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Do not rename registers that do not start an independent live range

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llvm-svn: 270885
This commit is contained in:
Krzysztof Parzyszek 2016-05-26 18:22:53 +00:00
parent 41dc7af5f7
commit c5a589044f
2 changed files with 60 additions and 0 deletions
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25
lib/CodeGen/AggressiveAntiDepBreaker.cpp
View File

@ -787,6 +787,8 @@ unsigned AggressiveAntiDepBreaker::BreakAntiDependencies(
DEBUG(dbgs() << '\n');
#endif
BitVector RegAliases(TRI->getNumRegs());
// Attempt to break anti-dependence edges. Walk the instructions
// from the bottom up, tracking information about liveness as we go
// to help determine which registers are available.
@ -898,6 +900,29 @@ unsigned AggressiveAntiDepBreaker::BreakAntiDependencies(
}
if (AntiDepReg == 0) continue;
// If the definition of the anti-dependency register does not start
// a new live range, bail out. This can happen if the anti-dep
// register is a sub-register of another register whose live range
// spans over PathSU. In such case, PathSU defines only a part of
// the larger register.
RegAliases.reset();
for (MCRegAliasIterator AI(AntiDepReg, TRI, true); AI.isValid(); ++AI)
RegAliases.set(*AI);
for (SDep S : PathSU->Succs) {
SDep::Kind K = S.getKind();
if (K != SDep::Data && K != SDep::Output && K != SDep::Anti)
continue;
unsigned R = S.getReg();
if (!RegAliases[R])
continue;
if (R == AntiDepReg || TRI->isSubRegister(AntiDepReg, R))
continue;
AntiDepReg = 0;
break;
}
if (AntiDepReg == 0) continue;
}
assert(AntiDepReg != 0);

35
test/CodeGen/MIR/Hexagon/anti-dep-partial.mir Normal file
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@ -0,0 +1,35 @@
# RUN: llc -march=hexagon -post-RA-scheduler -run-pass post-RA-sched %s 2>&1 -o /dev/null | FileCheck %s
--- |
declare void @check(i64, i32, i32, i64)
define void @foo() {
ret void
}
...
---
name: foo
tracksRegLiveness: true
allVRegsAllocated: true
body: |
bb.0:
successors:
liveins: %r0, %r1, %d1, %d2, %r16, %r17, %r19, %r22, %r23
%r2 = A2_add %r23, killed %r17
%r6 = M2_mpyi %r16, %r16
%r22 = M2_accii %r22, killed %r2, 2
%r7 = A2_tfrsi 12345678
%r3 = A2_tfr killed %r16
%d2 = A2_tfrp killed %d0
%r2 = L2_loadri_io %r29, 28
%r2 = M2_mpyi killed %r6, killed %r2
%r23 = S2_asr_i_r %r22, 31
S2_storeri_io killed %r29, 0, killed %r7
; The anti-dependency on r23 between the first A2_add and the
; S2_asr_i_r was causing d11 to be renamed, while r22 remained
; unchanged. Check that the renaming of d11 does not happen.
; CHECK: d11
%d0 = A2_tfrp killed %d11
J2_call @check, implicit-def %d0, implicit-def %d1, implicit-def %d2, implicit %d0, implicit %d1, implicit %d2
...