X86: Use StackRegister instead of FrameRegister in getFrameIndexReference (to generate debug info for local variables) if stack needs realignment

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@155917 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 56 insertions, 0 deletions

diff --git a/lib/Target/X86/X86FrameLowering.cpp b/lib/Target/X86/X86FrameLowering.cpp
index 000e375..626f121 100644
--- a/lib/Target/X86/X86FrameLowering.cpp
+++ b/lib/Target/X86/X86FrameLowering.cpp
@@ -1174,6 +1174,18 @@ int X86FrameLowering::getFrameIndexOffset(const MachineFunction &MF, int FI) con
   return Offset;
 }
 
+int X86FrameLowering::getFrameIndexReference(const MachineFunction &MF, int FI,
+                                             unsigned &FrameReg) const {
+  const X86RegisterInfo *RI =
+      static_cast<const X86RegisterInfo*>(MF.getTarget().getRegisterInfo());
+  // We can't calculate offset from frame pointer if the stack is realigned,
+  // so enforce usage of stack pointer.
+  FrameReg = (RI->needsStackRealignment(MF)) ? RI->getStackRegister()
+                                             : RI->getFrameRegister(MF);
+  return getFrameIndexOffset(MF, FI);
+}
+
+
 bool X86FrameLowering::spillCalleeSavedRegisters(MachineBasicBlock &MBB,
                                              MachineBasicBlock::iterator MI,
                                         const std::vector<CalleeSavedInfo> &CSI,
diff --git a/lib/Target/X86/X86FrameLowering.h b/lib/Target/X86/X86FrameLowering.h
index d55a497..dc515dc 100644
--- a/lib/Target/X86/X86FrameLowering.h
+++ b/lib/Target/X86/X86FrameLowering.h
@@ -60,6 +60,8 @@ public:
   bool hasReservedCallFrame(const MachineFunction &MF) const;
 
   int getFrameIndexOffset(const MachineFunction &MF, int FI) const;
+  int getFrameIndexReference(const MachineFunction &MF, int FI,
+                             unsigned &FrameReg) const;
   uint32_t getCompactUnwindEncoding(MachineFunction &MF) const;
 };
 
diff --git a/test/DebugInfo/X86/aligned_stack_var.ll b/test/DebugInfo/X86/aligned_stack_var.ll
new file mode 100644
index 0000000..9e6c7ff
--- /dev/null
+++ b/test/DebugInfo/X86/aligned_stack_var.ll
@@ -0,0 +1,42 @@
+; RUN: llc %s -mtriple=x86_64-pc-linux-gnu -O0 -filetype=obj -o %t
+; RUN: llvm-dwarfdump %t | FileCheck %s
+
+; If stack is realigned, we shouldn't describe locations of local
+; variables by giving offset from the frame pointer (%rbp):
+; push %rpb
+; mov  %rsp,%rbp
+; and  ALIGNMENT,%rsp ; (%rsp and %rbp are different now)
+; It's better to use offset from %rsp instead.
+
+; DW_AT_location of variable "x" shouldn't be equal to
+; (DW_OP_fbreg: .*): DW_OP_fbreg has code 0x91
+
+; CHECK: {{0x.* DW_TAG_variable}}
+; CHECK-NOT: {{DW_AT_location.*DW_FORM_block1.*0x.*91}}
+; CHECK: NULL
+
+define void @_Z3runv() nounwind uwtable {
+entry:
+  %x = alloca i32, align 32
+  call void @llvm.dbg.declare(metadata !{i32* %x}, metadata !9), !dbg !12
+  ret void, !dbg !13
+}
+
+declare void @llvm.dbg.declare(metadata, metadata) nounwind readnone
+
+!llvm.dbg.cu = !{!0}
+
+!0 = metadata !{i32 786449, i32 0, i32 4, metadata !"test.cc", metadata !"/home/samsonov/debuginfo", metadata !"clang version 3.2 (trunk 155696:155697) (llvm/trunk 155696)", i1 true, i1 false, metadata !"", i32 0, metadata !1, metadata !1, metadata !3, metadata !1} ; [ DW_TAG_compile_unit ]
+!1 = metadata !{metadata !2}
+!2 = metadata !{i32 0}
+!3 = metadata !{metadata !4}
+!4 = metadata !{metadata !5}
+!5 = metadata !{i32 786478, i32 0, metadata !6, metadata !"run", metadata !"run", metadata !"_Z3runv", metadata !6, i32 1, metadata !7, i1 false, i1 true, i32 0, i32 0, null, i32 256, i1 false, void ()* @_Z3runv, null, null, metadata !1, i32 1} ; [ DW_TAG_subprogram ]
+!6 = metadata !{i32 786473, metadata !"test.cc", metadata !"/home/samsonov/debuginfo", null} ; [ DW_TAG_file_type ]
+!7 = metadata !{i32 786453, i32 0, metadata !"", i32 0, i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !8, i32 0, i32 0} ; [ DW_TAG_subroutine_type ]
+!8 = metadata !{null}
+!9 = metadata !{i32 786688, metadata !10, metadata !"x", metadata !6, i32 2, metadata !11, i32 0, i32 0} ; [ DW_TAG_auto_variable ]
+!10 = metadata !{i32 786443, metadata !5, i32 1, i32 12, metadata !6, i32 0} ; [ DW_TAG_lexical_block ]
+!11 = metadata !{i32 786468, null, metadata !"int", null, i32 0, i64 32, i64 32, i64 0, i32 0, i32 5} ; [ DW_TAG_base_type ]
+!12 = metadata !{i32 2, i32 7, metadata !10, null}
+!13 = metadata !{i32 3, i32 1, metadata !10, null}