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llvm-mirror/test/CodeGen/AArch64/loh-use-between-adrp-add.mir
Amara Emerson 9e0493b789 [AArch64] Fix CollectLOH creating an AdrpAdd LOH when there's a live used reg
between the two instructions.

If there's a pattern like:
$xA = ADRP foo @PAGE
[some killing use of reg Xb]
$Xb = ADDXri $Xa, 0, @PAGEOFF

CollectLOH would create an AdrpAdd LOH that resulted in the linker optimizing
this sequence into:
$xB = ADR foo
[some killing use of reg $Xb]
... and therefore clobbers the live $Xb register that was used by the
instruction in between.

This was discovered by a GlobalISel patch D78465 which broke up global variable
accesses into two pseudos, which in some cases could be moved apart.

Differential Revision: https://reviews.llvm.org/D80834
2020-06-01 16:00:55 -07:00

57 lines
1.7 KiB
YAML

# RUN: llc -o - %s -mtriple=aarch64-apple-ios -run-pass=aarch64-collect-loh -debug-only=aarch64-collect-loh 2>&1 | FileCheck %s
# REQUIRES: asserts
--- |
@rrdpb = local_unnamed_addr global i32 zeroinitializer, align 8
define internal void @test_use_between() {
ret void
}
define internal void @test_no_use_between() {
ret void
}
...
# CHECK-LABEL: ********** AArch64 Collect LOH **********
# CHECK-LABEL: Looking in function test_use_between
# Check that we don't have an AdrpAdd LOH because there's a use of the ADD defreg
# in between the two.
# CHECK-NOT: MCLOH_AdrpAdd
# CHECK-LABEL: Looking in function test_no_use_between
# CHECK: MCLOH_AdrpAdd
---
name: test_use_between
alignment: 4
tracksRegLiveness: true
liveins:
- { reg: '$x11', virtual-reg: '' }
- { reg: '$x12', virtual-reg: '' }
body: |
bb.0:
liveins: $x11, $x12
renamable $x15 = ADRP target-flags(aarch64-page) @rrdpb
STRXui renamable $x12, killed renamable $x11, 1 :: (store 8)
renamable $x11 = ADDXri killed renamable $x15, target-flags(aarch64-pageoff, aarch64-nc) @rrdpb, 0
STRXui renamable $x11, killed renamable $x11, 0
RET undef $lr
...
---
name: test_no_use_between
alignment: 4
tracksRegLiveness: true
liveins:
- { reg: '$x11', virtual-reg: '' }
- { reg: '$x12', virtual-reg: '' }
body: |
bb.0:
liveins: $x11, $x12
STRXui renamable $x12, killed renamable $x11, 1 :: (store 8)
renamable $x15 = ADRP target-flags(aarch64-page) @rrdpb
renamable $x11 = ADDXri killed renamable $x15, target-flags(aarch64-pageoff, aarch64-nc) @rrdpb, 0
STRXui renamable $x11, killed renamable $x11, 0
RET undef $lr
...