[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

llvm-svn: 363245

4 files changed, 4 insertions, 19 deletions

diff --git a/llvm/test/DebugInfo/COFF/pieces.ll b/llvm/test/DebugInfo/COFF/pieces.ll
index 8fbdce3cbeb..2ca07aa4f5a 100644
--- a/llvm/test/DebugInfo/COFF/pieces.ll
+++ b/llvm/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/llvm/test/DebugInfo/X86/dbg-addr.ll b/llvm/test/DebugInfo/X86/dbg-addr.ll
index 7bf83442b4c..4e27cf5754c 100644
--- a/llvm/test/DebugInfo/X86/dbg-addr.ll
+++ b/llvm/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/llvm/test/DebugInfo/X86/debug-loc-offset.mir b/llvm/test/DebugInfo/X86/debug-loc-offset.mir
index 89641addc2e..be4213c8298 100644
--- a/llvm/test/DebugInfo/X86/debug-loc-offset.mir
+++ b/llvm/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/llvm/test/DebugInfo/X86/pr19307.mir b/llvm/test/DebugInfo/X86/pr19307.mir
index a688d4b9f3e..06b95bc928a 100644
--- a/llvm/test/DebugInfo/X86/pr19307.mir
+++ b/llvm/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,