From: Chad Rosier <mcrosier@codeaurora.org>
Date: Mon, 25 Apr 2016 17:23:36 +0000 (+0000)
Subject: [ValueTracking] Improve isImpliedCondition when the dominating cond is false.
X-Git-Tag: android-x86-7.1-r4~34604
X-Git-Url: http://git.osdn.net/view?a=commitdiff_plain;h=3ac68db42d1a07ace19bb48c3f89c2de3f65adcd;p=android-x86%2Fexternal-llvm.git

[ValueTracking] Improve isImpliedCondition when the dominating cond is false.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@267430 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/include/llvm/Analysis/ValueTracking.h b/include/llvm/Analysis/ValueTracking.h
index 6e58ee07998..76249b9634f 100644
--- a/include/llvm/Analysis/ValueTracking.h
+++ b/include/llvm/Analysis/ValueTracking.h
@@ -463,11 +463,10 @@ template <typename T> class ArrayRef;
   ///  T | T | F
   ///  F | T | T
   /// (A)
-  Optional<bool> isImpliedCondition(Value *LHS, Value *RHS,
-                                    const DataLayout &DL, unsigned Depth = 0,
-                                    AssumptionCache *AC = nullptr,
-                                    const Instruction *CxtI = nullptr,
-                                    const DominatorTree *DT = nullptr);
+  Optional<bool> isImpliedCondition(
+      Value *LHS, Value *RHS, const DataLayout &DL, bool InvertAPred = false,
+      unsigned Depth = 0, AssumptionCache *AC = nullptr,
+      const Instruction *CxtI = nullptr, const DominatorTree *DT = nullptr);
 } // end namespace llvm
 
 #endif
diff --git a/lib/Analysis/ValueTracking.cpp b/lib/Analysis/ValueTracking.cpp
index 5ada78a5350..a9b8af1017c 100644
--- a/lib/Analysis/ValueTracking.cpp
+++ b/lib/Analysis/ValueTracking.cpp
@@ -3962,8 +3962,8 @@ static Optional<bool> isImpliedCondMatchingOperands(CmpInst::Predicate APred,
 }
 
 Optional<bool> llvm::isImpliedCondition(Value *LHS, Value *RHS,
-                                        const DataLayout &DL, unsigned Depth,
-                                        AssumptionCache *AC,
+                                        const DataLayout &DL, bool InvertAPred,
+                                        unsigned Depth, AssumptionCache *AC,
                                         const Instruction *CxtI,
                                         const DominatorTree *DT) {
   assert(LHS->getType() == RHS->getType() && "mismatched type");
@@ -3971,7 +3971,7 @@ Optional<bool> llvm::isImpliedCondition(Value *LHS, Value *RHS,
   assert(OpTy->getScalarType()->isIntegerTy(1));
 
   // LHS ==> RHS by definition
-  if (LHS == RHS)
+  if (!InvertAPred && LHS == RHS)
     return true;
 
   if (OpTy->isVectorTy())
@@ -3987,6 +3987,9 @@ Optional<bool> llvm::isImpliedCondition(Value *LHS, Value *RHS,
       !match(RHS, m_ICmp(BPred, m_Value(BLHS), m_Value(BRHS))))
     return None;
 
+  if (InvertAPred)
+    APred = CmpInst::getInversePredicate(APred);
+
   Optional<bool> Implication =
       isImpliedCondMatchingOperands(APred, ALHS, ARHS, BPred, BLHS, BRHS);
   if (Implication)
diff --git a/lib/Transforms/Scalar/JumpThreading.cpp b/lib/Transforms/Scalar/JumpThreading.cpp
index ba406a8e8b3..75c340fd593 100644
--- a/lib/Transforms/Scalar/JumpThreading.cpp
+++ b/lib/Transforms/Scalar/JumpThreading.cpp
@@ -925,11 +925,14 @@ bool JumpThreading::ProcessImpliedCondition(BasicBlock *BB) {
 
   while (CurrentPred && Iter++ < ImplicationSearchThreshold) {
     auto *PBI = dyn_cast<BranchInst>(CurrentPred->getTerminator());
-    if (!PBI || !PBI->isConditional() || PBI->getSuccessor(0) != CurrentBB)
+    if (!PBI || !PBI->isConditional())
+      return false;
+    if (PBI->getSuccessor(0) != CurrentBB && PBI->getSuccessor(1) != CurrentBB)
       return false;
 
+    bool FalseDest = PBI->getSuccessor(1) == CurrentBB;
     Optional<bool> Implication =
-        isImpliedCondition(PBI->getCondition(), Cond, DL);
+      isImpliedCondition(PBI->getCondition(), Cond, DL, FalseDest);
     if (Implication) {
       BI->getSuccessor(*Implication ? 1 : 0)->removePredecessor(BB);
       BranchInst::Create(BI->getSuccessor(*Implication ? 0 : 1), BI);
diff --git a/lib/Transforms/Utils/SimplifyCFG.cpp b/lib/Transforms/Utils/SimplifyCFG.cpp
index 53bea2191bc..23199b37b29 100644
--- a/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -2703,11 +2703,13 @@ static bool SimplifyCondBranchToCondBranch(BranchInst *PBI, BranchInst *BI,
 
   // If BI is reached from the true path of PBI and PBI's condition implies
   // BI's condition, we know the direction of the BI branch.
-  if (PBI->getSuccessor(0) == BI->getParent() &&
+  if ((PBI->getSuccessor(0) == BI->getParent() ||
+       PBI->getSuccessor(1) == BI->getParent()) &&
       PBI->getSuccessor(0) != PBI->getSuccessor(1) &&
       BB->getSinglePredecessor()) {
-    Optional<bool> Implication =
-        isImpliedCondition(PBI->getCondition(), BI->getCondition(), DL);
+    bool FalseDest = PBI->getSuccessor(1) == BI->getParent();
+    Optional<bool> Implication = isImpliedCondition(
+        PBI->getCondition(), BI->getCondition(), DL, FalseDest);
     if (Implication) {
       // Turn this into a branch on constant.
       auto *OldCond = BI->getCondition();
diff --git a/test/Transforms/JumpThreading/implied-cond.ll b/test/Transforms/JumpThreading/implied-cond.ll
index 991f78ff497..6da05791456 100644
--- a/test/Transforms/JumpThreading/implied-cond.ll
+++ b/test/Transforms/JumpThreading/implied-cond.ll
@@ -125,3 +125,53 @@ if.end:
 if.end3:
   ret void
 }
+
+declare void @is(i1)
+
+; If A >=s B is false then A <=s B is implied true.
+; CHECK-LABEL: @test_sge_sle
+; CHECK: call void @is(i1 true)
+; CHECK-NOT: call void @is(i1 false)
+define void @test_sge_sle(i32 %a, i32 %b) {
+  %cmp1 = icmp sge i32 %a, %b
+  br i1 %cmp1, label %untaken, label %taken
+
+taken:
+  %cmp2 = icmp sle i32 %a, %b
+  br i1 %cmp2, label %istrue, label %isfalse
+
+istrue:
+  call void @is(i1 true)
+  ret void
+
+isfalse:
+  call void @is(i1 false)
+  ret void
+
+untaken:
+  ret void
+}
+
+; If A <=s B is false then A <=s B is implied false.
+; CHECK-LABEL: @test_sle_sle
+; CHECK-NOT: call void @is(i1 true)
+; CHECK: call void @is(i1 false)
+define void @test_sle_sle(i32 %a, i32 %b) {
+  %cmp1 = icmp sle i32 %a, %b
+  br i1 %cmp1, label %untaken, label %taken
+
+taken:
+  %cmp2 = icmp sle i32 %a, %b
+  br i1 %cmp2, label %istrue, label %isfalse
+
+istrue:
+  call void @is(i1 true)
+  ret void
+
+isfalse:
+  call void @is(i1 false)
+  ret void
+
+untaken:
+  ret void
+}
diff --git a/test/Transforms/SimplifyCFG/implied-cond-matching-false-dest.ll b/test/Transforms/SimplifyCFG/implied-cond-matching-false-dest.ll
new file mode 100644
index 00000000000..1d29813ecfa
--- /dev/null
+++ b/test/Transforms/SimplifyCFG/implied-cond-matching-false-dest.ll
@@ -0,0 +1,339 @@
+; RUN: opt %s -S -simplifycfg | FileCheck %s
+
+declare void @is(i1)
+
+; If A == B is false then A == B is implied false.
+; CHECK-LABEL: @test_eq_eq
+; CHECK-NOT: call void @is(i1 true)
+; CHECK: call void @is(i1 false)
+define void @test_eq_eq(i32 %a, i32 %b) {
+  %cmp1 = icmp eq i32 %a, %b
+  br i1 %cmp1, label %untaken, label %taken
+
+taken:
+  %cmp2 = icmp eq i32 %a, %b
+  br i1 %cmp2, label %istrue, label %isfalse
+
+istrue:
+  call void @is(i1 true)
+  ret void
+
+isfalse:
+  call void @is(i1 false)
+  ret void
+
+untaken:
+  ret void
+}
+
+; If A == B is false then A != B is implied true.
+; CHECK-LABEL: @test_eq_ne
+; CHECK: call void @is(i1 true)
+; CHECK-NOT: call void @is(i1 false)
+define void @test_eq_ne(i32 %a, i32 %b) {
+  %cmp1 = icmp eq i32 %a, %b
+  br i1 %cmp1, label %untaken, label %taken
+
+taken:
+  %cmp2 = icmp ne i32 %a, %b
+  br i1 %cmp2, label %istrue, label %isfalse
+
+istrue:
+  call void @is(i1 true)
+  ret void
+
+isfalse:
+  call void @is(i1 false)
+  ret void
+
+untaken:
+  ret void
+}
+
+; If A != B is false then A != B is implied false.
+; CHECK-LABEL: @test_ne_ne
+; CHECK-NOT: call void @is(i1 true)
+; CHECK: call void @is(i1 false)
+define void @test_ne_ne(i32 %a, i32 %b) {
+  %cmp1 = icmp ne i32 %a, %b
+  br i1 %cmp1, label %untaken, label %taken
+
+taken:
+  %cmp2 = icmp ne i32 %a, %b
+  br i1 %cmp2, label %istrue, label %isfalse
+
+istrue:
+  call void @is(i1 true)
+  ret void
+
+isfalse:
+  call void @is(i1 false)
+  ret void
+
+untaken:
+  ret void
+}
+
+; If A != B is false then A >u B is implied false.
+; CHECK-LABEL: @test_ne_ugt
+; CHECK-NOT: call void @is(i1 true)
+; CHECK: call void @is(i1 false)
+define void @test_ne_ugt(i32 %a, i32 %b) {
+  %cmp1 = icmp ne i32 %a, %b
+  br i1 %cmp1, label %untaken, label %taken
+
+taken:
+  %cmp2 = icmp ugt i32 %a, %b
+  br i1 %cmp2, label %istrue, label %isfalse
+
+istrue:
+  call void @is(i1 true)
+  ret void
+
+isfalse:
+  call void @is(i1 false)
+  ret void
+
+untaken:
+  ret void
+}
+
+; If A != B is false then A >=u B is implied true.
+; CHECK-LABEL: @test_ne_uge
+; CHECK: call void @is(i1 true)
+; CHECK-NOT: call void @is(i1 false)
+define void @test_ne_uge(i32 %a, i32 %b) {
+  %cmp1 = icmp ne i32 %a, %b
+  br i1 %cmp1, label %untaken, label %taken
+
+taken:
+  %cmp2 = icmp uge i32 %a, %b
+  br i1 %cmp2, label %istrue, label %isfalse
+
+istrue:
+  call void @is(i1 true)
+  ret void
+
+isfalse:
+  call void @is(i1 false)
+  ret void
+
+untaken:
+  ret void
+}
+
+; If A != B is false then A <u B is implied false.
+; CHECK-LABEL: @test_ne_ult
+; CHECK-NOT: call void @is(i1 true)
+; CHECK: call void @is(i1 false)
+define void @test_ne_ult(i32 %a, i32 %b) {
+  %cmp1 = icmp ne i32 %a, %b
+  br i1 %cmp1, label %untaken, label %taken
+
+taken:
+  %cmp2 = icmp ult i32 %a, %b
+  br i1 %cmp2, label %istrue, label %isfalse
+
+istrue:
+  call void @is(i1 true)
+  ret void
+
+isfalse:
+  call void @is(i1 false)
+  ret void
+
+untaken:
+  ret void
+}
+
+; If A != B is false then A <=u B is implied true.
+; CHECK-LABEL: @test_ne_ule
+; CHECK: call void @is(i1 true)
+; CHECK-NOT: call void @is(i1 false)
+define void @test_ne_ule(i32 %a, i32 %b) {
+  %cmp1 = icmp ne i32 %a, %b
+  br i1 %cmp1, label %untaken, label %taken
+
+taken:
+  %cmp2 = icmp ule i32 %a, %b
+  br i1 %cmp2, label %istrue, label %isfalse
+
+istrue:
+  call void @is(i1 true)
+  ret void
+
+isfalse:
+  call void @is(i1 false)
+  ret void
+
+untaken:
+  ret void
+}
+
+; If A >u B is false then A >u B is implied false.
+; CHECK-LABEL: @test_ugt_ugt
+; CHECK-NOT: call void @is(i1 true)
+; CHECK: call void @is(i1 false)
+define void @test_ugt_ugt(i32 %a, i32 %b) {
+  %cmp1 = icmp ugt i32 %a, %b
+  br i1 %cmp1, label %untaken, label %taken
+
+taken:
+  %cmp2 = icmp ugt i32 %a, %b
+  br i1 %cmp2, label %istrue, label %isfalse
+
+istrue:
+  call void @is(i1 true)
+  ret void
+
+isfalse:
+  call void @is(i1 false)
+  ret void
+
+untaken:
+  ret void
+}
+
+; If A >u B is false then A <=u B is implied true.
+; CHECK-LABEL: @test_ugt_ule
+; CHECK: call void @is(i1 true)
+; CHECK-NOT: call void @is(i1 false)
+define void @test_ugt_ule(i32 %a, i32 %b) {
+  %cmp1 = icmp ugt i32 %a, %b
+  br i1 %cmp1, label %untaken, label %taken
+
+taken:
+  %cmp2 = icmp ule i32 %a, %b
+  br i1 %cmp2, label %istrue, label %isfalse
+
+istrue:
+  call void @is(i1 true)
+  ret void
+
+isfalse:
+  call void @is(i1 false)
+  ret void
+
+untaken:
+  ret void
+}
+
+; If A >=u B is false then A >=u B is implied false.
+; CHECK-LABEL: @test_uge_uge
+; CHECK-NOT: call void @is(i1 true)
+; CHECK: call void @is(i1 false)
+define void @test_uge_uge(i32 %a, i32 %b) {
+  %cmp1 = icmp uge i32 %a, %b
+  br i1 %cmp1, label %untaken, label %taken
+
+taken:
+  %cmp2 = icmp uge i32 %a, %b
+  br i1 %cmp2, label %istrue, label %isfalse
+
+istrue:
+  call void @is(i1 true)
+  ret void
+
+isfalse:
+  call void @is(i1 false)
+  ret void
+
+untaken:
+  ret void
+}
+
+; If A >=u B is false then A <u B is implied true.
+; CHECK-LABEL: @test_uge_ult
+; CHECK: call void @is(i1 true)
+; CHECK-NOT: call void @is(i1 false)
+define void @test_uge_ult(i32 %a, i32 %b) {
+  %cmp1 = icmp uge i32 %a, %b
+  br i1 %cmp1, label %untaken, label %taken
+
+taken:
+  %cmp2 = icmp ult i32 %a, %b
+  br i1 %cmp2, label %istrue, label %isfalse
+
+istrue:
+  call void @is(i1 true)
+  ret void
+
+isfalse:
+  call void @is(i1 false)
+  ret void
+
+untaken:
+  ret void
+}
+
+; If A >=u B is false then A <=u B is implied true.
+; CHECK-LABEL: @test_uge_ule
+; CHECK: call void @is(i1 true)
+; CHECK-NOT: call void @is(i1 false)
+define void @test_uge_ule(i32 %a, i32 %b) {
+  %cmp1 = icmp uge i32 %a, %b
+  br i1 %cmp1, label %untaken, label %taken
+
+taken:
+  %cmp2 = icmp ule i32 %a, %b
+  br i1 %cmp2, label %istrue, label %isfalse
+
+istrue:
+  call void @is(i1 true)
+  ret void
+
+isfalse:
+  call void @is(i1 false)
+  ret void
+
+untaken:
+  ret void
+}
+
+; If A <u B is false then A <u B is implied false.
+; CHECK-LABEL: @test_ult_ult
+; CHECK-NOT: call void @is(i1 true)
+; CHECK: call void @is(i1 false)
+define void @test_ult_ult(i32 %a, i32 %b) {
+  %cmp1 = icmp ult i32 %a, %b
+  br i1 %cmp1, label %untaken, label %taken
+
+taken:
+  %cmp2 = icmp ult i32 %a, %b
+  br i1 %cmp2, label %istrue, label %isfalse
+
+istrue:
+  call void @is(i1 true)
+  ret void
+
+isfalse:
+  call void @is(i1 false)
+  ret void
+
+untaken:
+  ret void
+}
+
+; If A <=u B is false then A <=u B is implied false.
+; CHECK-LABEL: @test_ule_ule
+; CHECK-NOT: call void @is(i1 true)
+; CHECK: call void @is(i1 false)
+define void @test_ule_ule(i32 %a, i32 %b) {
+  %cmp1 = icmp ule i32 %a, %b
+  br i1 %cmp1, label %untaken, label %taken
+
+taken:
+  %cmp2 = icmp ule i32 %a, %b
+  br i1 %cmp2, label %istrue, label %isfalse
+
+istrue:
+  call void @is(i1 true)
+  ret void
+
+isfalse:
+  call void @is(i1 false)
+  ret void
+
+untaken:
+  ret void
+}