aa2810b6e7
[InstSimplify] Add test case to show bad sign bit handling for integer abs idiom in computeKnownBits.
...
computeKnownBits will indicate the sign bit of abs is 0 if the
the RHS operand returned by matchSelectPattern has the nsw flag set.
For abs idioms like (X >= 0) ? X : -X, the RHS returns -X. But
we can also match ((X-Y) >= 0 ? X-Y : Y-X as abs. In this case
RHS will be the Y-X operand. According to Alive, the sign bit for
this is only 0 if both the X-Y and Y-X operands have the nsw flag.
But we're only checking the Y-X operand.
llvm-svn: 367747
2019-08-03 02:54:54 +00:00
cee313d288
Revert "Temporarily Revert "Add basic loop fusion pass.""
...
The reversion apparently deleted the test/Transforms directory.
Will be re-reverting again.
llvm-svn: 358552
2019-04-17 04:52:47 +00:00
a863435128
Temporarily Revert "Add basic loop fusion pass."
...
As it's causing some bot failures (and per request from kbarton).
This reverts commit r358543/ab70da07286e618016e78247e4a24fcb84077fda.
llvm-svn: 358546
2019-04-17 02:12:23 +00:00
00b5ecab5d
[ValueTracking] Compute range for abs without nsw
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This is a small followup to D59511. The code that was moved into
computeConstantRange() there is a bit overly conversative: If the
abs is not nsw, it does not compute any range. However, abs without
nsw still has a well-defined contiguous unsigned range from 0 to
SIGNED_MIN. This is a lot less useful than the usual 0 to SIGNED_MAX
range, but if we're already here we might as well specify it...
Differential Revision: https://reviews.llvm.org/D59563
llvm-svn: 356586
2019-03-20 18:16:02 +00:00
2dd1566e8b
[InstSimplify] Add additional cmp of abs without nsw tests; NFC
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llvm-svn: 356520
2019-03-19 21:12:21 +00:00
746ebb4ee8
[InstSimplify] fold icmp based on range of abs/nabs (2nd try)
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This is retrying the fold from rL345717
(reverted at rL347780)
...with a fix for the miscompile
demonstrated by PR39510:
https://bugs.llvm.org/show_bug.cgi?id=39510
Original commit message:
This is a fix for PR39475:
https://bugs.llvm.org/show_bug.cgi?id=39475
We managed to get some of these patterns using computeKnownBits in https://reviews.llvm.org/D47041 , but that
can't be used for nabs(). Instead, put in some range-based logic, so we can fold
both abs/nabs with icmp with a constant value.
Alive proofs:
https://rise4fun.com/Alive/21r
Name: abs_nsw_is_positive
%cmp = icmp slt i32 %x, 0
%negx = sub nsw i32 0, %x
%abs = select i1 %cmp, i32 %negx, i32 %x
%r = icmp sgt i32 %abs, -1
=>
%r = i1 true
Name: abs_nsw_is_not_negative
%cmp = icmp slt i32 %x, 0
%negx = sub nsw i32 0, %x
%abs = select i1 %cmp, i32 %negx, i32 %x
%r = icmp slt i32 %abs, 0
=>
%r = i1 false
Name: nabs_is_negative_or_0
%cmp = icmp slt i32 %x, 0
%negx = sub i32 0, %x
%nabs = select i1 %cmp, i32 %x, i32 %negx
%r = icmp slt i32 %nabs, 1
=>
%r = i1 true
Name: nabs_is_not_over_0
%cmp = icmp slt i32 %x, 0
%negx = sub i32 0, %x
%nabs = select i1 %cmp, i32 %x, i32 %negx
%r = icmp sgt i32 %nabs, 0
=>
%r = i1 false
Differential Revision: https://reviews.llvm.org/D53844
llvm-svn: 345832
2018-11-01 14:07:39 +00:00
056807b01e
[InstSimplify] add tests for icmp fold bug (PR39510); NFC
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Verify that set intersection/subset are not confused.
llvm-svn: 345831
2018-11-01 14:03:22 +00:00
72fe03f93b
revert rL345717 : [InstSimplify] fold icmp based on range of abs/nabs
...
This can miscompile as shown in PR39510:
https://bugs.llvm.org/show_bug.cgi?id=39510
llvm-svn: 345780
2018-10-31 21:37:40 +00:00
2efccd2cf2
[InstSimplify] fold icmp based on range of abs/nabs
...
This is a fix for PR39475:
https://bugs.llvm.org/show_bug.cgi?id=39475
We managed to get some of these patterns using computeKnownBits in D47041, but that
can't be used for nabs(). Instead, put in some range-based logic, so we can fold
both abs/nabs with icmp with a constant value.
Alive proofs:
https://rise4fun.com/Alive/21r
Name: abs_nsw_is_positive
%cmp = icmp slt i32 %x, 0
%negx = sub nsw i32 0, %x
%abs = select i1 %cmp, i32 %negx, i32 %x
%r = icmp sgt i32 %abs, -1
=>
%r = i1 true
Name: abs_nsw_is_not_negative
%cmp = icmp slt i32 %x, 0
%negx = sub nsw i32 0, %x
%abs = select i1 %cmp, i32 %negx, i32 %x
%r = icmp slt i32 %abs, 0
=>
%r = i1 false
Name: nabs_is_negative_or_0
%cmp = icmp slt i32 %x, 0
%negx = sub i32 0, %x
%nabs = select i1 %cmp, i32 %x, i32 %negx
%r = icmp slt i32 %nabs, 1
=>
%r = i1 true
Name: nabs_is_not_over_0
%cmp = icmp slt i32 %x, 0
%negx = sub i32 0, %x
%nabs = select i1 %cmp, i32 %x, i32 %negx
%r = icmp sgt i32 %nabs, 0
=>
%r = i1 false
Differential Revision: https://reviews.llvm.org/D53844
llvm-svn: 345717
2018-10-31 13:25:10 +00:00
33603198f2
[InstSimplify] add tests for abs/nabs+icmp folding; NFC
...
llvm-svn: 345541
2018-10-29 21:05:41 +00:00
Craig Topper