Commit Graph

3 Commits

Author SHA1 Message Date
Nadav Rotem
d16c8d0d33 1. Remove the part of r153848 which optimizes shuffle-of-shuffle into a new
shuffle node because it could introduce new shuffle nodes that were not
   supported efficiently by the target.

2. Add a more restrictive shuffle-of-shuffle optimization for cases where the
   second shuffle reverses the transformation of the first shuffle.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@154266 91177308-0d34-0410-b5e6-96231b3b80d8
2012-04-07 21:19:08 +00:00
Nadav Rotem
4ac9081c71 This commit contains a few changes that had to go in together.
1. Simplify xor/and/or (bitcast(A), bitcast(B)) -> bitcast(op (A,B))
   (and also scalar_to_vector).

2. Xor/and/or are indifferent to the swizzle operation (shuffle of one src).
   Simplify xor/and/or (shuff(A), shuff(B)) -> shuff(op (A, B))

3. Optimize swizzles of shuffles:  shuff(shuff(x, y), undef) -> shuff(x, y).

4. Fix an X86ISelLowering optimization which was very bitcast-sensitive.

Code which was previously compiled to this:

movd    (%rsi), %xmm0
movdqa  .LCPI0_0(%rip), %xmm2
pshufb  %xmm2, %xmm0
movd    (%rdi), %xmm1
pshufb  %xmm2, %xmm1
pxor    %xmm0, %xmm1
pshufb  .LCPI0_1(%rip), %xmm1
movd    %xmm1, (%rdi)
ret

Now compiles to this:

movl    (%rsi), %eax
xorl    %eax, (%rdi)
ret




git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153848 91177308-0d34-0410-b5e6-96231b3b80d8
2012-04-01 19:31:22 +00:00
Nadav Rotem
b00418af67 Add a new DAGCombine optimization for BUILD_VECTOR.
If all of the inputs are zero/any_extended, create a new simple BV
which can be further optimized by other BV optimizations.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@143297 91177308-0d34-0410-b5e6-96231b3b80d8
2011-10-29 21:23:04 +00:00