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Re-apply r201292. We're not going to enforce proper stack frame alignment on i386/x86_64 

because there are too many trap handlers that will have an improperly aligned caller sp 
and this will cause the unwinder to stop too early.  

llvm-svn: 201637
This commit is contained in:
Jason Molenda 2014-02-19 03:42:19 +00:00
parent b50b23f9ac
commit 9c37cbdb86
3 changed files with 36 additions and 39 deletions
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22
lldb/source/Plugins/ABI/MacOSX-i386/ABIMacOSX_i386.cpp
View File

@ -235,22 +235,12 @@ ABIMacOSX_i386::GetRedZoneSize () const
ABISP
ABIMacOSX_i386::CreateInstance (const ArchSpec &arch)
{
static ABISP g_abi_mac_sp;
static ABISP g_abi_other_sp;
if (arch.GetTriple().getArch() == llvm::Triple::x86)
{
if (arch.GetTriple().isOSDarwin())
{
if (!g_abi_mac_sp)
g_abi_mac_sp.reset (new ABIMacOSX_i386(true));
return g_abi_mac_sp;
}
else
{
if (!g_abi_other_sp)
g_abi_other_sp.reset (new ABIMacOSX_i386(false));
return g_abi_other_sp;
}
static ABISP g_abi_sp;
if (arch.GetTriple().getArch() == llvm::Triple::x86)
{
if (!g_abi_sp)
g_abi_sp.reset (new ABIMacOSX_i386);
return g_abi_sp;
}
return ABISP();
}

37
lldb/source/Plugins/ABI/MacOSX-i386/ABIMacOSX_i386.h
View File

@ -71,24 +71,25 @@ public:
return true;
}
// The Darwin i386 ABI requires that stack frames be 16 byte aligned.
// When there is a trap handler on the stack, e.g. _sigtramp in userland
// code, we've seen that the stack pointer is often not aligned properly
// before the handler is invoked. This means that lldb will stop the unwind
// early -- before the function which caused the trap.
//
// To work around this, we relax that alignment to be just word-size (4-bytes).
// Whitelisting the trap handlers for user space would be easy (_sigtramp) but
// in other environments there can be a large number of different functions
// involved in async traps.
//
// If we were to enforce 16-byte alignment, we also need to relax to 4-byte
// alignment for non-darwin i386 targets.
virtual bool
CallFrameAddressIsValid (lldb::addr_t cfa)
{
// Darwin call frame addresses must be 16-byte aligned, but other OS's
// only need 4-byte alignment. Otherwise the ABI matches, so we have
// this one minor override here.
if (target_is_darwin)
{
// Make sure the stack call frame addresses are are 16 byte aligned
if (cfa & (16ull - 1ull))
return false; // Not 16 byte aligned
}
else
{
// Make sure the stack call frame addresses are are 4 byte aligned
if (cfa & (4ull - 1ull))
return false; // Not 4 byte aligned
}
// Make sure the stack call frame addresses are are 4 byte aligned
if (cfa & (4ull - 1ull))
return false; // Not 4 byte aligned
if (cfa == 0)
return false; // Zero is not a valid stack address
return true;
@ -139,11 +140,7 @@ protected:
RegisterIsCalleeSaved (const lldb_private::RegisterInfo *reg_info);
private:
ABIMacOSX_i386(bool is_darwin) : lldb_private::ABI(),
target_is_darwin(is_darwin)
{ } // Call CreateInstance instead.
bool target_is_darwin;
ABIMacOSX_i386() : lldb_private::ABI() { } // Call CreateInstance instead.
};

16
lldb/source/Plugins/ABI/SysV-x86_64/ABISysV_x86_64.h
View File

@ -68,12 +68,22 @@ public:
return true;
}
// The SysV x86_64 ABI requires that stack frames be 16 byte aligned.
// When there is a trap handler on the stack, e.g. _sigtramp in userland
// code, we've seen that the stack pointer is often not aligned properly
// before the handler is invoked. This means that lldb will stop the unwind
// early -- before the function which caused the trap.
//
// To work around this, we relax that alignment to be just word-size (8-bytes).
// Whitelisting the trap handlers for user space would be easy (_sigtramp) but
// in other environments there can be a large number of different functions
// involved in async traps.
virtual bool
CallFrameAddressIsValid (lldb::addr_t cfa)
{
// Make sure the stack call frame addresses are 16 byte aligned
if (cfa & (16ull - 1ull))
return false; // Not 16 byte aligned
// Make sure the stack call frame addresses are 8 byte aligned
if (cfa & (8ull - 1ull))
return false; // Not 8 byte aligned
if (cfa == 0)
return false; // Zero is not a valid stack address
return true;