From 6be75ae196e0138048f685d4df7128d24245be5e Mon Sep 17 00:00:00 2001 From: Jakob Stoklund Olesen Date: Mon, 8 Oct 2012 22:06:44 +0000 Subject: [PATCH] Don't crash on extra evil irreducible control flow. When the CFG contains a loop with multiple entry blocks, the traces computed by MachineTraceMetrics don't always have the same nice properties. Loop back-edges are normally excluded from traces, but MachineLoopInfo doesn't recognize loops with multiple entry blocks, so those back-edges may be included. Avoid asserting when that happens by adding an isEarlierInSameTrace() function that accurately determines if a dominating block is part of the same trace AND is above the currrent block in the trace. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@165434 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/CodeGen/MachineTraceMetrics.cpp | 4 +- lib/CodeGen/MachineTraceMetrics.h | 8 +++ test/CodeGen/X86/early-ifcvt.ll | 75 +++++++++++++++++++++++++++++ 3 files changed, 85 insertions(+), 2 deletions(-) diff --git a/lib/CodeGen/MachineTraceMetrics.cpp b/lib/CodeGen/MachineTraceMetrics.cpp index 9b91af541db..b3abec76bc9 100644 --- a/lib/CodeGen/MachineTraceMetrics.cpp +++ b/lib/CodeGen/MachineTraceMetrics.cpp @@ -677,7 +677,7 @@ computeCrossBlockCriticalPath(const TraceBlockInfo &TBI) { const MachineInstr *DefMI = MTM.MRI->getVRegDef(LIR.Reg); // Ignore dependencies outside the current trace. const TraceBlockInfo &DefTBI = BlockInfo[DefMI->getParent()->getNumber()]; - if (!DefTBI.hasValidDepth() || DefTBI.Head != TBI.Head) + if (!DefTBI.isEarlierInSameTrace(TBI)) continue; unsigned Len = LIR.Height + Cycles[DefMI].Depth; MaxLen = std::max(MaxLen, Len); @@ -740,7 +740,7 @@ computeInstrDepths(const MachineBasicBlock *MBB) { const TraceBlockInfo&DepTBI = BlockInfo[Dep.DefMI->getParent()->getNumber()]; // Ignore dependencies from outside the current trace. - if (!DepTBI.hasValidDepth() || DepTBI.Head != TBI.Head) + if (!DepTBI.isEarlierInSameTrace(TBI)) continue; assert(DepTBI.HasValidInstrDepths && "Inconsistent dependency"); unsigned DepCycle = Cycles.lookup(Dep.DefMI).Depth; diff --git a/lib/CodeGen/MachineTraceMetrics.h b/lib/CodeGen/MachineTraceMetrics.h index d329c51634a..5f3b1d23e41 100644 --- a/lib/CodeGen/MachineTraceMetrics.h +++ b/lib/CodeGen/MachineTraceMetrics.h @@ -165,6 +165,14 @@ public: /// Invalidate height resources when a block below this one has changed. void invalidateHeight() { InstrHeight = ~0u; HasValidInstrHeights = false; } + /// Determine if this block belongs to the same trace as TBI and comes + /// before it in the trace. + /// Also returns true when TBI == this. + bool isEarlierInSameTrace(const TraceBlockInfo &TBI) const { + return hasValidDepth() && TBI.hasValidDepth() && + Head == TBI.Head && InstrDepth <= TBI.InstrDepth; + } + // Data-dependency-related information. Per-instruction depth and height // are computed from data dependencies in the current trace, using // itinerary data. diff --git a/test/CodeGen/X86/early-ifcvt.ll b/test/CodeGen/X86/early-ifcvt.ll index 17b3cb22cd4..2e1852d3e3a 100644 --- a/test/CodeGen/X86/early-ifcvt.ll +++ b/test/CodeGen/X86/early-ifcvt.ll @@ -67,3 +67,78 @@ if.end41: } declare void @fprintf(...) nounwind + +; CHECK: BZ2_decompress +; This test case contains irreducible control flow, so MachineLoopInfo doesn't +; recognize the cycle in the CFG. This would confuse MachineTraceMetrics. +define void @BZ2_decompress(i8* %s) nounwind ssp { +entry: + switch i32 undef, label %sw.default [ + i32 39, label %if.end.sw.bb2050_crit_edge + i32 36, label %sw.bb1788 + i32 37, label %if.end.sw.bb1855_crit_edge + i32 40, label %sw.bb2409 + i32 38, label %sw.bb1983 + i32 44, label %if.end.sw.bb3058_crit_edge + ] + +if.end.sw.bb3058_crit_edge: ; preds = %entry + br label %save_state_and_return + +if.end.sw.bb1855_crit_edge: ; preds = %entry + br label %save_state_and_return + +if.end.sw.bb2050_crit_edge: ; preds = %entry + br label %sw.bb2050 + +sw.bb1788: ; preds = %entry + br label %save_state_and_return + +sw.bb1983: ; preds = %entry + br i1 undef, label %save_state_and_return, label %if.then1990 + +if.then1990: ; preds = %sw.bb1983 + br label %while.body2038 + +while.body2038: ; preds = %sw.bb2050, %if.then1990 + %groupPos.8 = phi i32 [ 0, %if.then1990 ], [ %groupPos.9, %sw.bb2050 ] + br i1 undef, label %save_state_and_return, label %if.end2042 + +if.end2042: ; preds = %while.body2038 + br i1 undef, label %if.end2048, label %while.end2104 + +if.end2048: ; preds = %if.end2042 + %bsLive2054.pre = getelementptr inbounds i8* %s, i32 8 + br label %sw.bb2050 + +sw.bb2050: ; preds = %if.end2048, %if.end.sw.bb2050_crit_edge + %groupPos.9 = phi i32 [ 0, %if.end.sw.bb2050_crit_edge ], [ %groupPos.8, %if.end2048 ] + %and2064 = and i32 undef, 1 + br label %while.body2038 + +while.end2104: ; preds = %if.end2042 + br i1 undef, label %save_state_and_return, label %if.end2117 + +if.end2117: ; preds = %while.end2104 + br i1 undef, label %while.body2161.lr.ph, label %while.body2145.lr.ph + +while.body2145.lr.ph: ; preds = %if.end2117 + br label %save_state_and_return + +while.body2161.lr.ph: ; preds = %if.end2117 + br label %save_state_and_return + +sw.bb2409: ; preds = %entry + br label %save_state_and_return + +sw.default: ; preds = %entry + call void @BZ2_bz__AssertH__fail() nounwind + br label %save_state_and_return + +save_state_and_return: + %groupPos.14 = phi i32 [ 0, %sw.default ], [ %groupPos.8, %while.body2038 ], [ %groupPos.8, %while.end2104 ], [ 0, %if.end.sw.bb3058_crit_edge ], [ 0, %if.end.sw.bb1855_crit_edge ], [ %groupPos.8, %while.body2161.lr.ph ], [ %groupPos.8, %while.body2145.lr.ph ], [ 0, %sw.bb2409 ], [ 0, %sw.bb1788 ], [ 0, %sw.bb1983 ] + store i32 %groupPos.14, i32* undef, align 4 + ret void +} + +declare void @BZ2_bz__AssertH__fail()