[llvm] [DSE] Split memory intrinsics if they are dead in the middle (PR #75478)

[Nabeel Omer via llvm-commits]

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@@ -0,0 +1,305 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 4
+; RUN: opt < %s -passes=dse -S | FileCheck %s
+
+; Check a dbg.assign is inserted that sets the dead middle bits to no-location (see tryToSplitMiddle).
+
+define dso_local void @_Z22overwrite_middle_localv() local_unnamed_addr #0 !dbg !103 {
+; CHECK-LABEL: define dso_local void @_Z22overwrite_middle_localv(
+; CHECK-SAME: ) local_unnamed_addr #[[ATTR0:[0-9]+]] !dbg [[DBG103:![0-9]+]] {
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[BLOB:%.*]] = alloca [1000 x i8], align 16, !DIAssignID [[DIASSIGNID112:![0-9]+]]
+; CHECK-NEXT:    call void @llvm.dbg.assign(metadata i1 undef, metadata [[META108:![0-9]+]], metadata !DIExpression(), metadata [[DIASSIGNID112]], metadata ptr [[BLOB]], metadata !DIExpression()), !dbg [[DBG113:![0-9]+]]
+; CHECK-NEXT:    call void @llvm.lifetime.start.p0(i64 1000, ptr nonnull [[BLOB]]) #[[ATTR5:[0-9]+]], !dbg [[DBG114:![0-9]+]]
+; CHECK-NEXT:    [[TMP0:%.*]] = getelementptr inbounds i8, ptr [[BLOB]], i64 976
+; CHECK-NEXT:    call void @llvm.memset.p0.i64(ptr noundef nonnull align 16 dereferenceable(24) [[TMP0]], i8 5, i64 24, i1 false), !dbg [[DBG115:![0-9]+]], !DIAssignID [[DIASSIGNID116:![0-9]+]]
+; CHECK-NEXT:    call void @llvm.memset.p0.i64(ptr noundef nonnull align 16 dereferenceable(10) [[BLOB]], i8 5, i64 10, i1 false), !dbg [[DBG115]], !DIAssignID [[DIASSIGNID116]]
+; CHECK-NEXT:    call void @llvm.dbg.assign(metadata i1 undef, metadata [[META108]], metadata !DIExpression(), metadata [[DIASSIGNID116]], metadata ptr [[BLOB]], metadata !DIExpression()), !dbg [[DBG113]]
+; CHECK-NEXT:    call void @llvm.dbg.assign(metadata i1 undef, metadata [[META108]], metadata !DIExpression(DW_OP_LLVM_fragment, 80, 7920), metadata [[META117:![0-9]+]], metadata ptr undef, metadata !DIExpression()), !dbg [[DBG113]]
+; CHECK-NEXT:    [[ADD_PTR:%.*]] = getelementptr inbounds i8, ptr [[BLOB]], i64 10, !dbg [[DBG118:![0-9]+]]
+; CHECK-NEXT:    call void @llvm.memset.p0.i64(ptr noundef nonnull align 2 dereferenceable(980) [[ADD_PTR]], i8 3, i64 980, i1 false), !dbg [[DBG119:![0-9]+]], !DIAssignID [[DIASSIGNID120:![0-9]+]]
+; CHECK-NEXT:    call void @llvm.dbg.assign(metadata i1 undef, metadata [[META108]], metadata !DIExpression(DW_OP_LLVM_fragment, 80, 7840), metadata [[DIASSIGNID120]], metadata ptr [[ADD_PTR]], metadata !DIExpression()), !dbg [[DBG113]]
+; CHECK-NEXT:    call void @_Z3escPc(ptr noundef nonnull [[BLOB]]), !dbg [[DBG121:![0-9]+]]
+; CHECK-NEXT:    call void @llvm.lifetime.end.p0(i64 1000, ptr nonnull [[BLOB]]) #[[ATTR5]], !dbg [[DBG122:![0-9]+]]
+; CHECK-NEXT:    ret void, !dbg [[DBG122]]
+;
+entry:
+  %blob = alloca [1000 x i8], align 16, !DIAssignID !112
+  call void @llvm.dbg.assign(metadata i1 undef, metadata !108, metadata !DIExpression(), metadata !112, metadata ptr %blob, metadata !DIExpression()), !dbg !113
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omern1 wrote:

I've simplified the test and removed the lifetimes, but I've not removed the debuginfo entirely because that specific test is for dbg.assign intrinsic updates.

https://github.com/llvm/llvm-project/pull/75478