I tracked it down to the following code, which is not compiled as expected, if
optimization (> O1) is turned on.
Contents of fg.c:
---8<------8<---------8<---
extern volatile int ReadyFlag_NotProperlyInitialized;
volatile int ReadyFlag_NotProperlyInitialized=1;
volatile int ReadyFlag_InitializationOk=1;
---8<------8<---------8<---
My command line for GCC 4.3-20070223:
powerpc-elf-gcc -O1 -S -o fg_O1.s fg.i
In the generated assembler output, the variable ReadyFlag_InitializationOk is
placed in section .sbss (instead of .sdata) an is initialized with 0 instead of
1.
ReadyFlag_InitializationOk is initialized as expected. The only difference is
the extern declaration for ReadyFlag_NotProperlyInitialized.
Contents of fg_O1.s:
---8<------8<---------8<---
.file "fg.c"
.globl ReadyFlag_NotProperlyInitialized
.globl ReadyFlag_InitializationOk
.section .sbss,"aw",@nobits
.align 2
.type ReadyFlag_NotProperlyInitialized, @object
.size ReadyFlag_NotProperlyInitialized, 4
ReadyFlag_NotProperlyInitialized:
.zero 4
.section .sdata,"aw",@progbits
.align 2
.type ReadyFlag_InitializationOk, @object
.size ReadyFlag_InitializationOk, 4
ReadyFlag_InitializationOk:
.long 1
.ident "GCC: (GNU) 4.3.0 20070223 (experimental)"
---8<------8<---------8<---
gcc-3.4.6 built with the same system (same build, host and target) is ok!
gcc-4.1.2 built with the same system (same build, host and target) is ok!
gcc-4.2-20070221 shows the same error as 4.3-20070223 (both built as above)
--
Summary: Wrong code for volatile var with initalization and
optimization
Product: gcc
Version: 4.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: a_fisch at gmx dot de
GCC build triplet: mingw32
GCC host triplet: mingw32
GCC target triplet: powerpc-elf
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31072
