Added opt.

Author: egorshamshura

llvm/lib/Transforms/Scalar/InferAlignment.cpp

@@ -16,11 +16,13 @@
 #include "llvm/Analysis/ValueTracking.h"
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/PatternMatch.h"
 #include "llvm/Support/KnownBits.h"
 #include "llvm/Transforms/Scalar.h"
 #include "llvm/Transforms/Utils/Local.h"
 
 using namespace llvm;
+using namespace llvm::PatternMatch;
 
 static bool tryToImproveAlign(
     const DataLayout &DL, Instruction *I,
@@ -136,6 +138,25 @@ bool inferAlignment(Function &F, AssumptionCache &AC, DominatorTree &DT) {
                             InferFromBasePointer(PtrOp, OldAlign));
           });
     }
+
+    for (Instruction &I : BB) {
+      Value *PtrOp;
+      ConstantInt *Const;
+      if (match(&I,
+                m_c_And(m_PtrToInt(m_Value(PtrOp)), m_ConstantInt(Const)))) {
+        Align KnownAlign = InferFromKnownBits(I, PtrOp);
+        Align BaseAlign = PtrOp->getPointerAlignment(DL);
+        if (auto It = BestBasePointerAligns.find(PtrOp);
+            It != BestBasePointerAligns.end()) {
+          BaseAlign = std::max(BaseAlign, It->second);
+        }
+        Align ActualAlign = std::max(KnownAlign, BaseAlign);
+        if (Const->getValue().ult(ActualAlign.value())) {
+          I.replaceAllUsesWith(Constant::getNullValue(I.getType()));
+          Changed = true;
+        }
+      }
+    }
   }
 
   return Changed;

llvm/test/Transforms/InferAlignment/ptrtoint.ll

@@ -7,7 +7,7 @@ define i64 @base(ptr %0) {
 ; CHECK-NEXT:    [[V1:%.*]] = load i32, ptr [[TMP0]], align 4
 ; CHECK-NEXT:    [[V3:%.*]] = ptrtoint ptr [[TMP0]] to i64
 ; CHECK-NEXT:    [[V5:%.*]] = and i64 [[V3]], 2
-; CHECK-NEXT:    ret i64 [[V5]]
+; CHECK-NEXT:    ret i64 0
 ;
   %v1 = load i32, ptr %0, align 4
   %v3 = ptrtoint ptr %0 to i64
@@ -22,7 +22,7 @@ define i64 @best_alignment(ptr %0) {
 ; CHECK-NEXT:    [[V1_3:%.*]] = load i32, ptr [[TMP0]], align 16
 ; CHECK-NEXT:    [[V3:%.*]] = ptrtoint ptr [[TMP0]] to i64
 ; CHECK-NEXT:    [[V5:%.*]] = and i64 [[V3]], 15
-; CHECK-NEXT:    ret i64 [[V5]]
+; CHECK-NEXT:    ret i64 0
 ;
   %v1 = load i32, ptr %0, align 8
   %v2 = load i32, ptr %0, align 16