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Author SHA1 Message Date
Chris Lattner f12c4a3d37 *FINALLY* Fix a really nasty nondeterministic bug that has been haunting us 
since May 1st.  In this code, the pred iterator was being invalidated sometimes
causing the wrong entries to be added to PHI nodes.

The fix for this is to defererence and safe the *PI value before we hack on
branch instructions, which changes use/def chains, which SOMETIMES invalidates
the iterator.

llvm-svn: 14278
 2004-06-21 07:19:01 +00:00
Chris Lattner 9734fd0980 Add some DEBUG output to the simplifycfg routines 
Fix another non-deterministic behavior, this one should actually speed up the
code though as it was doing silly things.

llvm-svn: 14258
 2004-06-20 01:13:18 +00:00
Chris Lattner b2b151d297 Do not sort by the address of LLVM ConstantInt* objects. This produces 
nondeterministic results that depend on where these objects land in memory.
Instead, sort by the value of the constant, which is stable.

Before this patch, the -simplifycfg pass run from two different compilers
could cause different code to be generated, though it was semantically the
same:

@@ -12258,8 +12258,8 @@
        %s_addr.1 = phi sbyte* [ %s, %entry ], [ %inc.0, %no_exit ]             ; <sbyte*> [#uses=5]
        %tmp.1 = load sbyte* %s_addr.1          ; <sbyte> [#uses=1]
        switch sbyte %tmp.1, label %no_exit [
-                sbyte 0, label %loopexit
                 sbyte 46, label %loopexit
+                sbyte 0, label %loopexit
        ]

We need to stomp all of this stuff out.

llvm-svn: 14243
 2004-06-19 07:02:14 +00:00
Chris Lattner be6f06818c Do not clone arbitrary condition instructions. 
llvm-svn: 13316
 2004-05-02 05:19:36 +00:00
Chris Lattner 51a6dbcb65 Do not infinitely "unroll" single BB loops. 
llvm-svn: 13315
 2004-05-02 05:02:03 +00:00
Chris Lattner 1e94ed606e Dont' merge terminators that are needed to select PHI node values. 
llvm-svn: 13312
 2004-05-02 01:00:44 +00:00
Chris Lattner 2e93c4275e Implement SimplifyCFG/branch-cond-merge.ll 
Turning "if (A < B && B < C)" into "if (A < B & B < C)"

llvm-svn: 13311
 2004-05-01 23:35:43 +00:00
Chris Lattner 4cbd160b45 Fix my missing parens 
llvm-svn: 13307
 2004-05-01 22:41:51 +00:00
Chris Lattner 88da6f7b52 Implement SimplifyCFG/branch-cond-prop.ll 
llvm-svn: 13306
 2004-05-01 22:36:37 +00:00
Chris Lattner 0aa565647c Fold code like: 
if (C)
    V1 |= V2;

into:
  Vx = V1 | V2;
  V1 = select C, V1, Vx

when the expression can be evaluated unconditionally and is *cheap* to
execute.  This limited form of if conversion is quite handy in lots of cases.
For example, it turns this testcase into straight-line code:

int in0 ; int in1 ; int in2 ; int in3 ;
int in4 ; int in5 ; int in6 ; int in7 ;
int in8 ; int in9 ; int in10; int in11;
int in12; int in13; int in14; int in15;
long output;

void mux(void) {
  output =
      (in0   ?  0x00000001 : 0) | (in1   ?  0x00000002 : 0) |
      (in2   ?  0x00000004 : 0) | (in3   ?  0x00000008 : 0) |
      (in4   ?  0x00000010 : 0) | (in5   ?  0x00000020 : 0) |
      (in6   ?  0x00000040 : 0) | (in7   ?  0x00000080 : 0) |
      (in8   ?  0x00000100 : 0) | (in9   ?  0x00000200 : 0) |
      (in10  ?  0x00000400 : 0) | (in11  ?  0x00000800 : 0) |
      (in12  ?  0x00001000 : 0) | (in13  ?  0x00002000 : 0) |
      (in14  ?  0x00004000 : 0) | (in15  ?  0x00008000 : 0) ;
}

llvm-svn: 12798
 2004-04-09 22:50:22 +00:00
Chris Lattner eed034bcd3 Fix the obvious bug in my previous checkin 
llvm-svn: 12618
 2004-04-02 18:15:10 +00:00
Chris Lattner 9f0db32625 Implement Transforms/SimplifyCFG/return-merge.ll 
This actually causes us to turn code like:

  return C ? A : B;

into a select instruction.

llvm-svn: 12617
 2004-04-02 18:13:43 +00:00
Chris Lattner 81bdcb90ce Now that all the code generators support the select instruction, and the instcombine 
pass can eliminate many nasty cases of them, start generating them in the optimizers

llvm-svn: 12545
 2004-03-30 19:44:05 +00:00
Chris Lattner a078f47b39 Fix compilation of mesa, which I broke earlier today 
llvm-svn: 12465
 2004-03-17 02:02:47 +00:00
Chris Lattner a64923ad26 Do not copy gigantic switch instructions 
llvm-svn: 12441
 2004-03-16 19:45:22 +00:00
Chris Lattner d3e6ae263c Implement switch->br and br->switch folding by ripping out the switch->switch 
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
 2004-02-28 21:28:10 +00:00
Chris Lattner 21e941fbfd turn things like: 
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
 2004-02-26 07:13:46 +00:00
Chris Lattner 90ea78edba If a block is made dead, make sure to promptly remove it. 
llvm-svn: 11799
 2004-02-24 16:09:21 +00:00
Chris Lattner a2ab489135 Implement SimplifyCFG/switch_switch_fold.ll 
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
 2004-02-24 07:23:58 +00:00
Chris Lattner 3cd98f054a Rearrange code a bit 
llvm-svn: 11793
 2004-02-24 05:54:22 +00:00
Chris Lattner 6f4b45acf5 Implement: test/Regression/Transforms/SimplifyCFG/switch_create.ll 
This turns code like this:
  if (X == 4 | X == 7)
and
  if (X != 4 & X != 7)
into switch instructions.

llvm-svn: 11792
 2004-02-24 05:38:11 +00:00
Chris Lattner e42732e75f Implement test/Regression/Transforms/SimplifyCFG/UncondBranchToReturn.ll, 
see the testcase for the reasoning.

llvm-svn: 11496
 2004-02-16 06:35:48 +00:00
Chris Lattner 18d1f19fba Implement SimplifyCFG/PhiEliminate.ll 
Having a proper 'select' instruction would allow the elimination of a lot
of the special case cruft in this patch, but we don't have one yet.

llvm-svn: 11307
 2004-02-11 03:36:04 +00:00
Chris Lattner 838b845781 The hasConstantReferences predicate always returns false. 
llvm-svn: 11301
 2004-02-11 01:17:07 +00:00
Chris Lattner fae8ab3088 rename the "exceptional" destination of an invoke instruction to the 'unwind' dest 
llvm-svn: 11202
 2004-02-08 21:44:31 +00:00
Chris Lattner df3c342a4c Finegrainify namespacification 
llvm-svn: 10727
 2004-01-09 06:12:26 +00:00
Brian Gaeke 960707c335 Put all LLVM code into the llvm namespace, as per bug 109. 
llvm-svn: 9903
 2003-11-11 22:41:34 +00:00
John Criswell 482202a601 Added LLVM project notice to the top of every C++ source file. 
Header files will be on the way.

llvm-svn: 9298
 2003-10-20 19:43:21 +00:00
Misha Brukman 8b2bd4ed47 Fix spelling. 
llvm-svn: 9027
 2003-10-10 17:57:28 +00:00
Chris Lattner 04ecefe232 Eliminate support for the llvm.unwind intrinisic, using the Unwind instruction instead 
llvm-svn: 8411
 2003-09-08 19:44:26 +00:00
Chris Lattner 3f5823f131 Implement SimplifyCFG/InvokeEliminate.ll 
llvm-svn: 8126
 2003-08-24 18:36:16 +00:00
Chris Lattner 031340a551 Fix bug: SimplifyCFG/2003-08-17-BranchFoldOrdering.ll 
llvm-svn: 7921
 2003-08-17 19:41:53 +00:00
Chris Lattner edc8c54e16 Fix bug: SimplifyCFG/2003-08-05-InvokeCrash.ll 
Fix bug: SimplifyCFG/2003-08-05-MishandleInvoke.ll

llvm-svn: 7599
 2003-08-05 16:27:44 +00:00
Chris Lattner 889f620841 Remove unnecesary &*'s 
llvm-svn: 5872
 2003-04-23 16:37:45 +00:00
Chris Lattner 569a57f9ff Fix bug: SimplifyCFG/2003-03-07-DominateProblem.ll 
llvm-svn: 5722
 2003-03-07 18:13:41 +00:00
Chris Lattner e54d214fcb Implement CFGSimplify/PhiBlockMerge*.ll 
llvm-svn: 5702
 2003-03-05 21:36:33 +00:00
Chris Lattner 31116bafed Implement testcase CFGSimplify/EqualPHIEdgeBlockMerge.ll 
llvm-svn: 5699
 2003-03-05 21:01:52 +00:00
Misha Brukman 632df28deb Fix spelling of `propagate'. 
llvm-svn: 4423
 2002-10-29 23:06:16 +00:00
Chris Lattner a704ac8a66 Changes to support PHINode::removeIncoming changes 
llvm-svn: 4079
 2002-10-08 21:36:33 +00:00
Chris Lattner d6dcd8ec32 Fix bug: SimplifyCFG/2002-09-24-PHIAssertion.ll 
llvm-svn: 3913
 2002-09-24 16:09:17 +00:00
Chris Lattner 5325c5f340 Minor cleanups 
llvm-svn: 3904
 2002-09-24 00:09:26 +00:00
Chris Lattner 1cec4d90cd Allow folding of basic blocks that have PHI nodes in them, fixing "bug": 
test/Regression/Transforms/SimplifyCFG/2002-06-24-PHINode.ll

llvm-svn: 3128
 2002-07-29 21:26:30 +00:00
Chris Lattner fda72b1aad *** empty log message *** 
llvm-svn: 2777
 2002-06-25 16:12:52 +00:00
Chris Lattner 466a049b67 Add implementation of SimplifyCFG 
llvm-svn: 2701
 2002-05-21 20:50:24 +00:00