llvm-svn: 37408

(landing pad) when an exception unwinds through the call.  This doesn't
quite match the way the dwarf unwinder works: by default it only jumps to
the landing pad if the catch or filter specification matches, and otherwise
it keeps on unwinding.  There are two ways of specifying to the unwinder
that it should "always" (more on why there are quotes here later) jump to
the landing pad: follow the specification by a 0 typeid, or follow it by
the typeid for the NULL typeinfo.  GCC does the first, and this patch makes
LLVM do the same as gcc.  However there is a problem: the unwinder performs
optimizations based on C++ semantics (it only expects destructors to be
run if the 0 typeid fires - known as "cleanups"), meaning it assumes that no
exceptions will be raised and that the raised exception will be reraised
at the end of the cleanup code.  So if someone writes their own LLVM code
using the exception intrinsics they will get a nasty surprise if they don't
follow these rules.  The other possibility of using the typeid corresponding
to NULL (catch-all) causes the unwinder to make no assumptions, so this is
probably what we should use in the long-run.  However since we are still
having trouble getting exception handling working properly, for the moment
it seems best to closely imitate GCC.

llvm-svn: 37399

simplifies the code in DwarfWriter, allows for multiple filters and
makes it trivial to specify filters accompanied by cleanups or catch-all
specifications (see next patch).  What a deal!  Patch blessed by Anton.

llvm-svn: 37398

llvm-svn: 37397

llvm-svn: 37394

llvm-svn: 37393

See test/CodeGen/X86/test-pic-jtbl.ll for a case where it works well;
shaves another 10K off our favorite benchmark.  I was hesitant about
this because of compile speed, but seems to do OK on a bootstrap.

llvm-svn: 37392

llvm-svn: 37387

as a null i8 pointer not as a 0 i32.

llvm-svn: 37383

Ifcvt triangle: don't ifcvt 'true' BB if it has other predecessors; don't merge 'false' BB if it has other predecessors.

llvm-svn: 37382

Remove a bogus check. Even terminators in a ifcvt need to be predicated. Unconditional branches can usually be converted to conditional ones.

llvm-svn: 37380

llvm-svn: 37379

Do not remove empty landing pads (EH table needs to be updated)

llvm-svn: 37375

llvm-svn: 37374

smaller than the preferred alignment, but so that the target can actually
specify a minimum alignment if needed.  This fixes some objc protocol
failures Devang tracked down.

llvm-svn: 37373

When a function has FP, the register scavenging spill slot offset already
was calculated.

llvm-svn: 37371

llvm-svn: 37365

llvm-svn: 37362

llvm-svn: 37355

matter until my last change).  Reenable tail merging by default.

llvm-svn: 37354

llvm-svn: 37353

If there is an empty block between a source and its successor block, it still requires a unconditional branch.

llvm-svn: 37344

llvm-svn: 37341

llvm-svn: 37331

llvm-svn: 37330

llvm-svn: 37328

only one successor.

llvm-svn: 37324

Temporarily, this breaks CodeGen/Generic/2006-02-12-InsertLibraryCall.ll
by exposing an unrelated latent problem; working on that.

llvm-svn: 37323

llvm-svn: 37321

llvm-svn: 37320

Fix a typo that caused combiner to create mal-formed pre-indexed store where value store is the same as the base pointer.

llvm-svn: 37318

When considering blocks with more than 2 predecessors, merge the block with
the largest number of matching insns, rather than the first block found.
Considering that 1 matching insn is enough to show a win for candidates that
already end with a branch.

llvm-svn: 37315

Mark all calls as "could throw", when exceptions are enabled. Emit necessary LP info too. This fixes PR1439

llvm-svn: 37311

llvm-svn: 37310

llvm-svn: 37309

llvm-svn: 37289

llvm-svn: 37288

for a target-dependent default with a command-line override; this way
should be generally usable.

llvm-svn: 37285

llvm-svn: 37270

it occurs for multiple landing pads.

llvm-svn: 37267