Track frame layout changes. (#1204)

* Track frame layout changes.

cranelift/codegen/src/ir/function.rs

@@ -11,7 +11,7 @@ use crate::ir::{
     Ebb, ExtFuncData, FuncRef, GlobalValue, GlobalValueData, Heap, HeapData, Inst, JumpTable,
     JumpTableData, SigRef, StackSlot, StackSlotData, Table, TableData,
 };
-use crate::ir::{EbbOffsets, InstEncodings, SourceLocs, StackSlots, ValueLocations};
+use crate::ir::{EbbOffsets, FrameLayout, InstEncodings, SourceLocs, StackSlots, ValueLocations};
 use crate::ir::{JumpTableOffsets, JumpTables};
 use crate::isa::{CallConv, EncInfo, Encoding, Legalize, TargetIsa};
 use crate::regalloc::{EntryRegDiversions, RegDiversions};
@@ -92,6 +92,13 @@ pub struct Function {
     ///
     /// This is used for some calling conventions to track the end of unwind information.
     pub prologue_end: Option<Inst>,
+
+    /// Frame layout for the instructions.
+    ///
+    /// The stack unwinding requires to have information about which registers and where they
+    /// are saved in the frame. This information is created during the prologue and epilogue
+    /// passes.
+    pub frame_layout: Option<FrameLayout>,
 }
 
 impl Function {
@@ -115,6 +122,7 @@ impl Function {
             jt_offsets: SecondaryMap::new(),
             srclocs: SecondaryMap::new(),
             prologue_end: None,
+            frame_layout: None,
         }
     }
 
@@ -135,6 +143,7 @@ impl Function {
         self.jt_offsets.clear();
         self.srclocs.clear();
         self.prologue_end = None;
+        self.frame_layout = None;
     }
 
     /// Create a new empty, anonymous function with a Fast calling convention.
@@ -244,6 +253,7 @@ impl Function {
     /// Starts collection of debug information.
     pub fn collect_debug_info(&mut self) {
         self.dfg.collect_debug_info();
+        self.frame_layout = Some(FrameLayout::new());
     }
 
     /// Changes the destination of a jump or branch instruction.