llvm-6502/lib
Matthias Braun 2a46e4c020 LegalizeDAG: Fix and improve FCOPYSIGN/FABS legalization
- Factor out code to query and modify the sign bit of a floatingpoint
  value as an integer. This also works if none of the targets integer
  types is big enough to hold all bits of the floatingpoint value.

- Legalize FABS(x) as FCOPYSIGN(x, 0.0) if FCOPYSIGN is available,
  otherwise perform bit manipulation on the sign bit. The previous code
  used "x >u 0 ? x : -x" which is incorrect for x being -0.0! It also
  takes 34 instructions on ARM Cortex-M4. With this patch we only
  require 5:
    vldr d0, LCPI0_0
    vmov r2, r3, d0
    lsrs r2, r3, #31
    bfi r1, r2, #31, #1
    bx lr
  (This could be further improved if the compiler would recognize that
   r2, r3 is zero).

- Only lower FCOPYSIGN(x, y) = sign(x) ? -FABS(x) : FABS(x) if FABS is
  available otherwise perform bit manipulation on the sign bit.

- Perform the sign(x) test by masking out the sign bit and comparing
  with 0 rather than shifting the sign bit to the highest position and
  testing for "<s 0". For x86 copysignl (on 80bit values) this gets us:
    testl $32768, %eax
  rather than:
    shlq $48, %rax
    sets %al
    testb %al, %al

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242107 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-14 02:08:26 +00:00
..
Analysis Cleanup after r241809 - remove uncessary call to std::sort 2015-07-13 14:48:24 +00:00
AsmParser Add argmemonly attribute. 2015-07-11 10:30:36 +00:00
Bitcode Add argmemonly attribute. 2015-07-11 10:30:36 +00:00
CodeGen LegalizeDAG: Fix and improve FCOPYSIGN/FABS legalization 2015-07-14 02:08:26 +00:00
DebugInfo Return ErrorOr from getSymbolAddress. 2015-07-03 18:19:00 +00:00
ExecutionEngine Fix the -DBUILD_SHARED_LIBS=ON build. 2015-07-07 17:48:00 +00:00
Fuzzer
IR Add capability to get and set the personalitty function from the C API 2015-07-14 01:23:06 +00:00
IRReader
LibDriver Add support deterministic output in llvm-ar and make it the default. 2015-07-13 20:38:09 +00:00
LineEditor
Linker
LTO LTO: expose LTO_SYMBOL_ALIAS, which indicates that the symbol is an alias. 2015-07-04 03:42:35 +00:00
MC [MC] Correctly escape .safeseh's symbol 2015-07-13 18:51:15 +00:00
Object Add a herper function. NFC. 2015-07-14 01:06:16 +00:00
Option
Passes
ProfileData
Support Remove macro guards for extern template instantiations. 2015-07-13 17:21:31 +00:00
TableGen [TableGen] Change a couple methods to return an ArrayRef instead of a const std::vector reference. NFC 2015-07-06 06:23:01 +00:00
Target [PPC64LE] More improvements to VSX swap optimization 2015-07-13 22:58:19 +00:00
Transforms Update enforceKnownAlignment after the isWeakForLinker semantic change 2015-07-14 00:11:08 +00:00
CMakeLists.txt
LLVMBuild.txt
Makefile