nvptx64.rs

@@ -38,7 +38,7 @@ pub fn compute_abi_info<Ty>(fn_abi: &mut FnAbi<'_, Ty>) {
         classify_ret(&mut fn_abi.ret);
     }
 
-    for arg in &mut fn_abi.args {
+    for arg in fn_abi.args.iter_mut() {
         if arg.is_ignore() {
             continue;
         }
@@ -55,7 +55,7 @@ where
         panic!("Kernels should not return anything other than () or !");
     }
 
-    for arg in &mut fn_abi.args {
+    for arg in fn_abi.args.iter_mut() {
         if arg.is_ignore() {
             continue;
         }

compiler/rustc_target/src/abi/call/powerpc.rs

@@ -21,7 +21,7 @@ pub fn compute_abi_info<Ty>(fn_abi: &mut FnAbi<'_, Ty>) {
         classify_ret(&mut fn_abi.ret);
     }
 
-    for arg in &mut fn_abi.args {
+    for arg in fn_abi.args.iter_mut() {
         if arg.is_ignore() {
             continue;
         }

compiler/rustc_target/src/abi/call/powerpc64.rs

@@ -132,7 +132,7 @@ where
         classify_ret(cx, &mut fn_abi.ret, abi);
     }
 
-    for arg in &mut fn_abi.args {
+    for arg in fn_abi.args.iter_mut() {
         if arg.is_ignore() {
             continue;
         }

compiler/rustc_target/src/abi/call/riscv.rs

@@ -340,7 +340,7 @@ where
             arg,
             xlen,
             flen,
-            i >= fn_abi.fixed_count,
+            i >= fn_abi.fixed_count as usize,
             &mut avail_gprs,
             &mut avail_fprs,
         );

compiler/rustc_target/src/abi/call/s390x.rs

@@ -48,7 +48,7 @@ where
         classify_ret(&mut fn_abi.ret);
     }
 
-    for arg in &mut fn_abi.args {
+    for arg in fn_abi.args.iter_mut() {
         if arg.is_ignore() {
             continue;
         }

compiler/rustc_target/src/abi/call/sparc.rs

@@ -22,10 +22,8 @@ where
     let align = arg.layout.align.max(dl.i32_align).min(dl.i64_align).abi;
 
     if arg.layout.is_aggregate() {
-        arg.cast_to(Uniform { unit: Reg::i32(), total: size });
-        if !offset.is_aligned(align) {
-            arg.pad_with(Reg::i32());
-        }
+        let pad_i32 = !offset.is_aligned(align);
+        arg.cast_to_and_pad_i32(Uniform { unit: Reg::i32(), total: size }, pad_i32);
     } else {
         arg.extend_integer_width_to(32);
     }
@@ -42,7 +40,7 @@ where
         classify_ret(cx, &mut fn_abi.ret, &mut offset);
     }
 
-    for arg in &mut fn_abi.args {
+    for arg in fn_abi.args.iter_mut() {
         if arg.is_ignore() {
             continue;
         }

compiler/rustc_target/src/abi/call/sparc64.rs

@@ -217,7 +217,7 @@ where
         classify_arg(cx, &mut fn_abi.ret, Size { raw: 32 });
     }
 
-    for arg in &mut fn_abi.args {
+    for arg in fn_abi.args.iter_mut() {
         if arg.is_ignore() {
             continue;
         }

compiler/rustc_target/src/abi/call/wasm.rs

@@ -50,7 +50,7 @@ where
         classify_ret(cx, &mut fn_abi.ret);
     }
 
-    for arg in &mut fn_abi.args {
+    for arg in fn_abi.args.iter_mut() {
         if arg.is_ignore() {
             continue;
         }
@@ -66,7 +66,7 @@ pub fn compute_wasm_abi_info<Ty>(fn_abi: &mut FnAbi<'_, Ty>) {
         classify_ret(&mut fn_abi.ret);
     }
 
-    for arg in &mut fn_abi.args {
+    for arg in fn_abi.args.iter_mut() {
         if arg.is_ignore() {
             continue;
         }

compiler/rustc_target/src/abi/call/x86.rs

@@ -49,7 +49,7 @@ where
         }
     }
 
-    for arg in &mut fn_abi.args {
+    for arg in fn_abi.args.iter_mut() {
         if arg.is_ignore() {
             continue;
         }
@@ -72,7 +72,7 @@ where
 
         let mut free_regs = 2;
 
-        for arg in &mut fn_abi.args {
+        for arg in fn_abi.args.iter_mut() {
             let attrs = match arg.mode {
                 PassMode::Ignore
                 | PassMode::Indirect { attrs: _, extra_attrs: None, on_stack: _ } => {
@@ -81,7 +81,7 @@ where
                 PassMode::Direct(ref mut attrs) => attrs,
                 PassMode::Pair(..)
                 | PassMode::Indirect { attrs: _, extra_attrs: Some(_), on_stack: _ }
-                | PassMode::Cast(_) => {
+                | PassMode::Cast(..) => {
                     unreachable!("x86 shouldn't be passing arguments by {:?}", arg.mode)
                 }
             };

compiler/rustc_target/src/abi/call/x86_64.rs

@@ -239,7 +239,7 @@ where
         x86_64_arg_or_ret(&mut fn_abi.ret, false);
     }
 
-    for arg in &mut fn_abi.args {
+    for arg in fn_abi.args.iter_mut() {
         if arg.is_ignore() {
             continue;
         }

compiler/rustc_target/src/abi/call/x86_win64.rs

@@ -31,7 +31,7 @@ pub fn compute_abi_info<Ty>(fn_abi: &mut FnAbi<'_, Ty>) {
     if !fn_abi.ret.is_ignore() {
         fixup(&mut fn_abi.ret);
     }
-    for arg in &mut fn_abi.args {
+    for arg in fn_abi.args.iter_mut() {
         if arg.is_ignore() {
             continue;
         }