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Fix instruction scheduling live register tracking
Summary: This patch fixes PR23405 (https://llvm.org/bugs/show_bug.cgi?id=23405). During a node unscheduling an entry in LiveRegGens can be replaced with a new value. That corrupts the live reg tracking and LiveReg* structure is not cleared as should be during unscheduling. Problematic condition that enforces Gen replacement is `I->getSUnit()->getHeight() < LiveRegGens[I->getReg()]->getHeight()`. This condition should be checked only if LiveRegGen was set in current node unscheduling. Test Plan: Regression test included. Reviewers: hfinkel, atrick Reviewed By: atrick Subscribers: llvm-commits Differential Revision: http://reviews.llvm.org/D9993 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@240538 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -848,17 +848,26 @@ void ScheduleDAGRRList::UnscheduleNodeBottomUp(SUnit *SU) {
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}
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}
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for (SUnit::succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
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I != E; ++I) {
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if (I->isAssignedRegDep()) {
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if (!LiveRegDefs[I->getReg()])
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for (auto &Succ : SU->Succs) {
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if (Succ.isAssignedRegDep()) {
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auto Reg = Succ.getReg();
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if (!LiveRegDefs[Reg])
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++NumLiveRegs;
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// This becomes the nearest def. Note that an earlier def may still be
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// pending if this is a two-address node.
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LiveRegDefs[I->getReg()] = SU;
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if (LiveRegGens[I->getReg()] == nullptr ||
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I->getSUnit()->getHeight() < LiveRegGens[I->getReg()]->getHeight())
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LiveRegGens[I->getReg()] = I->getSUnit();
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LiveRegDefs[Reg] = SU;
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// Update LiveRegGen only if was empty before this unscheduling.
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// This is to avoid incorrect updating LiveRegGen set in previous run.
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if (!LiveRegGens[Reg]) {
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// Find the successor with the lowest height.
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LiveRegGens[Reg] = Succ.getSUnit();
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for (auto &Succ2 : SU->Succs) {
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if (Succ2.isAssignedRegDep() && Succ2.getReg() == Reg &&
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Succ2.getSUnit()->getHeight() < LiveRegGens[Reg]->getHeight())
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LiveRegGens[Reg] = Succ2.getSUnit();
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}
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}
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}
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}
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if (SU->getHeight() < MinAvailableCycle)
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26
test/CodeGen/X86/rrlist-livereg-corrutpion.ll
Normal file
26
test/CodeGen/X86/rrlist-livereg-corrutpion.ll
Normal file
@ -0,0 +1,26 @@
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; RUN: llc < %s -march=x86-64 | FileCheck %s
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; CHECK-LABEL: test
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define i64 @test(i64 %a, i256 %b, i1 %c) {
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%u = zext i64 %a to i256
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%s = add i256 %u, 1
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%o = trunc i256 %s to i1
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%j = add i256 %s, 1
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%i = icmp ule i64 %a, 1
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%f = select i1 %o, i256 undef, i256 %j
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%d = select i1 %i, i256 %f, i256 1
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%e = add i256 %b, 1
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%n = select i1 %c, i256 %e, i256 %b
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%m = trunc i256 %n to i64
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%h = add i64 %m, 1
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%r = zext i64 %h to i256
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%v = lshr i256 %d, %r
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%t = trunc i256 %v to i1
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%q = shl i256 1, %r
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%p = and i256 %d, %q
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%w = icmp ule i256 %n, 1
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%y = select i1 %t, i256 undef, i256 %p
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%x = select i1 %w, i256 %y, i256 %d
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%z = trunc i256 %x to i64
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ret i64 %z
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}
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