Merge branch 'john/erts/fix-hd-tl-loader-transformations/GH-7024/OTP-18519' into maint-25

* john/erts/fix-hd-tl-loader-transformations/GH-7024/OTP-18519:
  jit: Fix hd/1 and tl/1 BIF specialization

4 files changed, 44 insertions, 30 deletions

diff --git a/erts/emulator/beam/jit/arm/ops.tab b/erts/emulator/beam/jit/arm/ops.tab
index cc0bfeccf0..9cfce18e58 100644
--- a/erts/emulator/beam/jit/arm/ops.tab
+++ b/erts/emulator/beam/jit/arm/ops.tab
@@ -666,18 +666,14 @@ i_perf_counter
 bif0 u$bif:erlang:self/0 Dst=d => self Dst
 bif0 u$bif:erlang:node/0 Dst=d => node Dst
 
-bif1 Fail=f Bif=u$bif:erlang:hd/1 Src=n Dst =>
-    jump Fail
-bif1 Fail=f Bif=u$bif:erlang:hd/1 Src Dst =>
+bif1 Fail=f Bif=u$bif:erlang:hd/1 Src=xy Dst =>
     is_nonempty_list Fail Src | get_hd Src Dst
 bif1 Fail=p Bif=u$bif:erlang:hd/1 Src Dst =>
     bif_hd Src Dst
 
 bif_hd s d
 
-bif1 Fail=f Bif=u$bif:erlang:tl/1 Src=n Dst =>
-    jump Fail
-bif1 Fail=f Bif=u$bif:erlang:tl/1 Src Dst =>
+bif1 Fail=f Bif=u$bif:erlang:tl/1 Src=xy Dst =>
     is_nonempty_list Fail Src | get_tl Src Dst
 bif1 Fail=p Bif=u$bif:erlang:tl/1 Src Dst =>
     bif_tl Src Dst
diff --git a/erts/emulator/beam/jit/x86/instr_guard_bifs.cpp b/erts/emulator/beam/jit/x86/instr_guard_bifs.cpp
index 4dfe39cb98..26133d5ac0 100644
--- a/erts/emulator/beam/jit/x86/instr_guard_bifs.cpp
+++ b/erts/emulator/beam/jit/x86/instr_guard_bifs.cpp
@@ -60,24 +60,22 @@ void BeamGlobalAssembler::emit_handle_hd_error() {
  * The code size for this specialization of hd/1 is 21 bytes,
  * while the code size for the bif1 instruction is 24 bytes.
  */
-void BeamModuleAssembler::emit_bif_hd(const ArgLabel &Fail,
-                                      const ArgSource &Src,
+void BeamModuleAssembler::emit_bif_hd(const ArgSource &Src,
                                       const ArgRegister &Hd) {
+    Label good_cons = a.newLabel();
+
     mov_arg(RET, Src);
     a.test(RETb, imm(_TAG_PRIMARY_MASK - TAG_PRIMARY_LIST));
 
-    if (Fail.get() != 0) {
-        a.jne(resolve_beam_label(Fail));
-    } else {
-        Label next = a.newLabel();
-        a.short_().je(next);
-        safe_fragment_call(ga->get_handle_hd_error());
-        a.bind(next);
-    }
+    a.short_().je(good_cons);
+    safe_fragment_call(ga->get_handle_hd_error());
 
-    x86::Gp boxed_ptr = emit_ptr_val(RET, RET);
-    a.mov(ARG2, getCARRef(boxed_ptr));
-    mov_arg(Hd, ARG2);
+    a.bind(good_cons);
+    {
+        x86::Gp boxed_ptr = emit_ptr_val(RET, RET);
+        a.mov(ARG2, getCARRef(boxed_ptr));
+        mov_arg(Hd, ARG2);
+    }
 }
 
 void BeamGlobalAssembler::emit_handle_element_error() {
diff --git a/erts/emulator/beam/jit/x86/ops.tab b/erts/emulator/beam/jit/x86/ops.tab
index 1ce0d6f9c2..5481fff2d8 100644
--- a/erts/emulator/beam/jit/x86/ops.tab
+++ b/erts/emulator/beam/jit/x86/ops.tab
@@ -660,18 +660,14 @@ i_perf_counter
 bif0 u$bif:erlang:self/0 Dst=d => self Dst
 bif0 u$bif:erlang:node/0 Dst=d => node Dst
 
-bif1 Fail=f Bif=u$bif:erlang:hd/1 Src=n Dst =>
-    jump Fail
-bif1 Fail=f Bif=u$bif:erlang:hd/1 Src Dst =>
+bif1 Fail=f Bif=u$bif:erlang:hd/1 Src=xy Dst =>
     is_nonempty_list Fail Src | get_hd Src Dst
-bif1 Fail Bif=u$bif:erlang:hd/1 Src Dst =>
-    bif_hd Fail Src Dst
+bif1 Fail=p Bif=u$bif:erlang:hd/1 Src Dst =>
+    bif_hd Src Dst
 
-bif_hd j s d
+bif_hd s d
 
-bif1 Fail=f Bif=u$bif:erlang:tl/1 Src=n Dst =>
-    jump Fail
-bif1 Fail=f Bif=u$bif:erlang:tl/1 Src Dst =>
+bif1 Fail=f Bif=u$bif:erlang:tl/1 Src=xy Dst =>
     is_nonempty_list Fail Src | get_tl Src Dst
 
 bif1 Fail Bif=u$bif:erlang:get/1 Src=s Dst=d => get(Src, Dst)
diff --git a/lib/compiler/test/bif_SUITE.erl b/lib/compiler/test/bif_SUITE.erl
index 8480569507..34bf54a871 100644
--- a/lib/compiler/test/bif_SUITE.erl
+++ b/lib/compiler/test/bif_SUITE.erl
@@ -24,7 +24,8 @@
 -export([all/0,suite/0,groups/0,init_per_suite/1,end_per_suite/1,
 	 init_per_group/2,end_per_group/2,
 	 beam_validator/1,trunc_and_friends/1,cover_safe_and_pure_bifs/1,
-         cover_trim/1]).
+         cover_trim/1,
+         head_tail/1]).
 
 suite() ->
     [{ct_hooks,[ts_install_cth]}].
@@ -37,7 +38,8 @@ groups() ->
       [beam_validator,
        trunc_and_friends,
        cover_safe_and_pure_bifs,
-       cover_trim
+       cover_trim,
+       head_tail
       ]}].
 
 init_per_suite(Config) ->
@@ -167,6 +169,28 @@ cover_trim_3(Header, N)->
             false
     end.
 
+%% GH-7024: The loader transformations for hd/1 and tl/1 were incorrect and
+%% failed when certain optimizations were turned off.
+head_tail(_Config) ->
+    {1, ok} = head_case(),
+    {1, ok} = tail_case(),
+
+    1 = hd(id([1])),
+    [] = tl(id([1])),
+
+    ok.
+
+head_case() ->
+    case 1 of
+        X when hd(X) -> blurf;
+        X -> {X, ok}
+    end.
+
+tail_case() ->
+    case 1 of
+        X when tl(X) -> blurf;
+        X -> {X, ok}
+    end.
 
 id(I) ->
     I.