1 files changed, 134 insertions, 0 deletions
diff --git a/compiler/rustc_codegen_cranelift/src/pointer.rs b/compiler/rustc_codegen_cranelift/src/pointer.rs
new file mode 100644
index 000000000..31d827f83
--- /dev/null
+++ b/compiler/rustc_codegen_cranelift/src/pointer.rs
@@ -0,0 +1,134 @@
+//! Defines [`Pointer`] which is used to improve the quality of the generated clif ir for pointer
+//! operations.
+
+use crate::prelude::*;
+
+use rustc_target::abi::Align;
+
+use cranelift_codegen::ir::immediates::Offset32;
+
+/// A pointer pointing either to a certain address, a certain stack slot or nothing.
+#[derive(Copy, Clone, Debug)]
+pub(crate) struct Pointer {
+    base: PointerBase,
+    offset: Offset32,
+}
+
+#[derive(Copy, Clone, Debug)]
+pub(crate) enum PointerBase {
+    Addr(Value),
+    Stack(StackSlot),
+    Dangling(Align),
+}
+
+impl Pointer {
+    pub(crate) fn new(addr: Value) -> Self {
+        Pointer { base: PointerBase::Addr(addr), offset: Offset32::new(0) }
+    }
+
+    pub(crate) fn stack_slot(stack_slot: StackSlot) -> Self {
+        Pointer { base: PointerBase::Stack(stack_slot), offset: Offset32::new(0) }
+    }
+
+    pub(crate) fn const_addr(fx: &mut FunctionCx<'_, '_, '_>, addr: i64) -> Self {
+        let addr = fx.bcx.ins().iconst(fx.pointer_type, addr);
+        Pointer { base: PointerBase::Addr(addr), offset: Offset32::new(0) }
+    }
+
+    pub(crate) fn dangling(align: Align) -> Self {
+        Pointer { base: PointerBase::Dangling(align), offset: Offset32::new(0) }
+    }
+
+    pub(crate) fn debug_base_and_offset(self) -> (PointerBase, Offset32) {
+        (self.base, self.offset)
+    }
+
+    pub(crate) fn get_addr(self, fx: &mut FunctionCx<'_, '_, '_>) -> Value {
+        match self.base {
+            PointerBase::Addr(base_addr) => {
+                let offset: i64 = self.offset.into();
+                if offset == 0 { base_addr } else { fx.bcx.ins().iadd_imm(base_addr, offset) }
+            }
+            PointerBase::Stack(stack_slot) => {
+                fx.bcx.ins().stack_addr(fx.pointer_type, stack_slot, self.offset)
+            }
+            PointerBase::Dangling(align) => {
+                fx.bcx.ins().iconst(fx.pointer_type, i64::try_from(align.bytes()).unwrap())
+            }
+        }
+    }
+
+    pub(crate) fn offset(self, fx: &mut FunctionCx<'_, '_, '_>, extra_offset: Offset32) -> Self {
+        self.offset_i64(fx, extra_offset.into())
+    }
+
+    pub(crate) fn offset_i64(self, fx: &mut FunctionCx<'_, '_, '_>, extra_offset: i64) -> Self {
+        if let Some(new_offset) = self.offset.try_add_i64(extra_offset) {
+            Pointer { base: self.base, offset: new_offset }
+        } else {
+            let base_offset: i64 = self.offset.into();
+            if let Some(new_offset) = base_offset.checked_add(extra_offset) {
+                let base_addr = match self.base {
+                    PointerBase::Addr(addr) => addr,
+                    PointerBase::Stack(stack_slot) => {
+                        fx.bcx.ins().stack_addr(fx.pointer_type, stack_slot, 0)
+                    }
+                    PointerBase::Dangling(align) => {
+                        fx.bcx.ins().iconst(fx.pointer_type, i64::try_from(align.bytes()).unwrap())
+                    }
+                };
+                let addr = fx.bcx.ins().iadd_imm(base_addr, new_offset);
+                Pointer { base: PointerBase::Addr(addr), offset: Offset32::new(0) }
+            } else {
+                panic!(
+                    "self.offset ({}) + extra_offset ({}) not representable in i64",
+                    base_offset, extra_offset
+                );
+            }
+        }
+    }
+
+    pub(crate) fn offset_value(self, fx: &mut FunctionCx<'_, '_, '_>, extra_offset: Value) -> Self {
+        match self.base {
+            PointerBase::Addr(addr) => Pointer {
+                base: PointerBase::Addr(fx.bcx.ins().iadd(addr, extra_offset)),
+                offset: self.offset,
+            },
+            PointerBase::Stack(stack_slot) => {
+                let base_addr = fx.bcx.ins().stack_addr(fx.pointer_type, stack_slot, self.offset);
+                Pointer {
+                    base: PointerBase::Addr(fx.bcx.ins().iadd(base_addr, extra_offset)),
+                    offset: Offset32::new(0),
+                }
+            }
+            PointerBase::Dangling(align) => {
+                let addr =
+                    fx.bcx.ins().iconst(fx.pointer_type, i64::try_from(align.bytes()).unwrap());
+                Pointer {
+                    base: PointerBase::Addr(fx.bcx.ins().iadd(addr, extra_offset)),
+                    offset: self.offset,
+                }
+            }
+        }
+    }
+
+    pub(crate) fn load(self, fx: &mut FunctionCx<'_, '_, '_>, ty: Type, flags: MemFlags) -> Value {
+        match self.base {
+            PointerBase::Addr(base_addr) => fx.bcx.ins().load(ty, flags, base_addr, self.offset),
+            PointerBase::Stack(stack_slot) => fx.bcx.ins().stack_load(ty, stack_slot, self.offset),
+            PointerBase::Dangling(_align) => unreachable!(),
+        }
+    }
+
+    pub(crate) fn store(self, fx: &mut FunctionCx<'_, '_, '_>, value: Value, flags: MemFlags) {
+        match self.base {
+            PointerBase::Addr(base_addr) => {
+                fx.bcx.ins().store(flags, value, base_addr, self.offset);
+            }
+            PointerBase::Stack(stack_slot) => {
+                fx.bcx.ins().stack_store(value, stack_slot, self.offset);
+            }
+            PointerBase::Dangling(_align) => unreachable!(),
+        }
+    }
+}