[PATCH] D54653: Remove branch from CreateAlignmentAssumption

[Erich Keane via Phabricator via llvm-commits]

erichkeane updated this revision to Diff 176670.
erichkeane retitled this revision from "Correct CreateAlignmentAssumption to check sign and power-of-2 (LLVM Part)" to "    Remove branch from CreateAlignmentAssumption".
erichkeane edited the summary of this revision.
erichkeane added a comment.

As Hal suggested, revert the change to check for positivity at all.

Only test affected is in Clang, so I'll fix that as a part of submitting this.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D54653/new/

https://reviews.llvm.org/D54653

Files:
  include/llvm/IR/IRBuilder.h


Index: include/llvm/IR/IRBuilder.h
===================================================================
--- include/llvm/IR/IRBuilder.h
+++ include/llvm/IR/IRBuilder.h
@@ -2164,10 +2164,11 @@
                                       Value *OffsetValue = nullptr) {
     assert(isa<PointerType>(PtrValue->getType()) &&
            "trying to create an alignment assumption on a non-pointer?");
+    assert(Alignment != 0 && "Invalid Alignment");
     auto *PtrTy = cast<PointerType>(PtrValue->getType());
     Type *IntPtrTy = getIntPtrTy(DL, PtrTy->getAddressSpace());
 
-    Value *Mask = ConstantInt::get(IntPtrTy, Alignment > 0 ? Alignment - 1 : 0);
+    Value *Mask = ConstantInt::get(IntPtrTy, Alignment - 1);
     return CreateAlignmentAssumptionHelper(DL, PtrValue, Mask, IntPtrTy,
                                            OffsetValue);
   }
@@ -2192,13 +2193,7 @@
     if (Alignment->getType() != IntPtrTy)
       Alignment = CreateIntCast(Alignment, IntPtrTy, /*isSigned*/ true,
                                 "alignmentcast");
-    Value *IsPositive =
-        CreateICmp(CmpInst::ICMP_SGT, Alignment,
-                   ConstantInt::get(Alignment->getType(), 0), "ispositive");
-    Value *PositiveMask =
-        CreateSub(Alignment, ConstantInt::get(IntPtrTy, 1), "positivemask");
-    Value *Mask = CreateSelect(IsPositive, PositiveMask,
-                               ConstantInt::get(IntPtrTy, 0), "mask");
+    Value *Mask = CreateSub(Alignment, ConstantInt::get(IntPtrTy, 1), "mask");
 
     return CreateAlignmentAssumptionHelper(DL, PtrValue, Mask, IntPtrTy,
                                            OffsetValue);


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