[DebugInfo] LiveDebugValues: correctly discriminate kinds of variable locations

The missing line added by this patch ensures that only spilt variable
locations are candidates for being restored from the stack. Otherwise,
register or constant-value information can be interpreted as a spill
location, through a union.

The added regression test replicates a scenario where this occurs: the
stack load from [rsp] causes the register-location DBG_VALUE to be
"restored" to rsi, when it should be left alone. See PR43058 for details.

Un x-fail a test that was suffering from this from a previous patch.

Differential Revision: https://reviews.llvm.org/D66895

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@370334 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/LiveDebugValues.cpp b/lib/CodeGen/LiveDebugValues.cpp
index cd39950e392e8a8ca800c5f360c9bd5d3e1e9c09..29d307845cfe1c81b393bccc13a49295016d8ea7 100644 (file)
--- a/lib/CodeGen/LiveDebugValues.cpp
+++ b/lib/CodeGen/LiveDebugValues.cpp
@@ -875,6 +875,7 @@ void LiveDebugValues::transferSpillOrRestoreInst(MachineInstr &MI,
       LLVM_DEBUG(dbgs() << "Spilling Register " << printReg(Reg, TRI) << '('
                         << VarLocIDs[ID].Var.getVar()->getName() << ")\n");
     } else if (TKind == TransferKind::TransferRestore &&
+               VarLocIDs[ID].Kind == VarLoc::SpillLocKind &&
                VarLocIDs[ID].Loc.SpillLocation == *Loc) {
       LLVM_DEBUG(dbgs() << "Restoring Register " << printReg(Reg, TRI) << '('
                         << VarLocIDs[ID].Var.getVar()->getName() << ")\n");

diff --git a/test/CodeGen/ARM/debug-info-blocks.ll b/test/CodeGen/ARM/debug-info-blocks.ll
index 4f80db4827976cbc0cc073950e6d9af59c55f354..cc1a45f23da0772c24a61c542c51a18cec57a866 100644 (file)
--- a/test/CodeGen/ARM/debug-info-blocks.ll
+++ b/test/CodeGen/ARM/debug-info-blocks.ll
@@ -1,8 +1,5 @@
 ; RUN: llc -filetype=obj -O0 < %s | llvm-dwarfdump -v - | FileCheck %s
 
-; XFAIL: *
-; PR43058
-
 ; debug_info content
 ; CHECK: DW_AT_name {{.*}} "foobar_func_block_invoke_0"
 ; CHECK-NOT: DW_TAG_subprogram

diff --git a/test/DebugInfo/MIR/X86/live-debug-values-restore-collide.mir b/test/DebugInfo/MIR/X86/live-debug-values-restore-collide.mir
new file mode 100644 (file)
index 0000000..3d133d5
--- /dev/null
+++ b/test/DebugInfo/MIR/X86/live-debug-values-restore-collide.mir
@@ -0,0 +1,85 @@
+# RUN: llc %s -o - -run-pass=livedebugvalues -mtriple=x86_64-unknown-unknown | FileCheck %s
+#
+# This is a regression test for register/stack variable locations being
+# interpreted as each other. We place a variable location on the stack, based
+# on $rsp. We later make a memory load from $rsp. On faulty versions of LLVM
+# this gets interpreted as a stack restore of the spilt value (it's not).
+#
+# Test that LiveDebugValues does not create any new variable locations.
+#
+# CHECK-LABEL: name: baaar
+# CHECK-LABEL: bb.0.entry:
+# CHECK:       DBG_VALUE $r9d, $noreg, !{{[0-9]*}}, !DIExpression()
+# CHECK:       DBG_VALUE $rsp, 0, !{{[0-9]*}}, !DIExpression(DW_OP_plus_uconst, 16)
+# CHECK-NOT:   DBG_VALUE
+--- |
+  target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+  target triple = "x86_64-unknown-linux-gnu"
+  
+  define void @baaar() !dbg !4 {
+  entry:
+    ret void
+  }
+  
+  !llvm.module.flags = !{!0, !1}
+  !llvm.dbg.cu = !{!2}
+  
+  !0 = !{i32 2, !"Debug Info Version", i32 3}
+  !1 = !{i32 2, !"Dwarf Version", i32 4}
+  !2 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !3, producer: "", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug)
+  !3 = !DIFile(filename: "sheep.cpp", directory: ".")
+  !4 = distinct !DISubprogram(name: "baaar", scope: !3, file: !3, line: 1, type: !5, spFlags: DISPFlagDefinition, unit: !2, retainedNodes: !8)
+  !5 = !DISubroutineType(types: !6)
+  !6 = !{!7}
+  !7 = !DIBasicType(name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
+  !8 = !{!9}
+  !9 = !DILocalVariable(name: "moo", scope: !4, file: !3, line: 1, type: !7)
+  !10 = !DILocation(line: 1, scope: !4)
+
+...
+---
+name:            baaar
+alignment:       4
+tracksRegLiveness: true
+liveins:
+  - { reg: '$rdi', virtual-reg: '' }
+  - { reg: '$rsi', virtual-reg: '' }
+  - { reg: '$rdx', virtual-reg: '' }
+  - { reg: '$rcx', virtual-reg: '' }
+  - { reg: '$r8', virtual-reg: '' }
+  - { reg: '$r9d', virtual-reg: '' }
+frameInfo:
+  stackSize:       24
+  offsetAdjustment: -24
+  maxAlignment:    8
+  adjustsStack:    true
+  hasCalls:        true
+fixedStack:
+stack:
+  - { id: 0, name: '', type: spill-slot, offset: -16, size: 8, alignment: 8, 
+      stack-id: default, callee-saved-register: '', callee-saved-restored: true, 
+      debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
+  - { id: 1, name: '', type: spill-slot, offset: -32, size: 8, alignment: 8, 
+      stack-id: default, callee-saved-register: '', callee-saved-restored: true, 
+      debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
+body:             |
+  bb.0.entry:
+    liveins: $rcx, $rdi, $rdx, $rsi, $r8, $r9d, $rbp, $r15, $r14, $r13, $r12, $rbx
+  
+    ; Setup
+    DBG_VALUE $r9d, $noreg, !9, !DIExpression(), debug-location !10
+    $rsp = frame-setup SUB64ri8 $rsp, 24, implicit-def dead $eflags
+
+    ; Spill
+    MOV32mr $rsp, 1, $noreg, 16, $noreg, $r9d :: (store 4 into %stack.0)
+    DBG_VALUE $rsp, 0, !9, !DIExpression(DW_OP_plus_uconst, 16), debug-location !10
+
+    ; This load from the stack can be misinterpreted as a stack restore of
+    ; any DBG_VALUe pointing at $rsp.
+    $rsi = MOV64rm $rsp, 1, $noreg, 0, $noreg :: (load 8 from %stack.1)
+
+    ; Return faff
+    $eax = MOV32ri 0
+    $rsp = frame-destroy ADD64ri8 $rsp, 24, implicit-def dead $eflags
+    RETQ debug-location !10
+...