[llvm] a41ce98 - [FastISel][DebugInfo] Handle dbg.value targeting allocas (#67187)

[via llvm-commits]

Author: Felipe de Azevedo Piovezan
Date: 2023-10-02T07:10:11-07:00
New Revision: a41ce98064f6d67203337762b0e45e75e464ce88

URL: https://github.com/llvm/llvm-project/commit/a41ce98064f6d67203337762b0e45e75e464ce88
DIFF: https://github.com/llvm/llvm-project/commit/a41ce98064f6d67203337762b0e45e75e464ce88.diff

LOG: [FastISel][DebugInfo] Handle dbg.value targeting allocas (#67187)

FastISel currently drops dbg.values targeting allocas. It may seem
surprising that a simple case would fail to be lowered, but dbg.values
targeting allocas are not common; we usually have dbg.declares doing
that, and those are handled by the common code between FastISel and
SelectionDAGISel.

This patch addresses the issue by querying the static alloca map from
FuncInfo. If we have a frame index for it, we create a DBG_VALUE
intrinsic from it.

Added: 
    llvm/test/CodeGen/X86/fast-isel-dbg-value-alloca.ll

Modified: 
    llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
    llvm/test/DebugInfo/COFF/lines-bb-start.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp b/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
index f0affce7b6b805c..a831295863399b5 100644
--- a/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
@@ -1327,6 +1327,14 @@ bool FastISel::selectIntrinsicCall(const IntrinsicInst *II) {
                         << *DI << "\n");
       return true;
     }
+    if (auto SI = FuncInfo.StaticAllocaMap.find(dyn_cast<AllocaInst>(V));
+        SI != FuncInfo.StaticAllocaMap.end()) {
+      MachineOperand FrameIndexOp = MachineOperand::CreateFI(SI->second);
+      bool IsIndirect = false;
+      BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, MIMD.getDL(), II, IsIndirect,
+              FrameIndexOp, Var, Expr);
+      return true;
+    }
     if (Register Reg = lookUpRegForValue(V)) {
       // FIXME: This does not handle register-indirect values at offset 0.
       if (!FuncInfo.MF->useDebugInstrRef()) {

diff  --git a/llvm/test/CodeGen/X86/fast-isel-dbg-value-alloca.ll b/llvm/test/CodeGen/X86/fast-isel-dbg-value-alloca.ll
new file mode 100644
index 000000000000000..77f883ee9bd3a73
--- /dev/null
+++ b/llvm/test/CodeGen/X86/fast-isel-dbg-value-alloca.ll
@@ -0,0 +1,32 @@
+; RUN: llc -fast-isel -fast-isel-abort=1 -mtriple=x86_64-unknown-unknown -stop-after=finalize-isel %s -o - | \
+; RUN:    FileCheck %s
+
+define void @foo(ptr noalias nocapture %arg) !dbg !38 {
+  %k.debug = alloca ptr, align 8
+  store ptr %arg, ptr %k.debug, align 8, !dbg !70
+  call void @llvm.dbg.value(metadata ptr %k.debug, metadata !55, metadata !DIExpression(DW_OP_deref)), !dbg !70
+; CHECK: call void @llvm.dbg.value(metadata ptr %{{.*}}, metadata ![[VAR:.*]], metadata ![[EXPR:.*]])
+; CHECK: DBG_VALUE %stack.0{{.*}}, $noreg, ![[VAR]], ![[EXPR]]
+  ret void, !dbg !70
+}
+
+declare void @llvm.dbg.value(metadata, metadata, metadata)
+
+!llvm.module.flags = !{!6, !7, !8, !9}
+!llvm.dbg.cu = !{!16}
+
+!6 = !{i32 7, !"Dwarf Version", i32 4}
+!7 = !{i32 2, !"Debug Info Version", i32 3}
+!8 = !{i32 1, !"wchar_size", i32 4}
+!9 = !{i32 8, !"PIC Level", i32 2}
+!16 = distinct !DICompileUnit(language: DW_LANG_Swift, file: !17, producer: "blah", isOptimized: false, runtimeVersion: 5, emissionKind: FullDebug, sysroot: "blah", sdk: "blah")
+!17 = !DIFile(filename: "blah", directory: "blah")
+!38 = distinct !DISubprogram(name: "blah", linkageName: "$blah", scope: !17, file: !17, line: 34, type: !39, scopeLine: 34, spFlags: DISPFlagDefinition, unit: !16, retainedNodes: !43)
+!39 = !DISubroutineType(types: !40)
+!40 = !{!41, !41}
+!41 = !DICompositeType(tag: DW_TAG_structure_type, name: "blah")
+!43 = !{!49, !55}
+!49 = !DILocalVariable(name: "x", arg: 1, scope: !38, file: !17, line: 34, type: !41)
+!55 = !DILocalVariable(name: "k", scope: !56, file: !17, line: 36, type: !41)
+!56 = distinct !DILexicalBlock(scope: !38, file: !17, line: 36, column: 9)
+!70 = !DILocation(line: 36, column: 9, scope: !56)

diff  --git a/llvm/test/DebugInfo/COFF/lines-bb-start.ll b/llvm/test/DebugInfo/COFF/lines-bb-start.ll
index 9ff112cf7ae7c35..70c96b368c9ad9b 100644
--- a/llvm/test/DebugInfo/COFF/lines-bb-start.ll
+++ b/llvm/test/DebugInfo/COFF/lines-bb-start.ll
@@ -90,6 +90,8 @@ return:                                           ; preds = %if.end, %if.then
 ; CHECK:         .cv_loc {{.*}} # t.c:4:5
 ; CHECK:         jmp     LBB{{.*}}
 ; CHECK: LBB2_{{.*}}:                                 # %if.end
+; CHECK-NEXT: L{{.*}}:
+; CHECK-NEXT: DEBUG_VALUE: lea_dbg_value:
 ; CHECK-NEXT:    .cv_loc {{.*}} # t.c:5:3
 ; CHECK:         leal 4(%esp), %[[reg:[^ ]*]]
 ; CHECK:         movl    %[[reg]], (%esp)