moved crates in lib/ to src/, renamed crates, modified some files' text (#660)

moved crates in lib/ to src/, renamed crates, modified some files' text (#660)

cranelift/codegen/src/legalizer/globalvalue.rs

@@ -0,0 +1,129 @@
+//! Legalization of global values.
+//!
+//! This module exports the `expand_global_value` function which transforms a `global_value`
+//! instruction into code that depends on the kind of global value referenced.
+
+use crate::cursor::{Cursor, FuncCursor};
+use crate::flowgraph::ControlFlowGraph;
+use crate::ir::{self, InstBuilder};
+use crate::isa::TargetIsa;
+
+/// Expand a `global_value` instruction according to the definition of the global value.
+pub fn expand_global_value(
+    inst: ir::Inst,
+    func: &mut ir::Function,
+    _cfg: &mut ControlFlowGraph,
+    isa: &TargetIsa,
+) {
+    // Unpack the instruction.
+    let gv = match func.dfg[inst] {
+        ir::InstructionData::UnaryGlobalValue {
+            opcode,
+            global_value,
+        } => {
+            debug_assert_eq!(opcode, ir::Opcode::GlobalValue);
+            global_value
+        }
+        _ => panic!("Wanted global_value: {}", func.dfg.display_inst(inst, None)),
+    };
+
+    match func.global_values[gv] {
+        ir::GlobalValueData::VMContext => vmctx_addr(inst, func),
+        ir::GlobalValueData::IAddImm {
+            base,
+            offset,
+            global_type,
+        } => iadd_imm_addr(inst, func, base, offset.into(), global_type),
+        ir::GlobalValueData::Load {
+            base,
+            offset,
+            global_type,
+            readonly,
+        } => load_addr(inst, func, base, offset, global_type, readonly, isa),
+        ir::GlobalValueData::Symbol { .. } => symbol(inst, func, gv, isa),
+    }
+}
+
+/// Expand a `global_value` instruction for a vmctx global.
+fn vmctx_addr(inst: ir::Inst, func: &mut ir::Function) {
+    // Get the value representing the `vmctx` argument.
+    let vmctx = func
+        .special_param(ir::ArgumentPurpose::VMContext)
+        .expect("Missing vmctx parameter");
+
+    // Replace the `global_value` instruction's value with an alias to the vmctx arg.
+    let result = func.dfg.first_result(inst);
+    func.dfg.clear_results(inst);
+    func.dfg.change_to_alias(result, vmctx);
+    func.layout.remove_inst(inst);
+}
+
+/// Expand a `global_value` instruction for an iadd_imm global.
+fn iadd_imm_addr(
+    inst: ir::Inst,
+    func: &mut ir::Function,
+    base: ir::GlobalValue,
+    offset: i64,
+    global_type: ir::Type,
+) {
+    let mut pos = FuncCursor::new(func).at_inst(inst);
+
+    // Get the value for the lhs. For tidiness, expand VMContext here so that we avoid
+    // `vmctx_addr` which creates an otherwise unneeded value alias.
+    let lhs = if let ir::GlobalValueData::VMContext = pos.func.global_values[base] {
+        pos.func
+            .special_param(ir::ArgumentPurpose::VMContext)
+            .expect("Missing vmctx parameter")
+    } else {
+        pos.ins().global_value(global_type, base)
+    };
+
+    // Simply replace the `global_value` instruction with an `iadd_imm`, reusing the result value.
+    pos.func.dfg.replace(inst).iadd_imm(lhs, offset);
+}
+
+/// Expand a `global_value` instruction for a load global.
+fn load_addr(
+    inst: ir::Inst,
+    func: &mut ir::Function,
+    base: ir::GlobalValue,
+    offset: ir::immediates::Offset32,
+    global_type: ir::Type,
+    readonly: bool,
+    isa: &TargetIsa,
+) {
+    // We need to load a pointer from the `base` global value, so insert a new `global_value`
+    // instruction. This depends on the iterative legalization loop. Note that the IR verifier
+    // detects any cycles in the `load` globals.
+    let ptr_ty = isa.pointer_type();
+    let mut pos = FuncCursor::new(func).at_inst(inst);
+    pos.use_srcloc(inst);
+
+    // Get the value for the base. For tidiness, expand VMContext here so that we avoid
+    // `vmctx_addr` which creates an otherwise unneeded value alias.
+    let base_addr = if let ir::GlobalValueData::VMContext = pos.func.global_values[base] {
+        pos.func
+            .special_param(ir::ArgumentPurpose::VMContext)
+            .expect("Missing vmctx parameter")
+    } else {
+        pos.ins().global_value(ptr_ty, base)
+    };
+
+    // Global-value loads are always notrap and aligned. They may be readonly.
+    let mut mflags = ir::MemFlags::trusted();
+    if readonly {
+        mflags.set_readonly();
+    }
+
+    // Perform the load.
+    pos.func
+        .dfg
+        .replace(inst)
+        .load(global_type, mflags, base_addr, offset);
+}
+
+/// Expand a `global_value` instruction for a symbolic name global.
+fn symbol(inst: ir::Inst, func: &mut ir::Function, gv: ir::GlobalValue, isa: &TargetIsa) {
+    let ptr_ty = isa.pointer_type();
+    func.dfg.replace(inst).symbol_value(ptr_ty, gv);
+}