Add const_addr instruction

This new instruction calculates the effective address of a constant in the constant pool using LEA (x86).

cranelift/codegen/meta/src/isa/x86/encodings.rs

@@ -2179,6 +2179,7 @@ fn define_entity_ref(
     let formats = &shared_defs.formats;
 
     // Shorthands for instructions.
+    let const_addr = shared.by_name("const_addr");
     let func_addr = shared.by_name("func_addr");
     let stack_addr = shared.by_name("stack_addr");
     let symbol_value = shared.by_name("symbol_value");
@@ -2188,6 +2189,7 @@ fn define_entity_ref(
     let rec_allones_fnaddr8 = r.template("allones_fnaddr8");
     let rec_fnaddr4 = r.template("fnaddr4");
     let rec_fnaddr8 = r.template("fnaddr8");
+    let rec_const_addr = r.template("const_addr");
     let rec_got_fnaddr8 = r.template("got_fnaddr8");
     let rec_got_gvaddr8 = r.template("got_gvaddr8");
     let rec_gvaddr4 = r.template("gvaddr4");
@@ -2285,6 +2287,10 @@ fn define_entity_ref(
     // don't get legalized to stack_addr + load/store.
     e.enc32(stack_addr.bind(I32), rec_spaddr4_id.opcodes(&LEA));
     e.enc64(stack_addr.bind(I64), rec_spaddr8_id.opcodes(&LEA).rex().w());
+
+    // Constant addresses (PIC).
+    e.enc64(const_addr.bind(I64), rec_const_addr.opcodes(&LEA).rex().w());
+    e.enc32(const_addr.bind(I32), rec_const_addr.opcodes(&LEA));
 }
 
 /// Control flow opcodes.

cranelift/codegen/meta/src/isa/x86/recipes.rs

@@ -1463,6 +1463,21 @@ pub(crate) fn define<'shared>(
             ),
     );
 
+    // Constant addresses.
+
+    recipes.add_template_recipe(
+        EncodingRecipeBuilder::new("const_addr", &formats.unary_const, 5)
+            .operands_out(vec![gpr])
+            .clobbers_flags(false)
+            .emit(
+                r#"
+                    {{PUT_OP}}(bits, rex2(0, out_reg0), sink);
+                    modrm_riprel(out_reg0, sink);
+                    const_disp4(constant_handle, func, sink);
+                "#,
+            ),
+    );
+
     // Store recipes.
 
     {

cranelift/codegen/meta/src/shared/instructions.rs

@@ -1542,6 +1542,21 @@ pub(crate) fn define(
         .operands_out(vec![a]),
     );
 
+    let constant =
+        &Operand::new("constant", &imm.pool_constant).with_doc("A constant in the constant pool");
+    let address = &Operand::new("address", iAddr);
+    ig.push(
+        Inst::new(
+            "const_addr",
+            r#"
+        Calculate the base address of a value in the constant pool.
+        "#,
+            &formats.unary_const,
+        )
+        .operands_in(vec![constant])
+        .operands_out(vec![address]),
+    );
+
     let mask = &Operand::new("mask", &imm.uimm128)
         .with_doc("The 16 immediate bytes used for selecting the elements to shuffle");
     let Tx16 = &TypeVar::new(

cranelift/filetests/filetests/isa/x86/simd-vconst-binemit.clif

@@ -19,3 +19,11 @@ block0:
 [-, %xmm3]  v1 = vconst.i32x4 const43  ; bin: 0f 10 1d 00000011 PCRelRodata4(31)
             return
 }
+
+function %address_of_vconst() {
+const42 = i32x4 [1 0 0 0]
+
+block0:
+[-, %rax]   v0 = const_addr.i64 const42  ; bin: 48 8d 05 00000001 PCRelRodata4(8)
+            return
+}