mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-11-04 06:09:05 +00:00
817812f61c
This patch teaches the backend how to canonicalize a shuffle vectors
according to the rule:
- (shuffle (FADD A, B), (FSUB A, B), Mask) ->
(shuffle (FSUB A, -B), (FADD A, -B), Mask)
Where 'Mask' is:
<0,5,2,7> ;; for v4f32 and v4f64 shuffles.
<0,3> ;; for v2f64 shuffles.
<0,9,2,11,4,13,6,15> ;; for v8f32 shuffles.
In general, ISel only knows how to pattern-match a canonical
'fadd + fsub + blendi' dag node sequence into an ADDSUB instruction.
This new rule allows to convert a non-canonical dag sequence into a
canonical one that will be matched by a single ADDSUB at ISel stage.
The idea of converting a non-canonical ADDSUB into a canonical one by
swapping the first two operands of the shuffle, and then negating the
second operand of the FADD and FSUB, was originally proposed by Hal Finkel.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211771 91177308-0d34-0410-b5e6-96231b3b80d8
|
||
|---|---|---|
| .. | ||
| AArch64 | ||
| ARM | ||
| CPP | ||
| Generic | ||
| Hexagon | ||
| Inputs | ||
| Mips | ||
| MSP430 | ||
| NVPTX | ||
| PowerPC | ||
| R600 | ||
| SPARC | ||
| SystemZ | ||
| Thumb | ||
| Thumb2 | ||
| X86 | ||
| XCore | ||