[InstCombine] Fold Select with AND/OR condition

Summary:
Fold
```
%A = icmp ne i8 %X, %V1
%B = icmp ne i8 %X, %V2
%C = or i1 %A, %B
%D = select i1 %C, i8 %X, i8 %V1
ret i8 %D
  =>
ret i8 %X

Fixes https://bugs.llvm.org/show_bug.cgi?id=38334
Proof: https://rise4fun.com/Alive/plI8

Reviewers: spatel, lebedev.ri

Reviewed By: lebedev.ri

Subscribers: craig.topper, llvm-commits

Differential Revision: https://reviews.llvm.org/D49919

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@338191 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp
index 519d6d6..257fa70 100644 (file)
--- a/lib/Analysis/InstructionSimplify.cpp
+++ b/lib/Analysis/InstructionSimplify.cpp
@@ -65,6 +65,40 @@ static Value *SimplifyCastInst(unsigned, Value *, Type *,
 static Value *SimplifyGEPInst(Type *, ArrayRef<Value *>, const SimplifyQuery &,
                               unsigned);
 
+/// Fold
+///   %A = icmp ne/eq i8 %X, %V1
+///   %B = icmp ne/eq i8 %X, %V2
+///   %C = or/and i1 %A, %B
+///   %D = select i1 %C, i8 %X, i8 %V1
+/// To
+///   %X/%V1
+static Value *foldSelectWithBinaryOp(Value *Cond, Value *TrueVal,
+                                     Value *FalseVal) {
+  BinaryOperator::BinaryOps BinOpCode;
+  if (auto *BO = dyn_cast<BinaryOperator>(Cond))
+    BinOpCode = BO->getOpcode();
+  else
+    return nullptr;
+
+  CmpInst::Predicate ExpectedPred;
+  if (BinOpCode == BinaryOperator::Or) {
+    ExpectedPred = ICmpInst::ICMP_NE;
+  } else if (BinOpCode == BinaryOperator::And) {
+    ExpectedPred = ICmpInst::ICMP_EQ;
+  } else
+    return nullptr;
+
+  CmpInst::Predicate Pred1, Pred2;
+  if (!match(
+          Cond,
+          m_c_BinOp(m_c_ICmp(Pred1, m_Specific(TrueVal), m_Specific(FalseVal)),
+                    m_c_ICmp(Pred2, m_Specific(TrueVal), m_Value()))) ||
+      Pred1 != Pred2 || Pred1 != ExpectedPred)
+    return nullptr;
+
+  return BinOpCode == BinaryOperator::Or ? TrueVal : FalseVal;
+}
+
 /// For a boolean type or a vector of boolean type, return false or a vector
 /// with every element false.
 static Constant *getFalse(Type *Ty) {
@@ -3752,6 +3786,9 @@ static Value *SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal,
           simplifySelectWithICmpCond(Cond, TrueVal, FalseVal, Q, MaxRecurse))
     return V;
 
+  if (Value *V = foldSelectWithBinaryOp(Cond, TrueVal, FalseVal))
+    return V;
+
   return nullptr;
 }
 

diff --git a/test/Transforms/InstCombine/select-and-cmp.ll b/test/Transforms/InstCombine/select-and-cmp.ll
index 05908b9..aa733f4 100644 (file)
--- a/test/Transforms/InstCombine/select-and-cmp.ll
+++ b/test/Transforms/InstCombine/select-and-cmp.ll
@@ -5,11 +5,7 @@ target triple = "x86_64-unknown-linux-gnu"
 
 define i32 @select_and_icmp(i32 %x, i32 %y, i32 %z) {
 ; CHECK-LABEL: @select_and_icmp(
-; CHECK-NEXT:    [[A:%.*]] = icmp eq i32 [[X:%.*]], [[Z:%.*]]
-; CHECK-NEXT:    [[B:%.*]] = icmp eq i32 [[Y:%.*]], [[Z]]
-; CHECK-NEXT:    [[C:%.*]] = and i1 [[A]], [[B]]
-; CHECK-NEXT:    [[D:%.*]] = select i1 [[C]], i32 [[Z]], i32 [[X]]
-; CHECK-NEXT:    ret i32 [[D]]
+; CHECK-NEXT:    ret i32 [[X:%.*]]
 ;
   %A = icmp eq i32 %x, %z
   %B = icmp eq i32 %y, %z
@@ -20,11 +16,7 @@ define i32 @select_and_icmp(i32 %x, i32 %y, i32 %z) {
 
 define <2 x i8> @select_and_icmp_vec(<2 x i8> %x, <2 x i8> %y, <2 x i8> %z) {
 ; CHECK-LABEL: @select_and_icmp_vec(
-; CHECK-NEXT:    [[A:%.*]] = icmp eq <2 x i8> [[X:%.*]], [[Z:%.*]]
-; CHECK-NEXT:    [[B:%.*]] = icmp eq <2 x i8> [[Y:%.*]], [[Z]]
-; CHECK-NEXT:    [[C:%.*]] = and <2 x i1> [[A]], [[B]]
-; CHECK-NEXT:    [[D:%.*]] = select <2 x i1> [[C]], <2 x i8> [[Z]], <2 x i8> [[X]]
-; CHECK-NEXT:    ret <2 x i8> [[D]]
+; CHECK-NEXT:    ret <2 x i8> [[X:%.*]]
 ;
   %A = icmp eq <2 x i8> %x, %z
   %B = icmp eq <2 x i8> %y, %z
@@ -35,11 +27,7 @@ define <2 x i8> @select_and_icmp_vec(<2 x i8> %x, <2 x i8> %y, <2 x i8> %z) {
 
 define i32 @select_and_icmp2(i32 %x, i32 %y, i32 %z) {
 ; CHECK-LABEL: @select_and_icmp2(
-; CHECK-NEXT:    [[A:%.*]] = icmp eq i32 [[X:%.*]], [[Z:%.*]]
-; CHECK-NEXT:    [[B:%.*]] = icmp eq i32 [[Y:%.*]], [[Z]]
-; CHECK-NEXT:    [[C:%.*]] = and i1 [[A]], [[B]]
-; CHECK-NEXT:    [[D:%.*]] = select i1 [[C]], i32 [[Z]], i32 [[Y]]
-; CHECK-NEXT:    ret i32 [[D]]
+; CHECK-NEXT:    ret i32 [[Y:%.*]]
 ;
   %A = icmp eq i32 %x, %z
   %B = icmp eq i32 %y, %z
@@ -50,11 +38,7 @@ define i32 @select_and_icmp2(i32 %x, i32 %y, i32 %z) {
 
 define i32 @select_and_inv_icmp(i32 %x, i32 %y, i32 %z) {
 ; CHECK-LABEL: @select_and_inv_icmp(
-; CHECK-NEXT:    [[A:%.*]] = icmp eq i32 [[X:%.*]], [[Z:%.*]]
-; CHECK-NEXT:    [[B:%.*]] = icmp eq i32 [[Y:%.*]], [[Z]]
-; CHECK-NEXT:    [[C:%.*]] = and i1 [[B]], [[A]]
-; CHECK-NEXT:    [[D:%.*]] = select i1 [[C]], i32 [[Z]], i32 [[X]]
-; CHECK-NEXT:    ret i32 [[D]]
+; CHECK-NEXT:    ret i32 [[X:%.*]]
 ;
   %A = icmp eq i32 %x, %z
   %B = icmp eq i32 %y, %z
@@ -65,11 +49,7 @@ define i32 @select_and_inv_icmp(i32 %x, i32 %y, i32 %z) {
 
 define i32 @select_and_icmp_inv(i32 %x, i32 %y, i32 %z) {
 ; CHECK-LABEL: @select_and_icmp_inv(
-; CHECK-NEXT:    [[A:%.*]] = icmp eq i32 [[Z:%.*]], [[X:%.*]]
-; CHECK-NEXT:    [[B:%.*]] = icmp eq i32 [[Z]], [[Y:%.*]]
-; CHECK-NEXT:    [[C:%.*]] = and i1 [[A]], [[B]]
-; CHECK-NEXT:    [[D:%.*]] = select i1 [[C]], i32 [[Z]], i32 [[X]]
-; CHECK-NEXT:    ret i32 [[D]]
+; CHECK-NEXT:    ret i32 [[X:%.*]]
 ;
   %A = icmp eq i32 %z, %x
   %B = icmp eq i32 %z, %y

diff --git a/test/Transforms/InstCombine/select-or-cmp.ll b/test/Transforms/InstCombine/select-or-cmp.ll
index 98759fe..508dc59 100644 (file)
--- a/test/Transforms/InstCombine/select-or-cmp.ll
+++ b/test/Transforms/InstCombine/select-or-cmp.ll
@@ -5,11 +5,7 @@ target triple = "x86_64-unknown-linux-gnu"
 
 define i32 @select_or_icmp(i32 %x, i32 %y, i32 %z) {
 ; CHECK-LABEL: @select_or_icmp(
-; CHECK-NEXT:    [[A:%.*]] = icmp ne i32 [[X:%.*]], [[Z:%.*]]
-; CHECK-NEXT:    [[B:%.*]] = icmp ne i32 [[Y:%.*]], [[Z]]
-; CHECK-NEXT:    [[C:%.*]] = or i1 [[A]], [[B]]
-; CHECK-NEXT:    [[D:%.*]] = select i1 [[C]], i32 [[Z]], i32 [[X]]
-; CHECK-NEXT:    ret i32 [[D]]
+; CHECK-NEXT:    ret i32 [[Z:%.*]]
 ;
   %A = icmp ne i32 %x, %z
   %B = icmp ne i32 %y, %z
@@ -20,11 +16,7 @@ define i32 @select_or_icmp(i32 %x, i32 %y, i32 %z) {
 
 define <2 x i8> @select_or_icmp_vec(<2 x i8> %x, <2 x i8> %y, <2 x i8> %z) {
 ; CHECK-LABEL: @select_or_icmp_vec(
-; CHECK-NEXT:    [[A:%.*]] = icmp ne <2 x i8> [[X:%.*]], [[Z:%.*]]
-; CHECK-NEXT:    [[B:%.*]] = icmp ne <2 x i8> [[Y:%.*]], [[Z]]
-; CHECK-NEXT:    [[C:%.*]] = or <2 x i1> [[A]], [[B]]
-; CHECK-NEXT:    [[D:%.*]] = select <2 x i1> [[C]], <2 x i8> [[Z]], <2 x i8> [[X]]
-; CHECK-NEXT:    ret <2 x i8> [[D]]
+; CHECK-NEXT:    ret <2 x i8> [[Z:%.*]]
 ;
   %A = icmp ne <2 x i8> %x, %z
   %B = icmp ne <2 x i8> %y, %z
@@ -35,11 +27,7 @@ define <2 x i8> @select_or_icmp_vec(<2 x i8> %x, <2 x i8> %y, <2 x i8> %z) {
 
 define i32 @select_or_icmp2(i32 %x, i32 %y, i32 %z) {
 ; CHECK-LABEL: @select_or_icmp2(
-; CHECK-NEXT:    [[A:%.*]] = icmp ne i32 [[X:%.*]], [[Z:%.*]]
-; CHECK-NEXT:    [[B:%.*]] = icmp ne i32 [[Y:%.*]], [[Z]]
-; CHECK-NEXT:    [[C:%.*]] = or i1 [[A]], [[B]]
-; CHECK-NEXT:    [[D:%.*]] = select i1 [[C]], i32 [[Z]], i32 [[Y]]
-; CHECK-NEXT:    ret i32 [[D]]
+; CHECK-NEXT:    ret i32 [[Z:%.*]]
 ;
   %A = icmp ne i32 %x, %z
   %B = icmp ne i32 %y, %z
@@ -50,11 +38,7 @@ define i32 @select_or_icmp2(i32 %x, i32 %y, i32 %z) {
 
 define i32 @select_or_inv_icmp(i32 %x, i32 %y, i32 %z) {
 ; CHECK-LABEL: @select_or_inv_icmp(
-; CHECK-NEXT:    [[A:%.*]] = icmp ne i32 [[X:%.*]], [[Z:%.*]]
-; CHECK-NEXT:    [[B:%.*]] = icmp ne i32 [[Y:%.*]], [[Z]]
-; CHECK-NEXT:    [[C:%.*]] = or i1 [[B]], [[A]]
-; CHECK-NEXT:    [[D:%.*]] = select i1 [[C]], i32 [[Z]], i32 [[X]]
-; CHECK-NEXT:    ret i32 [[D]]
+; CHECK-NEXT:    ret i32 [[Z:%.*]]
 ;
   %A = icmp ne i32 %x, %z
   %B = icmp ne i32 %y, %z
@@ -65,11 +49,7 @@ define i32 @select_or_inv_icmp(i32 %x, i32 %y, i32 %z) {
 
 define i32 @select_or_icmp_inv(i32 %x, i32 %y, i32 %z) {
 ; CHECK-LABEL: @select_or_icmp_inv(
-; CHECK-NEXT:    [[A:%.*]] = icmp ne i32 [[Z:%.*]], [[X:%.*]]
-; CHECK-NEXT:    [[B:%.*]] = icmp ne i32 [[Z]], [[Y:%.*]]
-; CHECK-NEXT:    [[C:%.*]] = or i1 [[A]], [[B]]
-; CHECK-NEXT:    [[D:%.*]] = select i1 [[C]], i32 [[Z]], i32 [[X]]
-; CHECK-NEXT:    ret i32 [[D]]
+; CHECK-NEXT:    ret i32 [[Z:%.*]]
 ;
   %A = icmp ne i32 %z, %x
   %B = icmp ne i32 %z, %y