[committed] jit: use deep unsharing of trees [PR 95314]

[David Malcolm]

PR jit/95314 reports a internal error inside verify_gimple, which
turned out to be due to reusing the result of
gcc_jit_lvalue_get_address in several functions, leading to tree nodes
shared between multiple function bodies.

This patch fixes the issue by adopting the "Deep unsharing" strategy
described in the comment in gimplify.c preceding mostly_copy_tree_r:
to mark all of the jit "frontend"'s expression tree nodes with
TREE_VISITED, and to set LANG_HOOKS_DEEP_UNSHARING, so that "they are
unshared on the first reference within functions when the regular
unsharing algorithm runs".

Successfully bootstrapped & regrtested on x86_64-pc-linux-gnu.
Pushed to master as r11-668-gc98bd673ef93836f03491201f1c63929ea429cd6.

gcc/jit/ChangeLog:
	PR jit/95314
	* dummy-frontend.c (LANG_HOOKS_DEEP_UNSHARING): Define to be true.
	* jit-playback.h (gcc::jit::playback::rvalue): Mark tree node with
	TREE_VISITED.

gcc/testsuite/ChangeLog:
	PR jit/95314
	* jit.dg/all-non-failing-tests.h: Add test-pr95314-rvalue-reuse.c.
	* jit.dg/test-pr95314-rvalue-reuse.c: New test.
---
 gcc/jit/dummy-frontend.c                      |  3 +
 gcc/jit/jit-playback.h                        |  7 ++-
 gcc/testsuite/jit.dg/all-non-failing-tests.h  | 10 ++++
 .../jit.dg/test-pr95314-rvalue-reuse.c        | 56 +++++++++++++++++++
 4 files changed, 75 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/jit.dg/test-pr95314-rvalue-reuse.c

diff --git a/gcc/jit/dummy-frontend.c b/gcc/jit/dummy-frontend.c
index 27fe9d3db96..6c7b7992a4d 100644
--- a/gcc/jit/dummy-frontend.c
+++ b/gcc/jit/dummy-frontend.c
@@ -269,6 +269,9 @@ jit_langhook_getdecls (void)
 #undef LANG_HOOKS_GETDECLS
 #define LANG_HOOKS_GETDECLS		jit_langhook_getdecls
 
+#undef  LANG_HOOKS_DEEP_UNSHARING
+#define LANG_HOOKS_DEEP_UNSHARING	true
+
 struct lang_hooks lang_hooks = LANG_HOOKS_INITIALIZER;
 
 #include "gt-jit-dummy-frontend.h"
diff --git a/gcc/jit/jit-playback.h b/gcc/jit/jit-playback.h
index 074434a9f6b..f9b3e675368 100644
--- a/gcc/jit/jit-playback.h
+++ b/gcc/jit/jit-playback.h
@@ -576,7 +576,12 @@ public:
   rvalue (context *ctxt, tree inner)
     : m_ctxt (ctxt),
       m_inner (inner)
-  {}
+  {
+    /* Pre-mark tree nodes with TREE_VISITED so that they can be
+       deeply unshared during gimplification (including across
+       functions); this requires LANG_HOOKS_DEEP_UNSHARING to be true.  */
+    TREE_VISITED (inner) = 1;
+  }
 
   rvalue *
   as_rvalue () { return this; }
diff --git a/gcc/testsuite/jit.dg/all-non-failing-tests.h b/gcc/testsuite/jit.dg/all-non-failing-tests.h
index babcd3979b7..ca8d3df4193 100644
--- a/gcc/testsuite/jit.dg/all-non-failing-tests.h
+++ b/gcc/testsuite/jit.dg/all-non-failing-tests.h
@@ -234,6 +234,13 @@
 #undef create_code
 #undef verify_code
 
+/* test-pr95314-rvalue-reuse.c.  */
+#define create_code create_code_pr95314_rvalue_reuse
+#define verify_code verify_code_pr95314_rvalue_reuse
+#include "test-pr95314-rvalue-reuse.c"
+#undef create_code
+#undef verify_code
+
 /* test-reading-struct.c */
 #define create_code create_code_reading_struct
 #define verify_code verify_code_reading_struct
@@ -401,6 +408,9 @@ const struct testcase testcases[] = {
   {"pr95306_builtin_types",
    create_code_pr95306_builtin_types,
    verify_code_pr95306_builtin_types},
+  {"pr95314_rvalue_reuse",
+   create_code_pr95314_rvalue_reuse,
+   verify_code_pr95314_rvalue_reuse},
   {"reading_struct ",
    create_code_reading_struct ,
    verify_code_reading_struct },
diff --git a/gcc/testsuite/jit.dg/test-pr95314-rvalue-reuse.c b/gcc/testsuite/jit.dg/test-pr95314-rvalue-reuse.c
new file mode 100644
index 00000000000..6bed0bc52a4
--- /dev/null
+++ b/gcc/testsuite/jit.dg/test-pr95314-rvalue-reuse.c
@@ -0,0 +1,56 @@
+#include <libgccjit.h>
+#include "harness.h"
+
+void create_code (gcc_jit_context *ctxt, void *user_data)
+{
+  gcc_jit_type *t_int =  gcc_jit_context_get_type (ctxt, GCC_JIT_TYPE_INT);
+  gcc_jit_type *t_void = gcc_jit_context_get_type (ctxt, GCC_JIT_TYPE_VOID);
+  gcc_jit_type *t_const_char_ptr
+    = gcc_jit_context_get_type (ctxt, GCC_JIT_TYPE_CONST_CHAR_PTR);
+  gcc_jit_lvalue *global
+    = gcc_jit_context_new_global (ctxt, NULL, GCC_JIT_GLOBAL_INTERNAL,
+				  t_const_char_ptr, "pr95314_global");
+
+  gcc_jit_rvalue *global_ref = gcc_jit_lvalue_get_address(global, NULL);
+
+  gcc_jit_param *param_string
+    = gcc_jit_context_new_param (ctxt, NULL, t_const_char_ptr, "string");
+  gcc_jit_function *puts_func
+    = gcc_jit_context_new_function (ctxt, NULL, GCC_JIT_FUNCTION_IMPORTED,
+				    t_int, "puts", 1, &param_string, 0);
+
+#define NUM_INNER_FNS 3
+  gcc_jit_function *inner_fns[NUM_INNER_FNS];
+  for (int i = 0; i < NUM_INNER_FNS; i++)
+    {
+      char fnname[128];
+      sprintf (fnname, "pr95314_inner_%i", i);
+      inner_fns[i]
+	= gcc_jit_context_new_function (ctxt, NULL, GCC_JIT_FUNCTION_INTERNAL,
+					t_void, fnname, 0, NULL, 0);
+      gcc_jit_block *block = gcc_jit_function_new_block (inner_fns[i], NULL);
+      gcc_jit_rvalue *arg
+	= gcc_jit_context_new_cast (ctxt, NULL, global_ref, t_const_char_ptr);
+      gcc_jit_block_add_eval (block, NULL,
+			      gcc_jit_context_new_call (ctxt, NULL, puts_func,
+							1, &arg));
+      gcc_jit_block_end_with_void_return (block, NULL);
+    }
+
+  gcc_jit_function *outer_func
+    = gcc_jit_context_new_function (ctxt, NULL, GCC_JIT_FUNCTION_EXPORTED,
+				    t_void, "pr95314_outer", 0, NULL, 0);
+  gcc_jit_block *block = gcc_jit_function_new_block (outer_func, NULL);
+  for (int i = 0; i < NUM_INNER_FNS; i++)
+    gcc_jit_block_add_eval (block, NULL,
+			    gcc_jit_context_new_call (ctxt, NULL, inner_fns[i],
+						      0, NULL));
+  gcc_jit_block_end_with_void_return (block, NULL);
+}
+
+void
+verify_code (gcc_jit_context *ctxt, gcc_jit_result *result)
+{
+  CHECK_NON_NULL (result);
+  (void)gcc_jit_result_get_code (result, "pr95314_outer");
+}
-- 
2.21.0