Merging r310481, r310492 and r310510:

------------------------------------------------------------------------
r310481 | davide | 2017-08-09 08:13:50 -0700 (Wed, 09 Aug 2017) | 8 lines

[ValueTracking] Honour recursion limit.

The recently improved support for `icmp` in ValueTracking
(r307304) exposes the fact that `isImplied` condition doesn't
really bail out if we hit the recursion limit (and calls
`computeKnownBits` which increases the depth and asserts).

Differential Revision:  https://reviews.llvm.org/D36512
------------------------------------------------------------------------

------------------------------------------------------------------------
r310492 | davide | 2017-08-09 09:06:04 -0700 (Wed, 09 Aug 2017) | 1 line

[ValueTracking] Update tests to unbreak the bots.
------------------------------------------------------------------------

------------------------------------------------------------------------
r310510 | spatel | 2017-08-09 11:56:26 -0700 (Wed, 09 Aug 2017) | 6 lines

[SimplifyCFG] remove checks for crasher test from r310481

Not sure why the earlier version would fail, but trying to get the bots
(and my local machine) to pass again.


------------------------------------------------------------------------


git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_50@310634 91177308-0d34-0410-b5e6-96231b3b80d8

Author: zmodem

lib/Analysis/ValueTracking.cpp

@@ -4458,6 +4458,10 @@ Optional<bool> llvm::isImpliedCondition(const Value *LHS, const Value *RHS,
                                         unsigned Depth, AssumptionCache *AC,
                                         const Instruction *CxtI,
                                         const DominatorTree *DT) {
+  // Bail out when we hit the limit.
+  if (Depth == MaxDepth)
+    return None;
+
   // A mismatch occurs when we compare a scalar cmp to a vector cmp, for example.
   if (LHS->getType() != RHS->getType())
     return None;

test/Transforms/SimplifyCFG/pr34131.ll

@@ -0,0 +1,74 @@
+; RUN: opt -simplifycfg -S < %s | FileCheck %s
+
+; Just checking for lack of crash here, but we should be able to check the IR?
+; Earlier version using auto-generated checks from utils/update_test_checks.py
+; had bot problems though...
+
+define void @patatino() {
+
+; CHECK-LABEL: @patatino
+
+  br label %bb1
+bb1:                                              ; preds = %bb36, %0
+  br label %bb2
+bb2:                                              ; preds = %bb3, %bb1
+  br i1 undef, label %bb4, label %bb3
+bb3:                                              ; preds = %bb4, %bb2
+  br i1 undef, label %bb2, label %bb5
+bb4:                                              ; preds = %bb2
+  switch i32 undef, label %bb3 [
+  ]
+bb5:                                              ; preds = %bb3
+  br label %bb6
+bb6:                                              ; preds = %bb5
+  br i1 undef, label %bb7, label %bb9
+bb7:                                              ; preds = %bb6
+  %tmp = or i64 undef, 1
+  %tmp8 = icmp ult i64 %tmp, 0
+  br i1 %tmp8, label %bb12, label %bb9
+bb9:                                              ; preds = %bb35, %bb34, %bb33, %bb32, %bb31, %bb30, %bb27, %bb24, %bb21, %bb18, %bb16, %bb14, %bb12, %bb7, %bb6
+  br label %bb11
+bb10:                                             ; preds = %bb36
+  br label %bb11
+bb11:                                             ; preds = %bb10, %bb9
+  ret void
+bb12:                                             ; preds = %bb7
+  %tmp13 = icmp ult i64 0, 0
+  br i1 %tmp13, label %bb14, label %bb9
+bb14:                                             ; preds = %bb12
+  %tmp15 = icmp ult i64 undef, 0
+  br i1 %tmp15, label %bb16, label %bb9
+bb16:                                             ; preds = %bb14
+  %tmp17 = icmp ult i64 undef, 0
+  br i1 %tmp17, label %bb18, label %bb9
+bb18:                                             ; preds = %bb16
+  %tmp19 = or i64 undef, 5
+  %tmp20 = icmp ult i64 %tmp19, 0
+  br i1 %tmp20, label %bb21, label %bb9
+bb21:                                             ; preds = %bb18
+  %tmp22 = or i64 undef, 6
+  %tmp23 = icmp ult i64 %tmp22, 0
+  br i1 %tmp23, label %bb24, label %bb9
+bb24:                                             ; preds = %bb21
+  %tmp25 = or i64 undef, 7
+  %tmp26 = icmp ult i64 %tmp25, 0
+  br i1 %tmp26, label %bb27, label %bb9
+bb27:                                             ; preds = %bb24
+  %tmp28 = or i64 undef, 8
+  %tmp29 = icmp ult i64 %tmp28, 0
+  br i1 %tmp29, label %bb30, label %bb9
+bb30:                                             ; preds = %bb27
+  br i1 undef, label %bb31, label %bb9
+bb31:                                             ; preds = %bb30
+  br i1 undef, label %bb32, label %bb9
+bb32:                                             ; preds = %bb31
+  br i1 undef, label %bb33, label %bb9
+bb33:                                             ; preds = %bb32
+  br i1 undef, label %bb34, label %bb9
+bb34:                                             ; preds = %bb33
+  br i1 undef, label %bb35, label %bb9
+bb35:                                             ; preds = %bb34
+  br i1 undef, label %bb36, label %bb9
+bb36:                                             ; preds = %bb35
+  br i1 undef, label %bb1, label %bb10
+}