YJIT: ZJIT: Allow both JITs in the same build

This commit allows building YJIT and ZJIT simultaneously, a "combo
build". Previously, `./configure --enable-yjit --enable-zjit` failed. At
runtime, though, only one of the two can be enabled at a time.

Add a root Cargo workspace that contains both the yjit and zjit crate.
The common Rust build integration mechanisms are factored out into
defs/jit.mk.

Combo YJIT+ZJIT dev builds are supported; if either JIT uses
`--enable-*=dev`, both of them are built in dev mode.

The combo build requires Cargo, but building one JIT at a time with only
rustc in release build remains supported.

Author: XrXr

.github/auto_request_review.yml

@@ -10,6 +10,7 @@ files:
   'zjit/src/cruby_bindings.inc.rs': []
   'doc/zjit*': [team:jit]
   'test/ruby/test_zjit*': [team:jit]
+  'defs/jit.mk': [team:jit]
 options:
   ignore_draft: true
   # This currently doesn't work as intended. We want to skip reviews when only

.gitignore

@@ -246,6 +246,9 @@ lcov*.info
 /yjit-bench
 /yjit_exit_locations.dump
 
+# Rust
+/target
+
 # /wasm/
 /wasm/tests/*.wasm
 

Cargo.lock

@@ -0,0 +1,51 @@
+# Using Cargo's workspace feature to build all the Rust code in
+# into a single package.
+# TODO(alan) notes about rust version requirements. Undecided yet.
+
+[workspace]
+members = ["zjit", "yjit"]
+
+[package]
+name = "jit"
+version = "0.0.0"
+edition = "2024"
+rust-version = "1.85.0"
+publish = false # Don't publish to crates.io
+
+[dependencies]
+yjit = { path = "yjit", optional = true }
+zjit = { path = "zjit", optional = true }
+
+[lib]
+crate-type = ["staticlib"]
+path = "jit.rs"
+
+[features]
+disasm = []
+runtime_checks = []
+yjit = [ "dep:yjit" ]
+zjit = [ "dep:zjit" ]
+
+[profile.dev]
+opt-level = 0
+debug = true
+debug-assertions = true
+overflow-checks = true
+
+[profile.dev_nodebug]
+inherits = "dev"
+
+[profile.stats]
+inherits = "release"
+
+[profile.release]
+# NOTE: --enable-yjit and zjit builds use `rustc` without going through Cargo. You
+# might want to update the `rustc` invocation if you change this profile.
+opt-level = 3
+# The extra robustness that comes from checking for arithmetic overflow is
+# worth the performance cost for the compiler.
+overflow-checks = true
+# Generate debug info
+debug = true
+# Use ThinLTO. Much smaller output for a small amount of build time increase.
+lto = "thin"

Cargo.toml

@@ -186,10 +186,9 @@ COMMONOBJS    = array.$(OBJEXT) \
 		weakmap.$(OBJEXT) \
 		$(PRISM_FILES) \
 		$(YJIT_OBJ) \
-		$(YJIT_LIBOBJ) \
 		$(ZJIT_OBJ) \
-		$(ZJIT_LIBOBJ) \
 		$(JIT_OBJ) \
+		$(RUST_LIBOBJ) \
 		$(COROUTINE_OBJ) \
 		$(DTRACE_OBJ) \
 		$(BUILTIN_ENCOBJS) \
@@ -345,7 +344,7 @@ YJIT_RUSTC_ARGS = --crate-name=yjit \
 	-C opt-level=3 \
 	-C overflow-checks=on \
 	'--out-dir=$(CARGO_TARGET_DIR)/release/' \
-	$(top_srcdir)/yjit/src/lib.rs
+	'$(top_srcdir)/yjit/src/lib.rs'
 
 ZJIT_RUSTC_ARGS = --crate-name=zjit \
 	--crate-type=staticlib \
@@ -354,8 +353,8 @@ ZJIT_RUSTC_ARGS = --crate-name=zjit \
 	-C lto=thin \
 	-C opt-level=3 \
 	-C overflow-checks=on \
-	'--out-dir=$(ZJIT_CARGO_TARGET_DIR)/release/' \
-	$(top_srcdir)/zjit/src/lib.rs
+	'--out-dir=$(CARGO_TARGET_DIR)/release/' \
+	'$(top_srcdir)/zjit/src/lib.rs'
 
 all: $(SHOWFLAGS) main
 
@@ -735,8 +734,8 @@ clean-local:: clean-runnable
 	$(Q)$(RM) probes.h probes.$(OBJEXT) probes.stamp ruby-glommed.$(OBJEXT) ruby.imp ChangeLog $(STATIC_RUBY)$(EXEEXT)
 	$(Q)$(RM) GNUmakefile.old Makefile.old $(arch)-fake.rb bisect.sh $(ENC_TRANS_D) builtin_binary.inc
 	$(Q)$(RM) $(PRISM_BUILD_DIR)/.time $(PRISM_BUILD_DIR)/*/.time yjit_exit_locations.dump
-	-$(Q)$(RMALL) yjit/target
-	-$(Q) $(RMDIR) enc/jis enc/trans enc $(COROUTINE_H:/Context.h=) coroutine yjit \
+	-$(Q)$(RMALL) target
+	-$(Q) $(RMDIR) enc/jis enc/trans enc $(COROUTINE_H:/Context.h=) coroutine target \
 	  $(PRISM_BUILD_DIR)/*/ $(PRISM_BUILD_DIR) tmp \
 	2> $(NULL) || $(NULLCMD)
 

common.mk

@@ -3926,46 +3926,33 @@ AC_ARG_ENABLE(yjit,
 CARGO=
 CARGO_BUILD_ARGS=
 YJIT_LIBS=
+JIT_CARGO_SUPPORT=no
 AS_CASE(["${YJIT_SUPPORT}"],
 [yes|dev|stats|dev_nodebug], [
     AS_IF([test x"$RUSTC" = "xno"],
         AC_MSG_ERROR([rustc is required. Installation instructions available at https://www.rust-lang.org/tools/install])
     )
-    AS_IF([test x"$ZJIT_SUPPORT" != "xno"],
-        AC_MSG_ERROR([YJIT cannot be enabled when ZJIT is enabled])
-    )
 
     AS_CASE(["${YJIT_SUPPORT}"],
     [yes], [
-	rb_rust_target_subdir=release
     ],
     [dev], [
-	rb_rust_target_subdir=debug
-	CARGO_BUILD_ARGS='--features disasm,runtime_checks'
+        rb_cargo_features='disasm,runtime_checks'
+        JIT_CARGO_SUPPORT=dev
 	AC_DEFINE(RUBY_DEBUG, 1)
     ],
     [dev_nodebug], [
-	rb_rust_target_subdir=dev_nodebug
-	CARGO_BUILD_ARGS='--profile dev_nodebug --features disasm'
+        rb_cargo_features='disasm'
+        JIT_CARGO_SUPPORT=dev_nodebug
 	AC_DEFINE(YJIT_STATS, 1)
     ],
     [stats], [
-	rb_rust_target_subdir=stats
-	CARGO_BUILD_ARGS='--profile stats'
+        JIT_CARGO_SUPPORT=stats
 	AC_DEFINE(YJIT_STATS, 1)
     ])
 
-    AS_IF([test -n "${CARGO_BUILD_ARGS}"], [
-             AC_CHECK_TOOL(CARGO, [cargo], [no])
-             AS_IF([test x"$CARGO" = "xno"],
-                AC_MSG_ERROR([cargo is required. Installation instructions available at https://www.rust-lang.org/tools/install])
-             ]))
-
-    YJIT_LIBS="yjit/target/${rb_rust_target_subdir}/libyjit.a"
-    AS_CASE(["$target_os"],[openbsd*],[
-        # Link libc++abi (which requires libpthread) for _Unwind_* functions needed by yjit
-        LDFLAGS="$LDFLAGS -lpthread -lc++abi"
-    ])
+    YJIT_LIBS="target/release/libyjit.a"
+    RUST_LIB='$(YJIT_LIBS)'
     YJIT_OBJ='yjit.$(OBJEXT)'
     JIT_OBJ='jit.$(OBJEXT)'
     AS_IF([test x"$YJIT_SUPPORT" != "xyes" ], [
@@ -3976,38 +3963,23 @@ AS_CASE(["${YJIT_SUPPORT}"],
     AC_DEFINE(USE_YJIT, 0)
 ])
 
-ZJIT_CARGO_BUILD_ARGS=
 ZJIT_LIBS=
 AS_CASE(["${ZJIT_SUPPORT}"],
 [yes|dev], [
     AS_IF([test x"$RUSTC" = "xno"],
         AC_MSG_ERROR([rustc is required. Installation instructions available at https://www.rust-lang.org/tools/install])
     )
-    AS_IF([test x"$YJIT_SUPPORT" != "xno"],
-        AC_MSG_ERROR([ZJIT cannot be enabled when YJIT is enabled])
-    )
 
     AS_CASE(["${ZJIT_SUPPORT}"],
     [yes], [
-	rb_rust_target_subdir=release
     ],
     [dev], [
-	rb_rust_target_subdir=debug
-	ZJIT_CARGO_BUILD_ARGS='--profile dev --features disasm'
+        JIT_CARGO_SUPPORT=dev
 	AC_DEFINE(RUBY_DEBUG, 1)
     ])
 
-    AS_IF([test -n "${ZJIT_CARGO_BUILD_ARGS}"], [
-             AC_CHECK_TOOL(CARGO, [cargo], [no])
-             AS_IF([test x"$CARGO" = "xno"],
-                AC_MSG_ERROR([cargo is required. Installation instructions available at https://www.rust-lang.org/tools/install])
-             ]))
-
-    ZJIT_LIBS="zjit/target/${rb_rust_target_subdir}/libzjit.a"
-    AS_CASE(["$target_os"],[openbsd*],[
-        # Link libc++abi (which requires libpthread) for _Unwind_* functions needed by yjit
-        LDFLAGS="$LDFLAGS -lpthread -lc++abi"
-    ])
+    ZJIT_LIBS="target/release/libzjit.a"
+    RUST_LIB='$(ZJIT_LIBS)'
     ZJIT_OBJ='zjit.$(OBJEXT)'
     JIT_OBJ='jit.$(OBJEXT)'
     AS_IF([test x"$ZJIT_SUPPORT" != "xyes" ], [
@@ -4018,18 +3990,57 @@ AS_CASE(["${ZJIT_SUPPORT}"],
     AC_DEFINE(USE_ZJIT, 0)
 ])
 
+# if YJIT+ZJIT release build, or any build that requires Cargo
+AS_IF([test x"$JIT_CARGO_SUPPORT" != "xno" -o \( x"$YJIT_SUPPORT" != "xno" -a x"$ZJIT_SUPPORT" != "xno" \)], [
+    AC_CHECK_TOOL(CARGO, [cargo], [no])
+    AS_IF([test x"$CARGO" = "xno"],
+        AC_MSG_ERROR([cargo is required. Installation instructions available at https://www.rust-lang.org/tools/install]))
+
+    YJIT_LIBS=
+    ZJIT_LIBS=
+
+    AS_IF([test x"${YJIT_SUPPORT}" != x"no"], [
+        rb_cargo_features="$rb_cargo_features,yjit"
+    ])
+    AS_IF([test x"${ZJIT_SUPPORT}" != x"no"], [
+        rb_cargo_features="$rb_cargo_features,zjit"
+    ])
+    # if YJIT and ZJIT release mode
+    AS_IF([test "${YJIT_SUPPORT}:${ZJIT_SUPPORT}" = "yes:yes"], [
+        JIT_CARGO_SUPPORT=release
+    ])
+    CARGO_BUILD_ARGS="--profile ${JIT_CARGO_SUPPORT} --features ${rb_cargo_features}"
+    AS_IF([test "${JIT_CARGO_SUPPORT}" = "dev"], [
+        RUST_LIB="target/debug/libjit.a"
+    ], [
+        RUST_LIB="target/${JIT_CARGO_SUPPORT}/libjit.a"
+    ])
+])
+
+# In case either we're linking rust code
+AS_IF([test -n "$RUST_LIB"], [
+    AS_CASE(["$target_os"],[openbsd*],[
+        # Link libc++abi (which requires libpthread) for _Unwind_* functions needed by rust stdlib
+        LDFLAGS="$LDFLAGS -lpthread -lc++abi"
+    ])
+
+    # absolute path to stop the "target" dir in src dir from interfering through VPATH
+    RUST_LIB="$(pwd)/${RUST_LIB}"
+])
+
 dnl These variables end up in ::RbConfig::CONFIG
-AC_SUBST(YJIT_SUPPORT)dnl what flavor of YJIT the Ruby build includes
 AC_SUBST(RUSTC)dnl Rust compiler command
 AC_SUBST(CARGO)dnl Cargo command for Rust builds
 AC_SUBST(CARGO_BUILD_ARGS)dnl for selecting Rust build profiles
-AC_SUBST(ZJIT_CARGO_BUILD_ARGS)dnl for selecting Rust build profiles
-AC_SUBST(YJIT_LIBS)dnl for optionally building the Rust parts of YJIT
+AC_SUBST(YJIT_SUPPORT)dnl what flavor of YJIT the Ruby build includes
+AC_SUBST(YJIT_LIBS)dnl the .a library of YJIT
 AC_SUBST(YJIT_OBJ)dnl for optionally building the C parts of YJIT
 AC_SUBST(ZJIT_SUPPORT)dnl what flavor of ZJIT the Ruby build includes
-AC_SUBST(ZJIT_LIBS)dnl for optionally building the Rust parts of ZJIT
+AC_SUBST(ZJIT_LIBS)dnl path to the .a library of ZJIT
 AC_SUBST(ZJIT_OBJ)dnl for optionally building the C parts of ZJIT
 AC_SUBST(JIT_OBJ)dnl for optionally building C glue code for Rust FFI
+AC_SUBST(RUST_LIB)dnl path to the rust .a library that contains either or both JITs
+AC_SUBST(JIT_CARGO_SUPPORT)dnl "no" or the cargo profile of the rust code
 }
 
 [begin]_group "build section" && {

configure.ac

@@ -443,6 +443,7 @@ endif
 
 include $(top_srcdir)/yjit/yjit.mk
 include $(top_srcdir)/zjit/zjit.mk
+include $(top_srcdir)/defs/jit.mk
 
 # Query on the generated rdoc
 #