Cranelift: refactoring of unwind info (#2289)

* factor common code

* move fde/unwind emit to more abstract level

* code_len -> function_size

* speedup block scanning

* better function_size calciulation

* Rename UnwindCode enums

cranelift/codegen/src/isa/unwind.rs

@@ -14,3 +14,55 @@ pub enum UnwindInfo {
     /// System V ABI unwind information.
     SystemV(systemv::UnwindInfo),
 }
+
+pub(crate) mod input {
+    use crate::binemit::CodeOffset;
+    use alloc::vec::Vec;
+    #[cfg(feature = "enable-serde")]
+    use serde::{Deserialize, Serialize};
+
+    #[derive(Clone, Debug, PartialEq, Eq)]
+    #[cfg_attr(feature = "enable-serde", derive(Serialize, Deserialize))]
+    pub(crate) enum UnwindCode<Reg> {
+        SaveRegister {
+            offset: CodeOffset,
+            reg: Reg,
+        },
+        RestoreRegister {
+            offset: CodeOffset,
+            reg: Reg,
+        },
+        SaveXmmRegister {
+            offset: CodeOffset,
+            reg: Reg,
+            stack_offset: u32,
+        },
+        StackAlloc {
+            offset: CodeOffset,
+            size: u32,
+        },
+        StackDealloc {
+            offset: CodeOffset,
+            size: u32,
+        },
+        SetFramePointer {
+            offset: CodeOffset,
+            reg: Reg,
+        },
+        RememberState {
+            offset: CodeOffset,
+        },
+        RestoreState {
+            offset: CodeOffset,
+        },
+    }
+
+    #[derive(Clone, Debug, PartialEq, Eq)]
+    #[cfg_attr(feature = "enable-serde", derive(Serialize, Deserialize))]
+    pub struct UnwindInfo<Reg> {
+        pub(crate) prologue_size: CodeOffset,
+        pub(crate) prologue_unwind_codes: Vec<UnwindCode<Reg>>,
+        pub(crate) epilogues_unwind_codes: Vec<Vec<UnwindCode<Reg>>>,
+        pub(crate) function_size: CodeOffset,
+    }
+}