[DAGCombine] Disable select(c, load,load) for indexed loads

This turned up after r235333, but was a pre-existing bug. The optimization
which transforms select(c, load, load) into a load of a select of the addresses
does not handle indexed loads (pre/post inc/dec). However, it did not check for
them either, leading to a crash if it tried to transform one of them.

llvm-svn: 235497

llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

@@ -12799,6 +12799,9 @@ bool DAGCombiner::SimplifySelectOps(SDNode *TheSelect, SDValue LHS,
     if (LHS.getOperand(0) != RHS.getOperand(0) ||
         // Do not let this transformation reduce the number of volatile loads.
         LLD->isVolatile() || RLD->isVolatile() ||
+        // FIXME: If either is a pre/post inc/dec load,
+        // we'd need to split out the address adjustment.
+        LLD->isIndexed() || RLD->isIndexed() ||
         // If this is an EXTLOAD, the VT's must match.
         LLD->getMemoryVT() != RLD->getMemoryVT() ||
         // If this is an EXTLOAD, the kind of extension must match.

llvm/test/CodeGen/PowerPC/preinc-ld-sel-crash.ll

@@ -0,0 +1,63 @@
+; RUN: llc < %s | FileCheck %s
+target datalayout = "E-m:e-i64:64-n32:64"
+target triple = "powerpc64-bgq-linux"
+
+%t1 = type { %t2*, %t3* }
+%t2 = type <{ %t3*, i32, [4 x i8] }>
+%t3 = type { %t3* }
+
+@_ZN4Foam10SLListBase13endConstIter_E = external global %t1
+
+define void @_ZN4FoamrsIbEERNS_7IstreamES2_RNS_4ListIT_EE() #0 {
+entry:
+  switch i32 undef, label %if.else82 [
+    i32 9, label %if.then
+    i32 6, label %invoke.cont10
+    i32 1, label %invoke.cont61
+  ]
+
+if.then:                                          ; preds = %entry
+  unreachable
+
+invoke.cont10:                                    ; preds = %entry
+  unreachable
+
+invoke.cont61:                                    ; preds = %entry
+  br i1 undef, label %if.end75, label %if.then64
+
+if.then64:                                        ; preds = %invoke.cont61
+  unreachable
+
+if.end75:                                         ; preds = %invoke.cont61
+  br i1 undef, label %if.then17.i, label %if.then.i181
+
+if.then.i181:                                     ; preds = %if.end75
+  unreachable
+
+if.then17.i:                                      ; preds = %if.end75
+  %tobool.i.i.i = icmp eq i32 undef, 0
+  %0 = load i64*, i64** undef, align 8
+  %agg.tmp.sroa.3.0.copyload33.in.i = select i1 %tobool.i.i.i, i64* bitcast (%t3** getelementptr inbounds (%t1, %t1* @_ZN4Foam10SLListBase13endConstIter_E, i64 0, i32 1) to i64*), i64* %0
+  %agg.tmp.sroa.3.0.copyload33.i = load i64, i64* %agg.tmp.sroa.3.0.copyload33.in.i, align 8
+  %1 = inttoptr i64 %agg.tmp.sroa.3.0.copyload33.i to %t3*
+  %2 = load %t3*, %t3** getelementptr inbounds (%t1, %t1* @_ZN4Foam10SLListBase13endConstIter_E, i64 0, i32 1), align 8
+  %cmp.i37.i = icmp eq %t3* %1, %2
+  br i1 %cmp.i37.i, label %invoke.cont79, label %for.body.lr.ph.i
+
+; CHECK-LABEL: @_ZN4FoamrsIbEERNS_7IstreamES2_RNS_4ListIT_EE
+
+for.body.lr.ph.i:                                 ; preds = %if.then17.i
+  br label %for.body.i
+
+for.body.i:                                       ; preds = %for.body.i, %for.body.lr.ph.i
+  br i1 undef, label %invoke.cont79, label %for.body.i
+
+invoke.cont79:                                    ; preds = %for.body.i, %if.then17.i
+  unreachable
+
+if.else82:                                        ; preds = %entry
+  ret void
+}
+
+attributes #0 = { "target-cpu"="a2q" }
+