[CGP] Fix the handling an assert in complex addressing mode

[skatkov]

Summary

When we put the value in select placeholder we must pass
the value through simplification tracker due to the value might
be already simplified and erased.

This is a fix for PR35658.

[uabelho]

I don't know this code at all so I can't say if the fix makes sense or not, but I've tested it on my out-of-tree target
and it indeed solves the problem I reported in PR35658 and I haven't seen anything odd so it's probably good.

Thanks for fixing!

[skatkov]

Thank you for an update!

Let's wait for a review from John, he knows this code very well...

[john.brawn]

Given that it looks like we're already doing the same thing for phi nodes this looks like a sensible fix, so LGTM.

llvm/trunk/lib/CodeGen/CodeGenPrepare.cpp

while (!TraverseOrder.empty()) {
       if (SelectInst *Select = dyn_cast<SelectInst>(V)) {
         // CurrentValue also must be Select.
         auto *CurrentSelect = cast<SelectInst>(CurrentValue);
         auto *TrueValue = CurrentSelect->getTrueValue();
         ValueInBB TrueItem = { TrueValue, isa<Instruction>(TrueValue)
                                               ? CurrentBlock
                                               : nullptr };
         assert(Map.find(TrueItem) != Map.end() && "No True Value!");
-        Select->setTrueValue(Map[TrueItem]);
+        Select->setTrueValue(ST.Get(Map[TrueItem]));
         auto *FalseValue = CurrentSelect->getFalseValue();
         ValueInBB FalseItem = { FalseValue, isa<Instruction>(FalseValue)
                                                 ? CurrentBlock
                                                 : nullptr };
         assert(Map.find(FalseItem) != Map.end() && "No False Value!");
-        Select->setFalseValue(Map[FalseItem]);
+        Select->setFalseValue(ST.Get(Map[FalseItem]));
       } else {
         // Must be a Phi node then.
         PHINode *PHI = cast<PHINode>(V);
         // Fill the Phi node with values from predecessors.
         bool IsDefinedInThisBB =
             cast<Instruction>(CurrentValue)->getParent() == CurrentBlock;
         auto *CurrentPhi = dyn_cast<PHINode>(CurrentValue);
         for (auto B : predecessors(CurrentBlock)) {

llvm/trunk/test/Transforms/CodeGenPrepare/X86/pr35658.ll

+; RUN: opt -S -codegenprepare -disable-complex-addr-modes=false -addr-sink-new-phis=true -addr-sink-new-select=true  %s | FileCheck %s
+target datalayout =
+"e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128"
+target triple = "x86_64-unknown-linux-gnu"
+define void @f2() {
+entry:
+  %arraydecay = getelementptr inbounds [2 x i16], [2 x i16]* undef, i16 0, i16 0
+  %arrayidx1 = getelementptr inbounds [2 x i16], [2 x i16]* undef, i16 0, i16 1
+  br label %for.body
+
+for.body:                                         ; preds = %for.body, %entry
+  %e.03 = phi i16* [ %arraydecay, %entry ], [ %arrayidx1, %for.body ]
+  %tobool = icmp eq i16 undef, 0
+  br i1 undef, label %for.body, label %for.end
+
+for.end:                                          ; preds = %for.body
+; CHECK: sunkaddr
+  %e.1.le = select i1 %tobool, i16* %arrayidx1, i16* %e.03
+  store i16 0, i16* %e.1.le, align 1
+  ret void
+}