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Tests: Add a shootout test for implementations of operator==

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That's for a structure mimicking QMakeStepConfig, comparing
a.x == b.x && a.y == b.y ... with
std::tie(a.x, a.y, ...) == std::tie(b.x, b.y, ...)

Executive summary: gcc 4.9.1 optimizes the traditional == && == better.
This is solely due to the sequence of four bools in the struct.

Change-Id: I77cc8d685c6b7b7ead651cd1f44ff1b2e9b39f3d
Reviewed-by: Daniel Teske <daniel.teske@theqtcompany.com>
This commit is contained in:
hjk
2015-03-23 12:49:01 +01:00
parent 7502169622
commit 2b7c83bfbf
1 changed files with 46 additions and 0 deletions
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46
tests/manual/shootout/tst_codesize.cpp
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@@ -165,6 +165,7 @@ void tst_CodeSize::codesize()
QFile mainPro(t->buildPath + "/main.pro");
QVERIFY(mainPro.open(QIODevice::ReadWrite));
mainPro.write("\n\nSOURCES += main.cpp");
mainPro.write("\nCONFIG += c++11\n");
QFile mainCpp(t->buildPath + QLatin1String("/main.cpp"));
QVERIFY(mainCpp.open(QIODevice::ReadWrite));
@@ -355,6 +356,51 @@ void tst_CodeSize::codesize_data()
QTest::newRow("lambdas") << s;
s.clear();
QByteArray std_tie_code =
"struct QMakeStepConfig\n"
"{\n"
" enum TargetArchConfig { NoArch, X86, X86_64, PPC, PPC64 };\n"
" enum OsType { NoOsType, IphoneSimulator, IphoneOS };\n"
"\n"
" QMakeStepConfig()\n"
" : e1(NoArch),\n"
" e2(NoOsType),\n"
" b1(false),\n"
" b2(false),\n"
" b3(false),\n"
" b4(false)\n"
" {}\n"
"\n"
" TargetArchConfig e1;\n"
" OsType e2;\n"
" bool b1;\n"
" bool b2;\n"
" bool b3;\n"
" bool b4;\n"
"};\n";
c.file = "std__tie";
c.gist = "std::tie";
c.code = "#include <tuple>\n" + std_tie_code +
"bool operator ==(const QMakeStepConfig &a, const QMakeStepConfig &b) {\n"
" return std::tie(a.e1, a.e2, a.b1, a.b2, a.b3, a.b4)\n"
" == std::tie(b.e1, b.e2, b.b1, b.b2, b.b3, b.b4);\n"
"}\n";
s.cases.append(c);
c.file = "conventional";
c.gist = "conventional";
c.code = "" + std_tie_code +
"bool operator ==(const QMakeStepConfig &a, const QMakeStepConfig &b) {\n"
" return a.e1 == b.e1 && a.e2 == b.e2 && a.b1 == b.b1\n"
" && a.b2 == b.b2 && a.b3 == b.b3 && a.b4 == b.b4;\n"
"}\n";
s.cases.append(c);
QTest::newRow("std_tie") << s;
s.clear();
}
int main(int argc, char *argv[])