https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70892
Bug ID: 70892
Summary: additional memory access generated in loop if
destructor is inlined
Product: gcc
Version: 5.3.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: wr0112358 at gmail dot com
Target Milestone: ---
Created attachment 38388
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=38388&action=edit
testcase
The attached reduced testcase is compiled differently if a simple raii helper
type is used.
testcase:
double array[expected];
double sum = 0.0;
for(int j = 0; j < expected; j++)
array[j] = (double)j;
g++ -std=c++1y -O2 -Wall -Wextra -Werror double_bug_minimal.cc
400950: f2 0f 58 00 addsd (%rax),%xmm0
400954: 48 83 c0 08 add $0x8,%rax
400958: 48 39 d0 cmp %rdx,%rax
40095b: 75 f3 jne 400950 <main+0x70>
g++ -std=c++1y -O2 -Wall -Wextra -Werror -DA double_bug_minimal.cc
400a98: f2 0f 10 4c 24 08 movsd 0x8(%rsp),%xmm1
400a9e: 48 83 c0 08 add $0x8,%rax
400aa2: f2 0f 58 48 f8 addsd -0x8(%rax),%xmm1
400aa7: 48 39 d0 cmp %rdx,%rax
400aaa: f2 0f 11 4c 24 08 movsd %xmm1,0x8(%rsp)
400ab0: 75 e6 jne 400a98 <main+0x78>
g++ --version | head -n1; cat /etc/fedora-release; uname -a
g++ (GCC) 5.3.1 20160406 (Red Hat 5.3.1-6)
Fedora release 23 (Twenty Three)
Linux lautreamont 4.4.7-300.fc23.x86_64 #1 SMP Wed Apr 13 02:52:52 UTC 2016
x86_64 x86_64 x86_64 GNU/Linux
