From a802c827119bf72a152ef214b24000e7b1ed51ff Mon Sep 17 00:00:00 2001 From: Chad Rosier Date: Fri, 30 Jan 2015 19:55:40 +0000 Subject: [PATCH] [AArch64] Make AArch64A57FPLoadBalancing output stable. Add tie breaker to colorChainSet() sort so that processing order doesn't depend on std::set order, which depends on pointer order, which is unstable from run to run. No test case as this is nearly impossible to reproduce. Phabricator Review: http://reviews.llvm.org/D7265 Patch by Geoff Berry ! llvm-svn: 227606 --- lib/Target/AArch64/AArch64A57FPLoadBalancing.cpp | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/lib/Target/AArch64/AArch64A57FPLoadBalancing.cpp b/lib/Target/AArch64/AArch64A57FPLoadBalancing.cpp index 1d437614e88..2cf3c2275d6 100644 --- a/lib/Target/AArch64/AArch64A57FPLoadBalancing.cpp +++ b/lib/Target/AArch64/AArch64A57FPLoadBalancing.cpp @@ -272,7 +272,7 @@ public: } /// Return true if this chain starts before Other. - bool startsBefore(Chain *Other) { + bool startsBefore(const Chain *Other) const { return StartInstIdx < Other->StartInstIdx; } @@ -442,10 +442,17 @@ bool AArch64A57FPLoadBalancing::colorChainSet(std::vector GV, // chains that we cannot change before we look at those we can, // so the parity counter is updated and we know what color we should // change them to! + // Final tie-break with instruction order so pass output is stable (i.e. not + // dependent on malloc'd pointer values). std::sort(GV.begin(), GV.end(), [](const Chain *G1, const Chain *G2) { if (G1->size() != G2->size()) return G1->size() > G2->size(); - return G1->requiresFixup() > G2->requiresFixup(); + if (G1->requiresFixup() != G2->requiresFixup()) + return G1->requiresFixup() > G2->requiresFixup(); + // Make sure startsBefore() produces a stable final order. + assert((G1 == G2 || (G1->startsBefore(G2) ^ G2->startsBefore(G1))) && + "Starts before not total order!"); + return G1->startsBefore(G2); }); Color PreferredColor = Parity < 0 ? Color::Even : Color::Odd;