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

The Assignment Tracking debug-info feature is outlined in this RFC:

https://discourse.llvm.org/t/
rfc-assignment-tracking-a-better-way-of-specifying-variable-locations-in-ir

Reviewed By: StephenTozer

Differential Revision: https://reviews.llvm.org/D136255

diff --git a/llvm/lib/CodeGen/CodeGenPrepare.cpp b/llvm/lib/CodeGen/CodeGenPrepare.cpp
index 355f5a2..c96352e 100644 (file)
--- a/llvm/lib/CodeGen/CodeGenPrepare.cpp
+++ b/llvm/lib/CodeGen/CodeGenPrepare.cpp
@@ -2345,6 +2345,7 @@ bool CodeGenPrepare::optimizeCallInst(CallInst *CI, ModifyDT &ModifiedDT) {
     case Intrinsic::fshl:
     case Intrinsic::fshr:
       return optimizeFunnelShift(II);
+    case Intrinsic::dbg_assign:
     case Intrinsic::dbg_value:
       return fixupDbgValue(II);
     case Intrinsic::vscale: {

diff --git a/llvm/test/DebugInfo/Generic/assignment-tracking/codegenprepare/sunk-addr.ll b/llvm/test/DebugInfo/Generic/assignment-tracking/codegenprepare/sunk-addr.ll
new file mode 100644 (file)
index 0000000..4971df2
--- /dev/null
+++ b/llvm/test/DebugInfo/Generic/assignment-tracking/codegenprepare/sunk-addr.ll
@@ -0,0 +1,60 @@
+; 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()