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[PATCH] preserve 'to' bits when generating bytecode for a narrowing conversion
- From: Robert O'Callahan <robert at ocallahan dot org>
- To: gdb-patches at sourceware dot org
- Date: Fri, 3 Jul 2015 13:09:47 +1200
- Subject: [PATCH] preserve 'to' bits when generating bytecode for a narrowing conversion
- Authentication-results: sourceware.org; auth=none
The existing code preserves 'from' bits, which is incorrect. E.g.
(gdb) maint agent-eval (char)255L
Scope: 0x4008d6
Reg mask: 00
0 const16 255
3 ext 64
5 end
'ext 64' should be 'ext 8'; this bytecode evaluates to 255 instead of the
correct result of -1. The fix is simple. I ran the entire test suite on x86-64
and there were no new test failures.
gdb/ChangeLog:
2014-06-18 Robert O'Callahan <robert@ocallahan.org>
* ax-gdb.c (gen_conversion): Update.
gdb/testsuite/ChangeLog:
2014-06-18 Robert O'Callahan <robert@ocallahan.org>
* ax.exp: Add test.
---
gdb/ax-gdb.c | 2 +-
gdb/testsuite/gdb.trace/ax.exp | 2 ++
2 files changed, 3 insertions(+), 1 deletion(-)
diff --git a/gdb/ax-gdb.c b/gdb/ax-gdb.c
index 7a9d1e7..38dacac 100644
--- a/gdb/ax-gdb.c
+++ b/gdb/ax-gdb.c
@@ -885,7 +885,7 @@ gen_conversion (struct agent_expr *ax, struct type *from, struct type *to)
/* If we're converting to a narrower type, then we need to clear out
the upper bits. */
if (TYPE_LENGTH (to) < TYPE_LENGTH (from))
- gen_extend (ax, from);
+ gen_extend (ax, to);
/* If the two values have equal width, but different signednesses,
then we need to extend. */
diff --git a/gdb/testsuite/gdb.trace/ax.exp b/gdb/testsuite/gdb.trace/ax.exp
index e3d0479..d064475 100644
--- a/gdb/testsuite/gdb.trace/ax.exp
+++ b/gdb/testsuite/gdb.trace/ax.exp
@@ -80,6 +80,8 @@ gdb_test "maint agent &gdb_long_test == &gdb_short_test" "" "maint agent &gdb_lo
gdb_test "maint agent &gdb_long_test < &gdb_short_test" "" "maint agent &gdb_long_test < &gdb_short_test"
+gdb_test "maint agent (unsigned char)1L" ".*ext 8.*" "maint agent (unsigned char)1L"
+
# Now test eval version of agent expressions.
gdb_test "maint agent-eval 12" ".*const8 12.*end.*" "maint agent-eval 12"
--
2.4.3