https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64236
Bug ID: 64236
Summary: Missing alignment
Product: gcc
Version: 4.8.3
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: wolfgang.roe...@gi-de.com
Hi,
I would like to post a bug report for the GNU C/C++ compiler 4.8.3.
We use the compiler to generate code for a PowerPC processor.
Invokation line for the GNU C++ compiler:
ccppc -c -x c++ -std=c++11 -Wall -Werror -g -mcpu=8540 -meabi
-ftls-model=local-exec -msdata=sysv -fno-common -mspe -mabi=spe
-mfloat-gprs=double -mbig -mmultiple -mno-string -misel -mstrict-align
-fverbose-asm -fno-exceptions -fno-rtti -fgcse-sm -fno-section-anchors
-ftemplate-backtrace-limit=20 -G 8 -O3
-I<some include paths>
-D<some #define's>
X.CPP -oX.O
// file X.CPP
#define SIZE_DATA_CACHE_BLOCK 32u
struct S
{ double d; };
struct alignas(sizeof(S)) S1
{ char d[sizeof(S)]; };
struct alignas(SIZE_DATA_CACHE_BLOCK) alignas(sizeof(S)) S2
{ char d[sizeof(S)]; };
alignas(S) char s1[sizeof(S)];
alignas(SIZE_DATA_CACHE_BLOCK) alignas(S) char s2[sizeof(S)];
S1 s3;
S2 s4;
An inspection of the generated assembler file (see below) shows the following
alignments:
. s1: alignment = 8
. s2: alignment = 32
. s3: alignment = 8
. s4: alignment = 8 ???
I think that s4 should also be aligned on a 32-byte boundary (C++11 standard,
7.6.2/4).
Following is the generated assembler file:
.globl s4
.section ".sbss","aw",@nobits
.align 3 <--- 8-byte alignment ???
s4:
.zero 8
.size s4, 8
.type s4, @object
.globl s3
.align 3 <--- 8-byte alignment
s3:
.zero 8
.size s3, 8
.type s3, @object
.globl s2
.align 5 <--- 32-byte alignment
s2:
.zero 8
.size s2, 8
.type s2, @object
.globl s1
.align 3 <--- 8-byte alignment
s1:
.zero 8
.size s1, 8
.type s1, @object
Kind regards
W. Roehrl
