[all-commits] [llvm/llvm-project] c8a282: [GlobalISel] Fix computing known bits for loads wi...
Jessica Paquette via All-commits
all-commits at lists.llvm.org
Thu Aug 6 16:50:28 PDT 2020
Branch: refs/heads/master
Home: https://github.com/llvm/llvm-project
Commit: c8a282bcf7b6304e99f65bf22eea4553e240fb40
https://github.com/llvm/llvm-project/commit/c8a282bcf7b6304e99f65bf22eea4553e240fb40
Author: Jessica Paquette <jpaquette at apple.com>
Date: 2020-08-06 (Thu, 06 Aug 2020)
Changed paths:
M llvm/lib/Analysis/ValueTracking.cpp
M llvm/unittests/CodeGen/GlobalISel/KnownBitsTest.cpp
Log Message:
-----------
[GlobalISel] Fix computing known bits for loads with range metadata
In GlobalISel, if you have a load into a small type with a range, you'll hit
an assert if you try to compute known bits on it starting at a larger type.
e.g.
```
%x:_(s8) = G_LOAD %whatever(p0) :: (load 1 ... !range !n)
...
%y:_(s32) = G_SOMETHING %x
```
When we walk through G_SOMETHING and hit the load, the width of our known bits
is 32. However, the width of the range is going to be 8. This will cause us
to hit an assert.
To fix this, make computeKnownBitsFromRangeMetadata zero extend or truncate
the range type to match the bitwidth of the known bits we're calculating.
Add a testcase in CodeGen/GlobalISel/KnownBitsTest.cpp to reflect that this
works now.
https://reviews.llvm.org/D85375
More information about the All-commits
mailing list