17e85cd410
This patch is in preparation for the async unwind CFI. Put the first `LDP` the end, so that the load-store optimizer can run and merge the `LDP` and the `ADD` into a post-index `LDP`. Do this always and as early as at the time of the initial creation of the CSR restore instructions, even if that `LDP` is not guaranteed to be mergeable with a subsequent `SP` increment. This greatly simplifies the CFI generation for prologue, as otherwise we have to take extra steps to ensure reordering does not cross CFI instructions. Reviewed By: danielkiss Differential Revision: https://reviews.llvm.org/D112328
102 lines
3.1 KiB
YAML
102 lines
3.1 KiB
YAML
# RUN: llc -run-pass=prologepilog -reverse-csr-restore-seq -o - -mtriple=aarch64-- %s | FileCheck %s --check-prefixes=CHECK
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# RUN: llc -start-before=prologepilog -stop-after=aarch64-ldst-opt -reverse-csr-restore-seq -o - -mtriple=aarch64-- %s | FileCheck %s --check-prefixes=CHECK
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#
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--- |
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define void @foo() nounwind { entry: unreachable }
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define void @bar() nounwind { entry: unreachable }
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define void @baz() nounwind { entry: unreachable }
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...
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---
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name: foo
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# CHECK-LABEL: name: foo
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tracksRegLiveness: true
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body: |
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bb.0:
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$x19 = IMPLICIT_DEF
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$x20 = IMPLICIT_DEF
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$x21 = IMPLICIT_DEF
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$x22 = IMPLICIT_DEF
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$x23 = IMPLICIT_DEF
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$x24 = IMPLICIT_DEF
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$x25 = IMPLICIT_DEF
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$x26 = IMPLICIT_DEF
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; The local stack size is 0, so the last ldp in the sequence will also
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; restore the stack.
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; CHECK: $x24, $x23 = frame-destroy LDPXi $sp, 2
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; CHECK-NEXT: $x22, $x21 = frame-destroy LDPXi $sp, 4
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; CHECK-NEXT: $x20, $x19 = frame-destroy LDPXi $sp, 6
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; The ldp and the stack increment get merged even before
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; the load-store optimizer.
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; CHECK-NEXT: early-clobber $sp, $x26, $x25 = frame-destroy LDPXpost $sp, 8
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RET_ReallyLR
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...
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---
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name: bar
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# CHECK-LABEL: name: bar
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tracksRegLiveness: true
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stack:
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- { id : 0, size: 8, alignment: 4,
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stack-id: default, callee-saved-register: '', callee-saved-restored: true,
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local-offset: -4, debug-info-variable: '', debug-info-expression: '',
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debug-info-location: '' }
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body: |
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bb.0:
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$x19 = IMPLICIT_DEF
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$x20 = IMPLICIT_DEF
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$x21 = IMPLICIT_DEF
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$x22 = IMPLICIT_DEF
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$x23 = IMPLICIT_DEF
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$x24 = IMPLICIT_DEF
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$x25 = IMPLICIT_DEF
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$x26 = IMPLICIT_DEF
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; The local stack size is not 0, and we can combine the CSR stack size with
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; the local stack size. This results in rewriting the offsets for all the
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; save/restores and forbids us to merge the stack adjustment and the last pop.
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; In this case, there is no point of moving the first CSR pair at the end.
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; We do it anyway, as it's a small price to pay for the resulting
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; simplification in the epilogue emission code.
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; CHECK: $x24, $x23 = frame-destroy LDPXi $sp, 4
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; CHECK-NEXT: $x22, $x21 = frame-destroy LDPXi $sp, 6
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; CHECK-NEXT: $x20, $x19 = frame-destroy LDPXi $sp, 8
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; CHECK-NEXT: $x26, $x25 = frame-destroy LDPXi $sp, 2
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; CHECK-NEXT: $sp = frame-destroy ADDXri $sp, 80, 0
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RET_ReallyLR
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...
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---
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# Check that the load from the offset 0 is moved at the end even when hasFP is
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# false.
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name: baz
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# CHECK-LABEL: name: baz
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alignment: 4
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tracksRegLiveness: true
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frameInfo:
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adjustsStack: true
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hasCalls: true
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body: |
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bb.0:
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successors: %bb.1
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$x0 = IMPLICIT_DEF
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$x20 = IMPLICIT_DEF
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$x21 = IMPLICIT_DEF
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ADJCALLSTACKDOWN 0, 0, implicit-def dead $sp, implicit $sp
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BL @foo, csr_aarch64_aapcs, implicit-def dead $lr, implicit $sp, implicit $x0, implicit-def $sp, implicit-def $x0
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ADJCALLSTACKUP 0, 0, implicit-def dead $sp, implicit $sp
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B %bb.1
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bb.1:
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; CHECK: $x21, $x20 = frame-destroy LDPXi $sp, 2
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; CHECK-NEXT: early-clobber $sp, $lr = frame-destroy LDRXpost $sp, 32
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RET_ReallyLR
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...
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