[llvm] 4059c1c - [SimplifyInst] Use correct type for GEPs with vector indices.

[Florian Hahn via llvm-commits]

Author: Florian Hahn
Date: 2021-04-06T17:56:10+01:00
New Revision: 4059c1c32d37ff3738428dcc2a4c98c4677d3a24

URL: https://github.com/llvm/llvm-project/commit/4059c1c32d37ff3738428dcc2a4c98c4677d3a24
DIFF: https://github.com/llvm/llvm-project/commit/4059c1c32d37ff3738428dcc2a4c98c4677d3a24.diff

LOG: [SimplifyInst] Use correct type for GEPs with vector indices.

The current code does not properly handle vector indices unless they are
the first index.

At the moment LangRef gives the impression that the vector index must be
the one and only index (https://llvm.org/docs/LangRef.html#getelementptr-instruction).

But vector indices can appear at any position and according to the
verifier there may be multiple vector indices. If that's the case, the
number of elements must match.

This patch updates SimplifyGEPInst to properly handle those additional
cases.

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D99961

Added: 
    

Modified: 
    llvm/lib/Analysis/InstructionSimplify.cpp
    llvm/test/Transforms/InstSimplify/gep.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index 5804f6868052b..a6d3ca64189d1 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -4321,10 +4321,14 @@ static Value *SimplifyGEPInst(Type *SrcTy, ArrayRef<Value *> Ops,
   // Compute the (pointer) type returned by the GEP instruction.
   Type *LastType = GetElementPtrInst::getIndexedType(SrcTy, Ops.slice(1));
   Type *GEPTy = PointerType::get(LastType, AS);
-  if (VectorType *VT = dyn_cast<VectorType>(Ops[0]->getType()))
-    GEPTy = VectorType::get(GEPTy, VT->getElementCount());
-  else if (VectorType *VT = dyn_cast<VectorType>(Ops[1]->getType()))
-    GEPTy = VectorType::get(GEPTy, VT->getElementCount());
+  for (Value *Op : Ops) {
+    // If one of the operands is a vector, the result type is a vector of
+    // pointers. All vector operands must have the same number of elements.
+    if (VectorType *VT = dyn_cast<VectorType>(Op->getType())) {
+      GEPTy = VectorType::get(GEPTy, VT->getElementCount());
+      break;
+    }
+  }
 
   // getelementptr poison, idx -> poison
   // getelementptr baseptr, poison -> poison

diff  --git a/llvm/test/Transforms/InstSimplify/gep.ll b/llvm/test/Transforms/InstSimplify/gep.ll
index e1da60ee56684..0a5b27e12b6c8 100644
--- a/llvm/test/Transforms/InstSimplify/gep.ll
+++ b/llvm/test/Transforms/InstSimplify/gep.ll
@@ -315,3 +315,32 @@ define i32* @D98611_3(i32* %c1, i64 %offset) {
   %gep = getelementptr inbounds i32, i32* %c1, i64 %ashr
   ret i32* %gep
 }
+
+define <8 x i32*> @gep_vector_index_op2_poison([144 x i32]* %ptr) {
+; CHECK-LABEL: @gep_vector_index_op2_poison(
+; CHECK-NEXT:    ret <8 x i32*> poison
+;
+  %res = getelementptr inbounds [144 x i32], [144 x i32]* %ptr, i64 0, <8 x i64> poison
+  ret <8 x i32*> %res
+}
+
+%t.1 = type { i32, [144 x i32] }
+
+define <8 x i32*> @gep_vector_index_op3_poison(%t.1* %ptr) {
+; CHECK-LABEL: @gep_vector_index_op3_poison(
+; CHECK-NEXT:    ret <8 x i32*> poison
+;
+  %res = getelementptr inbounds %t.1, %t.1* %ptr, i64 0, i32 1, <8 x i64> poison
+  ret <8 x i32*> %res
+}
+
+%t.2 = type { i32, i32 }
+%t.3 = type { i32, [144 x %t.2 ] }
+
+define <8 x i32*> @gep_vector_index_op3_poison_constant_index_afterwards(%t.3* %ptr) {
+; CHECK-LABEL: @gep_vector_index_op3_poison_constant_index_afterwards(
+; CHECK-NEXT:    ret <8 x i32*> poison
+;
+  %res = getelementptr inbounds %t.3, %t.3* %ptr, i64 0, i32 1, <8 x i64> poison, i32 1
+  ret <8 x i32*> %res
+}