[PATCH] D154126: [InstCombine] Transform (A > 0) | (A < 0) -> zext (A != 0) fold

[Hongyu Chen via Phabricator via llvm-commits]

XChy updated this revision to Diff 536512.
XChy marked 2 inline comments as done.
XChy set the repository for this revision to rG LLVM Github Monorepo.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D154126/new/

https://reviews.llvm.org/D154126

Files:
  llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
  llvm/test/Transforms/InstCombine/and-or-icmps.ll


Index: llvm/test/Transforms/InstCombine/and-or-icmps.ll
===================================================================
--- llvm/test/Transforms/InstCombine/and-or-icmps.ll
+++ llvm/test/Transforms/InstCombine/and-or-icmps.ll
@@ -2571,10 +2571,8 @@
 
 define i32 @icmp_slt_0_or_icmp_sgt_0_i32(i32 %x) {
 ; CHECK-LABEL: @icmp_slt_0_or_icmp_sgt_0_i32(
-; CHECK-NEXT:    [[B:%.*]] = icmp sgt i32 [[X:%.*]], 0
-; CHECK-NEXT:    [[X_LOBIT:%.*]] = lshr i32 [[X]], 31
-; CHECK-NEXT:    [[D:%.*]] = zext i1 [[B]] to i32
-; CHECK-NEXT:    [[E:%.*]] = or i32 [[X_LOBIT]], [[D]]
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp ne i32 [[X:%.*]], 0
+; CHECK-NEXT:    [[E:%.*]] = zext i1 [[TMP1]] to i32
 ; CHECK-NEXT:    ret i32 [[E]]
 ;
   %A = icmp slt i32 %x, 0
@@ -2587,10 +2585,8 @@
 
 define i64 @icmp_slt_0_or_icmp_sgt_0_i64(i64 %x) {
 ; CHECK-LABEL: @icmp_slt_0_or_icmp_sgt_0_i64(
-; CHECK-NEXT:    [[B:%.*]] = icmp sgt i64 [[X:%.*]], 0
-; CHECK-NEXT:    [[X_LOBIT:%.*]] = lshr i64 [[X]], 63
-; CHECK-NEXT:    [[D:%.*]] = zext i1 [[B]] to i64
-; CHECK-NEXT:    [[E:%.*]] = or i64 [[X_LOBIT]], [[D]]
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp ne i64 [[X:%.*]], 0
+; CHECK-NEXT:    [[E:%.*]] = zext i1 [[TMP1]] to i64
 ; CHECK-NEXT:    ret i64 [[E]]
 ;
   %A = icmp slt i64 %x, 0
@@ -2659,10 +2655,8 @@
 
 define <2 x i64> @icmp_slt_0_or_icmp_sgt_0_i64x2(<2 x i64> %x) {
 ; CHECK-LABEL: @icmp_slt_0_or_icmp_sgt_0_i64x2(
-; CHECK-NEXT:    [[B:%.*]] = icmp sgt <2 x i64> [[X:%.*]], zeroinitializer
-; CHECK-NEXT:    [[X_LOBIT:%.*]] = lshr <2 x i64> [[X]], <i64 63, i64 63>
-; CHECK-NEXT:    [[D:%.*]] = zext <2 x i1> [[B]] to <2 x i64>
-; CHECK-NEXT:    [[E:%.*]] = or <2 x i64> [[X_LOBIT]], [[D]]
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp ne <2 x i64> [[X:%.*]], zeroinitializer
+; CHECK-NEXT:    [[E:%.*]] = zext <2 x i1> [[TMP1]] to <2 x i64>
 ; CHECK-NEXT:    ret <2 x i64> [[E]]
 ;
   %A = icmp slt <2 x i64> %x, <i64 0,i64 0>
Index: llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
===================================================================
--- llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -1712,6 +1712,31 @@
   assert(I.isBitwiseLogicOp() && "Unexpected opcode for bitwise logic folding");
 
   Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+  // ( A << (X - 1) ) | ((A > 0) zext to iX)
+  // <=> A < 0 | A > 0
+  // <=> (A != 0) zext to iX
+  Value *A;
+  const APInt *B;
+  ICmpInst::Predicate Pred;
+
+  auto MatchOrZExtICmp = [&](Value *Op0, Value *Op1) -> bool {
+    return match(Op0, m_LShr(m_Value(A), m_APInt(B))) &&
+           match(Op1, m_ZExt(m_ICmp(Pred, m_Specific(A), m_Zero())));
+  };
+
+  if (LogicOpc == Instruction::Or &&
+      (MatchOrZExtICmp(Op0, Op1) || MatchOrZExtICmp(Op1, Op0)) &&
+      Pred == ICmpInst::ICMP_SGT) {
+    uint64_t X = A->getType()->getScalarSizeInBits();
+
+    if (B->getZExtValue() == X - 1) {
+      Value *Cmp =
+          Builder.CreateICmpNE(A, Constant::getNullValue(A->getType()));
+      return new ZExtInst(Cmp, A->getType());
+    }
+  }
+
   CastInst *Cast0 = dyn_cast<CastInst>(Op0);
   if (!Cast0)
     return nullptr;


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