Commit Graph

18 Commits

Author SHA1 Message Date
Roman Lebedev 3dce0326fe [DAGCombine][X86][AArch64][MIPS][LANAI] (C - x) - y -> C - (x + y) fold (PR41952)
Summary:
This *might* be the last fold for `sink-addsub-of-const.ll`, but i'm not sure yet.

As far as i can tell, there are no regressions here (ignoring x86-32),
all changes are either good or neutral.

This, almost surprisingly to me, fixes the motivational tests (in `shift-amount-mod.ll`)
`@reg32_lshr_by_sub_from_negated` from [[ https://bugs.llvm.org/show_bug.cgi?id=41952 | PR41952 ]].

https://rise4fun.com/Alive/vMd3

Reviewers: RKSimon, t.p.northover, craig.topper, spatel, efriedma

Reviewed By: RKSimon

Subscribers: sdardis, javed.absar, arichardson, kristof.beyls, jrtc27, atanasyan, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62774

llvm-svn: 362488
2019-06-04 11:06:21 +00:00
Roman Lebedev be6ce7b3f2 [DAGCombine][X86][AArch64][ARM] (C - x) + y -> (y - x) + C fold
Summary:
All changes except ARM look **great**.
https://rise4fun.com/Alive/R2M

The regression `test/CodeGen/ARM/addsubcarry-promotion.ll`
is recovered fully by D62392 + D62450.

Reviewers: RKSimon, craig.topper, spatel, rogfer01, efriedma

Reviewed By: efriedma

Subscribers: dmgreen, javed.absar, kristof.beyls, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62266

llvm-svn: 362487
2019-06-04 11:06:08 +00:00
Roman Lebedev 1aaa23c0fc [NFC][Codegen] shift-amount-mod.ll: drop innermost operation
I have initially added it in for test to display both
whether the binop w/ constant is sinked or hoisted.
But as it can be seen from the 'sub (sub C, %x), %y'
test, that actually conceals the issues it is supposed to test.

At least two more patterns are unhandled:
* 'add (sub C, %x), %y' - D62266
* 'sub (sub C, %x), %y'

llvm-svn: 362295
2019-06-01 11:08:29 +00:00
Roman Lebedev a4e3b50e26 [DAGCombiner][X86][AArch64] (x - C) + y -> (x + y) - C fold. Try 2
Summary:
Only vector tests are being affected here,
since subtraction by scalar constant is rewritten
as addition by negated constant.

No surprising test changes.

https://rise4fun.com/Alive/pbT

This is a recommit, originally committed in rL361852, but reverted
to investigate test-suite compile-time hangs.

Reviewers: RKSimon, craig.topper, spatel

Reviewed By: RKSimon

Subscribers: javed.absar, kristof.beyls, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62257

llvm-svn: 362146
2019-05-30 20:37:49 +00:00
Roman Lebedev 57aa36ff91 [DAGCombine] (x - C) - y -> (x - y) - C fold. Try 3
Summary:
Again only vectors affected. Frustrating. Let me take a look into that..

https://rise4fun.com/Alive/AAq

This is a recommit, originally committed in rL361852, but reverted
to investigate test-suite compile-time hangs, and then reverted in
rL362109 to fix missing constant folds that were causing
endless combine loops.

Reviewers: RKSimon, craig.topper, spatel

Reviewed By: RKSimon

Subscribers: javed.absar, JDevlieghere, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62294

llvm-svn: 362145
2019-05-30 20:37:39 +00:00
Roman Lebedev 05ad5fd213 [DAGCombiner][X86][AArch64][SPARC][SystemZ] y - (x + C) -> (y - x) - C fold. Try 3
Summary:
Direct sibling of D62223 patch.
While i don't have a direct motivational pattern for this,
it would seem to make sense to handle both patterns (or none),
for symmetry?

The aarch64 changes look neutral;
sparc and systemz look like improvement (one less instruction each);
x86 changes - 32bit case improves, 64bit case shows that LEA no longer
gets constructed, which may be because that whole test is `-mattr=+slow-lea,+slow-3ops-lea`

https://rise4fun.com/Alive/ffh

This is a recommit, originally committed in rL361852, but reverted
to investigate test-suite compile-time hangs, and then reverted in
rL362109 to fix missing constant folds that were causing
endless combine loops.

Reviewers: RKSimon, craig.topper, spatel, t.p.northover

Reviewed By: t.p.northover

Subscribers: t.p.northover, jyknight, javed.absar, kristof.beyls, fedor.sergeev, jrtc27, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62252

llvm-svn: 362143
2019-05-30 20:37:18 +00:00
Roman Lebedev 1d9ec7a81b [DAGCombiner][X86][AArch64][AMDGPU] (x + C) - y -> (x - y) + C fold. Try 3
Summary:
The main motivation is shown by all these `neg` instructions that are now created.
In particular, the `@reg32_lshr_by_negated_unfolded_sub_b` test.

AArch64 test changes all look good (`neg` created), or neutral.

X86 changes look neutral (vectors), or good (`neg` / `xor eax, eax` created).

I'm not sure about `X86/ragreedy-hoist-spill.ll`, it looks like the spill
is now hoisted into preheader (which should still be good?),
2 4-byte reloads become 1 8-byte reload, and are elsewhere,
but i'm not sure how that affects that loop.

I'm unable to interpret AMDGPU change, looks neutral-ish?

This is hopefully a step towards solving [[ https://bugs.llvm.org/show_bug.cgi?id=41952 | PR41952 ]].

https://rise4fun.com/Alive/pkdq (we are missing more patterns, i'll submit them later)

This is a recommit, originally committed in rL361852, but reverted
to investigate test-suite compile-time hangs, and then reverted in
rL362109 to fix missing constant folds that were causing
endless combine loops.

Reviewers: craig.topper, RKSimon, spatel, arsenm

Reviewed By: RKSimon

Subscribers: bjope, qcolombet, kzhuravl, jvesely, wdng, nhaehnle, yaxunl, javed.absar, dstuttard, tpr, t-tye, kristof.beyls, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62223

llvm-svn: 362142
2019-05-30 20:36:54 +00:00
Roman Lebedev 019d270e43 [DAGCombine] Revert of recommit of "binop-with-const hoisting" patches
I was looking into an endless combine loop the uncommitted follow-up patch
was causing, and it appears even these patches can exibit such an
endless loop. The root cause is that we try to hoist one binop (add/sub) with
constant operand, and if we get two such binops both of which are
eligible for this hoisting, we get stuck.

Some cases may highlight missing constant-folds.

Reverts r361871,r361872,r361873,r361874.

llvm-svn: 362109
2019-05-30 16:07:11 +00:00
Roman Lebedev dfc34f0211 [DAGCombine] (x - C) - y -> (x - y) - C fold. Try 2
Summary:
Again only vectors affected. Frustrating. Let me take a look into that..

https://rise4fun.com/Alive/AAq

This is a recommit, originally committed in rL361856, but reverted
to investigate test-suite compile-time hangs.

Reviewers: RKSimon, craig.topper, spatel

Reviewed By: RKSimon

Subscribers: javed.absar, JDevlieghere, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62294

llvm-svn: 361874
2019-05-28 20:40:10 +00:00
Roman Lebedev 96c9986199 [DAGCombiner][X86][AArch64][SPARC][SystemZ] y - (x + C) -> (y - x) - C fold. Try 2
Summary:
Direct sibling of D62223 patch.
While i don't have a direct motivational pattern for this,
it would seem to make sense to handle both patterns (or none),
for symmetry?

The aarch64 changes look neutral;
sparc and systemz look like improvement (one less instruction each);
x86 changes - 32bit case improves, 64bit case shows that LEA no longer
gets constructed, which may be because that whole test is `-mattr=+slow-lea,+slow-3ops-lea`

https://rise4fun.com/Alive/ffh

This is a recommit, originally committed in rL361853, but reverted
to investigate test-suite compile-time hangs.

Reviewers: RKSimon, craig.topper, spatel, t.p.northover

Reviewed By: t.p.northover

Subscribers: t.p.northover, jyknight, javed.absar, kristof.beyls, fedor.sergeev, jrtc27, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62252

llvm-svn: 361872
2019-05-28 20:39:55 +00:00
Roman Lebedev 2feb7e56e2 [DAGCombiner][X86][AArch64][AMDGPU] (x + C) - y -> (x - y) + C fold. Try 2
Summary:
The main motivation is shown by all these `neg` instructions that are now created.
In particular, the `@reg32_lshr_by_negated_unfolded_sub_b` test.

AArch64 test changes all look good (`neg` created), or neutral.

X86 changes look neutral (vectors), or good (`neg` / `xor eax, eax` created).

I'm not sure about `X86/ragreedy-hoist-spill.ll`, it looks like the spill
is now hoisted into preheader (which should still be good?),
2 4-byte reloads become 1 8-byte reload, and are elsewhere,
but i'm not sure how that affects that loop.

I'm unable to interpret AMDGPU change, looks neutral-ish?

This is hopefully a step towards solving [[ https://bugs.llvm.org/show_bug.cgi?id=41952 | PR41952 ]].

https://rise4fun.com/Alive/pkdq (we are missing more patterns, i'll submit them later)

This is a recommit, originally committed in rL361852, but reverted
to investigate test-suite compile-time hangs.

Reviewers: craig.topper, RKSimon, spatel, arsenm

Reviewed By: RKSimon

Subscribers: bjope, qcolombet, kzhuravl, jvesely, wdng, nhaehnle, yaxunl, javed.absar, dstuttard, tpr, t-tye, kristof.beyls, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62223

llvm-svn: 361871
2019-05-28 20:39:39 +00:00
Roman Lebedev 272d70c366 Revert DAGCombine "hoist binop with const" folds
Appear to introduce test-suite compile-time hang.

http://lab.llvm.org:8011/builders/clang-cmake-x86_64-sde-avx512-linux/builds/22825

This reverts r361852,r361853,r361854,r361855,r361856

llvm-svn: 361865
2019-05-28 19:04:21 +00:00
Roman Lebedev 7669665432 [DAGCombine] (x - C) - y -> (x - y) - C fold
Summary:
Again only vectors affected. Frustrating. Let me take a look into that..

https://rise4fun.com/Alive/AAq

Reviewers: RKSimon, craig.topper, spatel

Reviewed By: RKSimon

Subscribers: javed.absar, JDevlieghere, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62294

llvm-svn: 361856
2019-05-28 17:54:21 +00:00
Roman Lebedev 6a24c9b9ab [DAGCombiner][X86][AArch64] (x - C) + y -> (x + y) - C fold
Summary:
Only vector tests are being affected here,
since subtraction by scalar constant is rewritten
as addition by negated constant.

No surprising test changes.

https://rise4fun.com/Alive/pbT

Reviewers: RKSimon, craig.topper, spatel

Reviewed By: RKSimon

Subscribers: javed.absar, kristof.beyls, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62257

llvm-svn: 361854
2019-05-28 17:54:04 +00:00
Roman Lebedev 1499f65ac1 [DAGCombiner][X86][AArch64][SPARC][SystemZ] y - (x + C) -> (y - x) - C fold
Summary:
Direct sibling of D62223 patch.
While i don't have a direct motivational pattern for this,
it would seem to make sense to handle both patterns (or none),
for symmetry?

The aarch64 changes look neutral;
sparc and systemz look like improvement (one less instruction each);
x86 changes - 32bit case improves, 64bit case shows that LEA no longer
gets constructed, which may be because that whole test is `-mattr=+slow-lea,+slow-3ops-lea`

https://rise4fun.com/Alive/ffh

Reviewers: RKSimon, craig.topper, spatel, t.p.northover

Reviewed By: t.p.northover

Subscribers: t.p.northover, jyknight, javed.absar, kristof.beyls, fedor.sergeev, jrtc27, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62252

llvm-svn: 361853
2019-05-28 17:53:54 +00:00
Roman Lebedev 19f51ec04a [DAGCombiner][X86][AArch64][AMDGPU] (x + C) - y -> (x - y) + C fold
Summary:
The main motivation is shown by all these `neg` instructions that are now created.
In particular, the `@reg32_lshr_by_negated_unfolded_sub_b` test.

AArch64 test changes all look good (`neg` created), or neutral.

X86 changes look neutral (vectors), or good (`neg` / `xor eax, eax` created).

I'm not sure about `X86/ragreedy-hoist-spill.ll`, it looks like the spill
is now hoisted into preheader (which should still be good?),
2 4-byte reloads become 1 8-byte reload, and are elsewhere,
but i'm not sure how that affects that loop.

I'm unable to interpret AMDGPU change, looks neutral-ish?

This is hopefully a step towards solving [[ https://bugs.llvm.org/show_bug.cgi?id=41952 | PR41952 ]].

https://rise4fun.com/Alive/pkdq (we are missing more patterns, i'll submit them later)

Reviewers: craig.topper, RKSimon, spatel, arsenm

Reviewed By: RKSimon

Subscribers: bjope, qcolombet, kzhuravl, jvesely, wdng, nhaehnle, yaxunl, javed.absar, dstuttard, tpr, t-tye, kristof.beyls, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62223

llvm-svn: 361852
2019-05-28 17:53:43 +00:00
Roman Lebedev 406421b332 [NFC][X86][AArch64] Rewrite sink-addsub-of-const.ll tests to have full permutation coverage
Somehow missed some patterns initially..
While there, add comments.

llvm-svn: 361390
2019-05-22 14:42:41 +00:00
Roman Lebedev a7e88f8570 [NFC][X86][AArch64] Add tests for sinking of add/sub by constant through add/sub
Looks we can transform all 8 variants of the pattern:
https://rise4fun.com/Alive/auH

This comes up as an issue on the path towards
https://bugs.llvm.org/show_bug.cgi?id=41952

llvm-svn: 361303
2019-05-21 20:14:54 +00:00