llvm-svn: 12317

llvm-svn: 12225

llvm-svn: 12224

llvm-svn: 12221

This allows pointers to aggregate objects, whose elements are only read, to
be promoted and passed in by element instead of by reference.  This can
enable a LOT of subsequent optimizations in the caller function.

It's worth pointing out that this stuff happens a LOT of C++ programs, because
objects in templates are generally passed around by reference.  When these
templates are instantiated on small aggregate or scalar types, however, it is
more efficient to pass them in by value than by reference.

This transformation triggers most on C++ codes (e.g. 334 times on eon), but
does happen on C codes as well.  For example, on mesa it triggers 72 times,
and on gcc it triggers 35 times.  this is amazingly good considering that
we are using 'basicaa' so far.

llvm-svn: 12202

llvm-svn: 12200

llvm-svn: 12198

a zero value is the most likely way to cause further simplification, so we do it.

llvm-svn: 12197

llvm-svn: 12195

variables.

llvm-svn: 12193

llvm-svn: 12086

llvm-svn: 12070

llvm-svn: 12068

* Add comments to ExtractLoop()

llvm-svn: 12053

llvm-svn: 12021

* Removing extraneous empty space and empty comment lines

llvm-svn: 12014

... which tickled the lowerinvoke pass because it used the BCE routines.

llvm-svn: 12012

Note that this is a band-aid put over a band-aid.  This just undisables
tail duplication in on very specific case that it seems to work in.

llvm-svn: 11989

and br->br code and generalizing it.  This allows us to compile code like this:

int test(Instruction *I) {
  if (isa<CastInst>(I))
    return foo(7);
  else if (isa<BranchInst>(I))
    return foo(123);
  else if (isa<UnwindInst>(I))
    return foo(1241);
  else if (isa<SetCondInst>(I))
    return foo(1);
  else if (isa<VAArgInst>(I))
    return foo(42);
  return foo(-1);
}

into:

int %_Z4testPN4llvm11InstructionE("struct.llvm::Instruction"* %I) {
entry:
        %tmp.1.i.i.i.i.i.i.i = getelementptr "struct.llvm::Instruction"* %I, long 0, ubyte 4            ; <uint*> [#uses=1]
        %tmp.2.i.i.i.i.i.i.i = load uint* %tmp.1.i.i.i.i.i.i.i          ; <uint> [#uses=2]
        %tmp.2.i.i.i.i.i.i = seteq uint %tmp.2.i.i.i.i.i.i.i, 27                ; <bool> [#uses=0]
        switch uint %tmp.2.i.i.i.i.i.i.i, label %endif.0 [
                 uint 27, label %then.0
                 uint 2, label %then.1
                 uint 5, label %then.2
                 uint 14, label %then.3
                 uint 15, label %then.3
                 uint 16, label %then.3
                 uint 17, label %then.3
                 uint 18, label %then.3
                 uint 19, label %then.3
                 uint 32, label %then.4
        ]
...

As well as handling the cases in 176.gcc and many other programs more effectively.

llvm-svn: 11964

Do not just inject a new prototype.

llvm-svn: 11951

Create a new AddUsesToWorkList method
optimize memmove/set/cpy of zero bytes to a noop.

llvm-svn: 11941

llvm-svn: 11940

llvm-svn: 11939

function, as long as the loop isn't the only one in that function. This should
help debugging passes easier with BugPoint.

llvm-svn: 11936

a new function, taking care of inputs and outputs.

llvm-svn: 11935

llvm-svn: 11919

This is a really minor thing, but might help out the 'switch statement induction'
code in simplifycfg.

llvm-svn: 11900

multiple type names for the same structural type.  Make DTE eliminate all
but one of the type names

llvm-svn: 11879

   if (X == 0 || X == 2)

...where the comparisons and branches are in different blocks... into a switch
instruction.  This comes up a lot in various programs, and works well with
the switch/switch merging code I checked earlier.  For example, this testcase:

int switchtest(int C) {
  return C == 0 ? f(123) :
         C == 1 ? f(3123) :
         C == 4 ? f(312) :
         C == 5 ? f(1234): f(444);
}

is converted into this:
        switch int %C, label %cond_false.3 [
                 int 0, label %cond_true.0
                 int 1, label %cond_true.1
                 int 4, label %cond_true.2
                 int 5, label %cond_true.3
        ]

instead of a whole bunch of conditional branches.

Admittedly the code is ugly, and incomplete.  To be complete, we need to add
br -> switch merging and switch -> br merging.  For example, this testcase:

struct foo { int Q, R, Z; };
#define A (X->Q+X->R * 123)
int test(struct foo *X) {
  return A  == 123 ? X1() :
        A == 12321 ? X2():
        (A == 111 || A == 222) ? X3() :
        A == 875 ? X4() : X5();
}

Gets compiled to this:
        switch int %tmp.7, label %cond_false.2 [
                 int 123, label %cond_true.0
                 int 12321, label %cond_true.1
                 int 111, label %cond_true.2
                 int 222, label %cond_true.2
        ]
...
cond_false.2:           ; preds = %entry
        %tmp.52 = seteq int %tmp.7, 875         ; <bool> [#uses=1]
        br bool %tmp.52, label %cond_true.3, label %cond_false.3

where the branch could be folded into the switch.

This kind of thing occurs *ALL OF THE TIME*, especially in programs like
176.gcc, which is a horrible mess of code.  It contains stuff like *shudder*:

#define SWITCH_TAKES_ARG(CHAR) \
  (   (CHAR) == 'D' \
   || (CHAR) == 'U' \
   || (CHAR) == 'o' \
   || (CHAR) == 'e' \
   || (CHAR) == 'u' \
   || (CHAR) == 'I' \
   || (CHAR) == 'm' \
   || (CHAR) == 'L' \
   || (CHAR) == 'A' \
   || (CHAR) == 'h' \
   || (CHAR) == 'z')

and

#define CONST_OK_FOR_LETTER_P(VALUE, C)                 \
  ((C) == 'I' ? SMALL_INTVAL (VALUE)                    \
   : (C) == 'J' ? SMALL_INTVAL (-(VALUE))               \
   : (C) == 'K' ? (unsigned)(VALUE) < 32                \
   : (C) == 'L' ? ((VALUE) & 0xffff) == 0               \
   : (C) == 'M' ? integer_ok_for_set (VALUE)            \
   : (C) == 'N' ? (VALUE) < 0                           \
   : (C) == 'O' ? (VALUE) == 0                          \
   : (C) == 'P' ? (VALUE) >= 0                          \
   : 0)

and

#define LEGITIMIZE_ADDRESS(X,OLDX,MODE,WIN)                     \
{                                                               \
  if (GET_CODE (X) == PLUS && CONSTANT_ADDRESS_P (XEXP (X, 1))) \
    (X) = gen_rtx (PLUS, SImode, XEXP (X, 0),                   \
                   copy_to_mode_reg (SImode, XEXP (X, 1)));     \
  if (GET_CODE (X) == PLUS && CONSTANT_ADDRESS_P (XEXP (X, 0))) \
    (X) = gen_rtx (PLUS, SImode, XEXP (X, 1),                   \
                   copy_to_mode_reg (SImode, XEXP (X, 0)));     \
  if (GET_CODE (X) == PLUS && GET_CODE (XEXP (X, 0)) == MULT)   \
    (X) = gen_rtx (PLUS, SImode, XEXP (X, 1),                   \
                   force_operand (XEXP (X, 0), 0));             \
  if (GET_CODE (X) == PLUS && GET_CODE (XEXP (X, 1)) == MULT)   \
    (X) = gen_rtx (PLUS, SImode, XEXP (X, 0),                   \
                   force_operand (XEXP (X, 1), 0));             \
  if (GET_CODE (X) == PLUS && GET_CODE (XEXP (X, 0)) == PLUS)   \
    (X) = gen_rtx (PLUS, Pmode, force_operand (XEXP (X, 0), NULL_RTX),\
                   XEXP (X, 1));                                \
  if (GET_CODE (X) == PLUS && GET_CODE (XEXP (X, 1)) == PLUS)   \
    (X) = gen_rtx (PLUS, Pmode, XEXP (X, 0),                    \
                   force_operand (XEXP (X, 1), NULL_RTX));      \
  if (GET_CODE (X) == SYMBOL_REF || GET_CODE (X) == CONST       \
           || GET_CODE (X) == LABEL_REF)                        \
    (X) = legitimize_address (flag_pic, X, 0, 0);               \
  if (memory_address_p (MODE, X))                               \
    goto WIN; }

and others.  These macros get used multiple times of course.  These are such
lovely candidates for macros, aren't they?  :)

This code also nicely handles LLVM constructs that look like this:

  if (isa<CastInst>(I))
   ...
  else if (isa<BranchInst>(I))
   ...
  else if (isa<SetCondInst>(I))
   ...
  else if (isa<UnwindInst>(I))
   ...
  else if (isa<VAArgInst>(I))
   ...

where the isa can obviously be a dyn_cast as well.  Switch instructions are a
good thing.

llvm-svn: 11870

assume that if they don't intend to write to a global variable, that they
would mark it as constant.  However, there are people that don't understand
that the compiler can do nice things for them if they give it the information
it needs.

This pass looks for blatently obvious globals that are only ever read from.
Though it uses a trivially simple "alias analysis" of sorts, it is still able
to do amazing things to important benchmarks.  253.perlbmk, for example,
contains several ***GIANT*** function pointer tables that are not marked
constant and should be.  Marking them constant allows the optimizer to turn
a whole bunch of indirect calls into direct calls.  Note that only a link-time
optimizer can do this transformation, but perlbmk does have several strings
and other minor globals that can be marked constant by this pass when run
from GCCAS.

176.gcc has a ton of strings and large tables that are marked constant, both
at compile time (38 of them) and at link time (48 more).  Other benchmarks
give similar results, though it seems like big ones have disproportionally
more than small ones.

This pass is extremely quick and does good things.  I'm going to enable it
in gccas & gccld.  Not bad for 50 SLOC.

llvm-svn: 11836

llvm-svn: 11821

llvm-svn: 11801

llvm-svn: 11799

This case occurs many times in various benchmarks, especially when combined
with the previous patch.  This allows it to get stuff like:
  if (X == 4 || X == 3)
    if (X == 5 || X == 8)

and

switch (X) {
case 4: case 5: case 6:
  if (X == 4 || X == 5)

llvm-svn: 11797

llvm-svn: 11793

This turns code like this:
  if (X == 4 | X == 7)
and
  if (X != 4 & X != 7)
into switch instructions.

llvm-svn: 11792

llvm-svn: 11775

llvm-svn: 11774

Also, turn 'shr int %X, 1234' into 'shr int %X, 31'

llvm-svn: 11768

llvm-svn: 11742