Apply transformations

Author: leewei05

llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp

@@ -24,6 +24,7 @@
 #include "llvm/IR/ConstantRange.h"
 #include "llvm/IR/DataLayout.h"
 #include "llvm/IR/InstrTypes.h"
+#include "llvm/IR/Instructions.h"
 #include "llvm/IR/IntrinsicInst.h"
 #include "llvm/IR/PatternMatch.h"
 #include "llvm/Support/KnownBits.h"
@@ -7687,6 +7688,29 @@ Instruction *InstCombinerImpl::visitICmpInst(ICmpInst &I) {
   if (Instruction *Res = foldReductionIdiom(I, Builder, DL))
     return Res;
 
+  {
+    Value *A, *B;
+    const APInt *C;
+    ICmpInst::Predicate PredEq = ICmpInst::ICMP_EQ;
+    if (I.getPredicate() == PredEq) {
+      if (match(Op0, m_And(m_Value(A), m_APInt(C))) && match(Op1, m_One())) {
+        if (*C == APInt::getSignedMinValue(C->getBitWidth()) + 1) {
+          if (match(A, m_SExt(m_Value(B))) &&
+              B->getType()->getIntegerBitWidth() > 2) {
+            auto *InputTy = B->getType();
+            Value *AndInst = Builder.CreateAnd(
+                B,
+                ConstantInt::get(InputTy, APInt::getSignedMinValue(
+                                              InputTy->getIntegerBitWidth()) +
+                                              1));
+            return CmpInst::Create(Instruction::ICmp, PredEq, AndInst,
+                                   ConstantInt::get(InputTy, 1));
+          }
+        }
+      }
+    }
+  }
+
   return Changed ? &I : nullptr;
 }
 

llvm/test/Transforms/InstCombine/sext-and.ll

@@ -6,9 +6,8 @@ declare void @use(i8)
 define i1 @fold_sext_to_and(i8 %x) {
 ; CHECK-LABEL: define i1 @fold_sext_to_and(
 ; CHECK-SAME: i8 [[X:%.*]]) {
-; CHECK-NEXT:    [[TMP1:%.*]] = sext i8 [[X]] to i32
-; CHECK-NEXT:    [[TMP2:%.*]] = and i32 [[TMP1]], -2147483647
-; CHECK-NEXT:    [[TMP3:%.*]] = icmp eq i32 [[TMP2]], 1
+; CHECK-NEXT:    [[TMP1:%.*]] = and i8 [[X]], -127
+; CHECK-NEXT:    [[TMP3:%.*]] = icmp eq i8 [[TMP1]], 1
 ; CHECK-NEXT:    ret i1 [[TMP3]]
 ;
   %1 = sext i8 %x to i32
@@ -22,8 +21,8 @@ define i1 @fold_sext_to_and_multi_use(i8 %x) {
 ; CHECK-SAME: i8 [[X:%.*]]) {
 ; CHECK-NEXT:    [[TMP1:%.*]] = sext i8 [[X]] to i32
 ; CHECK-NEXT:    call void @use(i32 [[TMP1]])
-; CHECK-NEXT:    [[TMP2:%.*]] = and i32 [[TMP1]], -2147483647
-; CHECK-NEXT:    [[TMP3:%.*]] = icmp eq i32 [[TMP2]], 1
+; CHECK-NEXT:    [[TMP2:%.*]] = and i8 [[X]], -127
+; CHECK-NEXT:    [[TMP3:%.*]] = icmp eq i8 [[TMP2]], 1
 ; CHECK-NEXT:    ret i1 [[TMP3]]
 ;
   %1 = sext i8 %x to i32