[PATCH] D66671: [InstCombine] icmp eq/ne (gep inbounds P, Idx..), null -> icmp eq/ne P, null for vectors

[Philip Reames via Phabricator via llvm-commits]

reames created this revision.
reames added reviewers: jdoerfert, nikic, xbolva00.
Herald added subscribers: bollu, mcrosier.
Herald added a project: LLVM.

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


Repository:
  rL LLVM

https://reviews.llvm.org/D66671

Files:
  lib/Transforms/InstCombine/InstCombineCompares.cpp
  test/Transforms/InstCombine/gep-inbounds-null.ll


Index: test/Transforms/InstCombine/gep-inbounds-null.ll
===================================================================
--- test/Transforms/InstCombine/gep-inbounds-null.ll
+++ test/Transforms/InstCombine/gep-inbounds-null.ll
@@ -79,8 +79,7 @@
 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 +91,9 @@
 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 +105,7 @@
 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:
Index: lib/Transforms/InstCombine/InstCombineCompares.cpp
===================================================================
--- lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -895,7 +895,6 @@
     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 @@
     // 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()));


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D66671.216915.patch
Type: text/x-patch
Size: 3276 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20190823/b1ed05ec/attachment.bin>