Added opt.

Author: egorshamshura

llvm/lib/Transforms/Scalar/InferAlignment.cpp

@@ -12,15 +12,20 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Transforms/Scalar/InferAlignment.h"
+#include "llvm/ADT/APInt.h"
+#include "llvm/ADT/STLFunctionalExtras.h"
 #include "llvm/Analysis/AssumptionCache.h"
 #include "llvm/Analysis/ValueTracking.h"
+#include "llvm/IR/Instruction.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,
@@ -37,6 +42,16 @@ static bool tryToImproveAlign(
     }
   }
 
+  Value *PtrOp;
+  const APInt *Const;
+  if (match(I, m_And(m_PtrToIntOrAddr(m_Value(PtrOp)), m_APInt(Const)))) {
+    Align ActualAlign = Fn(PtrOp, Align(1), Align(1));
+    if (Const->ult(ActualAlign.value())) {
+      I->replaceAllUsesWith(Constant::getNullValue(I->getType()));
+      return true;
+    }
+  }
+
   IntrinsicInst *II = dyn_cast<IntrinsicInst>(I);
   if (!II)
     return false;
@@ -120,6 +135,15 @@ bool inferAlignment(Function &F, AssumptionCache &AC, DominatorTree &DT) {
     return LoadStoreAlign;
   };
 
+  auto ActualAlginFn = [&](Value *PtrOp) {
+    Align BaseAlign = PtrOp->getPointerAlignment(DL);
+    if (auto It = BestBasePointerAligns.find(PtrOp);
+        It != BestBasePointerAligns.end()) {
+      BaseAlign = std::max(BaseAlign, It->second);
+    }
+    return BaseAlign;
+  };
+
   for (BasicBlock &BB : F) {
     // We need to reset the map for each block because alignment information
     // can only be propagated from instruction A to B if A dominates B.

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
@@ -55,7 +55,7 @@ define i64 @ptrtoaddr(ptr %0) {
 ; CHECK-NEXT:    [[V3:%.*]] = ptrtoaddr ptr [[TMP0]] to i64
 ; CHECK-NEXT:    [[V1:%.*]] = load i32, ptr [[TMP0]], align 4
 ; CHECK-NEXT:    [[V5:%.*]] = and i64 [[V3]], 2
-; CHECK-NEXT:    ret i64 [[V5]]
+; CHECK-NEXT:    ret i64 0
 ;
   %v3 = ptrtoaddr ptr %0 to i64
   %v1 = load i32, ptr %0, align 4