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compiler: Don't use memcmp for equality if struct has trailing padding. 

From-SVN: r193791
This commit is contained in:
Ian Lance Taylor 2012-11-25 00:55:35 +00:00
parent 489a33f9c1
commit 99303b325e
2 changed files with 35 additions and 25 deletions
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28
gcc/go/gofrontend/types.cc
View File

@ -2382,7 +2382,7 @@ class Error_type : public Type
protected:
bool
do_compare_is_identity(Gogo*) const
do_compare_is_identity(Gogo*)
{ return false; }
Btype*
@ -2420,7 +2420,7 @@ class Void_type : public Type
protected:
bool
do_compare_is_identity(Gogo*) const
do_compare_is_identity(Gogo*)
{ return false; }
Btype*
@ -2458,7 +2458,7 @@ class Boolean_type : public Type
protected:
bool
do_compare_is_identity(Gogo*) const
do_compare_is_identity(Gogo*)
{ return true; }
Btype*
@ -3085,7 +3085,7 @@ class Sink_type : public Type
protected:
bool
do_compare_is_identity(Gogo*) const
do_compare_is_identity(Gogo*)
{ return false; }
Btype*
@ -3963,7 +3963,7 @@ class Nil_type : public Type
protected:
bool
do_compare_is_identity(Gogo*) const
do_compare_is_identity(Gogo*)
{ return false; }
Btype*
@ -4014,7 +4014,7 @@ class Call_multiple_result_type : public Type
}
bool
do_compare_is_identity(Gogo*) const
do_compare_is_identity(Gogo*)
{ return false; }
Btype*
@ -4291,7 +4291,7 @@ Struct_type::struct_has_hidden_fields(const Named_type* within,
// comparisons.
bool
Struct_type::do_compare_is_identity(Gogo* gogo) const
Struct_type::do_compare_is_identity(Gogo* gogo)
{
const Struct_field_list* fields = this->fields_;
if (fields == NULL)
@ -4323,6 +4323,16 @@ Struct_type::do_compare_is_identity(Gogo* gogo) const
return false;
offset += field_size;
}
unsigned int struct_size;
if (!this->backend_type_size(gogo, &struct_size))
return false;
if (offset != struct_size)
{
// Trailing padding may not be zero when on the stack.
return false;
}
return true;
}
@ -5267,7 +5277,7 @@ Array_type::do_verify()
// Whether we can use memcmp to compare this array.
bool
Array_type::do_compare_is_identity(Gogo* gogo) const
Array_type::do_compare_is_identity(Gogo* gogo)
{
if (this->length_ == NULL)
return false;
@ -7968,7 +7978,7 @@ Named_type::do_has_pointer() const
// function.
bool
Named_type::do_compare_is_identity(Gogo* gogo) const
Named_type::do_compare_is_identity(Gogo* gogo)
{
// We don't use this->seen_ here because compare_is_identity may
// call base() later, and that will mess up if seen_ is set here.

32
gcc/go/gofrontend/types.h
View File

@ -576,7 +576,7 @@ class Type
// identity function which gets nothing but a pointer to the value
// and a size.
bool
compare_is_identity(Gogo* gogo) const
compare_is_identity(Gogo* gogo)
{ return this->do_compare_is_identity(gogo); }
// Return a hash code for this type for the method hash table.
@ -950,7 +950,7 @@ class Type
{ return false; }
virtual bool
do_compare_is_identity(Gogo*) const = 0;
do_compare_is_identity(Gogo*) = 0;
virtual unsigned int
do_hash_for_method(Gogo*) const;
@ -1458,7 +1458,7 @@ class Integer_type : public Type
protected:
bool
do_compare_is_identity(Gogo*) const
do_compare_is_identity(Gogo*)
{ return true; }
unsigned int
@ -1535,7 +1535,7 @@ class Float_type : public Type
protected:
bool
do_compare_is_identity(Gogo*) const
do_compare_is_identity(Gogo*)
{ return false; }
unsigned int
@ -1604,7 +1604,7 @@ class Complex_type : public Type
protected:
bool
do_compare_is_identity(Gogo*) const
do_compare_is_identity(Gogo*)
{ return false; }
unsigned int
@ -1664,7 +1664,7 @@ class String_type : public Type
{ return true; }
bool
do_compare_is_identity(Gogo*) const
do_compare_is_identity(Gogo*)
{ return false; }
Btype*
@ -1778,7 +1778,7 @@ class Function_type : public Type
{ return true; }
bool
do_compare_is_identity(Gogo*) const
do_compare_is_identity(Gogo*)
{ return false; }
unsigned int
@ -1853,7 +1853,7 @@ class Pointer_type : public Type
{ return true; }
bool
do_compare_is_identity(Gogo*) const
do_compare_is_identity(Gogo*)
{ return true; }
unsigned int
@ -2139,7 +2139,7 @@ class Struct_type : public Type
do_has_pointer() const;
bool
do_compare_is_identity(Gogo*) const;
do_compare_is_identity(Gogo*);
unsigned int
do_hash_for_method(Gogo*) const;
@ -2272,7 +2272,7 @@ class Array_type : public Type
}
bool
do_compare_is_identity(Gogo*) const;
do_compare_is_identity(Gogo*);
unsigned int
do_hash_for_method(Gogo*) const;
@ -2365,7 +2365,7 @@ class Map_type : public Type
{ return true; }
bool
do_compare_is_identity(Gogo*) const
do_compare_is_identity(Gogo*)
{ return false; }
unsigned int
@ -2451,7 +2451,7 @@ class Channel_type : public Type
{ return true; }
bool
do_compare_is_identity(Gogo*) const
do_compare_is_identity(Gogo*)
{ return true; }
unsigned int
@ -2582,7 +2582,7 @@ class Interface_type : public Type
{ return true; }
bool
do_compare_is_identity(Gogo*) const
do_compare_is_identity(Gogo*)
{ return false; }
unsigned int
@ -2865,7 +2865,7 @@ class Named_type : public Type
do_has_pointer() const;
bool
do_compare_is_identity(Gogo*) const;
do_compare_is_identity(Gogo*);
unsigned int
do_hash_for_method(Gogo*) const;
@ -2949,7 +2949,7 @@ class Named_type : public Type
// function exits.
mutable bool seen_;
// Like seen_, but used only by do_compare_is_identity.
mutable bool seen_in_compare_is_identity_;
bool seen_in_compare_is_identity_;
// Like seen_, but used only by do_get_backend.
bool seen_in_get_backend_;
};
@ -3004,7 +3004,7 @@ class Forward_declaration_type : public Type
{ return this->real_type()->has_pointer(); }
bool
do_compare_is_identity(Gogo* gogo) const
do_compare_is_identity(Gogo* gogo)
{ return this->real_type()->compare_is_identity(gogo); }
unsigned int