As it's causing some bot failures (and per request from kbarton).
This reverts commit r358543/ab70da07286e618016e78247e4a24fcb84077fda.
llvm-svn: 358546
This is D59386 for the signed add case. The computeConstantRange()
result is now intersected into the existing known bits information,
allowing to detect additional no-overflow/always-overflow conditions
(though the latter isn't used yet).
This (finally...) covers the motivating case from D59071.
Differential Revision: https://reviews.llvm.org/D60420
llvm-svn: 358014
Name: op_ugt_sum
%a = add i8 %x, %y
%r = icmp ugt i8 %x, %a
=>
%notx = xor i8 %x, -1
%r = icmp ugt i8 %y, %notx
Name: sum_ult_op
%a = add i8 %x, %y
%r = icmp ult i8 %a, %x
=>
%notx = xor i8 %x, -1
%r = icmp ugt i8 %y, %notx
https://rise4fun.com/Alive/ZRxI
AFAICT, this doesn't interfere with any add-saturation patterns
because those have >1 use for the 'add'. But this should be
better for IR analysis and codegen in the basic cases.
This is another fold inspired by PR14613:
https://bugs.llvm.org/show_bug.cgi?id=14613
llvm-svn: 342004
There were two combines not covered by the check before now, neither of which
actually differed from normal in the benefit analysis.
The most recent seems to be because it was just added at the top of the
function (naturally). The older is from way back in 2008 (r46687) when we just
didn't put those checks in so routinely, and has been diligently maintained
since.
llvm-svn: 341831
Changing to 'or' (rather than 'xor' when no wrapping flags are set)
allows icmp simplifies to happen as expected.
Differential Revision: https://reviews.llvm.org/D29729
llvm-svn: 295574
Eric Christopher