[NFC][MSAN] Extract llvm.abs handling into a function

[eugenis]

llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp

2688

Add it to a list in visitIntrinsicInst

[vitalybuka]

use visitIntrinsicInst

[eugenis]

LGTM

llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp

#endif
   bool maybeHandleSimpleNomemIntrinsic(IntrinsicInst &I) {
     Type *RetTy = I.getType();
     if (!(RetTy->isIntOrIntVectorTy() ||
           RetTy->isFPOrFPVectorTy() ||
           RetTy->isX86_MMXTy()))
       return false;
 
     unsigned NumArgOperands = I.getNumArgOperands();
-    if (I.getIntrinsicID() == Intrinsic::abs) {
-      assert(NumArgOperands == 2);
-      // The last argument is just a boolean flag.
-      NumArgOperands = 1;
-    }
-
     for (unsigned i = 0; i < NumArgOperands; ++i) {
       Type *Ty = I.getArgOperand(i)->getType();
       if (Ty != RetTy)
         return false;
     }
 
     IRBuilder<> IRB(&I);
     ShadowAndOriginCombiner SC(this, IRB);
bool handleUnknownIntrinsic(IntrinsicInst &I) {
     if (NumArgOperands == 1 &&
         I.getArgOperand(0)->getType()->isPointerTy() &&
         I.getType()->isVectorTy() &&
         I.onlyReadsMemory()) {
       // This looks like a vector load.
       return handleVectorLoadIntrinsic(I);
     }
 
     if (I.doesNotAccessMemory())
       if (maybeHandleSimpleNomemIntrinsic(I))
         return true;
 
     // FIXME: detect and handle SSE maskstore/maskload
     return false;
   }
 
   void handleInvariantGroup(IntrinsicInst &I) {
void handleBinarySdIntrinsic(IntrinsicInst &I) {
     // High word of first operand, low word of both OR'd together
     Value *Shadow = IRB.CreateShuffleVector(First, OrShadow,
                                             llvm::makeArrayRef<int>({2, 1}));
 
     setShadow(&I, Shadow);
     setOriginForNaryOp(I);
   }
 
+  // Instrument abs intrinsic.
+  // handleUnknownIntrinsic can't handle it because of the last
+  // is_int_min_poison argument which does not match the result type.
+  void handleAbsIntrinsic(IntrinsicInst &I) {
+    assert(I.getType()->isIntOrIntVectorTy());
+    assert(I.getArgOperand(0)->getType() == I.getType());
+
+    // FIXME: Handle is_int_min_poison.
+    IRBuilder<> IRB(&I);
+    setShadow(&I, getShadow(&I, 0));
+    setOrigin(&I, getOrigin(&I, 0));
+  }
+
   void visitIntrinsicInst(IntrinsicInst &I) {
     switch (I.getIntrinsicID()) {
+    case Intrinsic::abs:
+      handleAbsIntrinsic(I);
+      break;
     case Intrinsic::lifetime_start:
       handleLifetimeStart(I);
       break;
     case Intrinsic::launder_invariant_group:
     case Intrinsic::strip_invariant_group:
       handleInvariantGroup(I);
       break;
     case Intrinsic::bswap: