[Assignment Tracking][25/*] Replace sunk address uses in dbg.assign intrinsics

[StephenTozer]

Not too important, but I'd find it preferable to delete the debug intrinsics for variables other than the one being tested, to reduce noise when reading the test. You could also remove debug intrinsics that aren't needed for the test to work, but YMMV on that.

llvm/test/DebugInfo/Generic/assignment-tracking/codegenprepare/sunk-addr.ll

5–6

[Orlando]

Note to self: the test no longer works with opaque pointers, so I'll need to regenerate it.

[Orlando]

+ Replace test with one that uses opaque pointers.

llvm/lib/CodeGen/CodeGenPrepare.cpp

if (II) {
     case Intrinsic::cttz:
     case Intrinsic::ctlz:
       // If counting zeros is expensive, try to avoid it.
       return despeculateCountZeros(II, TLI, DL, ModifiedDT, FreshBBs,
                                    IsHugeFunc);
     case Intrinsic::fshl:
     case Intrinsic::fshr:
       return optimizeFunnelShift(II);
+    case Intrinsic::dbg_assign:
     case Intrinsic::dbg_value:
       return fixupDbgValue(II);
     case Intrinsic::vscale: {
       // If datalayout has no special restrictions on vector data layout,
       // replace `llvm.vscale` by an equivalent constant expression
       // to benefit from cheap constant propagation.
       Type *ScalableVectorTy =
           VectorType::get(Type::getInt8Ty(II->getContext()), 1, true);

llvm/test/DebugInfo/Generic/assignment-tracking/codegenprepare/sunk-addr.ll

+; REQUIRES: x86-registered-target
+; RUN: llc -start-before=codegenprepare -stop-after=codegenprepare \
+; RUN:   -mtriple=x86_64-unknown-unknown -experimental-assignment-tracking %s -o - \
+; RUN: | FileCheck %s --implicit-check-not="call void @llvm.dbg."
+
+;; Check that when CodeGenPrepare moves an address computation to a block it's
+;; used in its dbg.assign uses are updated.
+;;
+;; Based on llvm/test/DebugInfo/X86/codegenprepare-addrsink.ll
+
+define dso_local i8 @foo(ptr %p, i32 %cond) !dbg !7 {
+entry:
+  %casted = bitcast ptr %p to ptr
+  %arith = getelementptr i8, ptr %casted, i32 3
+  %load1 = load i8, ptr %arith
+  %cmpresult = icmp eq i32 %cond, 0
+  br i1 %cmpresult, label %next, label %ret
+
+next:
+; Address calcs should be duplicated into this block. One dbg.value should be
+; updated, and the other should not.
+; CHECK-LABEL: next:
+; CHECK:       %[[CASTVAR:[0-9a-zA-Z]+]] = bitcast ptr %p to ptr
+; CHECK-NEXT:  dbg.assign(metadata ptr %arith, metadata ![[DIVAR:[0-9]+]],
+; CHECK-NEXT:  %[[GEPVAR:[0-9a-zA-Z]+]] = getelementptr i8, ptr %[[CASTVAR]], i64 3
+; CHECK-NEXT:  %loaded = load i8, ptr %[[GEPVAR]]
+; CHECK-NEXT:  dbg.assign(metadata ptr %[[GEPVAR]], metadata ![[DIVAR]],
+  call void @llvm.dbg.assign(metadata ptr %arith, metadata !12, metadata !DIExpression(), metadata !21, metadata ptr undef, metadata !DIExpression()), !dbg !14
+  %loaded = load i8, ptr %arith
+  call void @llvm.dbg.assign(metadata ptr %arith, metadata !12, metadata !DIExpression(), metadata !21, metadata ptr undef, metadata !DIExpression()), !dbg !14
+  ret i8 %loaded
+
+ret:
+  ret i8 0
+}
+
+; CHECK: ![[DIVAR]] = !DILocalVariable(name: "p",
+
+declare void @llvm.dbg.assign(metadata, metadata, metadata, metadata, metadata, metadata)
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4, !5}
+!llvm.ident = !{!6}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, nameTableKind: None)
+!1 = !DIFile(filename: "test.cpp", directory: ".")
+!2 = !{}
+!3 = !{i32 2, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{i32 1, !"wchar_size", i32 4}
+!6 = !{!"clang version 8.0.0 (trunk 348209)"}
+!7 = distinct !DISubprogram(name: "foo", linkageName: "foo", scope: !1, file: !1, line: 4, type: !8, scopeLine: 5, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !11)
+!8 = !DISubroutineType(types: !9)
+!9 = !{null, !10}
+!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!11 = !{!12}
+!12 = !DILocalVariable(name: "p", arg: 1, scope: !7, file: !1, line: 4, type: !10)
+!14 = !DILocation(line: 4, column: 15, scope: !7)
+!20 = distinct !DILexicalBlock(scope: !7, file: !1, line: 8, column: 7)
+!21 = distinct !DIAssignID()