[PATCH dwarves v3 3/9] dwarf_loader: Refactor initial ret -1 to be macro PARM_DEFAULT_FAIL

Yonghong Song
2026-03-20T19:09:45Z

Later on, More macro return values will be implemented to make
code easier to understand.

Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
---
dwarf_loader.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/dwarf_loader.c b/dwarf_loader.c
index a6e6587..7b3f551 100644
--- a/dwarf_loader.c
+++ b/dwarf_loader.c
@@ -1195,12 +1195,14 @@ struct func_info {
int skip_idx;
};

+#define PARM_DEFAULT_FAIL -1
+
/* For DW_AT_location 'attr':
* - if first location is DW_OP_regXX with expected number, return the register;
* otherwise save the register for later return
* - if location DW_OP_entry_value(DW_OP_regXX) with expected number is in the
* list, return the register; otherwise save register for later return
- * - otherwise if no register was found for locations, return -1.
+ * - otherwise if no register was found for locations, return PARM_DEFAULT_FAIL.
*/
static int parameter__reg(Dwarf_Attribute *attr, int expected_reg)
{
@@ -1210,7 +1212,7 @@ static int parameter__reg(Dwarf_Attribute *attr, int expected_reg)
size_t exprlen, entry_len;
ptrdiff_t offset = 0;
int loc_num = -1;
- int ret = -1;
+ int ret = PARM_DEFAULT_FAIL;

/* use libdw__lock as dwarf_getlocation(s) has concurrency issues
* when libdw is not compiled with experimental --enable-thread-safety
@@ -1327,7 +1329,7 @@ static struct parameter *parameter__new(Dwarf_Die *die, struct cu *cu,
int expected_reg = cu->register_params[reg_idx];
int actual_reg = parameter__reg(&attr, expected_reg);

- if (actual_reg < 0)
+ if (actual_reg == PARM_DEFAULT_FAIL)
parm->optimized = 1;
else if (expected_reg >= 0 && expected_reg != actual_reg)
/* mark parameters that use an unexpected
--
2.52.0