From: Philip Reames <listmail@philipreames.com>
Date: Mon, 26 Aug 2019 19:11:49 +0000 (+0000)
Subject: [InstCombine] icmp eq/ne (gep inbounds P, Idx..), null -> icmp eq/ne P, null for... 
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=bcb37b91cc85eb67ebb247a6895f9bbf5a4b9ba5;p=llvm

[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



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@369949 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Transforms/InstCombine/InstCombineCompares.cpp b/lib/Transforms/InstCombine/InstCombineCompares.cpp
index b80e9ade75d..c4491178018 100644
--- a/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -895,7 +895,6 @@ Instruction *InstCombiner::foldGEPICmp(GEPOperator *GEPLHS, Value *RHS,
     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(GEPOperator *GEPLHS, Value *RHS,
     // 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()));
diff --git a/test/Transforms/InstCombine/gep-inbounds-null.ll b/test/Transforms/InstCombine/gep-inbounds-null.ll
index 544f9a3f2e3..6cf294add74 100644
--- a/test/Transforms/InstCombine/gep-inbounds-null.ll
+++ b/test/Transforms/InstCombine/gep-inbounds-null.ll
@@ -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: