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Re: middle-end/6679: wrong code generated for dead code
- From: Volker Reichelt <reichelt at igpm dot rwth-aachen dot de>
- To: gcc-gnats at gcc dot gnu dot org, gcc-bugs at gcc dot gnu dot org, nobody at gcc dot gnu dot org, rveldema at cs dot vu dot nl
- Date: Fri, 8 Nov 2002 00:52:44 +0100
- Subject: Re: middle-end/6679: wrong code generated for dead code
Hi,
the problem can be demonstrated with the following testcase:
--------------------------snip here-------------------------
bool foo (int i)
{
switch (i)
{
case 0: return false;
case 1: return false;
case 2: return false;
case 3: return false;
case 4: return false;
}
return false;
}
int main() { return 0; }
--------------------------snip here-------------------------
Compiling this with gcc 3.1, 3.2 or the 3.2-branch on i686-pc-linux-gnu I get
the following error message:
/tmp/ccii3YKY.o: In function `foo(int)':
/tmp/ccii3YKY.o(.text+0x11): undefined reference to `.L8'
collect2: ld returned 1 exit status
The assembler code for the function "foo" is:
.align 2
.globl _Z3fooi
.type _Z3fooi,@function
_Z3fooi:
.LFB1:
pushl %ebp
.LCFI0:
movl %esp, %ebp
.LCFI1:
cmpl $4, 8(%ebp)
ja .L1
movl 8(%ebp), %eax
sall $2, %eax
movl .L8(%eax), %eax <--------- !!!!!
.L1:
movl $0, %eax
popl %ebp
ret
.LFE1:
.Lfe1:
.size _Z3fooi,.Lfe1-_Z3fooi
Note that the problem disappears with only four cases in the switch statement.
The problem doesn't arise on the main trunk, though.
Because this is a regression from 3.0.x, I rate the PR as "high priority".
Greetings,
Volker
http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=6679