llvm-project

Commit Graph

Author	SHA1	Message	Date
Sanjay Patel	4b537aaf6d	[DAGCombiner] allow narrowing of add followed by truncate trunc (add X, C ) --> add (trunc X), C' If we're throwing away the top bits of an 'add' instruction, do it in the narrow destination type. This makes the truncate-able opcode list identical to the sibling transform done in IR (in instcombine). This change used to show regressions for x86, but those are gone after D55494. This gets us closer to deleting the x86 custom function (combineTruncatedArithmetic) that does almost the same thing. Differential Revision: https://reviews.llvm.org/D55866 llvm-svn: 350006	2018-12-22 17:10:31 +00:00
Matt Arsenault	4dca0a9904	AMDGPU: Fix assert in truncate combine with vectors The piece above probably has the same problem, but I need to try to come up with a test for it. llvm-svn: 336935	2018-07-12 19:40:16 +00:00
Matt Arsenault	762d498808	AMDGPU: Add combine for trunc of bitcast from build_vector If the truncate is only accessing the first element of the vector, we can use the original source value. This helps with some combine ordering issues after operations are lowered to integer operations between bitcasts of build_vector. In particular it stops unnecessarily materializing the unused top half of a vector in some cases. llvm-svn: 331909	2018-05-09 18:37:39 +00:00

Author

SHA1

Message

Date

Sanjay Patel

4b537aaf6d

[DAGCombiner] allow narrowing of add followed by truncate

trunc (add X, C ) --> add (trunc X), C'

If we're throwing away the top bits of an 'add' instruction, do it in the narrow destination type.
This makes the truncate-able opcode list identical to the sibling transform done in IR (in instcombine).

This change used to show regressions for x86, but those are gone after D55494. 
This gets us closer to deleting the x86 custom function (combineTruncatedArithmetic) 
that does almost the same thing.

Differential Revision: https://reviews.llvm.org/D55866

llvm-svn: 350006

2018-12-22 17:10:31 +00:00

Matt Arsenault

4dca0a9904

AMDGPU: Fix assert in truncate combine with vectors

The piece above probably has the same problem, but I need
to try to come up with a test for it.

llvm-svn: 336935

2018-07-12 19:40:16 +00:00

Matt Arsenault

762d498808

AMDGPU: Add combine for trunc of bitcast from build_vector

If the truncate is only accessing the first element of the vector,
we can use the original source value.

This helps with some combine ordering issues after operations are
lowered to integer operations between bitcasts of build_vector.
In particular it stops unnecessarily materializing the unused
top half of a vector in some cases.

llvm-svn: 331909

2018-05-09 18:37:39 +00:00

3 Commits