[PATCH] libc: replace weak_alias and wrapper functions with linker symbol copy mechanism

[Waldemar Kozaczuk]

This patch eliminates 3 wrapper functions in libc/math/aliases.c and
3 week_alias macro defined symbols in libc/math/finite*.c using
new linker symbol copy mechanism designed by Nadav.

I have also replaced 3 __finite*( functions with finite*(
ones which will make it easy to drop all 3 libc/math/finite*.c
files once we upgrade to musl 1.1.24 which provides the finite*(
functions.

Finally this patch also adds some simple unit tests to verify
that modified functions still work.

Signed-off-by: Waldemar Kozaczuk <jwkoz...@gmail.com>
---
Makefile | 3 +--
libc/aliases.ld | 13 +++++++++++++
libc/math/aliases.c | 36 ------------------------------------
libc/math/finite.c | 4 +---
libc/math/finitef.c | 4 +---
libc/math/finitel.c | 4 +---
tests/tst-math.cc | 15 +++++++++++++++
7 files changed, 32 insertions(+), 47 deletions(-)
delete mode 100644 libc/math/aliases.c

diff --git a/Makefile b/Makefile
index 9bab08c0..78590d40 100644
--- a/Makefile
+++ b/Makefile
@@ -1164,7 +1164,7 @@ musl += math/fminl.o
musl += math/fmod.o
musl += math/fmodf.o
musl += math/fmodl.o
-libc += math/finite.o
+libc += math/finite.o #This 3 libc modules will go away once we upgrade to musl 1.1.24
libc += math/finitef.o
libc += math/finitel.o
musl += math/frexp.o
@@ -1288,7 +1288,6 @@ musl += math/tgammal.o
musl += math/trunc.o
musl += math/truncf.o
musl += math/truncl.o
-libc += math/aliases.o

# Issue #867: Gcc 4.8.4 has a bug where it optimizes the trivial round-
# related functions incorrectly - it appears to convert calls to any
diff --git a/libc/aliases.ld b/libc/aliases.ld
index 89a87373..a44b7572 100644
--- a/libc/aliases.ld
+++ b/libc/aliases.ld
@@ -9,4 +9,17 @@
* address.
*/

+/* network */
__res_init = res_init;
+
+/* math */
+__exp_finite = exp;
+__exp2_finite = exp2;
+__log10_finite = log10;
+__log2_finite = log2;
+__log2f_finite = log2f;
+__log_finite = log;
+__pow_finite = pow;
+__finite = finite;
+__finitef = finitef;
+__finitel = finitel;
diff --git a/libc/math/aliases.c b/libc/math/aliases.c
deleted file mode 100644
index b137d530..00000000
--- a/libc/math/aliases.c
+++ /dev/null
@@ -1,36 +0,0 @@
-#include "libm.h"
-
-double __exp_finite(double x)
-{
- return exp(x);
-}
-
-double __exp2_finite(double x)
-{
- return exp2(x);
-}
-
-double __log10_finite(double x)
-{
- return log10(x);
-}
-
-double __log2_finite(double x)
-{
- return log2(x);
-}
-
-double __log2f_finite(double x)
-{
- return log2f(x);
-}
-
-double __log_finite(double x)
-{
- return log(x);
-}
-
-double __pow_finite(double x, double y)
-{
- return pow(x, y);
-}
diff --git a/libc/math/finite.c b/libc/math/finite.c
index f8465101..c49bf53b 100644
--- a/libc/math/finite.c
+++ b/libc/math/finite.c
@@ -1,9 +1,7 @@
#include <math.h>
#include "libc.h"

-int __finite(double x)
+int finite(double x)
{
return isfinite(x);
}
-
-weak_alias(__finite,finite);
diff --git a/libc/math/finitef.c b/libc/math/finitef.c
index 4dc548f7..57ab73f1 100644
--- a/libc/math/finitef.c
+++ b/libc/math/finitef.c
@@ -1,9 +1,7 @@
#include <math.h>
#include "libc.h"

-int __finitef(float x)
+int finitef(float x)
{
return isfinite(x);
}
-
-weak_alias(__finitef,finitef);
diff --git a/libc/math/finitel.c b/libc/math/finitel.c
index a73c3bc9..b9a19cda 100644
--- a/libc/math/finitel.c
+++ b/libc/math/finitel.c
@@ -1,9 +1,7 @@
#include <math.h>
#include "libc.h"

-int __finitel(long double x)
+int finitel(long double x)
{
return isfinite(x);
}
-
-weak_alias(__finitel,finitel);
diff --git a/tests/tst-math.cc b/tests/tst-math.cc
index 497ce69e..9f9f6ce7 100644
--- a/tests/tst-math.cc
+++ b/tests/tst-math.cc
@@ -10,6 +10,12 @@

#include <math.h>

+extern "C" int __finite(double x);
+extern "C" int __finitef(float x);
+extern "C" int __finitel(long double x);
+
+extern "C" double __log10_finite(double x);
+
#include <iostream>

static int tests = 0, fails = 0;
@@ -38,6 +44,15 @@ int main(int argc, char **argv)
expect(nearbyint(1.3), 1.0);
expect(nearbyint(1.7), 2.0);

+ expect(finite(NAN), 0);
+ expect(__finite(NAN), 0);
+ expect(finitel(NAN), 0);
+ expect(__finitel(NAN), 0);
+ expect(finitef(NAN), 0);
+ expect(__finitef(NAN), 0);
+
+ expect(__log10_finite(100), log10(100));
+
std::cout << "SUMMARY: " << tests << " tests, " << fails << " failures\n";
return fails == 0 ? 0 : 1;
}
--
2.25.1

[Commit Bot]

From: Waldemar Kozaczuk <jwkoz...@gmail.com>
Committer: Nadav Har'El <n...@scylladb.com>
Branch: master

libc: replace weak_alias and wrapper functions with linker symbol copy mechanism

This patch eliminates 3 wrapper functions in libc/math/aliases.c and
3 week_alias macro defined symbols in libc/math/finite*.c using
new linker symbol copy mechanism designed by Nadav.

I have also replaced 3 __finite*( functions with finite*(
ones which will make it easy to drop all 3 libc/math/finite*.c
files once we upgrade to musl 1.1.24 which provides the finite*(
functions.

Finally this patch also adds some simple unit tests to verify
that modified functions still work.

Signed-off-by: Waldemar Kozaczuk <jwkoz...@gmail.com>

Message-Id: <20200805233028.1...@gmail.com>

---
diff --git a/Makefile b/Makefile

--- a/Makefile
+++ b/Makefile
@@ -1164,7 +1164,7 @@ musl += math/fminl.o
musl += math/fmod.o
musl += math/fmodf.o
musl += math/fmodl.o
-libc += math/finite.o
+libc += math/finite.o #This 3 libc modules will go away once we upgrade to musl 1.1.24
libc += math/finitef.o
libc += math/finitel.o
musl += math/frexp.o
@@ -1288,7 +1288,6 @@ musl += math/tgammal.o
musl += math/trunc.o
musl += math/truncf.o
musl += math/truncl.o
-libc += math/aliases.o

# Issue #867: Gcc 4.8.4 has a bug where it optimizes the trivial round-
# related functions incorrectly - it appears to convert calls to any
diff --git a/libc/aliases.ld b/libc/aliases.ld

--- a/libc/aliases.ld
+++ b/libc/aliases.ld
@@ -9,4 +9,17 @@
* address.
*/

+/* network */
__res_init = res_init;
+
+/* math */
+__exp_finite = exp;
+__exp2_finite = exp2;
+__log10_finite = log10;
+__log2_finite = log2;
+__log2f_finite = log2f;
+__log_finite = log;
+__pow_finite = pow;
+__finite = finite;
+__finitef = finitef;
+__finitel = finitel;
diff --git a/libc/math/aliases.c b/libc/math/aliases.c

--- a/libc/math/aliases.c
+++ b/libc/math/aliases.c

--- a/libc/math/finite.c
+++ b/libc/math/finite.c
@@ -1,9 +1,7 @@
#include <math.h>
#include "libc.h"

-int __finite(double x)
+int finite(double x)
{
return isfinite(x);
}
-
-weak_alias(__finite,finite);
diff --git a/libc/math/finitef.c b/libc/math/finitef.c

--- a/libc/math/finitef.c
+++ b/libc/math/finitef.c
@@ -1,9 +1,7 @@
#include <math.h>
#include "libc.h"

-int __finitef(float x)
+int finitef(float x)
{
return isfinite(x);
}
-
-weak_alias(__finitef,finitef);
diff --git a/libc/math/finitel.c b/libc/math/finitel.c

--- a/libc/math/finitel.c
+++ b/libc/math/finitel.c
@@ -1,9 +1,7 @@
#include <math.h>
#include "libc.h"

-int __finitel(long double x)
+int finitel(long double x)
{
return isfinite(x);
}
-
-weak_alias(__finitel,finitel);
diff --git a/tests/tst-math.cc b/tests/tst-math.cc