ZJIT: Add codegen for StringCopy

Prior to this commit we compiled `putstring` and `putchilledstring` to
`StringCopy`, but then failed to compile past HIR.

This commit adds codegen for `StringCopy` to call `rb_ec_str_ressurrect`
as the VM does for these instructions.

3 files changed, 37 insertions, 7 deletions

diff --git a/test/ruby/test_zjit.rb b/test/ruby/test_zjit.rb
index 7b582df2f5..d7249053e5 100644
--- a/test/ruby/test_zjit.rb
+++ b/test/ruby/test_zjit.rb
@@ -31,6 +31,20 @@ class TestZJIT < Test::Unit::TestCase
     }
   end
 
+  def test_putstring
+    assert_compiles '""', %q{
+      def test = "#{""}"
+      test
+    }, insns: [:putstring]
+  end
+
+  def test_putchilldedstring
+    assert_compiles '""', %q{
+      def test = ""
+      test
+    }, insns: [:putchilledstring]
+  end
+
   def test_leave_param
     assert_compiles '5', %q{
       def test(n) = n
diff --git a/zjit/src/codegen.rs b/zjit/src/codegen.rs
index 32ea9e1c15..286f3f39b4 100644
--- a/zjit/src/codegen.rs
+++ b/zjit/src/codegen.rs
@@ -252,6 +252,7 @@ fn gen_insn(cb: &mut CodeBlock, jit: &mut JITState, asm: &mut Assembler, functio
         Insn::NewArray { elements, state } => gen_new_array(jit, asm, elements, &function.frame_state(*state)),
         Insn::NewRange { low, high, flag, state } => gen_new_range(asm, opnd!(low), opnd!(high), *flag, &function.frame_state(*state)),
         Insn::ArrayDup { val, state } => gen_array_dup(asm, opnd!(val), &function.frame_state(*state)),
+        Insn::StringCopy { val, chilled } => gen_string_copy(asm, opnd!(val), *chilled),
         Insn::Param { idx } => unreachable!("block.insns should not have Insn::Param({idx})"),
         Insn::Snapshot { .. } => return Some(()), // we don't need to do anything for this instruction at the moment
         Insn::Jump(branch) => return gen_jump(jit, asm, branch),
@@ -611,6 +612,17 @@ fn gen_send_without_block_direct(
     Some(ret)
 }
 
+/// Compile a string resurrection
+fn gen_string_copy(asm: &mut Assembler, recv: Opnd, chilled: bool) -> Opnd {
+    asm_comment!(asm, "call rb_ec_str_resurrect");
+    // TODO: split rb_ec_str_resurrect into separate functions
+    let chilled = if chilled { Opnd::Imm(1) } else { Opnd::Imm(0) };
+    asm.ccall(
+        rb_ec_str_resurrect as *const u8,
+        vec![EC, recv, chilled],
+    )
+}
+
 /// Compile an array duplication instruction
 fn gen_array_dup(
     asm: &mut Assembler,
diff --git a/zjit/src/hir.rs b/zjit/src/hir.rs
index 17b4aad6cf..c67f25451a 100644
--- a/zjit/src/hir.rs
+++ b/zjit/src/hir.rs
@@ -396,7 +396,7 @@ pub enum Insn {
     /// SSA block parameter. Also used for function parameters in the function's entry block.
     Param { idx: usize },
 
-    StringCopy { val: InsnId },
+    StringCopy { val: InsnId, chilled: bool },
     StringIntern { val: InsnId },
 
     /// Put special object (VMCORE, CBASE, etc.) based on value_type
@@ -602,7 +602,7 @@ impl<'a> std::fmt::Display for InsnPrinter<'a> {
             Insn::ArraySet { array, idx, val } => { write!(f, "ArraySet {array}, {idx}, {val}") }
             Insn::ArrayDup { val, .. } => { write!(f, "ArrayDup {val}") }
             Insn::HashDup { val, .. } => { write!(f, "HashDup {val}") }
-            Insn::StringCopy { val } => { write!(f, "StringCopy {val}") }
+            Insn::StringCopy { val, .. } => { write!(f, "StringCopy {val}") }
             Insn::Test { val } => { write!(f, "Test {val}") }
             Insn::IsNil { val } => { write!(f, "IsNil {val}") }
             Insn::Jump(target) => { write!(f, "Jump {target}") }
@@ -978,7 +978,7 @@ impl Function {
                     }
                 },
             Return { val } => Return { val: find!(*val) },
-            StringCopy { val } => StringCopy { val: find!(*val) },
+            StringCopy { val, chilled } => StringCopy { val: find!(*val), chilled: *chilled },
             StringIntern { val } => StringIntern { val: find!(*val) },
             Test { val } => Test { val: find!(*val) },
             &IsNil { val } => IsNil { val: find!(val) },
@@ -1623,7 +1623,7 @@ impl Function {
                     worklist.push_back(high);
                     worklist.push_back(state);
                 }
-                Insn::StringCopy { val }
+                Insn::StringCopy { val, .. }
                 | Insn::StringIntern { val }
                 | Insn::Return { val }
                 | Insn::Defined { v: val, .. }
@@ -2142,10 +2142,14 @@ pub fn iseq_to_hir(iseq: *const rb_iseq_t) -> Result<Function, ParseError> {
                     let value_type = SpecialObjectType::from(get_arg(pc, 0).as_u32());
                     state.stack_push(fun.push_insn(block, Insn::PutSpecialObject { value_type }));
                 }
-                YARVINSN_putstring | YARVINSN_putchilledstring => {
-                    // TODO(max): Do something different for chilled string
+                YARVINSN_putstring => {
                     let val = fun.push_insn(block, Insn::Const { val: Const::Value(get_arg(pc, 0)) });
-                    let insn_id = fun.push_insn(block, Insn::StringCopy { val });
+                    let insn_id = fun.push_insn(block, Insn::StringCopy { val, chilled: false });
+                    state.stack_push(insn_id);
+                }
+                YARVINSN_putchilledstring => {
+                    let val = fun.push_insn(block, Insn::Const { val: Const::Value(get_arg(pc, 0)) });
+                    let insn_id = fun.push_insn(block, Insn::StringCopy { val, chilled: true });
                     state.stack_push(insn_id);
                 }
                 YARVINSN_putself => { state.stack_push(self_param); }