WIP : Glibc fixes to fix build errors and undefined symbol errors (#793)

* Added placeholder for libdl.a

* Added unwind_def object file for libc.a

* Updated s_frexpl.c with latest glibc code to fix the build error

* Disable compiler flags -mno-sse, -mno-mmx, -mfpmath-387 that are not supported by wasm and caused build errors

* Disable ELF symbol versioning and hidden visibility in glibc shared builds which caused undefined symbol error for pow etc

* Removed flags that is not supported in wasm

Author: vidyalakshmir

scripts/make_archive.sh

@@ -115,3 +115,14 @@ else
   echo "Failed to create the archive libpthread.a"
   return 1
 fi
+
+#libdl.a is created as a placeholder since static python build requires libdl.a
+llvm-ar crs "$GLIBC/sysroot/lib/wasm32-wasi/libdl.a"
+
+# Check if llvm-ar succeeded
+if [ $? -eq 0 ]; then
+  echo "SUCCESS: Created archive libdl.a"
+else
+  echo "Failed to create the archive libdl.a"
+  return 1
+fi

scripts/make_glibc_and_sysroot.sh

@@ -17,7 +17,7 @@ SYSROOT_ARCHIVE="$SYSROOT/lib/wasm32-wasi/libc.a"
 SCRIPT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )"
 
 # Define common flags
-CFLAGS="--target=wasm32-unknown-wasi -v -Wno-int-conversion -std=gnu11 -fgnu89-inline -matomics -mbulk-memory -O2 -g -fPIC"
+CFLAGS="--target=wasm32-unknown-wasi -v -Wno-int-conversion  -DNO_HIDDEN -std=gnu11 -fgnu89-inline -matomics -mbulk-memory -O2 -g -fPIC"
 WARNINGS="-Wall -Wwrite-strings -Wundef -Wstrict-prototypes -Wold-style-definition"
 EXTRA_FLAGS="-fmerge-all-constants -ftrapping-math -fno-stack-protector -fno-common"
 EXTRA_FLAGS+=" -Wp,-U_FORTIFY_SOURCE -fmath-errno -fPIE -ftls-model=local-exec"

scripts/object_lists/libc_objects.txt

@@ -1648,6 +1648,7 @@ misc/tsearch.o
 misc/ttyslot.o
 misc/ualarm.o
 misc/unwind-link.o
+misc/unwind_def.o
 misc/usleep.o
 misc/ustat.o
 misc/utimes.o

src/glibc/include/libc-symbols.h

@@ -320,31 +320,16 @@ for linking")
    past the last element in SET.  */
 #define symbol_set_end_p(set, ptr) ((ptr) >= (void *const *) &__stop_##set)
 
-#ifdef SHARED
-# define symbol_version(real, name, version) \
-  symbol_version_reference(real, name, version)
-# define default_symbol_version(real, name, version) \
-     _default_symbol_version(real, name, version)
-/* See <libc-symver.h>.  */
-# ifdef __ASSEMBLER__
-#  define _default_symbol_version(real, name, version) \
-  _set_symbol_version (real, name@@version)
-# else
-#  define _default_symbol_version(real, name, version) \
-  _set_symbol_version (real, #name "@@" #version)
-# endif
-
-/* Evaluates to a string literal for VERSION in LIB.  */
-# define symbol_version_string(lib, version) \
-  _symbol_version_stringify_1 (VERSION_##lib##_##version)
-# define _symbol_version_stringify_1(arg) _symbol_version_stringify_2 (arg)
-# define _symbol_version_stringify_2(arg) #arg
+/* Completely disable ELF symbol versioning for all builds */
+#define symbol_version(real, name, version)
+#define default_symbol_version(real, name, version) \
+  strong_alias(real, name)
 
-#else /* !SHARED */
-# define symbol_version(real, name, version)
-# define default_symbol_version(real, name, version) \
+/* Provide dummy fallbacks for internal macros to prevent undefined macro errors */
+#define _default_symbol_version(real, name, version) \
   strong_alias(real, name)
-#endif
+#define symbol_version_string(lib, version) #version
+
 
 #if defined SHARED || defined LIBC_NONSHARED \
   || (BUILD_PIE_DEFAULT && IS_IN (libc))

src/glibc/sysdeps/i386/Makefile

@@ -48,7 +48,8 @@ endif
 # the first 3 mm/xmm/ymm/zmm registers are used to pass vector parameters
 # which must be preserved.
 # With SSE disabled, ensure -fpmath is not set to use sse either.
-rtld-CFLAGS += -mno-sse -mno-mmx -mfpmath=387
+# Flags -mno-sse -mno-mmx -mfpmath=387 has been removed as they
+# are not supported by wasm
 ifeq ($(subdir),elf)
 CFLAGS-.os += $(if $(filter $(@F),$(patsubst %,%.os,$(all-rtld-routines))),\
 		   $(rtld-CFLAGS))

src/glibc/sysdeps/ieee754/ldbl-96/s_frexpl.c

@@ -1,60 +1,60 @@
-/* s_frexpl.c -- long double version of s_frexp.c.
- */
-
-/*
- * ====================================================
- * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
- *
- * Developed at SunPro, a Sun Microsystems, Inc. business.
- * Permission to use, copy, modify, and distribute this
- * software is freely granted, provided that this notice
- * is preserved.
- * ====================================================
- */
-
-#if defined(LIBM_SCCS) && !defined(lint)
-static char rcsid[] = "$NetBSD: $";
-#endif
-
-/*
- * for non-zero x
- *	x = frexpl(arg,&exp);
- * return a long double fp quantity x such that 0.5 <= |x| <1.0
- * and the corresponding binary exponent "exp". That is
- *	arg = x*2^exp.
- * If arg is inf, 0.0, or NaN, then frexpl(arg,&exp) returns arg
- * with *exp=0.
- */
+/* Optimized frexp implementation for intel96 (x87 80-bit).
+   Copyright (C) 2025-2026 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
 
 #include <float.h>
 #include <math.h>
 #include <math_private.h>
 #include <libm-alias-ldouble.h>
 
-static const long double
-#if LDBL_MANT_DIG == 64
-two65 =  3.68934881474191032320e+19L; /* 0x4040, 0x80000000, 0x00000000 */
-#else
-# error "Cannot handle this MANT_DIG"
-#endif
+#define EXPONENT_BIAS 16383
 
+static const long double two65 = 0x1p65L;
 
-long double __frexpl(long double x, int *eptr)
+long double
+__frexpl (long double x, int *eptr)
 {
-	uint32_t se, hx, ix, lx;
-	GET_LDOUBLE_WORDS(se,hx,lx,x);
-	ix = 0x7fff&se;
-	*eptr = 0;
-	if(ix==0x7fff||((ix|hx|lx)==0)) return x + x;	/* 0,inf,nan */
-	if (ix==0x0000) {		/* subnormal */
-	    x *= two65;
-	    GET_LDOUBLE_EXP(se,x);
-	    ix = se&0x7fff;
-	    *eptr = -65;
-	}
-	*eptr += ix-16382;
-	se = (se & 0x8000) | 0x3ffe;
-	SET_LDOUBLE_EXP(x,se);
-	return x;
+  uint32_t se, hx, lx;
+  GET_LDOUBLE_WORDS (se, hx, lx, x);
+  uint32_t ex = se & 0x7fff;
+
+  /* Fast path for normal numbers.  */
+  if (__glibc_likely ((ex - 1) < 0x7ffe))
+    {
+      ex -= EXPONENT_BIAS - 1;
+      *eptr = ex;
+      SET_LDOUBLE_EXP (x, se - ex);
+      return x;
+    }
+
+  /* Handle zero, infinity, and NaN.  */
+  if (__glibc_likely (ex == 0x7fff || (ex | hx | lx) == 0))
+    {
+      *eptr = 0;
+      return x + x;
+    }
+
+  /* Subnormal.  */
+  x *= two65;
+  GET_LDOUBLE_EXP (se, x);
+
+  ex = (se & 0x7fff) - EXPONENT_BIAS + 1;
+  *eptr = ex - 65;
+  SET_LDOUBLE_EXP (x, se - ex);
+  return x;
 }
 libm_alias_ldouble (__frexp, frexp)