llvm-6502

mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2025-01-16 14:31:59 +00:00

History

Chris Lattner b20c0b5092 Enhance the "compare with shift" and "compare with div"

optimizations to be much more aggressive in the face of
exact/nsw/nuw div and shifts.  For example, these (which
are the same except the first is 'exact' sdiv:

define i1 @sdiv_icmp4_exact(i64 %X) nounwind {
  %A = sdiv exact i64 %X, -5   ; X/-5 == 0 --> x == 0
  %B = icmp eq i64 %A, 0
  ret i1 %B
}

define i1 @sdiv_icmp4(i64 %X) nounwind {
  %A = sdiv i64 %X, -5   ; X/-5 == 0 --> x == 0
  %B = icmp eq i64 %A, 0
  ret i1 %B
}

compile down to:

define i1 @sdiv_icmp4_exact(i64 %X) nounwind {
  %1 = icmp eq i64 %X, 0
  ret i1 %1
}

define i1 @sdiv_icmp4(i64 %X) nounwind {
  %X.off = add i64 %X, 4
  %1 = icmp ult i64 %X.off, 9
  ret i1 %1
}

This happens when you do something like:
  (ptr1-ptr2) == 42

where the pointers are pointers to non-unit types.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125266 91177308-0d34-0410-b5e6-96231b3b80d8

2011-02-10 05:23:05 +00:00

Hello

…

InstCombine

Enhance the "compare with shift" and "compare with div"

2011-02-10 05:23:05 +00:00

Instrumentation

Implementation of path profiling.

2011-01-29 01:09:53 +00:00

IPO

When removing a function from the function set and adding it to deferred, we

2011-02-09 06:32:02 +00:00