Roman Lebedev
|
ecb7ea1ae7
|
[InstCombine] foldICmpBinOp(): consider inverted check in 'unsigned add overflow' check
A follow-up for r342004.
This will be changed to produce @llvm.add.with.overflow in a later patch,
but for now just make things more consistent overall.
https://rise4fun.com/Alive/qxE
Name: (Op1 + X) u< Op1 --> ~Op1 u< X
%t0 = add i8 %Op1, %X
%r = icmp ult i8 %t0, %Op1
=>
%n = xor i8 %Op1, -1
%r = icmp ult i8 %n, %X
Name: (Op1 + X) u>= Op1 --> ~Op1 u>= X
%t0 = add i8 %Op1, %X
%r = icmp uge i8 %t0, %Op1
=>
%n = xor i8 %Op1, -1
%r = icmp uge i8 %n, %X
;-------------------------------------------------------------------------------
Name: Op0 u> (Op0 + X) --> X u> ~Op0
%t0 = add i8 %Op0, %X
%r = icmp ugt i8 %Op0, %t0
=>
%n = xor i8 %Op0, -1
%r = icmp ugt i8 %X, %n
Name: Op0 u<= (Op0 + X) --> X u<= ~Op0
%t0 = add i8 %Op0, %X
%r = icmp ule i8 %Op0, %t0
=>
%n = xor i8 %Op0, -1
%r = icmp ule i8 %X, %n
llvm-svn: 371100
|
2019-09-05 17:40:49 +00:00 |
|
Roman Lebedev
|
745046c23f
|
[InstCombine][NFC] Tests for 'unsigned add overflow' check
----------------------------------------
Name: unsigned add, overflow, v0
%add = add i8 %x, %y
%ov = icmp ult i8 %add, %x
=>
%agg = uadd_overflow i8 %x, %y
%add = extractvalue {i8, i1} %agg, 0
%ov = extractvalue {i8, i1} %agg, 1
Done: 1
Optimization is correct!
----------------------------------------
Name: unsigned add, overflow, v1
%add = add i8 %x, %y
%ov = icmp ult i8 %add, %y
=>
%agg = uadd_overflow i8 %x, %y
%add = extractvalue {i8, i1} %agg, 0
%ov = extractvalue {i8, i1} %agg, 1
Done: 1
Optimization is correct!
----------------------------------------
Name: unsigned add, no overflow, v0
%add = add i8 %x, %y
%ov = icmp uge i8 %add, %x
=>
%agg = uadd_overflow i8 %x, %y
%add = extractvalue {i8, i1} %agg, 0
%not.ov = extractvalue {i8, i1} %agg, 1
%ov = xor %not.ov, -1
Done: 1
Optimization is correct!
----------------------------------------
Name: unsigned add, no overflow, v1
%add = add i8 %x, %y
%ov = icmp uge i8 %add, %y
=>
%agg = uadd_overflow i8 %x, %y
%add = extractvalue {i8, i1} %agg, 0
%not.ov = extractvalue {i8, i1} %agg, 1
%ov = xor %not.ov, -1
Done: 1
Optimization is correct!
llvm-svn: 371098
|
2019-09-05 17:40:28 +00:00 |