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Commit Graph

14 Commits

Author SHA1 Message Date
Stephen Lin
cf082ae903 Update Transforms tests to use CHECK-LABEL for easier debugging. No functionality change.
This update was done with the following bash script:

  find test/Transforms -name "*.ll" | \
  while read NAME; do
    echo "$NAME"
    if ! grep -q "^; *RUN: *llc" $NAME; then
      TEMP=`mktemp -t temp`
      cp $NAME $TEMP
      sed -n "s/^define [^@]*@\([A-Za-z0-9_]*\)(.*$/\1/p" < $NAME | \
      while read FUNC; do
        sed -i '' "s/;\(.*\)\([A-Za-z0-9_]*\):\( *\)@$FUNC\([( ]*\)\$/;\1\2-LABEL:\3@$FUNC(/g" $TEMP
      done
      mv $TEMP $NAME
    fi
  done

llvm-svn: 186268
2013-07-14 01:42:54 +00:00
Chandler Carruth
ce01d44307 Re-revert r173342, without losing the compile time improvements, flat
out bug fixes, or functionality preserving refactorings.

llvm-svn: 173610
2013-01-27 06:42:03 +00:00
Chandler Carruth
0e2f6c4f00 Switch this code away from Value::isUsedInBasicBlock. That code either
loops over instructions in the basic block or the use-def list of the
value, neither of which are really efficient when repeatedly querying
about values in the same basic block.

What's more, we already know that the CondBB is small, and so we can do
a much more efficient test by counting the uses in CondBB, and seeing if
those account for all of the uses.

Finally, we shouldn't blanket fail on any such instruction, instead we
should conservatively assume that those instructions are part of the
cost.

Note that this actually fixes a bug in the pass because
isUsedInBasicBlock has a really terrible bug in it. I'll fix that in my
next commit, but the fix for it would make this code suddenly take the
compile time hit I thought it already was taking, so I wanted to go
ahead and migrate this code to a faster & better pattern.

The bug in isUsedInBasicBlock was also causing other tests to test the
wrong thing entirely: for example we weren't actually disabling
speculation for floating point operations as intended (and tested), but
the test passed because we failed to speculate them due to the
isUsedInBasicBlock failure.

llvm-svn: 173417
2013-01-25 05:40:09 +00:00
Benjamin Kramer
78bb80941e Reapply chandlerc's r173342 now that the miscompile it was triggering is fixed.
Original commit message:
Plug TTI into the speculation logic, giving it a real cost interface
that can be specialized by targets.

The goal here is not to be more aggressive, but to just be more accurate
with very obvious cases. There are instructions which are known to be
truly free and which were not being modeled as such in this code -- see
the regression test which is distilled from an inner loop of zlib.

Everywhere the TTI cost model is insufficiently conservative I've added
explicit checks with FIXME comments to go add proper modelling of these
cost factors.

If this causes regressions, the likely solution is to make TTI even more
conservative in its cost estimates, but test cases will help here.

llvm-svn: 173357
2013-01-24 16:44:25 +00:00
Chandler Carruth
a1525efea7 Revert r173342 temporarily. It appears to cause a very late miscompile
of stage2 in a bootstrap. Still investigating....

llvm-svn: 173343
2013-01-24 13:24:24 +00:00
Chandler Carruth
b10553145f Plug TTI into the speculation logic, giving it a real cost interface
that can be specialized by targets.

The goal here is not to be more aggressive, but to just be more accurate
with very obvious cases. There are instructions which are known to be
truly free and which were not being modeled as such in this code -- see
the regression test which is distilled from an inner loop of zlib.

Everywhere the TTI cost model is insufficiently conservative I've added
explicit checks with FIXME comments to go add proper modelling of these
cost factors.

If this causes regressions, the likely solution is to make TTI even more
conservative in its cost estimates, but test cases will help here.

llvm-svn: 173342
2013-01-24 12:39:29 +00:00
Chandler Carruth
fd4cbdd2c2 Address a large chunk of this FIXME by accumulating the cost for
unfolded constant expressions rather than checking each one
independently.

llvm-svn: 173341
2013-01-24 12:05:17 +00:00
Chandler Carruth
bc67fc9f93 Switch the constant expression speculation cost evaluation away from
a cost fuction that seems both a bit ad-hoc and also poorly suited to
evaluating constant expressions.

Notably, it is missing any support for trivial expressions such as
'inttoptr'. I could fix this routine, but it isn't clear to me all of
the constraints its other users are operating under.

The core protection that seems relevant here is avoiding the formation
of a select instruction wich a further chain of select operations in
a constant expression operand. Just explicitly encode that constraint.

Also, update the comments and organization here to make it clear where
this needs to go -- this should be driven off of real cost measurements
which take into account the number of constants expressions and the
depth of the constant expression tree.

llvm-svn: 173340
2013-01-24 11:53:01 +00:00
Dan Gohman
4fc691d9ef Revert r56315. When the instruction to speculate is a load, this
code can incorrectly move the load across a store. This never
happens in practice today, but only because the current
heuristics accidentally preclude it.

llvm-svn: 147623
2012-01-05 22:54:35 +00:00
Nick Lewycky
9adbd36737 Make some intrinsics safe to speculatively execute.
llvm-svn: 147036
2011-12-21 05:52:02 +00:00
Chris Lattner
e8f2153059 fix a bunch of spurious failures for people whose home directory
is sabre.

llvm-svn: 81528
2009-09-11 17:02:12 +00:00
Dan Gohman
c95df8b6d8 Use opt -S instead of piping bitcode output through llvm-dis.
llvm-svn: 81257
2009-09-08 22:34:10 +00:00
Dan Gohman
8d84372836 Change these tests to feed the assembly files to opt directly, instead
of using llvm-as, now that opt supports this.

llvm-svn: 81226
2009-09-08 16:50:01 +00:00
Evan Cheng
c7ed1b9258 Speculatively execute a block when the the block is the then part of a triangle shape and it contains a single, side effect free, cheap instruction. The branch is eliminated by adding a select instruction. i.e.
Turn                                                                                                                                                                                                       
BB:                                                                                                                                                                                                        
    %t1 = icmp                                                                                                                                                                                             
    br i1 %t1, label %BB1, label %BB2                                                                                                                                                                      
BB1:                                                                                                                                                                                                       
    %t3 = add %t2, c                                                                                                                                                                                       
    br label BB2                                                                                                                                                                                           
BB2:                                                                                                                                                                                                       
=>                                                                                                                                                                                                         
BB:                                                                                                                                                                                                        
    %t1 = icmp                                                                                                                                                                                             
    %t4 = add %t2, c                                                                                                                                                                                       
    %t3 = select i1 %t1, %t2, %t3

llvm-svn: 52073
2008-06-07 08:52:29 +00:00