[DTrace-devel] [PATCH 3/4] Allow DIFOs to have a variety of flags

[Kris Van Hees]

DIFOs could be flagged as containing destructive operations using the
specific dtdo_destructive field in dtrace_difo_t.  There is a need for
other flags to be associated with DIFOs, so the dtdo_destructive field
is being changed into a dtdo_flags field.  DTDOFLG_* constants in
difo_defines.h provide the flags that can be set and checked for.

Signed-off-by: Kris Van Hees <kris.van.hees at oracle.com>
---
 include/dtrace/difo.h         | 2 +-
 include/dtrace/difo_defines.h | 5 +++++
 libdtrace/dt_as.c             | 4 ++--
 libdtrace/dt_cc.c             | 7 ++++---
 4 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/include/dtrace/difo.h b/include/dtrace/difo.h
index 4190bc93..173d0701 100644
--- a/include/dtrace/difo.h
+++ b/include/dtrace/difo.h
@@ -41,7 +41,7 @@ typedef struct dtrace_difo {
 	uint_t dtdo_varlen;			/* length of variable table */
 	uint_t dtdo_reclen;			/* length of trace record */
 	uint_t dtdo_refcnt;			/* owner reference count */
-	uint_t dtdo_destructive;		/* invokes destructive subroutines */
+	uint_t dtdo_flags;			/* flags (destructive, ...) */
 	struct dof_relodesc *dtdo_breltab;	/* BPF relocations */
 	struct dof_relodesc *dtdo_kreltab;	/* kernel relocations */
 	struct dof_relodesc *dtdo_ureltab;	/* user relocations */
diff --git a/include/dtrace/difo_defines.h b/include/dtrace/difo_defines.h
index b5a0f7a7..cb057182 100644
--- a/include/dtrace/difo_defines.h
+++ b/include/dtrace/difo_defines.h
@@ -17,4 +17,9 @@
 
 struct dtrace_difo;
 
+/*
+ * DIFO flags.
+ */
+#define DIFOFLG_DESTRUCTIVE		1	/* Uses destructive ops */
+
 #endif /* _DTRACE_DIFO_DEFINES_H */
diff --git a/libdtrace/dt_as.c b/libdtrace/dt_as.c
index 86d83298..528714fd 100644
--- a/libdtrace/dt_as.c
+++ b/libdtrace/dt_as.c
@@ -331,7 +331,7 @@ fail:
 	/*
 	 * Make a second pass through the instructions, relocating each branch
 	 * target (a label ID) to the relative location of the label and noting
-	 * any instruction-specific DIFO flags such as dtdo_destructive.
+	 * any instruction-specific flags such as DIFOFLG_DESTRUCTIVE.
 	 */
 	for (i = 0; i < dp->dtdo_len; i++) {
 		struct bpf_insn instr = dp->dtdo_buf[i];
@@ -352,7 +352,7 @@ fail:
 		if (op == DIF_OP_CALL) {
 			if (DIF_INSTR_SUBR(instr) == DIF_SUBR_COPYOUT ||
 			    DIF_INSTR_SUBR(instr) == DIF_SUBR_COPYOUTSTR)
-				dp->dtdo_destructive = 1;
+				dp->dtdo_flags |= DIFOFLG_DESTRUCTIVE;
 			continue;
 		}
 #endif
diff --git a/libdtrace/dt_cc.c b/libdtrace/dt_cc.c
index 0f8f7af9..e8865c45 100644
--- a/libdtrace/dt_cc.c
+++ b/libdtrace/dt_cc.c
@@ -135,13 +135,14 @@ dt_stmt_create(dtrace_hdl_t *dtp, dtrace_ecbdesc_t *edp,
 #ifdef FIXME
 /*
  * Utility function to determine if a given action description is destructive.
- * The dtdo_destructive bit is set for us by the DIF assembler (see dt_as.c).
+ * The DIFOFLG_DESTRUCTIVE bit is set for us by the DIF assembler (see dt_as.c).
  */
 static int
 dt_action_destructive(const dtrace_actdesc_t *ap)
 {
-	return (DTRACEACT_ISDESTRUCTIVE(ap->dtad_kind) || (ap->dtad_kind ==
-	    DTRACEACT_DIFEXPR && ap->dtad_difo->dtdo_destructive));
+	return (DTRACEACT_ISDESTRUCTIVE(ap->dtad_kind) ||
+		(ap->dtad_kind == DTRACEACT_DIFEXPR &&
+		 (ap->dtad_difo->dtdo_flags & DIFOFLG_DESTRUCTIVE)));
 }
 #endif
 
-- 
2.28.0