[PATCH] D52294: [InstCombine] Fix incongruous GEP type addrspace

[Ewan Crawford via Phabricator via llvm-commits]

EwanCrawford created this revision.
EwanCrawford added reviewers: majnemer, spatel, lebedev.ri.

Currently running the `@insertelem_after_gep` function testcase through the InstCombine pass with opt produces:

  define void @insertelem_after_gep(<16 x i32>* %t0) {
    %t3 = getelementptr inbounds <16 x i32>, <16 x i32>* %t0, i64 0, i64 0
    %t4 = insertelement <16 x i32 addrspace(3)*> undef, i32 addrspace(3)* %t3, i32 0
    call void @my_extern_func(<16 x i32 addrspace(3)*> %t4)
    ret void
  }

Which although causes no complaints when produced, isn't valid IR as the insertelement use of the %t3 GEP expects an address space.

  opt: /tmp/bad.ll:52:73: error: '%t3' defined with type 'i32*' but expected 'i32 addrspace(3)*'
    %t4 = insertelement <16 x i32 addrspace(3)*> undef, i32 addrspace(3)* %t3, i32 0

I've fixed this by adding an addrspacecast after the GEP, however please let me know if there's a better alternative solution.


Repository:
  rL LLVM

https://reviews.llvm.org/D52294

Files:
  lib/Transforms/InstCombine/InstructionCombining.cpp
  test/Transforms/InstCombine/gep-addrspace.ll


Index: test/Transforms/InstCombine/gep-addrspace.ll
===================================================================
--- test/Transforms/InstCombine/gep-addrspace.ll
+++ test/Transforms/InstCombine/gep-addrspace.ll
@@ -84,3 +84,21 @@
   store <16 x i32> %call, <16 x i32> addrspace(3)* %t4
   ret void
 }
+
+declare void @extern_vec_pointers_func(<16 x i32 addrspace(3)*>)
+
+define void @insertelem_after_gep(<16 x i32>* %t0) {
+; CHECK-LABEL: @insertelem_after_gep(
+; CHECK-NEXT:    [[T3:%.*]] = getelementptr inbounds <16 x i32>, <16 x i32>* [[T0:%.*]], i64 0, i64 0
+; CHECK-NEXT:    [[TMP1:%.*]] = addrspacecast i32* [[T3]] to i32 addrspace(3)*
+; CHECK-NEXT:    [[T4:%.*]] = insertelement <16 x i32 addrspace(3)*> undef, i32 addrspace(3)* [[TMP1]], i32 0
+; CHECK-NEXT:    call void @extern_vec_pointers_func(<16 x i32 addrspace(3)*> [[T4]])
+; CHECK-NEXT:    ret void
+;
+  %t1 = bitcast <16 x i32>* %t0 to [16 x i32]*
+  %t2 = addrspacecast [16 x i32]* %t1 to [16 x i32] addrspace(3)*
+  %t3 = getelementptr inbounds [16 x i32], [16 x i32] addrspace(3)* %t2, i64 0, i64 0
+  %t4 = insertelement <16 x i32 addrspace(3)*> undef, i32 addrspace(3)* %t3, i32 0
+  call void @extern_vec_pointers_func(<16 x i32 addrspace(3)*> %t4)
+  ret void
+}
Index: lib/Transforms/InstCombine/InstructionCombining.cpp
===================================================================
--- lib/Transforms/InstCombine/InstructionCombining.cpp
+++ lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -2029,9 +2029,17 @@
           areMatchingArrayAndVecTypes(GEPEltType, SrcEltType)) ||
          (GEPEltType->isVectorTy() && SrcEltType->isArrayTy() &&
           areMatchingArrayAndVecTypes(SrcEltType, GEPEltType)))) {
-      GEP.setOperand(0, SrcOp);
-      GEP.setSourceElementType(SrcEltType);
-      return &GEP;
+
+      Value *NGEP =
+            GEP.isInBounds()
+                ? Builder.CreateInBoundsGEP(nullptr, SrcOp, makeArrayRef(Ops).slice(1))
+                : Builder.CreateGEP(nullptr, SrcOp,makeArrayRef(Ops).slice(1));
+      NGEP->takeName(&GEP);
+
+      if (NGEP->getType()->getPointerAddressSpace() != GEP.getAddressSpace())
+        return new AddrSpaceCastInst(NGEP, GEPType);
+
+      return replaceInstUsesWith(GEP, NGEP);
     }
 
     // See if we can simplify:


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