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114 Commits

Author SHA1 Message Date
Evan Cheng df75785594 Move ReplaceUsesOfBlockWith() out of BranchFolding into a MachineBasicBlock general facility. 
llvm-svn: 37408
 2007-06-04 06:44:01 +00:00
Dale Johannesen 6e7cdce773 Fix CorrectExtraCFGEdges to allow for multiple LandingPad targets. 
llvm-svn: 37394
 2007-06-02 00:08:15 +00:00
Dale Johannesen 3c0a13762d Implement smarter algorithm for choosing which blocks to tail-merge. 
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
 2007-06-01 23:02:45 +00:00
Dale Johannesen 1a401e68a8 Arrange for only 1 of multiple branches to landing pad to be kept. 
Do not remove empty landing pads (EH table needs to be updated)

llvm-svn: 37375
 2007-05-31 21:54:00 +00:00
Dale Johannesen d14ad078c6 Changed per review comment. 
llvm-svn: 37355
 2007-05-30 00:32:01 +00:00
Dale Johannesen a69ebdbebc Make stable_sort in tail merging actually be stable (it never was, but didn't 
matter until my last change).  Reenable tail merging by default.

llvm-svn: 37354
 2007-05-29 23:47:50 +00:00
Dale Johannesen 1409b6a59b Blocks that cond-br and uncond-br/fallthrough to same block should have 
only one successor.

llvm-svn: 37324
 2007-05-24 18:31:55 +00:00
Dale Johannesen 1af8c870c7 Fix for PR1444: do not create two successors to the same block. 
Temporarily, this breaks CodeGen/Generic/2006-02-12-InsertLibraryCall.ll
by exposing an unrelated latent problem; working on that.

llvm-svn: 37323
 2007-05-24 17:39:32 +00:00
Dale Johannesen f4a77d2481 Two tail merging improvements: 
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
 2007-05-23 21:07:20 +00:00
Dale Johannesen 82810c8a13 Make tail merging the default, except on powerPC. There was no prior art 
for a target-dependent default with a command-line override; this way
should be generally usable.

llvm-svn: 37285
 2007-05-22 17:14:46 +00:00
Dale Johannesen f8956178af Remove some unneeded branches. (spotted by Evan, thanks) 
llvm-svn: 37198
 2007-05-18 01:28:58 +00:00
Dale Johannesen 420a85d0cf Remove extra CFG edges before doing these passes; it makes them happier. 
llvm-svn: 37089
 2007-05-15 21:19:17 +00:00
Dale Johannesen cc8f571bc8 Do not generate branches to entry block. This fixes several test suite 
failures on PPC (can happen only when prologue code is null)

llvm-svn: 36979
 2007-05-10 23:59:23 +00:00
Dale Johannesen 6e16d09252 Make tail merging handle many more cases (all it can, I think). 
llvm-svn: 36966
 2007-05-10 01:01:49 +00:00
Dale Johannesen 9a25b3afcd Handle some non-exit blocks in tail merging. 
llvm-svn: 36907
 2007-05-07 20:57:21 +00:00
Devang Patel 8c78a0bff0 Drop 'const' 
llvm-svn: 36662
 2007-05-03 01:11:54 +00:00
Devang Patel e95c6ad802 Use 'static const char' instead of 'static const int'. 
Due to darwin gcc bug, one version of darwin linker coalesces
static const int, which defauts PassID based pass identification.

llvm-svn: 36652
 2007-05-02 21:39:20 +00:00
Devang Patel 09f162ca6a Do not use typeinfo to identify pass in pass manager. 
llvm-svn: 36632
 2007-05-01 21:15:47 +00:00
Chris Lattner 4dbbace4ff Fix PR1228 and CodeGen/Generic/2007-04-30-LandingPadBranchFolding.ll 
llvm-svn: 36602
 2007-04-30 23:35:00 +00:00
Dale Johannesen d05a1a2ade maintain LiveIn when splitting blocks (register scavenging needs it) 
llvm-svn: 35226
 2007-03-20 21:35:06 +00:00
Jim Laskey 9df1a1d8d8 Remove isAccessable. 
llvm-svn: 34497
 2007-02-22 16:39:03 +00:00
Jim Laskey 2dc5245c4a Make branch folding behave in the presence of landing pads. 
llvm-svn: 34476
 2007-02-21 22:42:20 +00:00
Dale Johannesen 12920dda9e Fixes PR 1200 
llvm-svn: 34359
 2007-02-17 00:44:34 +00:00
Jim Laskey c56315c2b5 Change the MachineDebugInfo to MachineModuleInfo to better reflect usage 
for debugging and exception handling.

llvm-svn: 33550
 2007-01-26 21:22:28 +00:00
Jim Laskey f9e5445ed4 Make LABEL a builtin opcode. 
llvm-svn: 33537
 2007-01-26 14:34:52 +00:00
Chris Lattner aee775a6b7 Eliminate static ctors from Statistics 
llvm-svn: 32698
 2006-12-19 22:41:21 +00:00
Chris Lattner 700b873130 Detemplatize the Statistic class. The only type it is instantiated with 
is 'unsigned'.

llvm-svn: 32279
 2006-12-06 17:46:33 +00:00
Chris Lattner ea017f66f7 Don't transform in another bad case: if the block is empty, it should be 
simplified before we do this xform so that our cost model is accurate.

llvm-svn: 31864
 2006-11-18 22:25:39 +00:00
Chris Lattner 56ec81ff73 Fix another case we *don't* want to do this xform. 
llvm-svn: 31861
 2006-11-18 21:56:39 +00:00
Chris Lattner 7acdc17fe4 make the previous change more aggressive, moving any block with no fallthrough. 
This speeds up yacr2 by 7% on a core2.

llvm-svn: 31856
 2006-11-18 21:30:35 +00:00
Chris Lattner 47ce26158f Minor code layout tweak: if we have something like this: 
if (cond) goto BB2
BB1:
    ...
    return;
BB2:
   ...

Move BB1 to the end of the function so that the code falls through in the
non-return case.  This has the effect of moving assert (and other no-return
call) bodies and return blocks out of loops.

llvm-svn: 31855
 2006-11-18 20:47:54 +00:00
Chris Lattner bf3b57f221 optimize single MBB loops better. In particular, produce: 
LBB1_57:        #bb207.i
        movl 72(%esp), %ecx
        movb (%ecx,%eax), %cl
        movl 80(%esp), %edx
        movb %cl, 1(%edx,%eax)
        incl %eax
        cmpl $143, %eax
        jne LBB1_57     #bb207.i
        jmp LBB1_64     #cond_next255.i

intead of:

LBB1_57:        #bb207.i
        movl 72(%esp), %ecx
        movb (%ecx,%eax), %cl
        movl 80(%esp), %edx
        movb %cl, 1(%edx,%eax)
        incl %eax
        cmpl $143, %eax
        je LBB1_64      #cond_next255.i
        jmp LBB1_57     #bb207.i

This eliminates a branch per iteration of the loop.  This hurted PPC
particularly, because the extra branch meant another dispatch group for each
iteration of the loop.

llvm-svn: 31530
 2006-11-08 01:03:21 +00:00
Jeff Cohen 7d6f3db3e2 Unbreak VC++ build. 
llvm-svn: 31464
 2006-11-05 19:31:28 +00:00
Reid Spencer de46e48420 For PR786: 
Turn on -Wunused and -Wno-unused-parameter. Clean up most of the resulting
fall out by removing unused variables. Remaining warnings have to do with
unused functions (I didn't want to delete code without review) and unused
variables in generated code. Maintainers should clean up the remaining
issues when they see them. All changes pass DejaGnu tests and Olden.

llvm-svn: 31380
 2006-11-02 20:25:50 +00:00
Chris Lattner 7cee6ddcd8 give branch folding a simple heuristic to decide which block to split so that 
it inserts an uncond branch where it is less likely to cause a problem.  This
fixes some perf issues on ppc.

llvm-svn: 31354
 2006-11-01 19:36:29 +00:00
Chris Lattner f505a5a063 make tail merging more aggressive. If two blocks share a common tail, but the 
tail is not an entire block for either of them, pick one, split it, then
merge the common part.

llvm-svn: 31336
 2006-11-01 01:16:12 +00:00
Chris Lattner 3ac71b31f0 enable branch folding with an option 
llvm-svn: 31335
 2006-11-01 00:38:31 +00:00
Chris Lattner 504eeda365 Make CanFallThrough more intelligent (so it can handle blocks with (e.g.) no 
successors), and make island block movement more general.

This compiles CodeGen/X86/2006-04-27-ISelFoldingBug.ll to:

_loadAndRLEsource_no_exit_2E_1_label_2E_0:
        subl $8, %esp
        movl %esi, 4(%esp)
        movl %ebx, (%esp)
        movl 16(%esp), %eax
        movl 12(%esp), %ecx
LBB1_3: #label.0
        movl _last, %edx
        movl %edx, %esi
        incl %esi
        movl %esi, _last
        movl %ecx, %ebx
        # TRUNCATE movb %bl, %bl
        movl _block, %esi
        movb %bl, 1(%esi,%edx)
        cmpl %eax, _last
        jge LBB1_2      #codeRepl5.exitStub
LBB1_4: #label.0
        cmpl $257, %ecx
        je LBB1_2       #codeRepl5.exitStub
LBB1_1: #label.0.no_exit.1_crit_edge.exitStub
        movl $1, %eax
        movl (%esp), %ebx
        movl 4(%esp), %esi
        addl $8, %esp
        ret
LBB1_2: #codeRepl5.exitStub
        xorl %eax, %eax
        movl (%esp), %ebx
        movl 4(%esp), %esi
        addl $8, %esp
        ret

instead of:

_loadAndRLEsource_no_exit_2E_1_label_2E_0:
        subl $8, %esp
        movl %esi, 4(%esp)
        movl %ebx, (%esp)
        movl 16(%esp), %eax
        movl 12(%esp), %ecx
        jmp LBB1_3      #label.0
LBB1_1: #label.0.no_exit.1_crit_edge.exitStub
        movl $1, %eax
        movl (%esp), %ebx
        movl 4(%esp), %esi
        addl $8, %esp
        ret
LBB1_2: #codeRepl5.exitStub
        xorl %eax, %eax
        movl (%esp), %ebx
        movl 4(%esp), %esi
        addl $8, %esp
        ret
LBB1_3: #label.0
        movl _last, %edx
        movl %edx, %esi
        incl %esi
        movl %esi, _last
        movl %ecx, %ebx
        # TRUNCATE movb %bl, %bl
        movl _block, %esi
        movb %bl, 1(%esi,%edx)
        cmpl %eax, _last
        jge LBB1_2      #codeRepl5.exitStub
LBB1_4: #label.0
        cmpl $257, %ecx
        jne LBB1_1      #label.0.no_exit.1_crit_edge.exitStub
        jmp LBB1_2      #codeRepl5.exitStub

... which is much better layout :)

llvm-svn: 31282
 2006-10-29 21:05:41 +00:00
Chris Lattner c07657f59b Teach branch folding to fold identical jump tables together and to delete 
jump tables that are dead.

llvm-svn: 31273
 2006-10-28 18:34:47 +00:00
Chris Lattner af8383806b improve deletion of blocks that just contain branches by knowing that 
the pred block doesn't fall through into them if it's a jumptable.

llvm-svn: 31263
 2006-10-28 17:32:47 +00:00
Chris Lattner 0d4479b77d simplify code 
llvm-svn: 31188
 2006-10-25 22:21:37 +00:00
Chris Lattner 9feb308d51 turn off tail merging for now 
llvm-svn: 31180
 2006-10-25 18:08:50 +00:00
Chris Lattner ceb51d8427 move single basic blocks that are neither fallen into nor fall out of into 
a place more useful.  In particular, if we can put them in a place where code
will be able to fall into it, do so.  Otherwise, put it in a place it can fall
through into a successor.  Otherwise, if preventing a fallthrough, move to the
end of the function, out of the way.

This deletes several hundred unconditional branches from spass.

llvm-svn: 31149
 2006-10-24 01:12:32 +00:00
Chris Lattner ebdb1d6724 Enable tail merging by default. 
llvm-svn: 31140
 2006-10-23 22:10:12 +00:00
Jim Laskey 5e1a34032b More complete solution to deleting blocks and debug info. 
llvm-svn: 31129
 2006-10-23 14:56:37 +00:00
Chris Lattner 9f5a129543 don't break infinite loops 
llvm-svn: 31102
 2006-10-21 06:11:43 +00:00
Chris Lattner 28f17f45be Use branch reversal to do stuff like this: 
call L_strcmp$stub
        testl %eax, %eax
-       jne LBB26_208   #cond_true6020
-       jmp LBB26_227   #bb7119
+       je LBB26_227    #bb7119
 LBB26_208:     #cond_true6020
        movl $l31_str14, 4(%esp)

        testl %eax, %eax
-       jne LBB26_704   #cond_true13042
-       jmp LBB26_713   #bb13151
+       je LBB26_713    #bb13151
 LBB26_704:     #cond_true13042
        movl $_str52, 4(%esp)

        cmpl 76(%ecx), %eax
-       jge LBB26_1628  #cond_false63.i.i
-       jmp LBB26_1769  #_Z8makeGridP13mrSurfaceListidiidd.exit.i
+       jl LBB26_1769   #_Z8makeGridP13mrSurfaceListidiidd.exit.i
 LBB26_1628:    #cond_false63.i.i
        movl $0, 48964(%esp)

llvm-svn: 31100
 2006-10-21 05:54:00 +00:00
Chris Lattner 3ca52185af Transform code like: 
jle FOO
  jmp BAR
BAR:

into:

  jle FOO
BAR:

... whoa!

llvm-svn: 31098
 2006-10-21 05:43:30 +00:00
Chris Lattner 4fe01c42ca Three changes: 
1. Remove a bunch of ifdef'd code.
2. When a block just contains an uncond branch, change all blocks branching
   to it to jump to the destination instead.
3. If branch analysis tells us some edges in the machinecfg are not actually
   possible, remove them.

#2 triggers a suprisingly large number of times.

llvm-svn: 31094
 2006-10-21 05:08:28 +00:00
Chris Lattner 60c9d4dc76 Add an experimental cross-jumping implementation. 
This is currently disabled by default and limited in several ways, but does
have a positive effect.

llvm-svn: 31090
 2006-10-21 00:47:49 +00:00
Chris Lattner 73da320e50 Teach the branch folder to update debug info if it removes blocks with line 
# notes in it.

llvm-svn: 31026
 2006-10-17 23:17:27 +00:00
Chris Lattner bca3e297fe Enable deleting branches to successor blocks. With the previous patches, 
branch folding can now compile stuff like this:

void foo(int W, int X, int Y, int Z) {
  if (W & 1) {
    for (; X;--X) bar();
  } else if (W & 2) {
    for (; Y;--Y) bar();
  } else if (W & 4) {
    for (; Z;--Z) bar();
  } else if (W & 8) {
    for (; W;--W) bar();
  }

  if (W) {
    bar();
  }
}

contrived testcase where loops exits all end up merging together.  To have
the loop merges be:

...
        cmplw cr0, r30, r27
        bne cr0, LBB1_14        ;bb38
LBB1_16:        ;cond_next48.loopexit
        mr r27, r29
LBB1_20:        ;cond_next48
        cmplwi cr0, r27, 0
        beq cr0, LBB1_22        ;UnifiedReturnBlock
...

instead of:


...
        cmplw cr0, r30, r27
        bne cr0, LBB1_14        ;bb38
LBB1_16:        ;cond_next48.loopexit
        mr r27, r29
        b LBB1_20       ;cond_next48
LBB1_17:        ;cond_next48.loopexit1
        b LBB1_20       ;cond_next48
LBB1_18:        ;cond_next48.loopexit2
        b LBB1_20       ;cond_next48
LBB1_19:        ;cond_next48.loopexit3
LBB1_20:        ;cond_next48
        cmplwi cr0, r27, 0
        beq cr0, LBB1_22        ;UnifiedReturnBlock
...


This is CodeGen/PowerPC/branch-opt.ll

llvm-svn: 31006
 2006-10-17 18:16:40 +00:00
Chris Lattner 56c9d2597e Reenable this pass, fixing the bugs in it. 
It now correctly deletes unreachable blocks and blocks that are empty.

llvm-svn: 31000
 2006-10-17 17:13:52 +00:00
Chris Lattner 47db29a405 disable this pass for now, it's causing issues 
llvm-svn: 30951
 2006-10-14 00:30:06 +00:00
Chris Lattner 3218e0eed5 falling off the end of a function is ok with an unreachable instruction. 
llvm-svn: 30950
 2006-10-14 00:21:48 +00:00
Chris Lattner 3e8e57c771 disable some objectionable code, maybe we can bring this pass to life 
llvm-svn: 30939
 2006-10-13 20:43:10 +00:00
Misha Brukman 835702a094 Remove trailing whitespace 
llvm-svn: 21420
 2005-04-21 22:36:52 +00:00
Reid Spencer 7c16caa336 Changes For Bug 352 
Move include/Config and include/Support into include/llvm/Config,
include/llvm/ADT and include/llvm/Support. From here on out, all LLVM
public header files must be under include/llvm/.

llvm-svn: 16137
 2004-09-01 22:55:40 +00:00
Chris Lattner 356f5a13f5 Dereferencing end() is bad. 
llvm-svn: 15402
 2004-08-01 09:51:42 +00:00
Alkis Evlogimenos 62c979ba07 Make OptimizeBlock take a MachineFunction::iterator instead of a 
MachineBasicBlock* as a parameter so that nxext() and prior() helper
functions can work naturally on it.

llvm-svn: 15376
 2004-07-31 19:24:41 +00:00
Chris Lattner 0f1c2ed907 Next on a pointer increments the pointer, not an iterator 
llvm-svn: 15375
 2004-07-31 18:40:36 +00:00
Alkis Evlogimenos 2303d3f660 Use next() helper to make code more readable. Use 
MachineFunction::iterator instead of MachineBasicBlock* to avoid
dereferencing end iterators.

llvm-svn: 15373
 2004-07-31 15:14:29 +00:00
Alkis Evlogimenos 1e8d8fd81f Use MachineFunction::iterator instead of a MachineBasicBlock* because 
FallThrough maybe == to MF.end().

llvm-svn: 15372
 2004-07-31 15:03:52 +00:00
Chris Lattner 25e48dd2e0 Implement a simple target-independent CFG cleanup pass 
llvm-svn: 15368
 2004-07-31 10:01:27 +00:00