[DebugInfo] Use FrameDestroy to extend stack locations to end-of-function

We aim to ignore changes in variable locations during the prologue and
epilogue of functions, to avoid using space documenting location changes
that aren't visible. However in D61940 / r362951 this got ripped out as
the previous implementation was unsound.

Instead, use the FrameDestroy flag to identify when we're in the epilogue
of a function, and ignore variable location changes accordingly. This fits
in with existing code that examines the FrameSetup flag.

Some variable locations get shuffled in modified tests as they now cover
greater ranges, which is what would be expected. Some additional
single-location variables are generated too. Two tests are un-xfailed,
they were only xfailed due to r362951 deleting functionality they depended
on.

Apparently some out-of-tree backends don't accurately maintain FrameDestroy
flags -- if you're an out-of-tree maintainer and see changes in variable
locations disappear due to a faulty FrameDestroy flag, it's safe to back
this change out. The impact is just slightly more debug info than necessary.

Differential Revision: https://reviews.llvm.org/D62314

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@363245 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/AsmPrinter/DbgEntityHistoryCalculator.cpp b/lib/CodeGen/AsmPrinter/DbgEntityHistoryCalculator.cpp
index d87aac94c0485ef7a27c078dab1b37f6168ee12f..ee375529cf97dd4f5e948569187d880917b1cd61 100644 (file)
--- a/lib/CodeGen/AsmPrinter/DbgEntityHistoryCalculator.cpp
+++ b/lib/CodeGen/AsmPrinter/DbgEntityHistoryCalculator.cpp
@@ -275,9 +275,12 @@ void llvm::calculateDbgEntityHistory(const MachineFunction *MF,
             clobberRegisterUses(RegVars, MO.getReg(), DbgValues, LiveEntries,
                                 MI);
           // If this is a register def operand, it may end a debug value
-          // range. Ignore defs of the frame register in the prologue.
+          // range. Ignore frame-register defs in the epilogue and prologue,
+          // we expect debuggers to understand that stack-locations are
+          // invalid outside of the function body.
           else if (MO.getReg() != FrameReg ||
-                   !MI.getFlag(MachineInstr::FrameSetup)) {
+                   (!MI.getFlag(MachineInstr::FrameDestroy) &&
+                   !MI.getFlag(MachineInstr::FrameSetup))) {
             for (MCRegAliasIterator AI(MO.getReg(), TRI, true); AI.isValid();
                  ++AI)
               clobberRegisterUses(RegVars, *AI, DbgValues, LiveEntries, MI);

diff --git a/test/DebugInfo/COFF/pieces.ll b/test/DebugInfo/COFF/pieces.ll
index 8fbdce3cbeba3604a23c94be720fdbb1041cb7d4..2ca07aa4f5a0af0de4c65d683f5091ef625ddaf2 100644 (file)
--- a/test/DebugInfo/COFF/pieces.ll
+++ b/test/DebugInfo/COFF/pieces.ll
@@ -104,8 +104,9 @@
 ; ASM:         #APP
 ; ASM:         #NO_APP
 ; ASM:         movl    [[offset_o_x]](%rsp), %eax          # 4-byte Reload
-; ASM: [[spill_o_x_end:\.Ltmp[0-9]+]]:
 ; ASM:         retq
+; ASM-NEXT: [[spill_o_x_end:\.Ltmp[0-9]+]]:
+; ASM-NEXT: .Lfunc_end4:
 
 
 ; ASM-LABEL:  .short  4423                    # Record kind: S_GPROC32_ID
@@ -231,7 +232,7 @@
 ; ASM:        .asciz  "bitpiece_spill"        # Function name
 ; ASM:        .short  4414                    # Record kind: S_LOCAL
 ; ASM:        .asciz  "o"
-; ASM:        .cv_def_range    [[spill_o_x_start]] [[spill_o_x_end]], "E\021O\001A\000$\000\000\000"
+; ASM:        .cv_def_range    [[spill_o_x_start]] .Lfunc_end4, "E\021O\001A\000$\000\000\000"
 
 ; OBJ-LABEL: GlobalProcIdSym {
 ; OBJ:         Kind: S_GPROC32_ID (0x1147)

diff --git a/test/DebugInfo/X86/dbg-addr.ll b/test/DebugInfo/X86/dbg-addr.ll
index 7bf83442b4cf7be19fddae8b2aa66013140fbd10..4e27cf5754c7dd1e49ed9da96064eb1f1eb4d629 100644 (file)
--- a/test/DebugInfo/X86/dbg-addr.ll
+++ b/test/DebugInfo/X86/dbg-addr.ll
@@ -9,12 +9,8 @@
 ; CHECK-LABEL: use_dbg_addr:
 ; CHECK: #DEBUG_VALUE: use_dbg_addr:o <- [$rsp+0]
 
-; FIXME: Avoid the use of a single-location location list and use
-; DW_AT_start_offset instead.
-
 ; DWARF: DW_TAG_variable
-; DWARF-NEXT:              DW_AT_location (0x00000000
-; DWARF-NEXT:                          [0x{{.*}}, 0x{{.*}}): DW_OP_breg7 RSP+0)
+; DWARF-NEXT:              DW_AT_location (DW_OP_fbreg +0)
 ; DWARF-NEXT:              DW_AT_name ("o")
 
 

diff --git a/test/DebugInfo/X86/debug-loc-offset.mir b/test/DebugInfo/X86/debug-loc-offset.mir
index 89641addc2ef64c23268771be13a48f53b3c9c6c..be4213c8298a72892dbdd8adaccfd8fadf4e6734 100644 (file)
--- a/test/DebugInfo/X86/debug-loc-offset.mir
+++ b/test/DebugInfo/X86/debug-loc-offset.mir
@@ -1,11 +1,5 @@
 # RUN: llc -o - %s -start-after=patchable-function -filetype=obj -O0 -mtriple=i386-unknown-linux-gnu -dwarf-version=4 | llvm-dwarfdump -v - | FileCheck %s
 
-# XFAIL: *
-# Marked XFail due to the removal of "ChangingRegs" from
-# DbgEntityHistoryCalculator, shortening the checked range to not reach the
-# end of the function. Fixed by an about-to-land patch using the FrameDestroy
-# flag to identify the end of functions.
-
 # From the code:
 #
 # debug-loc-offset1.cc

diff --git a/test/DebugInfo/X86/pr19307.mir b/test/DebugInfo/X86/pr19307.mir
index a688d4b9f3eb8a2c2a10e8b4be3a09f0a52d7d5b..06b95bc928a63b2a826196b8bafa9157cc98cafa 100644 (file)
--- a/test/DebugInfo/X86/pr19307.mir
+++ b/test/DebugInfo/X86/pr19307.mir
@@ -1,11 +1,5 @@
 # RUN: llc -o - %s -start-after=patchable-function -O0 | FileCheck %s
 
-# XFAIL: *
-# Marked XFail due to the removal of "ChangingRegs" from
-# DbgEntityHistoryCalculator, shortening the checked range to not reach the
-# end of the function. Fixed by an about-to-land patch using the FrameDestroy
-# flag to identify the end of functions.
-
 # Generated from the source file pr19307.cc:
 # #include <string>
 # void parse_range(unsigned long long &offset, unsigned long long &limit,