# RUN: llc -march=hexagon -run-pass branch-folder -run-pass if-converter -verify-machineinstrs %s -o - | FileCheck %s
# The hoisting of common instructions from successors could cause registers
# to no longer be live-in in the successor blocks. The liveness was updated
# to include potential new live-in registres, but not to remove registers
# that were no longer live-in.
# This could cause if-converter to generate incorrect code.
#
# In this testcase, the "r1 = A2_sxth killed r0" was hoisted, and since r0
# was killed, it was no longer live-in in either successor. The if-converter
# then created code, where the first predicated instruction has incorrect
# implicit use of r0:
#
# %bb.0:
# liveins: %r0
# %r1 = A2_sxth killed %r0 ; hoisted, kills r0
# A2_nop implicit-def %P0
# %r0 = C2_cmoveit %P0, 2, implicit %r0 ; predicated A2_tfrsi
# %r0 = C2_cmoveif killed %P0, 1, implicit %r0 ; predicated A2_tfrsi
# %r0 = A2_add killed %r0, killed %r1
# J2_jumpr %r31, implicit dead %PC
#
# CHECK: $r1 = A2_sxth killed $r0
# CHECK: $r0 = C2_cmoveit $p0, 2
# CHECK-NOT: implicit-def $r0
# CHECK: $r0 = C2_cmoveif killed $p0, 1, implicit killed $r0
---
name: fred
tracksRegLiveness: true
body: |
bb.0:
liveins: $r0
successors: %bb.1, %bb.2
A2_nop implicit-def $p0
J2_jumpt killed $p0, %bb.2, implicit-def dead $pc
bb.1:
successors: %bb.3
liveins: $r0
$r1 = A2_sxth killed $r0
$r0 = A2_tfrsi 1
J2_jump %bb.3, implicit-def $pc
bb.2:
successors: %bb.3
liveins: $r0
$r1 = A2_sxth killed $r0
$r0 = A2_tfrsi 2
bb.3:
liveins: $r0, $r1
$r0 = A2_add killed $r0, killed $r1
J2_jumpr $r31, implicit-def dead $pc
...
Codebase Browser
llvm