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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
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@ -677,7 +677,7 @@ computeCrossBlockCriticalPath(const TraceBlockInfo &TBI) {
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const MachineInstr *DefMI = MTM.MRI->getVRegDef(LIR.Reg);
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// Ignore dependencies outside the current trace.
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const TraceBlockInfo &DefTBI = BlockInfo[DefMI->getParent()->getNumber()];
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if (!DefTBI.hasValidDepth() || DefTBI.Head != TBI.Head)
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if (!DefTBI.isEarlierInSameTrace(TBI))
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continue;
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unsigned Len = LIR.Height + Cycles[DefMI].Depth;
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MaxLen = std::max(MaxLen, Len);
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@ -740,7 +740,7 @@ computeInstrDepths(const MachineBasicBlock *MBB) {
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const TraceBlockInfo&DepTBI =
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BlockInfo[Dep.DefMI->getParent()->getNumber()];
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// Ignore dependencies from outside the current trace.
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if (!DepTBI.hasValidDepth() || DepTBI.Head != TBI.Head)
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if (!DepTBI.isEarlierInSameTrace(TBI))
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continue;
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assert(DepTBI.HasValidInstrDepths && "Inconsistent dependency");
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unsigned DepCycle = Cycles.lookup(Dep.DefMI).Depth;
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@ -165,6 +165,14 @@ public:
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/// Invalidate height resources when a block below this one has changed.
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void invalidateHeight() { InstrHeight = ~0u; HasValidInstrHeights = false; }
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/// Determine if this block belongs to the same trace as TBI and comes
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/// before it in the trace.
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/// Also returns true when TBI == this.
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bool isEarlierInSameTrace(const TraceBlockInfo &TBI) const {
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return hasValidDepth() && TBI.hasValidDepth() &&
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Head == TBI.Head && InstrDepth <= TBI.InstrDepth;
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}
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// Data-dependency-related information. Per-instruction depth and height
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// are computed from data dependencies in the current trace, using
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// itinerary data.
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@ -67,3 +67,78 @@ if.end41:
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}
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declare void @fprintf(...) nounwind
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; CHECK: BZ2_decompress
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; This test case contains irreducible control flow, so MachineLoopInfo doesn't
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; recognize the cycle in the CFG. This would confuse MachineTraceMetrics.
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define void @BZ2_decompress(i8* %s) nounwind ssp {
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entry:
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switch i32 undef, label %sw.default [
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i32 39, label %if.end.sw.bb2050_crit_edge
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i32 36, label %sw.bb1788
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i32 37, label %if.end.sw.bb1855_crit_edge
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i32 40, label %sw.bb2409
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i32 38, label %sw.bb1983
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i32 44, label %if.end.sw.bb3058_crit_edge
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]
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if.end.sw.bb3058_crit_edge: ; preds = %entry
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br label %save_state_and_return
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if.end.sw.bb1855_crit_edge: ; preds = %entry
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br label %save_state_and_return
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if.end.sw.bb2050_crit_edge: ; preds = %entry
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br label %sw.bb2050
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sw.bb1788: ; preds = %entry
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br label %save_state_and_return
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sw.bb1983: ; preds = %entry
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br i1 undef, label %save_state_and_return, label %if.then1990
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if.then1990: ; preds = %sw.bb1983
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br label %while.body2038
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while.body2038: ; preds = %sw.bb2050, %if.then1990
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%groupPos.8 = phi i32 [ 0, %if.then1990 ], [ %groupPos.9, %sw.bb2050 ]
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br i1 undef, label %save_state_and_return, label %if.end2042
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if.end2042: ; preds = %while.body2038
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br i1 undef, label %if.end2048, label %while.end2104
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if.end2048: ; preds = %if.end2042
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%bsLive2054.pre = getelementptr inbounds i8* %s, i32 8
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br label %sw.bb2050
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sw.bb2050: ; preds = %if.end2048, %if.end.sw.bb2050_crit_edge
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%groupPos.9 = phi i32 [ 0, %if.end.sw.bb2050_crit_edge ], [ %groupPos.8, %if.end2048 ]
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%and2064 = and i32 undef, 1
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br label %while.body2038
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while.end2104: ; preds = %if.end2042
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br i1 undef, label %save_state_and_return, label %if.end2117
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if.end2117: ; preds = %while.end2104
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br i1 undef, label %while.body2161.lr.ph, label %while.body2145.lr.ph
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while.body2145.lr.ph: ; preds = %if.end2117
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br label %save_state_and_return
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while.body2161.lr.ph: ; preds = %if.end2117
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br label %save_state_and_return
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sw.bb2409: ; preds = %entry
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br label %save_state_and_return
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sw.default: ; preds = %entry
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call void @BZ2_bz__AssertH__fail() nounwind
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br label %save_state_and_return
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save_state_and_return:
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%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 ]
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store i32 %groupPos.14, i32* undef, align 4
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ret void
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}
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declare void @BZ2_bz__AssertH__fail()
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