This is the mail archive of the
gcc-bugs@gcc.gnu.org
mailing list for the GCC project.
regmove question
- To: amylaar at cygnus dot com
- Subject: regmove question
- From: Jeffrey A Law <law at cygnus dot com>
- Date: Mon, 30 Aug 1999 02:11:25 -0600
- Cc: gcc-bugs at gcc dot gnu dot org
- Reply-To: law at cygnus dot com
I was looking at a bug caused by regmove tonight. Either I'm grossly
mis-understanding regmove, or we have a noteworthy bug.
In .combine we have:
(insn 11 10 13 (set (reg:DF 25)
(minus:DF (reg/v/u:DF 23)
(reg/v/u:DF 22))) 403 {ffshi_1+1} (insn_list 4 (insn_list 6 (nil)))
(nil))
(note 13 11 14 "" NOTE_INSN_DELETED)
(insn 14 13 15 (set (reg:DF 26)
(mult:DF (reg/v/u:DF 22)
(reg/v/u:DF 23))) 403 {ffshi_1+1} (nil)
(expr_list:REG_DEAD (reg/v/u:DF 22)
(nil)))
(insn 15 14 16 (set (reg:DF 28)
(plus:DF (reg:DF 26)
(reg/v/u:DF 23))) 403 {ffshi_1+1} (insn_list 14 (nil))
(expr_list:REG_DEAD (reg:DF 26)
(expr_list:REG_DEAD (reg/v/u:DF 23)
(nil))))
(insn 16 15 19 (set (reg/v:DF 24)
(div:DF (reg:DF 25)
(reg:DF 28))) 403 {ffshi_1+1} (insn_list 11 (insn_list 15 (nil)))
(expr_list:REG_DEAD (reg:DF 25)
(expr_list:REG_DEAD (reg:DF 28)
(nil))))
in .regmove we have:
(note 11 10 13 "" NOTE_INSN_DELETED)
(note 13 11 14 "" NOTE_INSN_DELETED)
(insn 14 13 15 (set (reg/v/u:DF 22)
(mult:DF (reg/v/u:DF 22)
(reg/v/u:DF 23))) 403 {ffshi_1+1} (nil)
(nil))
(insn 15 14 30 (set (reg/v/u:DF 22)
(plus:DF (reg/v/u:DF 22)
(reg/v/u:DF 23))) 403 {ffshi_1+1} (insn_list 14 (nil))
(nil))
(insn 30 15 16 (set (reg/v/u:DF 23)
(minus:DF (reg/v/u:DF 23)
(reg/v/u:DF 22))) 403 {ffshi_1+1} (nil)
(nil))
(insn 16 30 19 (set (reg/v/u:DF 23)
(div:DF (reg/v/u:DF 23)
(reg/v/u:DF 22))) 403 {ffshi_1+1} (insn_list 11 (insn_list 15 (nil)))
(expr_list:REG_DEAD (reg/v/u:DF 22)
(nil)))
Note how reg22 is clobbered by insn 14 and insn 15 in the regmove dump
and that it's clobbered *before* insn 30 which needs the original value.
I don't see any code in regmove which handles this case. Am I missing something
stupid?
The testcase for this is execute/990829-1.c -O2 on i686-pc-linux-gnu.
Thoughts?
jeff