[PATCH] D99845: [GlobalOpt] Delete write-only constants with cast users

[Johannes Doerfert via Phabricator via llvm-commits]

jdoerfert updated this revision to Diff 335104.
jdoerfert added a comment.

Check for pointer type, ptr2int test


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D99845/new/

https://reviews.llvm.org/D99845

Files:
  llvm/lib/Transforms/IPO/GlobalOpt.cpp
  llvm/test/Transforms/GlobalOpt/writeonly-internal-bitcast.ll


Index: llvm/test/Transforms/GlobalOpt/writeonly-internal-bitcast.ll
===================================================================
--- llvm/test/Transforms/GlobalOpt/writeonly-internal-bitcast.ll
+++ llvm/test/Transforms/GlobalOpt/writeonly-internal-bitcast.ll
@@ -11,17 +11,7 @@
 
 define void @f(i32 %I32)  {
 ; CHECK-LABEL: @f(
-; CHECK-NEXT:    [[G1:%.*]] = getelementptr inbounds [[STRUCT_S:%.*]], %struct.S* @CastAccess, i32 0, i32 1, i32 [[I32:%.*]]
-; CHECK-NEXT:    [[BC1:%.*]] = bitcast i8* [[G1]] to i32*
-; CHECK-NEXT:    store i32 0, i32* [[BC1]], align 4
-; CHECK-NEXT:    [[G2:%.*]] = getelementptr inbounds [[STRUCT_S]], %struct.S* @CastAccessConst, i32 0, i32 1, i32 42
-; CHECK-NEXT:    [[BC2:%.*]] = bitcast i8* [[G2]] to i32*
-; CHECK-NEXT:    store i32 0, i32* [[BC2]], align 4
-; CHECK-NEXT:    [[AS3:%.*]] = addrspacecast [[STRUCT_S]] addrspace(3)* @ASCastAccess to %struct.S*
-; CHECK-NEXT:    [[G3:%.*]] = getelementptr inbounds [[STRUCT_S]], %struct.S* [[AS3]], i32 0, i32 1, i32 [[I32]]
-; CHECK-NEXT:    [[BC3:%.*]] = bitcast i8* [[G3]] to i32*
-; CHECK-NEXT:    store i32 0, i32* [[BC3]], align 4
-; CHECK-NEXT:    [[G4:%.*]] = getelementptr inbounds [[STRUCT_S]], %struct.S* @P2ICastAccess, i32 0, i32 1, i32 42
+; CHECK-NEXT:    [[G4:%.*]] = getelementptr inbounds [[STRUCT_S:%.*]], %struct.S* @P2ICastAccess, i32 0, i32 1, i32 42
 ; CHECK-NEXT:    [[PTR2INT:%.*]] = ptrtoint i8* [[G4]] to i64
 ; CHECK-NEXT:    [[INT2PTR:%.*]] = inttoptr i64 [[PTR2INT]] to i32*
 ; CHECK-NEXT:    store i32 0, i32* [[INT2PTR]], align 4
Index: llvm/lib/Transforms/IPO/GlobalOpt.cpp
===================================================================
--- llvm/lib/Transforms/IPO/GlobalOpt.cpp
+++ llvm/lib/Transforms/IPO/GlobalOpt.cpp
@@ -315,6 +315,7 @@
                   CE->getType()->isPointerTy()) ||
                  CE->getOpcode() == Instruction::AddrSpaceCast) {
         // Pointer cast, delete any stores and memsets to the global.
+        // TODO: We should try to cast the Init value to the new type.
         Changed |= CleanupConstantGlobalUsers(CE, nullptr, DL, GetTLI);
       }
 
@@ -322,6 +323,16 @@
         CE->destroyConstant();
         Changed = true;
       }
+    } else if (CastInst *CI = dyn_cast<CastInst>(U)) {
+      if (CI->getType()->isPointerTy()) {
+        // Pointer cast, delete any stores and memsets to the global.
+        // TODO: We should try to cast the Init value to the new type.
+        Changed |= CleanupConstantGlobalUsers(CI, nullptr, DL, GetTLI);
+        if (CI->use_empty()) {
+          CI->eraseFromParent();
+          Changed = true;
+        }
+      }
     } else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(U)) {
       // Do not transform "gepinst (gep constexpr (GV))" here, because forming
       // "gepconstexpr (gep constexpr (GV))" will cause the two gep's to fold


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