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Differential D155939

[SimplifyCFG][NFC] Add tests for merging the combination of phis in switch
ClosedPublic

Authored by XChy on Jul 21 2023, 3:49 AM.

Details

Reviewers
skatkov
DamonFool
nikic
kazu
DianQK
XChy
Summary

Tests for an upcoming simplification to merge the combination of phis in switch.
Related issue:
Switch not fully optimized

Diff Detail

Event Timeline

XChy created this revision.Jul 21 2023, 3:49 AM
Herald added a project: Restricted Project. · View Herald TranscriptJul 21 2023, 3:49 AM
Herald added subscribers: khei4, StephenFan. · View Herald Transcript
XChy requested review of this revision.Jul 21 2023, 3:49 AM
Herald added a subscriber: llvm-commits. · View Herald TranscriptJul 21 2023, 3:49 AM
XChy updated this revision to Diff 542859.Jul 21 2023, 4:17 AM
XChy added a child revision: D155940: [SimplifyCFG] Transform for redirecting phis between unmergeable BB and SuccBB.Jul 21 2023, 5:55 AM
XChy added a reviewer: DianQK.
XChy updated this revision to Diff 542906.Jul 21 2023, 7:22 AM
XChy set the repository for this revision to rG LLVM Github Monorepo.
  • Avoid infinite loops
Herald added a subscriber: hiraditya. · View Herald TranscriptJul 21 2023, 7:22 AM
XChy updated this revision to Diff 542907.Jul 21 2023, 7:23 AM
Harbormaster completed remote builds in B247204: Diff 542907.Jul 21 2023, 11:17 AM
DianQK added inline comments.Jul 21 2023, 8:39 PM
llvm/test/Transforms/SimplifyCFG/merge-phis-in-switch.ll
73

Is the %unreachable necessary?
https://llvm.godbolt.org/z/cfj7Y8nnd

XChy marked an inline comment as done.Jul 21 2023, 9:52 PM
XChy added inline comments.
llvm/test/Transforms/SimplifyCFG/merge-phis-in-switch.ll
73

Not necessary for merging phis. But only with unreachable can we fold it into add i8 %arg, 1 through lookup table optimization.

DianQK added inline comments.Jul 21 2023, 10:07 PM
llvm/test/Transforms/SimplifyCFG/merge-phis-in-switch.ll
73

Oh, you're right.

XChy updated this revision to Diff 545350.Jul 29 2023, 2:07 AM
XChy marked an inline comment as done.

Add test for generalization.

Harbormaster completed remote builds in B248983: Diff 545350.Jul 29 2023, 2:57 AM
XChy accepted this revision.Sep 24 2023, 7:18 PM
This revision is now accepted and ready to land.Sep 24 2023, 7:18 PM
XChy closed this revision.Sep 24 2023, 7:18 PM

Revision Contents

PathSize
llvm/
test/
Transforms/
SimplifyCFG/
335 lines

Diff 542859

llvm/test/Transforms/SimplifyCFG/merge-phis-in-switch.ll

  • This file was added.
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 3
; RUN: opt < %s -passes=simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s
; Test a bunch of cases where the combination of phis in switch should be merged into one phi
declare void @use(i8)
define i8 @phis_of_switch_minimal(i8 noundef %arg) {
; CHECK-LABEL: define i8 @phis_of_switch_minimal
; CHECK-SAME: (i8 noundef [[ARG:%.*]]) {
; CHECK-NEXT: start:
; CHECK-NEXT: switch i8 [[ARG]], label [[UNREACHABLE:%.*]] [
; CHECK-NEXT: i8 0, label [[CASE01:%.*]]
; CHECK-NEXT: i8 1, label [[CASE1:%.*]]
; CHECK-NEXT: i8 2, label [[END:%.*]]
; CHECK-NEXT: ]
; CHECK: unreachable:
; CHECK-NEXT: unreachable
; CHECK: case1:
; CHECK-NEXT: br label [[CASE01]]
; CHECK: case01:
; CHECK-NEXT: [[PHI1:%.*]] = phi i8 [ 2, [[CASE1]] ], [ 1, [[START:%.*]] ]
; CHECK-NEXT: br label [[END]]
; CHECK: end:
; CHECK-NEXT: [[PHI2:%.*]] = phi i8 [ [[PHI1]], [[CASE01]] ], [ 3, [[START]] ]
; CHECK-NEXT: ret i8 [[PHI2]]
;
start:
switch i8 %arg, label %unreachable [
i8 0, label %case01
i8 1, label %case1
i8 2, label %end
]
unreachable:
unreachable
case1:
br label %case01
case01:
%phi1 = phi i8 [ 2, %case1 ], [1, %start]
br label %end
end:
%phi2 = phi i8 [ %phi1, %case01 ], [ 3, %start ]
ret i8 %phi2
}
define i8 @phis_of_switch(i8 noundef %arg) {
; CHECK-LABEL: define i8 @phis_of_switch
; CHECK-SAME: (i8 noundef [[ARG:%.*]]) {
; CHECK-NEXT: start:
; CHECK-NEXT: switch i8 [[ARG]], label [[UNREACHABLE:%.*]] [
; CHECK-NEXT: i8 0, label [[CASE012:%.*]]
; CHECK-NEXT: i8 1, label [[CASE1:%.*]]
; CHECK-NEXT: i8 2, label [[CASE2:%.*]]
; CHECK-NEXT: i8 3, label [[END:%.*]]
; CHECK-NEXT: ]
; CHECK: unreachable:
; CHECK-NEXT: unreachable
; CHECK: case1:
; CHECK-NEXT: br label [[CASE012]]
; CHECK: case2:
; CHECK-NEXT: br label [[CASE012]]
; CHECK: case012:
; CHECK-NEXT: [[PHI1:%.*]] = phi i8 [ 3, [[CASE2]] ], [ 2, [[CASE1]] ], [ 1, [[START:%.*]] ]
; CHECK-NEXT: br label [[END]]
; CHECK: end:
; CHECK-NEXT: [[PHI2:%.*]] = phi i8 [ [[PHI1]], [[CASE012]] ], [ 4, [[START]] ]
; CHECK-NEXT: ret i8 [[PHI2]]
;
start:
switch i8 %arg, label %unreachable [
i8 0, label %case012
DianQKUnsubmitted
Done
ReplyInline Actions

Is the %unreachable necessary?
https://llvm.godbolt.org/z/cfj7Y8nnd

DianQK: Is the `%unreachable` necessary? https://llvm.godbolt.org/z/cfj7Y8nnd
XChyAuthorUnsubmitted
Done
ReplyInline Actions

Not necessary for merging phis. But only with unreachable can we fold it into add i8 %arg, 1 through lookup table optimization.

XChy: Not necessary for merging phis. But only with unreachable can we fold it into `add i8 %arg, 1`…
DianQKUnsubmitted
Done
ReplyInline Actions

Oh, you're right.

DianQK: Oh, you're right.
i8 1, label %case1
i8 2, label %case2
i8 3, label %end
]
unreachable:
unreachable
case1:
br label %case012
case2:
br label %case012
case012:
%phi1 = phi i8 [ 3, %case2 ], [ 2, %case1 ], [1, %start]
br label %end
end:
%phi2 = phi i8 [ %phi1, %case012 ], [ 4, %start ]
ret i8 %phi2
}
define i8 @multiple_phis_of_switch(i8 noundef %arg) {
; CHECK-LABEL: define i8 @multiple_phis_of_switch
; CHECK-SAME: (i8 noundef [[ARG:%.*]]) {
; CHECK-NEXT: start:
; CHECK-NEXT: switch i8 [[ARG]], label [[UNREACHABLE:%.*]] [
; CHECK-NEXT: i8 0, label [[CASE012:%.*]]
; CHECK-NEXT: i8 1, label [[CASE1:%.*]]
; CHECK-NEXT: i8 2, label [[CASE2:%.*]]
; CHECK-NEXT: i8 3, label [[END:%.*]]
; CHECK-NEXT: ]
; CHECK: unreachable:
; CHECK-NEXT: unreachable
; CHECK: case1:
; CHECK-NEXT: br label [[CASE012]]
; CHECK: case2:
; CHECK-NEXT: br label [[CASE012]]
; CHECK: case012:
; CHECK-NEXT: [[PHI1_1:%.*]] = phi i8 [ 3, [[CASE2]] ], [ 2, [[CASE1]] ], [ 1, [[START:%.*]] ]
; CHECK-NEXT: [[PHI1_2:%.*]] = phi i8 [ 6, [[CASE2]] ], [ 5, [[CASE1]] ], [ 4, [[START]] ]
; CHECK-NEXT: br label [[END]]
; CHECK: end:
; CHECK-NEXT: [[PHI2_1:%.*]] = phi i8 [ [[PHI1_1]], [[CASE012]] ], [ 4, [[START]] ]
; CHECK-NEXT: [[PHI2_2:%.*]] = phi i8 [ [[PHI1_1]], [[CASE012]] ], [ 5, [[START]] ]
; CHECK-NEXT: [[PHI2_3:%.*]] = phi i8 [ [[PHI1_2]], [[CASE012]] ], [ 3, [[START]] ]
; CHECK-NEXT: call void @use(i8 [[PHI2_1]])
; CHECK-NEXT: call void @use(i8 [[PHI2_2]])
; CHECK-NEXT: call void @use(i8 [[PHI2_3]])
; CHECK-NEXT: ret i8 [[PHI2_1]]
;
start:
switch i8 %arg, label %unreachable [
i8 0, label %case012
i8 1, label %case1
i8 2, label %case2
i8 3, label %end
]
unreachable:
unreachable
case1:
br label %case012
case2:
br label %case012
case012:
%phi1_1 = phi i8 [ 3, %case2 ], [ 2, %case1 ], [1, %start]
%phi1_2 = phi i8 [ 6, %case2 ], [ 5, %case1 ], [4, %start]
br label %end
end:
%phi2_1 = phi i8 [ %phi1_1, %case012 ], [ 4, %start ]
%phi2_2 = phi i8 [ %phi1_1, %case012 ], [ 5, %start ]
%phi2_3 = phi i8 [ %phi1_2, %case012 ], [ 3, %start ]
call void @use(i8 %phi2_1)
call void @use(i8 %phi2_2)
call void @use(i8 %phi2_3)
ret i8 %phi2_1
}
define i8 @phis_of_switch_multiple_stage0(i8 noundef %arg) {
; CHECK-LABEL: define i8 @phis_of_switch_multiple_stage0
; CHECK-SAME: (i8 noundef [[ARG:%.*]]) {
; CHECK-NEXT: start:
; CHECK-NEXT: switch i8 [[ARG]], label [[UNREACHABLE:%.*]] [
; CHECK-NEXT: i8 0, label [[CASE0:%.*]]
; CHECK-NEXT: i8 1, label [[CASE1:%.*]]
; CHECK-NEXT: i8 2, label [[CASE2:%.*]]
; CHECK-NEXT: i8 3, label [[CASE0123:%.*]]
; CHECK-NEXT: i8 4, label [[CASE01234:%.*]]
; CHECK-NEXT: i8 5, label [[END:%.*]]
; CHECK-NEXT: ]
; CHECK: unreachable:
; CHECK-NEXT: unreachable
; CHECK: case0:
; CHECK-NEXT: br label [[CASE0123]]
; CHECK: case1:
; CHECK-NEXT: br label [[CASE0123]]
; CHECK: case2:
; CHECK-NEXT: br label [[CASE0123]]
; CHECK: case0123:
; CHECK-NEXT: [[PHI1:%.*]] = phi i8 [ 4, [[START:%.*]] ], [ 3, [[CASE2]] ], [ 2, [[CASE1]] ], [ 1, [[CASE0]] ]
; CHECK-NEXT: br label [[CASE01234]]
; CHECK: case01234:
; CHECK-NEXT: [[PHI2:%.*]] = phi i8 [ [[PHI1]], [[CASE0123]] ], [ 5, [[START]] ]
; CHECK-NEXT: br label [[END]]
; CHECK: end:
; CHECK-NEXT: [[PHI3:%.*]] = phi i8 [ [[PHI2]], [[CASE01234]] ], [ 6, [[START]] ]
; CHECK-NEXT: ret i8 [[PHI3]]
;
start:
switch i8 %arg, label %unreachable [
i8 0, label %case0
i8 1, label %case1
i8 2, label %case2
i8 3, label %case0123
i8 4, label %case01234
i8 5, label %end
]
unreachable:
unreachable
case0:
br label %case0123
case1:
br label %case0123
case2:
br label %case0123
case0123:
%phi1 = phi i8 [4, %start], [ 3, %case2 ], [ 2, %case1 ], [ 1, %case0 ]
br label %case01234
case01234:
%phi2 = phi i8 [ %phi1, %case0123 ], [ 5, %start ]
br label %end
end:
%phi3 = phi i8 [ %phi2, %case01234 ], [6, %start]
ret i8 %phi3
}
define i8 @phis_of_switch_multiple_stage1(i8 noundef %arg) {
; CHECK-LABEL: define i8 @phis_of_switch_multiple_stage1
; CHECK-SAME: (i8 noundef [[ARG:%.*]]) {
; CHECK-NEXT: start:
; CHECK-NEXT: switch i8 [[ARG]], label [[UNREACHABLE:%.*]] [
; CHECK-NEXT: i8 0, label [[CASE0:%.*]]
; CHECK-NEXT: i8 1, label [[CASE1:%.*]]
; CHECK-NEXT: i8 2, label [[CASE012:%.*]]
; CHECK-NEXT: i8 3, label [[CASE3:%.*]]
; CHECK-NEXT: i8 4, label [[CASE4:%.*]]
; CHECK-NEXT: i8 5, label [[CASE345:%.*]]
; CHECK-NEXT: i8 6, label [[CASE0123456:%.*]]
; CHECK-NEXT: ]
; CHECK: unreachable:
; CHECK-NEXT: unreachable
; CHECK: case0:
; CHECK-NEXT: br label [[CASE012]]
; CHECK: case1:
; CHECK-NEXT: br label [[CASE012]]
; CHECK: case012:
; CHECK-NEXT: [[PHI123:%.*]] = phi i8 [ 3, [[START:%.*]] ], [ 2, [[CASE1]] ], [ 1, [[CASE0]] ]
; CHECK-NEXT: br label [[CASE0123456]]
; CHECK: case3:
; CHECK-NEXT: br label [[CASE345]]
; CHECK: case4:
; CHECK-NEXT: br label [[CASE345]]
; CHECK: case345:
; CHECK-NEXT: [[PHI456:%.*]] = phi i8 [ 6, [[START]] ], [ 5, [[CASE4]] ], [ 4, [[CASE3]] ]
; CHECK-NEXT: br label [[CASE0123456]]
; CHECK: case0123456:
; CHECK-NEXT: [[PHI1234567:%.*]] = phi i8 [ 7, [[START]] ], [ [[PHI456]], [[CASE345]] ], [ [[PHI123]], [[CASE012]] ]
; CHECK-NEXT: ret i8 [[PHI1234567]]
;
start:
switch i8 %arg, label %unreachable [
i8 0, label %case0
i8 1, label %case1
i8 2, label %case012
i8 3, label %case3
i8 4, label %case4
i8 5, label %case345
i8 6, label %case0123456
]
unreachable:
unreachable
case0:
br label %case012
case1:
br label %case012
case012:
%phi123 = phi i8 [3, %start], [ 2, %case1 ], [ 1, %case0 ]
br label %case0123456
case3:
br label %case345
case4:
br label %case345
case345:
%phi456 = phi i8 [6, %start], [ 5, %case4 ], [ 4, %case3 ]
br label %case0123456
case0123456:
%phi1234567 = phi i8 [7, %start], [ %phi456, %case345 ], [ %phi123, %case012 ]
ret i8 %phi1234567
}
define i8 @phis_of_switch_extra_use_fail(i8 noundef %arg) {
; CHECK-LABEL: define i8 @phis_of_switch_extra_use_fail
; CHECK-SAME: (i8 noundef [[ARG:%.*]]) {
; CHECK-NEXT: start:
; CHECK-NEXT: switch i8 [[ARG]], label [[UNREACHABLE:%.*]] [
; CHECK-NEXT: i8 0, label [[CASE012:%.*]]
; CHECK-NEXT: i8 1, label [[CASE1:%.*]]
; CHECK-NEXT: i8 2, label [[CASE2:%.*]]
; CHECK-NEXT: i8 3, label [[END:%.*]]
; CHECK-NEXT: ]
; CHECK: unreachable:
; CHECK-NEXT: unreachable
; CHECK: case1:
; CHECK-NEXT: br label [[CASE012]]
; CHECK: case2:
; CHECK-NEXT: br label [[CASE012]]
; CHECK: case012:
; CHECK-NEXT: [[PHI1:%.*]] = phi i8 [ 3, [[CASE2]] ], [ 2, [[CASE1]] ], [ 1, [[START:%.*]] ]
; CHECK-NEXT: call void @use(i8 [[PHI1]])
; CHECK-NEXT: br label [[END]]
; CHECK: end:
; CHECK-NEXT: [[PHI2:%.*]] = phi i8 [ [[PHI1]], [[CASE012]] ], [ 4, [[START]] ]
; CHECK-NEXT: ret i8 [[PHI2]]
;
start:
switch i8 %arg, label %unreachable [
i8 0, label %case012
i8 1, label %case1
i8 2, label %case2 i8 3, label %end
]
unreachable:
unreachable
case1:
br label %case012
case2:
br label %case012
case012:
%phi1 = phi i8 [ 3, %case2 ], [ 2, %case1 ], [1, %start]
call void @use(i8 %phi1)
br label %end
end:
%phi2 = phi i8 [ %phi1, %case012 ], [ 4, %start ]
ret i8 %phi2
}