Commit Graph

8 Commits

Author SHA1 Message Date
Duncan Sands
124708d9b4 Revert commit 122654 at the request of Chris, who reckons that instsimplify
is the wrong hammer for this nail, and is probably right.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122661 91177308-0d34-0410-b5e6-96231b3b80d8
2011-01-01 20:08:02 +00:00
Duncan Sands
7cf85e74e3 Fix a README item by having InstructionSimplify do a mild form of value
numbering, in which it considers (for example) "%a = add i32 %x, %y" and
"%b = add i32 %x, %y" to be equal because the operands are equal and the
result of the instructions only depends on the values of the operands.
This has almost no effect (it removes 4 instructions from gcc-as-one-file),
and perhaps slows down compilation: I measured a 0.4% slowdown on the large
gcc-as-one-file testcase, but it wasn't statistically significant.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122654 91177308-0d34-0410-b5e6-96231b3b80d8
2011-01-01 16:12:09 +00:00
Duncan Sands
1cd05bb605 When determining whether the new instruction was already present in
the original instruction, half the cases were missed (making it not
wrong but suboptimal).  Also correct a typo (A <-> B) in the second
chunk. 


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122414 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-22 17:15:25 +00:00
Duncan Sands
025c98bdbd Add an additional InstructionSimplify factorization test.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122333 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-21 15:12:22 +00:00
Duncan Sands
07f30fbd73 While I don't think any later transforms can fire, it seems cleaner to
not assume this (for example in case more transforms get added below
it).  Suggested by Frits van Bommel.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122332 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-21 15:03:43 +00:00
Duncan Sands
9bd2c2e63c Fix typo in comment, spotted by Deewiant.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122329 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-21 13:39:20 +00:00
Duncan Sands
3421d90853 Teach InstructionSimplify about distributive laws. These transforms fire
quite often, but don't make much difference in practice presumably because
instcombine also knows them and more.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122328 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-21 13:32:22 +00:00
Duncan Sands
566edb04b8 Add generic simplification of associative operations, generalizing
a couple of existing transforms.  This fires surprisingly often, for
example when compiling gcc "(X+(-1))+1->X" fires quite a lot as well
as various "and" simplifications (usually with a phi node operand).
Most of the time this doesn't make a real difference since the same
thing would have been done elsewhere anyway, eg: by instcombine, but
there are a few places where this results in simplifications that we
were not doing before.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122326 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-21 08:49:00 +00:00