Merge pull request #214 from jhawthorn/skip_case_dispatch

maximecb · web-flow · commit 4959076802c1 · 2021-09-13T13:08:50.000-07:00
Skip over opt_case_dispatch instructions
diff --git a/yjit_codegen.c b/yjit_codegen.c
@@ -2446,6 +2446,22 @@ gen_opt_regexpmatch2(jitstate_t *jit, ctx_t *ctx)
     return gen_opt_send_without_block(jit, ctx);
 }
 
+static codegen_status_t
+gen_opt_case_dispatch(jitstate_t* jit, ctx_t* ctx)
+{
+    // Normally this instruction would lookup the key in a hash and jump to an
+    // offset based on that.
+    // Instead we can take the fallback case and continue with the next
+    // instruciton.
+    // We'd hope that our jitted code will be sufficiently fast without the
+    // hash lookup, at least for small hashes, but it's worth revisiting this
+    // assumption in the future.
+
+    ctx_stack_pop(ctx, 1);
+
+    return YJIT_KEEP_COMPILING; // continue with the next instruction
+}
+
 void
 gen_branchif_branch(codeblock_t* cb, uint8_t* target0, uint8_t* target1, uint8_t shape)
 {
@@ -4214,6 +4230,7 @@ yjit_init_codegen(void)
     yjit_reg_op(BIN(opt_getinlinecache), gen_opt_getinlinecache);
     yjit_reg_op(BIN(opt_invokebuiltin_delegate), gen_opt_invokebuiltin_delegate);
     yjit_reg_op(BIN(opt_invokebuiltin_delegate_leave), gen_opt_invokebuiltin_delegate);
+    yjit_reg_op(BIN(opt_case_dispatch), gen_opt_case_dispatch);
     yjit_reg_op(BIN(branchif), gen_branchif);
     yjit_reg_op(BIN(branchunless), gen_branchunless);
     yjit_reg_op(BIN(branchnil), gen_branchnil);
