From: Lifang Xia <lifang_xia@c-sky.com>
To: gdb-patches@sourceware.org
Cc: aburgess@redhat.com, palmer@dabbelt.com,
Lifang Xia <lifang_xia@linux.alibaba.com>
Subject: [PATCH] [RISC-V]: Handling optimized prologue
Date: Tue, 1 Mar 2022 15:32:31 +0800 [thread overview]
Message-ID: <20220301073231.1927-1-lifang_xia@c-sky.com> (raw)
From: Lifang Xia <lifang_xia@linux.alibaba.com>
The optimizer might shove anything into the prologue, if
we build up cache (cache != NULL) from scanning prologue,
we just skip what we don't recognize and scan further to
make cache as complete as possible. However, if we skip
prologue, we'll stop immediately on unrecognized
instruction.
The case is:
----------------------------
Disassembly of section .text:
0000000000010078 <foo>:
10078: 00100513 li a0,1
1007c: 008000ef jal ra,10084 <bar>
10080: 00008067 ret
0000000000010084 <bar>:
10084: 00051263 bnez a0,10088 <bar+0x4>
10088: ff010113 addi sp,sp,-16
1008c: 00813023 sd s0,0(sp)
10090: 00050413 mv s0,a0
10094: 00113423 sd ra,8(sp)
10098: 014000ef jal ra,100ac <aaa>
1009c: 00813083 ld ra,8(sp)
100a0: 00013403 ld s0,0(sp)
100a4: 01010113 addi sp,sp,16
100a8: 00008067 ret
00000000000100ac <aaa>:
100ac: 00000013 nop
>> 100b0: 00008067 ret
----------------------
(gdb) bt
#0 0x00000000000100b0 in aaa ()
#1 0x000000000001009c in bar ()
Backtrace stopped: frame did not save the PC
gdb/
* riscv-tdep.c (riscv_scan_prologue): Keep scaning if cache is not NULL.
---
gdb/riscv-tdep.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/gdb/riscv-tdep.c b/gdb/riscv-tdep.c
index 886996c..e46d441 100644
--- a/gdb/riscv-tdep.c
+++ b/gdb/riscv-tdep.c
@@ -1987,7 +1987,15 @@ riscv_scan_prologue (struct gdbarch *gdbarch,
else
{
end_prologue_addr = cur_pc;
- break;
+
+ /* The optimizer might shove anything into the prologue, if
+ we build up cache (cache != NULL) from scanning prologue,
+ we just skip what we don't recognize and scan further to
+ make cache as complete as possible. However, if we skip
+ prologue, we'll stop immediately on unrecognized
+ instruction. */
+ if (cache == NULL)
+ break;
}
}
--
2.7.4
next reply other threads:[~2022-03-01 7:32 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-01 7:32 Lifang Xia [this message]
2022-03-01 10:33 ` Andrew Burgess
2022-03-02 2:01 ` 答复: " lifang_xia
2022-03-02 10:14 ` Andrew Burgess
2022-03-02 11:37 ` 答复: " lifang_xia
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