Revert [SCEV] Make isLoopEntryGuardedByCond a bit smarter

Revert rL324453 commit which causes buildbot failures.

Differential Revision: https://reviews.llvm.org/D42835

llvm-svn: 324462

7 files changed, 12 insertions, 205 deletions

diff --git a/llvm/include/llvm/IR/InstrTypes.h b/llvm/include/llvm/IR/InstrTypes.h
index 9e938a462cf..871f702f95f 100644
--- a/llvm/include/llvm/IR/InstrTypes.h
+++ b/llvm/include/llvm/IR/InstrTypes.h
@@ -973,19 +973,6 @@ public:
   /// @brief Return the predicate as if the operands were swapped.
   static Predicate getSwappedPredicate(Predicate pred);
 
-  /// For example, SGT -> SGE, SLT -> SLE, ULT -> ULE, UGT -> UGE.
-  /// @brief Returns the non-strict version of strict comparisons.
-  Predicate getNonStrictPredicate() const {
-    return getNonStrictPredicate(getPredicate());
-  }
-
-  /// This is a static version that you can use without an instruction
-  /// available.
-  /// @returns the non-strict version of comparison provided in \p pred.
-  /// If \p pred is not a strict comparison predicate, returns \p pred.
-  /// @brief Returns the non-strict version of strict comparisons.
-  static Predicate getNonStrictPredicate(Predicate pred);
-
   /// @brief Provide more efficient getOperand methods.
   DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
 
diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index 8f5e0bc51df..f44bb8d447e 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -9073,59 +9073,6 @@ ScalarEvolution::isLoopEntryGuardedByCond(const Loop *L,
   if (isKnownPredicateViaConstantRanges(Pred, LHS, RHS))
     return true;
 
-  // If we cannot prove strict comparison (e.g. a > b), maybe we can prove
-  // the facts (a >= b && a != b) separately. A typical situation is when the
-  // non-strict comparison is known from ranges and non-equality is known from
-  // dominating predicates. If we are proving strict comparison, we always try
-  // to prove non-equality and non-strict comparison separately.
-  auto NonStrictPredicate = ICmpInst::getNonStrictPredicate(Pred);
-  const bool ProvingStrictComparison = (Pred != NonStrictPredicate);
-  bool ProvedNonStrictComparison = false;
-  bool ProvedNonEquality = false;
-
-  if (ProvingStrictComparison) {
-    ProvedNonStrictComparison =
-        isKnownPredicateViaConstantRanges(NonStrictPredicate, LHS, RHS);
-    ProvedNonEquality =
-        isKnownPredicateViaConstantRanges(ICmpInst::ICMP_NE, LHS, RHS);
-    assert((!ProvedNonStrictComparison || !ProvedNonEquality) &&
-           "Why we were unable to prove (Pred, LHS, RHS) via constant ranges?");
-  }
-
-  // Try to prove (Pred, LHS, RHS) using isImpliedViaGuard.
-  auto ProveViaGuard = [&](BasicBlock *Block) {
-    if (isImpliedViaGuard(Block, Pred, LHS, RHS))
-      return true;
-    if (ProvingStrictComparison) {
-      if (!ProvedNonStrictComparison)
-        ProvedNonStrictComparison =
-            isImpliedViaGuard(Block, NonStrictPredicate, LHS, RHS);
-      if (!ProvedNonEquality)
-        ProvedNonEquality =
-            isImpliedViaGuard(Block, ICmpInst::ICMP_NE, LHS, RHS);
-      if (ProvedNonStrictComparison && ProvedNonEquality)
-        return true;
-    }
-    return false;
-  };
-
-  // Try to prove (Pred, LHS, RHS) using isImpliedCond.
-  auto ProveViaCond = [&](Value *Condition, bool Inverse) {
-    if (isImpliedCond(Pred, LHS, RHS, Condition, Inverse))
-      return true;
-    if (ProvingStrictComparison) {
-      if (!ProvedNonStrictComparison)
-        ProvedNonStrictComparison =
-            isImpliedCond(NonStrictPredicate, LHS, RHS, Condition, Inverse);
-      if (!ProvedNonEquality)
-        ProvedNonEquality =
-            isImpliedCond(ICmpInst::ICMP_NE, LHS, RHS, Condition, Inverse);
-      if (ProvedNonStrictComparison && ProvedNonEquality)
-        return true;
-    }
-    return false;
-  };
-
   // Starting at the loop predecessor, climb up the predecessor chain, as long
   // as there are predecessors that can be found that have unique successors
   // leading to the original header.
@@ -9134,7 +9081,7 @@ ScalarEvolution::isLoopEntryGuardedByCond(const Loop *L,
        Pair.first;
        Pair = getPredecessorWithUniqueSuccessorForBB(Pair.first)) {
 
-    if (ProveViaGuard(Pair.first))
+    if (isImpliedViaGuard(Pair.first, Pred, LHS, RHS))
       return true;
 
     BranchInst *LoopEntryPredicate =
@@ -9143,8 +9090,9 @@ ScalarEvolution::isLoopEntryGuardedByCond(const Loop *L,
         LoopEntryPredicate->isUnconditional())
       continue;
 
-    if (ProveViaCond(LoopEntryPredicate->getCondition(),
-                     LoopEntryPredicate->getSuccessor(0) != Pair.second))
+    if (isImpliedCond(Pred, LHS, RHS,
+                      LoopEntryPredicate->getCondition(),
+                      LoopEntryPredicate->getSuccessor(0) != Pair.second))
       return true;
   }
 
@@ -9156,7 +9104,7 @@ ScalarEvolution::isLoopEntryGuardedByCond(const Loop *L,
     if (!DT.dominates(CI, L->getHeader()))
       continue;
 
-    if (ProveViaCond(CI->getArgOperand(0), false))
+    if (isImpliedCond(Pred, LHS, RHS, CI->getArgOperand(0), false))
       return true;
   }
 
diff --git a/llvm/lib/IR/Instructions.cpp b/llvm/lib/IR/Instructions.cpp
index 7fa4b06c566..490fcbce743 100644
--- a/llvm/lib/IR/Instructions.cpp
+++ b/llvm/lib/IR/Instructions.cpp
@@ -3467,20 +3467,6 @@ CmpInst::Predicate CmpInst::getSwappedPredicate(Predicate pred) {
   }
 }
 
-CmpInst::Predicate CmpInst::getNonStrictPredicate(Predicate pred) {
-  switch (pred) {
-  case ICMP_SGT: return ICMP_SGE;
-  case ICMP_SLT: return ICMP_SLE;
-  case ICMP_UGT: return ICMP_UGE;
-  case ICMP_ULT: return ICMP_ULE;
-  case FCMP_OGT: return FCMP_OGE;
-  case FCMP_OLT: return FCMP_OLE;
-  case FCMP_UGT: return FCMP_UGE;
-  case FCMP_ULT: return FCMP_ULE;
-  default: return pred;
-  }
-}
-
 CmpInst::Predicate CmpInst::getSignedPredicate(Predicate pred) {
   assert(CmpInst::isUnsigned(pred) && "Call only with signed predicates!");
 
diff --git a/llvm/test/Transforms/IRCE/conjunctive-checks.ll b/llvm/test/Transforms/IRCE/conjunctive-checks.ll
index b1a7063523d..f6a909e432c 100644
--- a/llvm/test/Transforms/IRCE/conjunctive-checks.ll
+++ b/llvm/test/Transforms/IRCE/conjunctive-checks.ll
@@ -4,10 +4,10 @@ define void @f_0(i32 *%arr, i32 *%a_len_ptr, i32 %n, i1* %cond_buf) {
 ; CHECK-LABEL: @f_0(
 
 ; CHECK: loop.preheader:
-; CHECK: [[not_safe_range_end:[^ ]+]] = sub i32 3, %len
 ; CHECK: [[not_n:[^ ]+]] = sub i32 -1, %n
-; CHECK: [[not_exit_main_loop_at_hiclamp_cmp:[^ ]+]] = icmp sgt i32 [[not_safe_range_end]], [[not_n]]
-; CHECK: [[not_exit_main_loop_at_hiclamp:[^ ]+]] = select i1 [[not_exit_main_loop_at_hiclamp_cmp]], i32 [[not_safe_range_end]], i32 [[not_n]]
+; CHECK: [[not_safe_range_end:[^ ]+]] = sub i32 3, %len
+; CHECK: [[not_exit_main_loop_at_hiclamp_cmp:[^ ]+]] = icmp sgt i32 [[not_n]], [[not_safe_range_end]]
+; CHECK: [[not_exit_main_loop_at_hiclamp:[^ ]+]] = select i1 [[not_exit_main_loop_at_hiclamp_cmp]], i32 [[not_n]], i32 [[not_safe_range_end]]
 ; CHECK: [[exit_main_loop_at_hiclamp:[^ ]+]] = sub i32 -1, [[not_exit_main_loop_at_hiclamp]]
 ; CHECK: [[exit_main_loop_at_loclamp_cmp:[^ ]+]] = icmp sgt i32 [[exit_main_loop_at_hiclamp]], 0
 ; CHECK: [[exit_main_loop_at_loclamp:[^ ]+]] = select i1 [[exit_main_loop_at_loclamp_cmp]], i32 [[exit_main_loop_at_hiclamp]], i32 0
diff --git a/llvm/test/Transforms/IRCE/decrementing-loop.ll b/llvm/test/Transforms/IRCE/decrementing-loop.ll
index 395e73c5566..fac873b4a24 100644
--- a/llvm/test/Transforms/IRCE/decrementing-loop.ll
+++ b/llvm/test/Transforms/IRCE/decrementing-loop.ll
@@ -1,8 +1,4 @@
-; RUN: opt -verify-loop-info -irce -debug-only=irce -S < %s 2>&1 | FileCheck %s
-
-; CHECK-LABEL: irce: in function decrementing_loop: constrained Loop at depth 1
-; CHECK-LABEL: irce: in function test_01: constrained Loop at depth 1
-; CHECK-LABEL: irce: in function test_02: constrained Loop at depth 1
+; RUN: opt -verify-loop-info -irce -S < %s | FileCheck %s
 
 define void @decrementing_loop(i32 *%arr, i32 *%a_len_ptr, i32 %n) {
  entry:
@@ -42,85 +38,5 @@ define void @decrementing_loop(i32 *%arr, i32 *%a_len_ptr, i32 %n) {
 ; CHECK:   %exit.preloop.at = add i32 [[not_exit_preloop_at]], -1
 }
 
-; Make sure that we can eliminate the range check when the loop looks like:
-; for (i = len.a - 1; i >= 0; --i)
-;   b[i] = a[i];
-define void @test_01(i32* %a, i32* %b, i32* %a_len_ptr, i32* %b_len_ptr) {
-
-; CHECK-LABEL: test_01
-; CHECK:       mainloop:
-; CHECK-NEXT:    br label %loop
-; CHECK:       loop:
-; CHECK:         %rc = and i1 true, true
-; CHECK:       loop.preloop:
-
- entry:
-  %len.a = load i32, i32* %a_len_ptr, !range !0
-  %len.b = load i32, i32* %b_len_ptr, !range !0
-  %first.itr.check = icmp ne i32 %len.a, 0
-  br i1 %first.itr.check, label %loop, label %exit
-
- loop:
-  %idx = phi i32 [ %len.a, %entry ] , [ %idx.next, %in.bounds ]
-  %idx.next = sub i32 %idx, 1
-  %rca = icmp ult i32 %idx.next, %len.a
-  %rcb = icmp ult i32 %idx.next, %len.b
-  %rc = and i1 %rca, %rcb
-  br i1 %rc, label %in.bounds, label %out.of.bounds, !prof !1
-
- in.bounds:
-  %el.a = getelementptr i32, i32* %a, i32 %idx.next
-  %el.b = getelementptr i32, i32* %b, i32 %idx.next
-  %v = load i32, i32* %el.a
-  store i32 %v, i32* %el.b
-  %loop.cond = icmp slt i32 %idx, 2
-  br i1 %loop.cond, label %exit, label %loop
-
- out.of.bounds:
-  ret void
-
- exit:
-  ret void
-}
-
-; Same as test_01, but the latch condition is unsigned
-define void @test_02(i32* %a, i32* %b, i32* %a_len_ptr, i32* %b_len_ptr) {
-
-; CHECK-LABEL: test_02
-; CHECK:       mainloop:
-; CHECK-NEXT:    br label %loop
-; CHECK:       loop:
-; CHECK:         %rc = and i1 true, true
-; CHECK:       loop.preloop:
-
- entry:
-  %len.a = load i32, i32* %a_len_ptr, !range !0
-  %len.b = load i32, i32* %b_len_ptr, !range !0
-  %first.itr.check = icmp ne i32 %len.a, 0
-  br i1 %first.itr.check, label %loop, label %exit
-
- loop:
-  %idx = phi i32 [ %len.a, %entry ] , [ %idx.next, %in.bounds ]
-  %idx.next = sub i32 %idx, 1
-  %rca = icmp ult i32 %idx.next, %len.a
-  %rcb = icmp ult i32 %idx.next, %len.b
-  %rc = and i1 %rca, %rcb
-  br i1 %rc, label %in.bounds, label %out.of.bounds, !prof !1
-
- in.bounds:
-  %el.a = getelementptr i32, i32* %a, i32 %idx.next
-  %el.b = getelementptr i32, i32* %b, i32 %idx.next
-  %v = load i32, i32* %el.a
-  store i32 %v, i32* %el.b
-  %loop.cond = icmp ult i32 %idx, 2
-  br i1 %loop.cond, label %exit, label %loop
-
- out.of.bounds:
-  ret void
-
- exit:
-  ret void
-}
-
 !0 = !{i32 0, i32 2147483647}
 !1 = !{!"branch_weights", i32 64, i32 4}
diff --git a/llvm/test/Transforms/IRCE/single-access-no-preloop.ll b/llvm/test/Transforms/IRCE/single-access-no-preloop.ll
index c9da4e28950..53f430d0ba3 100644
--- a/llvm/test/Transforms/IRCE/single-access-no-preloop.ll
+++ b/llvm/test/Transforms/IRCE/single-access-no-preloop.ll
@@ -85,10 +85,10 @@ define void @single_access_no_preloop_with_offset(i32 *%arr, i32 *%a_len_ptr, i3
 ; CHECK-LABEL: @single_access_no_preloop_with_offset(
 
 ; CHECK: loop.preheader:
-; CHECK: [[not_safe_range_end:[^ ]+]] = sub i32 3, %len
 ; CHECK: [[not_n:[^ ]+]] = sub i32 -1, %n
-; CHECK: [[not_exit_main_loop_at_hiclamp_cmp:[^ ]+]] = icmp sgt i32 [[not_safe_range_end]], [[not_n]]
-; CHECK: [[not_exit_main_loop_at_hiclamp:[^ ]+]] = select i1 [[not_exit_main_loop_at_hiclamp_cmp]], i32 [[not_safe_range_end]], i32 [[not_n]]
+; CHECK: [[not_safe_range_end:[^ ]+]] = sub i32 3, %len
+; CHECK: [[not_exit_main_loop_at_hiclamp_cmp:[^ ]+]] = icmp sgt i32 [[not_n]], [[not_safe_range_end]]
+; CHECK: [[not_exit_main_loop_at_hiclamp:[^ ]+]] = select i1 [[not_exit_main_loop_at_hiclamp_cmp]], i32 [[not_n]], i32 [[not_safe_range_end]]
 ; CHECK: [[exit_main_loop_at_hiclamp:[^ ]+]] = sub i32 -1, [[not_exit_main_loop_at_hiclamp]]
 ; CHECK: [[exit_main_loop_at_loclamp_cmp:[^ ]+]] = icmp sgt i32 [[exit_main_loop_at_hiclamp]], 0
 ; CHECK: [[exit_main_loop_at_loclamp:[^ ]+]] = select i1 [[exit_main_loop_at_loclamp_cmp]], i32 [[exit_main_loop_at_hiclamp]], i32 0
diff --git a/llvm/test/Transforms/IndVarSimplify/loop-invariant-conditions.ll b/llvm/test/Transforms/IndVarSimplify/loop-invariant-conditions.ll
index 30249828107..70cf714ba9f 100644
--- a/llvm/test/Transforms/IndVarSimplify/loop-invariant-conditions.ll
+++ b/llvm/test/Transforms/IndVarSimplify/loop-invariant-conditions.ll
@@ -325,36 +325,6 @@ exit:
   ret void
 }
 
-; check that we can figure out that iv.next > 1 from the facts that iv >= 0 and
-; iv.start != 0.
-define void @test11(i64* %inc_ptr) {
-; CHECK-LABEL: @test11
-entry:
-  %inc = load i64, i64* %inc_ptr, !range !0
-  %ne.cond = icmp ne i64 %inc, 0
-  br i1 %ne.cond, label %loop, label %exit
-
-loop:
-  %iv = phi i64 [ %inc, %entry ], [ %iv.next, %backedge ]
-  %iv.next = add i64 %iv, 1
-  %brcond = icmp sgt i64 %iv.next, 1
-  ; CHECK: br i1 true, label %if.true, label %if.false
-  br i1 %brcond, label %if.true, label %if.false
-
-if.true:
-  br label %backedge
-
-if.false:
-  br label %backedge
-
-backedge:
-  %loopcond = icmp slt i64 %iv, 200
-  br i1 %loopcond, label %loop, label %exit
-
-exit:
-  ret void
-}
-
 !1 = !{i64 -1, i64 100}