Hey all, I'm having some trouble getting Boost.Atomic working properly on OSX Leopard. After wrangling compilation (all instances of "lock" -> "lock;", and "+r" -> "+q"), I'm hitting what looks like bad generated assembly. The following code, compiled with -O2: #include <boost/atomic.hpp> #include <stdio.h> using namespace boost; int main() { signed char a1, c1; char a2, c2; { atomic<char> a(41); char c = a++; a1 = a.load(); c1 = c; } { atomic<signed char> a(41); signed char c = a++; a2 = a.load(); c2 = c; } printf("%d %d\n", a1, c1); printf("%d %d\n", a2, c2); } produces: Macintosh-2:test josh$ ./simple2 42 41 93 41 Changing the first atomic to be the same type as the second (atomic<signed char>) produces the correct output (42 41 for both). This same problem shows up with int vs. unsigned int as well (have only tested those two). The assembly that produces the correct output: LCFI2: movl $1, %ecx ^^^^^^^^^^^^^^^^ Move 1 into ecx movl %esp, %ebp LCFI3: movl %ecx, %eax ^^^^^^^^^^^^^^^^ And eax subl $72, %esp LCFI4: movl %ebx, -12(%ebp) LCFI5: movl %esi, -8(%ebp) LCFI6: movl %edi, -4(%ebp) LCFI7: call L11 "L00000000001$pb": L11: popl %ebx movb $41, -25(%ebp) lock; xaddb %al, -25(%ebp) ^^^^^^^^^^^^^^^^^ first reference after assignment to eax (through al) movzbl -25(%ebp), %edx lock; addl $0, (%esp) movb $41, -25(%ebp) lock; xaddb %cl, -25(%ebp) ^^^^^^^^^^^^^^^^^ first reference after assignment to ecx (through cl) movl %ecx, %edi movzbl -25(%ebp), %ecx movb %cl, -41(%ebp) lock; addl $0, (%esp) The assembly that produces the incorrect output (when one is atomic<char> and the other is atomic<signed char>): movl $1, %eax ^^^^^^^^^^^^^^^^^ Move 1 into eax movl %esp, %ebp LCFI3: subl $72, %esp LCFI4: movl %ebx, -12(%ebp) LCFI5: movl %esi, -8(%ebp) LCFI6: movl %edi, -4(%ebp) LCFI7: call L11 "L00000000001$pb": L11: popl %ebx movb $41, -25(%ebp) lock; xaddb %al, -25(%ebp) ^^^^^^^^^^^^^^^^^^ First reference after assignment to eax (through al) movzbl -25(%ebp), %edx lock; addl $0, (%esp) movb $41, -25(%ebp) lock; xaddb %cl, -25(%ebp) ^^^^^^^^^^^^^^^^^^ First reference to ecx (through cl), but NO ASSIGNMENT. cl is garbage? movl %ecx, %edi movzbl -25(%ebp), %ecx movb %cl, -41(%ebp) lock; addl $0, (%esp) I am by no means an assembly expert (this has been a huge learning experience in fact) but this doesn't look right. I'm on: gcc version 4.0.1 (Apple Inc. build 5493) OSX 10.5.8, Intel Core 2 Duo (2.16 GHz) Just pulled a git clone of Boost.Atomic from http://git.chaoticmind.net/boost.atomic, rev. 886a675aa982ab5875c7bc98697b2eb26c134d03 (I think... I have no experience with git, just grabbed the top guid from "git log"). building without -O2 yields correct results. Anyone with more knowledge than I have any ideas? Am I being stupid and something else is wrong? Josh