[MachineCSE] Clear kill-flag on registers imp-def'd by the CSE'd instruction.
Go through implicit defs of CSMI and MI, and clear the kill flags on
their uses in all the instructions between CSMI and MI.
We might have made some of the kill flags redundant, consider:
subs ... %NZCV<imp-def> <- CSMI
csinc ... %NZCV<imp-use,kill> <- this kill flag isn't valid anymore
subs ... %NZCV<imp-def> <- MI, to be eliminated
csinc ... %NZCV<imp-use,kill>
Since we eliminated MI, and reused a register imp-def'd by CSMI
(here %NZCV), that register, if it was killed before MI, should have
that kill flag removed, because it's lifetime was extended.
Also, add an exhaustive testcase for the motivating example.
Reviewed by: Juergen Ributzka <juergen@apple.com>
llvm-svn: 223133
2014-12-03 02:09:51 +08:00
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; RUN: llc < %s -mtriple=aarch64-apple-ios -fast-isel -verify-machineinstrs | FileCheck %s
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; Check that the kill flag is cleared between CSE'd instructions on their
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; imp-def'd registers.
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; The verifier would complain otherwise.
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define i64 @csed-impdef-killflag(i64 %a) {
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; CHECK-LABEL: csed-impdef-killflag
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; CHECK-DAG: orr [[REG1:w[0-9]+]], wzr, #0x1
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; CHECK-DAG: orr [[REG2:x[0-9]+]], xzr, #0x2
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; CHECK-DAG: orr [[REG3:x[0-9]+]], xzr, #0x3
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2016-11-11 07:46:44 +08:00
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; CHECK-DAG: cmp x0, #0
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; CHECK: csel w[[SELECT_WREG_1:[0-9]+]], wzr, [[REG1]], ne
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[MachineCSE] Clear kill-flag on registers imp-def'd by the CSE'd instruction.
Go through implicit defs of CSMI and MI, and clear the kill flags on
their uses in all the instructions between CSMI and MI.
We might have made some of the kill flags redundant, consider:
subs ... %NZCV<imp-def> <- CSMI
csinc ... %NZCV<imp-use,kill> <- this kill flag isn't valid anymore
subs ... %NZCV<imp-def> <- MI, to be eliminated
csinc ... %NZCV<imp-use,kill>
Since we eliminated MI, and reused a register imp-def'd by CSMI
(here %NZCV), that register, if it was killed before MI, should have
that kill flag removed, because it's lifetime was extended.
Also, add an exhaustive testcase for the motivating example.
Reviewed by: Juergen Ributzka <juergen@apple.com>
llvm-svn: 223133
2014-12-03 02:09:51 +08:00
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; CHECK-DAG: csel [[SELECT_XREG_2:x[0-9]+]], [[REG2]], [[REG3]], ne
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; CHECK: ubfx [[SELECT_XREG_1:x[0-9]+]], x[[SELECT_WREG_1]], #0, #32
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; CHECK-NEXT: add x0, [[SELECT_XREG_2]], [[SELECT_XREG_1]]
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; CHECK-NEXT: ret
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%1 = icmp ne i64 %a, 0
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%2 = select i1 %1, i32 0, i32 1
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%3 = icmp ne i64 %a, 0
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%4 = select i1 %3, i64 2, i64 3
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%5 = zext i32 %2 to i64
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%6 = add i64 %4, %5
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ret i64 %6
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}
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