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1d7e9b4115
Summary:
RegisterCoalescer::removePartialRedundancy tries to hoist B = A from
BB0/BB2 to BB1:
BB1:
...
BB0/BB2: ----
B = A; |
... |
A = B; |
|-------
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It does so if a number of conditions are fulfilled. However, it failed
to check if B was used by any of the terminators in BB1. Since we must
insert B = A before the terminators (since it's not a terminator itself),
this means that we could erroneously insert a new definition of B before a
use of it.
Reviewers: wmi, qcolombet
Reviewed By: wmi
Subscribers: MatzeB, llvm-commits, sdardis
Differential Revision: https://reviews.llvm.org/D44918
llvm-svn: 328689
42 lines
720 B
YAML
42 lines
720 B
YAML
# RUN: llc -march=mips64 -o - %s -run-pass=simple-register-coalescing | FileCheck %s
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---
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name: f
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tracksRegLiveness: true
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body: |
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bb.0:
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successors: %bb.1
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%21:gpr32 = ADDiu $zero, 0
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%22:gpr32 = COPY %21
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%22:gpr32 = ADDiu %22, 1
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J %bb.1, implicit-def dead $at
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bb.1:
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successors: %bb.2
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BEQ %22, $zero, %bb.2, implicit-def $at
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bb.2:
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successors: %bb.2, %bb.3
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%22:gpr32 = COPY %21
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%21:gpr32 = COPY %22
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BEQ undef %0:gpr32, $zero, %bb.2, implicit-def $at
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bb.3:
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...
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# We should not hoist the
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#
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# %22:gpr32 = COPY %21
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#
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# into bb.1 since %22 is used in the BEQ.
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# CHECK-LABEL: bb.1:
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# CHECK-NOT: COPY
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# CHECK: BEQ
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# CHECK-LABEL: bb.2:
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