Commit Graph

15 Commits

Author SHA1 Message Date
Dan Gohman df6b33e778 Eliminate the first have of the optimization which eliminates BRCOND
when the condition is constant. This optimization shouldn't be
necessary, because codegen shouldn't be able to find dead control
paths that the IR-level optimizer can't find. And it's undesirable,
because it encourages bugpoint to leave "br i1 false" branches
in its output. And it wasn't updating the CFG.

I updated all the tests I could, but some tests are too reduced
and I wasn't able to meaningfully preserve them.

llvm-svn: 106748
2010-06-24 15:04:11 +00:00
Evan Cheng 228c31f045 Re-apply 97040 with fix. This survives a ppc self-host llvm-gcc bootstrap.
llvm-svn: 97310
2010-02-27 07:36:59 +00:00
Daniel Dunbar 4811d004be Speculatively revert r97011, "Re-apply 96540 and 96556 with fixes.", again in
the hopes of fixing PPC bootstrap.

llvm-svn: 97040
2010-02-24 17:05:47 +00:00
Evan Cheng 328a607490 Re-apply 96540 and 96556 with fixes.
llvm-svn: 97011
2010-02-24 01:42:31 +00:00
Evan Cheng 2a33390e2b These should not have been committed.
llvm-svn: 96827
2010-02-22 23:37:48 +00:00
Evan Cheng 3688b8fa68 Instcombine constant folding can normalize gep with negative index to index with large offset. When instcombine objsize checking transformation sees these geps where the offset seemingly point out of bound, it should just return "i don't know" rather than asserting.
llvm-svn: 96825
2010-02-22 23:34:00 +00:00
Duncan Sands d0bf6f640f Revert commits 96556 and 96640, because commit 96556 breaks the
dragonegg self-host build.  I reverted 96640 in order to revert
96556 (96640 goes on top of 96556), but it also looks like with
both of them applied the breakage happens even earlier.  The
symptom of the 96556 miscompile is the following crash:

  llvm[3]: Compiling AlphaISelLowering.cpp for Release build
  cc1plus: /home/duncan/tmp/tmp/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp:4982: void llvm::SelectionDAG::ReplaceAllUsesWith(llvm::SDNode*, llvm::SDNode*, llvm::SelectionDAG::DAGUpdateListener*): Assertion `(!From->hasAnyUseOfValue(i) || From->getValueType(i) == To->getValueType(i)) && "Cannot use this version of ReplaceAllUsesWith!"' failed.
  Stack dump:
  0.	Running pass 'X86 DAG->DAG Instruction Selection' on function '@_ZN4llvm19AlphaTargetLowering14LowerOperationENS_7SDValueERNS_12SelectionDAGE'
  g++: Internal error: Aborted (program cc1plus)

This occurs when building LLVM using LLVM built by LLVM (via
dragonegg).  Probably LLVM has miscompiled itself, though it
may have miscompiled GCC and/or dragonegg itself: at this point
of the self-host build, all of GCC, LLVM and dragonegg were built
using LLVM.  Unfortunately this kind of thing is extremely hard
to debug, and while I did rummage around a bit I didn't find any
smoking guns, aka obviously miscompiled code.

Found by bisection.

r96556 | evancheng | 2010-02-18 03:13:50 +0100 (Thu, 18 Feb 2010) | 5 lines

Some dag combiner goodness:
Transform br (xor (x, y)) -> br (x != y)
Transform br (xor (xor (x,y), 1)) -> br (x == y)
Also normalize (and (X, 1) == / != 1 -> (and (X, 1)) != / == 0 to match to "test on x86" and "tst on arm"

r96640 | evancheng | 2010-02-19 01:34:39 +0100 (Fri, 19 Feb 2010) | 16 lines

Transform (xor (setcc), (setcc)) == / != 1 to
(xor (setcc), (setcc)) != / == 1.

e.g. On x86_64
  %0 = icmp eq i32 %x, 0
  %1 = icmp eq i32 %y, 0
  %2 = xor i1 %1, %0
  br i1 %2, label %bb, label %return
=>
	testl   %edi, %edi
	sete    %al
	testl   %esi, %esi
	sete    %cl
	cmpb    %al, %cl
	je      LBB1_2

llvm-svn: 96672
2010-02-19 11:30:41 +00:00
Evan Cheng 0ceb68a552 Some dag combiner goodness:
Transform br (xor (x, y)) -> br (x != y)
Transform br (xor (xor (x,y), 1)) -> br (x == y)
Also normalize (and (X, 1) == / != 1 -> (and (X, 1)) != / == 0 to match to "test on x86" and "tst on arm"

llvm-svn: 96556
2010-02-18 02:13:50 +00:00
Evan Cheng ea5c6be766 Run codegen dce pass for all targets at all optimization levels. Previously it's
only run for x86 with fastisel. I've found it being very effective in
eliminating some obvious dead code as result of formal parameter lowering
especially when tail call optimization eliminated the need for some of the loads
from fixed frame objects. It also shrinks a number of the tests. A couple of
tests no longer make sense and are now eliminated.

llvm-svn: 95493
2010-02-06 09:07:11 +00:00
Dan Gohman 40503396da Eliminate more uses of llvm-as and llvm-dis.
llvm-svn: 81290
2009-09-08 23:54:48 +00:00
Dan Gohman df7ea32af7 Enable the new no-SP register classes by default. This is to address
PR4572. A few tests have some minor code regressions due to different
coalescing.

llvm-svn: 78217
2009-08-05 17:40:24 +00:00
Evan Cheng 090db9b7a9 Catch more coalescing opportunities.
llvm-svn: 76282
2009-07-18 04:52:23 +00:00
Owen Anderson b358c8f482 Update the remaining tests not to use -disable-correct-folding, and remove two
that couldn't be updated.

llvm-svn: 54359
2008-08-05 18:19:14 +00:00
Owen Anderson 5018bd032a Update these tests to work by disabling the new correct CFG generation. This flag should ONLY be used to for tests like these.
llvm-svn: 54334
2008-08-04 23:55:29 +00:00
Evan Cheng c8eeb752a3 - More aggressively coalescing away copies whose source is defined by an implicit_def.
- Added insert_subreg coalescing support.

llvm-svn: 49448
2008-04-09 20:57:25 +00:00