[llvm] r369949 - [InstCombine] icmp eq/ne (gep inbounds P, Idx..), null -> icmp eq/ne P, null for vectors

[Philip Reames via llvm-commits]

Author: reames
Date: Mon Aug 26 12:11:49 2019
New Revision: 369949

URL: http://llvm.org/viewvc/llvm-project?rev=369949&view=rev
Log:
[InstCombine] icmp eq/ne (gep inbounds P, Idx..), null -> icmp eq/ne P, null for vectors

Extend the transform introduced in https://reviews.llvm.org/D66608 to work for vector geps as well.

Differential Revision: https://reviews.llvm.org/D66671


Modified:
    llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp
    llvm/trunk/test/Transforms/InstCombine/gep-inbounds-null.ll

Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp?rev=369949&r1=369948&r2=369949&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp Mon Aug 26 12:11:49 2019
@@ -895,7 +895,6 @@ Instruction *InstCombiner::foldGEPICmp(G
     return new ICmpInst(ICmpInst::getSignedPredicate(Cond), Offset,
                         Constant::getNullValue(Offset->getType()));
   } else if (GEPLHS->isInBounds() && ICmpInst::isEquality(Cond) &&
-             GEPLHS->getType()->isPointerTy() && // TODO: extend to vector geps
              isa<Constant>(RHS) && cast<Constant>(RHS)->isNullValue() &&
              !NullPointerIsDefined(I.getFunction(),
                                    RHS->getType()->getPointerAddressSpace())) {
@@ -914,7 +913,13 @@ Instruction *InstCombiner::foldGEPICmp(G
     // In general, we're allowed to make values less poison (i.e. remove
     //   sources of full UB), so in this case, we just select between the two
     //   non-poison cases (1 and 4 above).
+    //
+    // For vectors, we apply the same reasoning on a per-lane basis.
     auto *Base = GEPLHS->getPointerOperand();
+    if (GEPLHS->getType()->isVectorTy() && Base->getType()->isPointerTy()) {
+      int NumElts = GEPLHS->getType()->getVectorNumElements();
+      Base = Builder.CreateVectorSplat(NumElts, Base);
+    }
     return new ICmpInst(Cond, Base,
                         ConstantExpr::getBitCast(cast<Constant>(RHS),
                                                  Base->getType()));

Modified: llvm/trunk/test/Transforms/InstCombine/gep-inbounds-null.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/gep-inbounds-null.ll?rev=369949&r1=369948&r2=369949&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/gep-inbounds-null.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/gep-inbounds-null.ll Mon Aug 26 12:11:49 2019
@@ -75,12 +75,10 @@ entry:
   ret i1 %cnd
 }
 
-;; TODO: vectors not yet handled
 define <2 x i1> @test_vector_base(<2 x i8*> %base, i64 %idx) {
 ; CHECK-LABEL: @test_vector_base(
 ; CHECK-NEXT:  entry:
-; CHECK-NEXT:    [[GEP:%.*]] = getelementptr inbounds i8, <2 x i8*> [[BASE:%.*]], i64 [[IDX:%.*]]
-; CHECK-NEXT:    [[CND:%.*]] = icmp eq <2 x i8*> [[GEP]], zeroinitializer
+; CHECK-NEXT:    [[CND:%.*]] = icmp eq <2 x i8*> [[BASE:%.*]], zeroinitializer
 ; CHECK-NEXT:    ret <2 x i1> [[CND]]
 ;
 entry:
@@ -92,8 +90,9 @@ entry:
 define <2 x i1> @test_vector_index(i8* %base, <2 x i64> %idx) {
 ; CHECK-LABEL: @test_vector_index(
 ; CHECK-NEXT:  entry:
-; CHECK-NEXT:    [[GEP:%.*]] = getelementptr inbounds i8, i8* [[BASE:%.*]], <2 x i64> [[IDX:%.*]]
-; CHECK-NEXT:    [[CND:%.*]] = icmp eq <2 x i8*> [[GEP]], zeroinitializer
+; CHECK-NEXT:    [[DOTSPLATINSERT:%.*]] = insertelement <2 x i8*> undef, i8* [[BASE:%.*]], i32 0
+; CHECK-NEXT:    [[DOTSPLAT:%.*]] = shufflevector <2 x i8*> [[DOTSPLATINSERT]], <2 x i8*> undef, <2 x i32> zeroinitializer
+; CHECK-NEXT:    [[CND:%.*]] = icmp eq <2 x i8*> [[DOTSPLAT]], zeroinitializer
 ; CHECK-NEXT:    ret <2 x i1> [[CND]]
 ;
 entry:
@@ -105,8 +104,7 @@ entry:
 define <2 x i1> @test_vector_both(<2 x i8*> %base, <2 x i64> %idx) {
 ; CHECK-LABEL: @test_vector_both(
 ; CHECK-NEXT:  entry:
-; CHECK-NEXT:    [[GEP:%.*]] = getelementptr inbounds i8, <2 x i8*> [[BASE:%.*]], <2 x i64> [[IDX:%.*]]
-; CHECK-NEXT:    [[CND:%.*]] = icmp eq <2 x i8*> [[GEP]], zeroinitializer
+; CHECK-NEXT:    [[CND:%.*]] = icmp eq <2 x i8*> [[BASE:%.*]], zeroinitializer
 ; CHECK-NEXT:    ret <2 x i1> [[CND]]
 ;
 entry: