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[commit, arm] Fix single-step failures in Thumb mode
- From: "Ulrich Weigand" <uweigand at de dot ibm dot com>
- To: gdb-patches at sourceware dot org
- Date: Tue, 19 Oct 2010 23:34:00 +0200 (CEST)
- Subject: [commit, arm] Fix single-step failures in Thumb mode
Hello,
I ran into problems single-stepping though the Thumb version of __divsf3,
because thumb_get_next_pc_raw neglected to handle the Thumb-16 encoding
of a "mov pc, REG" instruction.
Fixed by the patch below, which also fixes the corresponding place in
thumb_instruction_changes_pc.
Tested on armv7l-linux-gnueabi. Fixes the following regressions where
libc debuginfo is unavailable:
FAIL: gdb.base/gdb1555.exp: Step into shared lib function (the program exited)
FAIL: gdb.base/gdb1555.exp: Next while in a shared lib function (the program is no longer running)
FAIL: gdb.base/step-test.exp: large struct by value (the program exited)
FAIL: gdb.base/step-test.exp: continue until exit at step-test.exp (the program is no longer running)
Committed to mainline as obvious.
Bye,
Ulrich
ChangeLog:
* arm-tdep.c (thumb_get_next_pc_raw): Handle Thumb-16 encoding
for "mov pc, REG" as well.
(thumb_instruction_changes_pc): Likewise.
Index: gdb/arm-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/arm-tdep.c,v
retrieving revision 1.310
diff -u -p -r1.310 arm-tdep.c
--- gdb/arm-tdep.c 12 Oct 2010 08:46:15 -0000 1.310
+++ gdb/arm-tdep.c 19 Oct 2010 17:26:49 -0000
@@ -537,6 +541,9 @@ thumb_instruction_changes_pc (unsigned s
if ((inst & 0xff00) == 0x4700) /* bx REG, blx REG */
return 1;
+ if ((inst & 0xff87) == 0x4687) /* mov pc, REG */
+ return 1;
+
if ((inst & 0xf500) == 0xb100) /* CBNZ or CBZ. */
return 1;
@@ -3572,6 +4210,15 @@ thumb_get_next_pc_raw (struct frame_info
else
nextpc = get_frame_register_unsigned (frame, bits (inst1, 3, 6));
}
+ else if ((inst1 & 0xff87) == 0x4687) /* mov pc, REG */
+ {
+ if (bits (inst1, 3, 6) == 0x0f)
+ nextpc = pc_val;
+ else
+ nextpc = get_frame_register_unsigned (frame, bits (inst1, 3, 6));
+
+ nextpc = MAKE_THUMB_ADDR (nextpc);
+ }
else if ((inst1 & 0xf500) == 0xb100)
{
/* CBNZ or CBZ. */
--
Dr. Ulrich Weigand
GNU Toolchain for Linux on System z and Cell BE
Ulrich.Weigand@de.ibm.com