Bug 603370 - Avoid Identical Code Folding messing with symbol reorder…

…ing. r=khuey

build/autoconf/compiler-opts.m4

@@ -41,7 +41,13 @@ if test "$GNU_CC" -a "$GCC_USE_GNU_LD" -a -z "$MOZ_DISABLE_ICF"; then
         fi
         rm -rf conftest*])
     if test "$LD_SUPPORTS_ICF" = yes; then
-        LDFLAGS="$LDFLAGS -Wl,--icf=safe"
+        _SAVE_LDFLAGS="$LDFLAGS -Wl,--icf=safe"
+        LDFLAGS="$LDFLAGS -Wl,--icf=safe -Wl,--print-icf-sections"
+        AC_TRY_LINK([], [],
+                    [LD_PRINT_ICF_SECTIONS=-Wl,--print-icf-sections],
+                    [LD_PRINT_ICF_SECTIONS=])
+        AC_SUBST([LD_PRINT_ICF_SECTIONS])
+        LDFLAGS="$_SAVE_LDFLAGS"
     fi
 fi
 

config/expandlibs_config.py.in

@@ -55,3 +55,4 @@ IMPORT_LIB_SUFFIX = normalize_suffix("@IMPORT_LIB_SUFFIX@")
 LIBS_DESC_SUFFIX = normalize_suffix("@LIBS_DESC_SUFFIX@")
 EXPAND_LIBS_LIST_STYLE = "@EXPAND_LIBS_LIST_STYLE@"
 EXPAND_LIBS_ORDER_STYLE = "@EXPAND_LIBS_ORDER_STYLE@"
+LD_PRINT_ICF_SECTIONS = "@LD_PRINT_ICF_SECTIONS@"

config/expandlibs_exec.py

@@ -141,16 +141,54 @@ def makelist(self):
         newlist = self[0:idx] + [ref] + [item for item in self[idx:] if item not in objs]
         self[0:] = newlist
 
+    def _getFoldedSections(self):
+        '''Returns a dict about folded sections.
+        When section A and B are folded into section C, the dict contains:
+        { 'A': 'C',
+          'B': 'C',
+          'C': ['A', 'B'] }'''
+        if not conf.LD_PRINT_ICF_SECTIONS:
+            return {}
+
+        proc = subprocess.Popen(self + [conf.LD_PRINT_ICF_SECTIONS], stdout = subprocess.PIPE, stderr = subprocess.PIPE)
+        (stdout, stderr) = proc.communicate()
+        result = {}
+        # gold's --print-icf-sections output looks like the following:
+        # ld: ICF folding section '.section' in file 'file.o'into '.section' in file 'file.o'
+        # In terms of words, chances are this will change in the future,
+        # especially considering "into" is misplaced. Splitting on quotes
+        # seems safer.
+        for l in stderr.split('\n'):
+            quoted = l.split("'")
+            if len(quoted) > 5 and quoted[1] != quoted[5]:
+                result[quoted[1]] = quoted[5]
+                if quoted[5] in result:
+                    result[quoted[5]].append(quoted[1])
+                else:
+                    result[quoted[5]] = [quoted[1]]
+        return result
+
     def _getOrderedSections(self, ordered_symbols):
         '''Given an ordered list of symbols, returns the corresponding list
         of sections following the order.'''
         if not conf.EXPAND_LIBS_ORDER_STYLE in ['linkerscript', 'section-ordering-file']:
             raise Exception('EXPAND_LIBS_ORDER_STYLE "%s" is not supported' % conf.EXPAND_LIBS_ORDER_STYLE)
         finder = SectionFinder([arg for arg in self if isObject(arg) or os.path.splitext(arg)[1] == conf.LIB_SUFFIX])
+        folded = self._getFoldedSections()
         sections = set()
         ordered_sections = []
         for symbol in ordered_symbols:
-            for section in finder.getSections(symbol):
+            symbol_sections = finder.getSections(symbol)
+            all_symbol_sections = []
+            for section in symbol_sections:
+                if section in folded:
+                    if isinstance(folded[section], str):
+                        section = folded[section]
+                    all_symbol_sections.append(section)
+                    all_symbol_sections.extend(folded[section])
+                else:
+                    all_symbol_sections.append(section)
+            for section in all_symbol_sections:
                 if not section in sections:
                     ordered_sections.append(section)
                     sections.add(section)

config/tests/unit-expandlibs.py

@@ -268,11 +268,12 @@ def call(args, **kargs):
         subprocess.call = subprocess_call
 
 class FakeProcess(object):
-    def __init__(self, out):
+    def __init__(self, out, err = ''):
         self.out = out
+        self.err = err
 
     def communicate(self):
-        return (self.out, '')
+        return (self.out, self.err)
 
 OBJDUMPS = {
 'foo.o': '''
@@ -287,25 +288,31 @@ def communicate(self):
 ''',
 }
 
-class ObjdumpSubprocessPopen(object):
+PRINT_ICF = '''
+ld: ICF folding section '.text.hello' in file 'foo.o'into '.text.hi' in file 'bar.o'
+ld: ICF folding section '.foo' in file 'foo.o'into '.foo' in file 'bar.o'
+'''
+
+class SubprocessPopen(object):
     def __init__(self, test):
         self.test = test
 
     def __call__(self, args, stdout = None, stderr = None):
         self.test.assertEqual(stdout, subprocess.PIPE)
         self.test.assertEqual(stderr, subprocess.PIPE)
-        self.test.assertEqual(args[0], 'objdump')
-        self.test.assertEqual(args[1], '-t')
-        self.test.assertTrue(args[2] in OBJDUMPS)
-
-        return FakeProcess(OBJDUMPS[args[2]])
+        if args[0] == 'objdump':
+            self.test.assertEqual(args[1], '-t')
+            self.test.assertTrue(args[2] in OBJDUMPS)
+            return FakeProcess(OBJDUMPS[args[2]])
+        else:
+            return FakeProcess('', PRINT_ICF)
 
 class TestSectionFinder(unittest.TestCase):
     def test_getSections(self):
         '''Test SectionFinder'''
         # Divert subprocess.Popen
         subprocess_popen = subprocess.Popen
-        subprocess.Popen = ObjdumpSubprocessPopen(self)
+        subprocess.Popen = SubprocessPopen(self)
         config.EXPAND_LIBS_ORDER_STYLE = 'linkerscript'
         config.OBJ_SUFFIX = '.o'
         config.LIB_SUFFIX = '.a'
@@ -321,14 +328,40 @@ def test_getOrderedSections(self):
         '''Test ExpandMoreArgs' _getOrderedSections'''
         # Divert subprocess.Popen
         subprocess_popen = subprocess.Popen
-        subprocess.Popen = ObjdumpSubprocessPopen(self)
+        subprocess.Popen = SubprocessPopen(self)
         config.EXPAND_LIBS_ORDER_STYLE = 'linkerscript'
         config.OBJ_SUFFIX = '.o'
         config.LIB_SUFFIX = '.a'
+        config.LD_PRINT_ICF_SECTIONS = ''
         args = ExpandArgsMore(['foo', '-bar', 'bar.o', 'foo.o'])
         self.assertEqual(args._getOrderedSections(['_Z6foobarv', '_Z6barbazv']), ['.text._Z6foobarv', '.text._ZThn4_6foobarv', '.text.hot._Z6barbazv'])
         self.assertEqual(args._getOrderedSections(['_ZThn4_6foobarv', '_Z6barbazv']), ['.text._Z6foobarv', '.text._ZThn4_6foobarv', '.text.hot._Z6barbazv'])
         subprocess.Popen = subprocess_popen
 
+    def test_getFoldedSections(self):
+        '''Test ExpandMoreArgs' _getFoldedSections'''
+        # Divert subprocess.Popen
+        subprocess_popen = subprocess.Popen
+        subprocess.Popen = SubprocessPopen(self)
+        config.LD_PRINT_ICF_SECTIONS = '-Wl,--print-icf-sections'
+        args = ExpandArgsMore(['foo', '-bar', 'bar.o', 'foo.o'])
+        self.assertEqual(args._getFoldedSections(), {'.text.hello': '.text.hi', '.text.hi': ['.text.hello']})
+        subprocess.Popen = subprocess_popen
+
+    def test_getOrderedSectionsWithICF(self):
+        '''Test ExpandMoreArgs' _getOrderedSections, with ICF'''
+        # Divert subprocess.Popen
+        subprocess_popen = subprocess.Popen
+        subprocess.Popen = SubprocessPopen(self)
+        config.EXPAND_LIBS_ORDER_STYLE = 'linkerscript'
+        config.OBJ_SUFFIX = '.o'
+        config.LIB_SUFFIX = '.a'
+        config.LD_PRINT_ICF_SECTIONS = '-Wl,--print-icf-sections'
+        args = ExpandArgsMore(['foo', '-bar', 'bar.o', 'foo.o'])
+        self.assertEqual(args._getOrderedSections(['hello', '_Z6barbazv']), ['.text.hi', '.text.hello', '.text.hot._Z6barbazv'])
+        self.assertEqual(args._getOrderedSections(['_ZThn4_6foobarv', 'hi', '_Z6barbazv']), ['.text._Z6foobarv', '.text._ZThn4_6foobarv', '.text.hi', '.text.hello', '.text.hot._Z6barbazv'])
+        subprocess.Popen = subprocess_popen
+
+
 if __name__ == '__main__':
     unittest.main(testRunner=MozTestRunner())

js/src/build/autoconf/compiler-opts.m4

@@ -41,7 +41,13 @@ if test "$GNU_CC" -a "$GCC_USE_GNU_LD" -a -z "$MOZ_DISABLE_ICF"; then
         fi
         rm -rf conftest*])
     if test "$LD_SUPPORTS_ICF" = yes; then
-        LDFLAGS="$LDFLAGS -Wl,--icf=safe"
+        _SAVE_LDFLAGS="$LDFLAGS -Wl,--icf=safe"
+        LDFLAGS="$LDFLAGS -Wl,--icf=safe -Wl,--print-icf-sections"
+        AC_TRY_LINK([], [],
+                    [LD_PRINT_ICF_SECTIONS=-Wl,--print-icf-sections],
+                    [LD_PRINT_ICF_SECTIONS=])
+        AC_SUBST([LD_PRINT_ICF_SECTIONS])
+        LDFLAGS="$_SAVE_LDFLAGS"
     fi
 fi
 

js/src/config/expandlibs_config.py.in

@@ -55,3 +55,4 @@ IMPORT_LIB_SUFFIX = normalize_suffix("@IMPORT_LIB_SUFFIX@")
 LIBS_DESC_SUFFIX = normalize_suffix("@LIBS_DESC_SUFFIX@")
 EXPAND_LIBS_LIST_STYLE = "@EXPAND_LIBS_LIST_STYLE@"
 EXPAND_LIBS_ORDER_STYLE = "@EXPAND_LIBS_ORDER_STYLE@"
+LD_PRINT_ICF_SECTIONS = "@LD_PRINT_ICF_SECTIONS@"

js/src/config/expandlibs_exec.py

@@ -141,16 +141,54 @@ def makelist(self):
         newlist = self[0:idx] + [ref] + [item for item in self[idx:] if item not in objs]
         self[0:] = newlist
 
+    def _getFoldedSections(self):
+        '''Returns a dict about folded sections.
+        When section A and B are folded into section C, the dict contains:
+        { 'A': 'C',
+          'B': 'C',
+          'C': ['A', 'B'] }'''
+        if not conf.LD_PRINT_ICF_SECTIONS:
+            return {}
+
+        proc = subprocess.Popen(self + [conf.LD_PRINT_ICF_SECTIONS], stdout = subprocess.PIPE, stderr = subprocess.PIPE)
+        (stdout, stderr) = proc.communicate()
+        result = {}
+        # gold's --print-icf-sections output looks like the following:
+        # ld: ICF folding section '.section' in file 'file.o'into '.section' in file 'file.o'
+        # In terms of words, chances are this will change in the future,
+        # especially considering "into" is misplaced. Splitting on quotes
+        # seems safer.
+        for l in stderr.split('\n'):
+            quoted = l.split("'")
+            if len(quoted) > 5 and quoted[1] != quoted[5]:
+                result[quoted[1]] = quoted[5]
+                if quoted[5] in result:
+                    result[quoted[5]].append(quoted[1])
+                else:
+                    result[quoted[5]] = [quoted[1]]
+        return result
+
     def _getOrderedSections(self, ordered_symbols):
         '''Given an ordered list of symbols, returns the corresponding list
         of sections following the order.'''
         if not conf.EXPAND_LIBS_ORDER_STYLE in ['linkerscript', 'section-ordering-file']:
             raise Exception('EXPAND_LIBS_ORDER_STYLE "%s" is not supported' % conf.EXPAND_LIBS_ORDER_STYLE)
         finder = SectionFinder([arg for arg in self if isObject(arg) or os.path.splitext(arg)[1] == conf.LIB_SUFFIX])
+        folded = self._getFoldedSections()
         sections = set()
         ordered_sections = []
         for symbol in ordered_symbols:
-            for section in finder.getSections(symbol):
+            symbol_sections = finder.getSections(symbol)
+            all_symbol_sections = []
+            for section in symbol_sections:
+                if section in folded:
+                    if isinstance(folded[section], str):
+                        section = folded[section]
+                    all_symbol_sections.append(section)
+                    all_symbol_sections.extend(folded[section])
+                else:
+                    all_symbol_sections.append(section)
+            for section in all_symbol_sections:
                 if not section in sections:
                     ordered_sections.append(section)
                     sections.add(section)