Bug#181096: gcc-3.2: gcc fails to optimise if (l&2) l|=2 away
Package: gcc-3.2
Version: 1:3.2.3-0pre1
Severity: wishlist
The following function doesn't get optimised away as a noop:
int k(int l)
{
if (l & 2)
l |= 2;
return l;
}
$ gcc-3.2 -O2 -S b.c
$ cat b.s
.file "b.c"
.text
.p2align 2,,3
.globl k
.type k,@function
k:
pushl %ebp
movl%esp, %ebp
movl8(%ebp), %eax
testl $2, %eax
je .L2
orl $2, %eax
.L2:
leave
ret
.Lfe1:
.size k,.Lfe1-k
.ident "GCC: (GNU) 3.2.3 20030210 (Debian prerelease)"
-- System Information
Debian Release: testing/unstable
Kernel Version: Linux gondolin 2.4.20-686-smp #1 SMP Mon Jan 13 23:06:41 EST
2003 i686 Pentium III (Coppermine) GenuineIntel GNU/Linux
Versions of the packages gcc-3.2 depends on:
ii binutils 2.13.90.0.10-1 The GNU assembler, linker and binary utiliti
ii cpp-3.23.2.1-0pre3The GNU C preprocessor.
ii gcc-3.2-base 3.2.1-0pre3The GNU Compiler Collection (base package).
ii libc6 2.2.5-14.3 GNU C Library: Shared libraries and Timezone
ii libgcc13.2.1-0pre3GCC support library.
Bug#180937: g++ internal compiler error: Error reporting routines re-entered
On Fri, Feb 14, 2003 at 12:50:43PM -0500, Daniel Jacobowitz wrote:
> On Fri, Feb 14, 2003 at 12:14:01AM -0500, H. S. Teoh wrote:
[snip]
> > Also, why doesn't g++ like the declaration of objects inside a switch
> > statement? Is this invalid according to the C++ spec, or is it a GCC
> > oddity? Regardless, the internal compiler error is certainly a bug.
>
> I'm pretty sure it's illegal. Consider this - what is the scope of
> obj1 in the below? It starts at the first label, and goes until the
> end of the case block. So it's in scope at CHOICE_B. But its
> constructor wasn't called
[snip]
Ah, I see. I guess I'm so used to writing cases with break's that I forgot
that C/C++ semantics allow cases to fall through to the next case. I had
intended the semantics to be:
switch (choice) {
case A: {
someobj x;
...
}
break;
case B: {
...
}
break;
...
}
Obviously, this isn't the case with what I actually wrote.
T
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