[LiveDebugValues] Close range for previous variable's location when adding newly...

When LiveDebugValues deduces new variable's location from spill, restore or
register copy instruction it should close old variable's location. Otherwise
we can have multiple block output locations for same variable. That could lead
to inserting two DBG_VALUEs for same variable to the beginning of the successor
block which results to ignoring of first DBG_VALUE.

Reviewers: aprantl, jmorse, wolfgangp, dstenb

Reviewed By: aprantl

Subscribers: probinson, asowda, ivanbaev, petarj, djtodoro

Tags: #debug-info

Differential Revision: https://reviews.llvm.org/D62196

llvm-svn: 362373

diff --git a/llvm/lib/CodeGen/LiveDebugValues.cpp b/llvm/lib/CodeGen/LiveDebugValues.cpp
index 7f95e12..8b8a340 100644 (file)
--- a/llvm/lib/CodeGen/LiveDebugValues.cpp
+++ b/llvm/lib/CodeGen/LiveDebugValues.cpp
@@ -430,9 +430,15 @@ void LiveDebugValues::insertTransferDebugPair(
   MachineFunction *MF = MI.getParent()->getParent();
   MachineInstr *NewDebugInstr;
 
-  auto ProcessVarLoc = [&MI, &OpenRanges, &Transfers,
+  auto ProcessVarLoc = [&MI, &OpenRanges, &Transfers, &DebugInstr,
                         &VarLocIDs](VarLoc &VL, MachineInstr *NewDebugInstr) {
     unsigned LocId = VarLocIDs.insert(VL);
+
+    // Close this variable's previous location range.
+    DebugVariable V(DebugInstr->getDebugVariable(),
+                    DebugInstr->getDebugLoc()->getInlinedAt());
+    OpenRanges.erase(V);
+
     OpenRanges.insert(LocId, VL.Var);
     // The newly created DBG_VALUE instruction NewDebugInstr must be inserted
     // after MI. Keep track of the pairing.
@@ -714,6 +720,10 @@ bool LiveDebugValues::transferTerminatorInst(MachineInstr &MI,
   });
   VarLocSet &VLS = OutLocs[CurMBB];
   Changed = VLS |= OpenRanges.getVarLocs();
+  // New OutLocs set may be different due to spill, restore or register
+  // copy instruction processing.
+  if (Changed)
+    VLS = OpenRanges.getVarLocs();
   OpenRanges.clear();
   return Changed;
 }

diff --git a/llvm/test/DebugInfo/X86/fission-ranges.ll b/llvm/test/DebugInfo/X86/fission-ranges.ll
index e120fed..e434773 100644 (file)
--- a/llvm/test/DebugInfo/X86/fission-ranges.ll
+++ b/llvm/test/DebugInfo/X86/fission-ranges.ll
@@ -5,6 +5,18 @@
 ; RUN: llc -dwarf-version=5 -O0 %s -mtriple=x86_64-unknown-linux-gnu -filetype=obj -o %t
 ; RUN: llvm-dwarfdump -v %t | FileCheck --check-prefix=V5RNGLISTS %s
 
+; RUN: llc -O0 %s -mtriple=x86_64-unknown-linux-gnu -stop-after=livedebugvalues -o -| FileCheck --check-prefix=CHECK-MIR %s
+
+; LiveDebugValues should produce DBG_VALUEs for variable "b" in successive
+; blocks once we recognize that it is spilled.
+; CHECK-MIR: ![[BDIVAR:[0-9]+]] = !DILocalVariable(name: "b"
+; CHECK-MIR: DBG_VALUE $rsp, 0, ![[BDIVAR]], !DIExpression(DW_OP_constu, 32, DW_OP_minus)
+; CHECK-MIR-LABEL: bb.6.for.inc13:
+; CHECK-MIR: DBG_VALUE $rsp, 0, ![[BDIVAR]], !DIExpression(DW_OP_constu, 32, DW_OP_minus)
+; CHECK-MIR-LABEL: bb.7.for.inc16:
+; CHECK-MIR: DBG_VALUE $rsp, 0, ![[BDIVAR]], !DIExpression(DW_OP_constu, 32, DW_OP_minus)
+
+
 ; CHECK: .debug_info contents:
 ; CHECK: DW_TAG_compile_unit
 ; CHECK-NEXT: DW_AT_stmt_list
@@ -31,22 +43,25 @@
 
 ; CHECK:      [[A]]:
 ; CHECK-NEXT:   Addr idx 2 (w/ length 169): DW_OP_consts +0, DW_OP_stack_value
-; CHECK-NEXT:   Addr idx 3 (w/ length 25): DW_OP_reg0 RAX
+; CHECK-NEXT:   Addr idx 3 (w/ length 15): DW_OP_reg0 RAX
+; CHECK-NEXT:   Addr idx 4 (w/ length 18): DW_OP_breg7 RSP-8
 ; CHECK:      [[E]]:
-; CHECK-NEXT:   Addr idx 4 (w/ length 19): DW_OP_reg0 RAX
+; CHECK-NEXT:   Addr idx 5 (w/ length 23): DW_OP_reg0 RAX
 ; CHECK:      [[B]]:
-; CHECK-NEXT:   Addr idx 5 (w/ length 17): DW_OP_reg0 RAX
+; CHECK-NEXT:   Addr idx 6 (w/ length 15): DW_OP_reg0 RAX
+; CHECK-NEXT:   Addr idx 7 (w/ length 66): DW_OP_breg7 RSP-32
 ; CHECK:      [[D]]:
-; CHECK-NEXT:   Addr idx 6 (w/ length 17): DW_OP_reg0 RAX
+; CHECK-NEXT:   Addr idx 8 (w/ length 15): DW_OP_reg0 RAX
+; CHECK-NEXT:   Addr idx 9 (w/ length 42): DW_OP_breg7 RSP-20
 
 ; Make sure we don't produce any relocations in any .dwo section (though in particular, debug_info.dwo)
 ; HDR-NOT: .rela.{{.*}}.dwo
 
 ; Make sure we have enough stuff in the debug_addr to cover the address indexes
-; (6 is the last index in debug_loc.dwo, making 7 entries of 8 bytes each, 7 * 8
-; == 56 base 10 == 38 base 16)
+; (9 is the last index in debug_loc.dwo, making 10 entries of 8 bytes each,
+; 10 * 8 == 80 base 10 == 50 base 16)
 
-; HDR: .debug_addr 00000038
+; HDR: .debug_addr 00000050
 ; HDR-NOT: .rela.{{.*}}.dwo
 
 ; Check for the existence of a DWARF v5-style range list table in the .debug_rnglists
@@ -134,13 +149,13 @@ for.body9:                                        ; preds = %for.body9, %for.con
   tail call void @llvm.dbg.value(metadata i32* @c, metadata !19, metadata !DIExpression()), !dbg !40
   %and = and i32 %and2, 1, !dbg !32
   %inc = add i32 %e.01, 1, !dbg !39
-  tail call void @llvm.dbg.value(metadata i32 %inc, metadata !18, metadata !DIExpression()), !dbg !39
+  tail call void @llvm.dbg.value(metadata i32 %inc, metadata !18, metadata !DIExpression()), !dbg !42
   %exitcond = icmp eq i32 %inc, 30, !dbg !39
   br i1 %exitcond, label %for.inc10, label %for.body9, !dbg !39
 
 for.inc10:                                        ; preds = %for.body9
   %inc11 = add nsw i32 %b.03, 1, !dbg !38
-  tail call void @llvm.dbg.value(metadata i32 %inc11, metadata !15, metadata !DIExpression()), !dbg !38
+  tail call void @llvm.dbg.value(metadata i32 %inc11, metadata !15, metadata !DIExpression()), !dbg !42
   %exitcond11 = icmp eq i32 %inc11, 30, !dbg !38
   br i1 %exitcond11, label %for.inc13, label %for.cond7.preheader, !dbg !38