[v3,3/3] Fix handling of DW_AT_entry_pc of inlined subroutines

Message ID AM8PR10MB47085EB2398D87DA39B5B6ADE4D19@AM8PR10MB4708.EURPRD10.PROD.OUTLOOK.COM
State New
Headers show
Series
  • Improve debugging of optimized code
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Commit Message

Bernd Edlinger Sept. 5, 2021, 7:16 p.m.
It may happen that the inline entry point is not the
start address of the first sub-range of an inline
function.

But the PC for a breakpoint on an inlined subroutine
is always the start address of the first sub-range.

This patch moves the sub-range starting at the entry
point to the first position of the block list.

Therefore the breakpoint on an inlined function
changes in rare cases from the start address of
the first sub-range to the real entry point.

There should always be a subrange that starts at the
entry point, even if that is an empty sub-range.

2021-01-01  Bernd Edlinger  <bernd.edlinger@hotmail.de>

	* dwarf2/read.c (dwarf2_record_block_ranges): Move range beginning
	at DW_AT_entry_pc to the first block range.
---
 gdb/dwarf2/read.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

Patch

From 4953f0891b62444cc6e59d37709051925aa27b78 Mon Sep 17 00:00:00 2001
From: Bernd Edlinger <bernd.edlinger@hotmail.de>
Date: Tue, 3 Nov 2020 18:41:43 +0100
Subject: [PATCH v3 3/3] Fix handling of DW_AT_entry_pc of inlined subroutines

It may happen that the inline entry point is not the
start address of the first sub-range of an inline
function.

But the PC for a breakpoint on an inlined subroutine
is always the start address of the first sub-range.

This patch moves the sub-range starting at the entry
point to the first position of the block list.

Therefore the breakpoint on an inlined function
changes in rare cases from the start address of
the first sub-range to the real entry point.

There should always be a subrange that starts at the
entry point, even if that is an empty sub-range.

2021-01-01  Bernd Edlinger  <bernd.edlinger@hotmail.de>

	* dwarf2/read.c (dwarf2_record_block_ranges): Move range beginning
	at DW_AT_entry_pc to the first block range.
---
 gdb/dwarf2/read.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index 358266a..4a9f47e 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -14265,6 +14265,18 @@  class process_die_scope
       if (die->tag != DW_TAG_compile_unit)
 	ranges_offset += cu->gnu_ranges_base;
 
+      CORE_ADDR entry_pc = (CORE_ADDR) -1;
+      if (die->tag == DW_TAG_inlined_subroutine)
+	{
+	  attr = dwarf2_attr (die, DW_AT_entry_pc, cu);
+	  if (attr != nullptr)
+	    {
+	      entry_pc = attr->as_address ();
+	      entry_pc += baseaddr;
+	      entry_pc = gdbarch_adjust_dwarf2_addr (gdbarch, entry_pc);
+	    }
+	}
+
       std::vector<blockrange> blockvec;
       dwarf2_ranges_process (ranges_offset, cu, die->tag,
 	[&] (CORE_ADDR start, CORE_ADDR end)
@@ -14275,6 +14287,8 @@  class process_die_scope
 	  end = gdbarch_adjust_dwarf2_addr (gdbarch, end);
 	  cu->get_builder ()->record_block_range (block, start, end - 1);
 	  blockvec.emplace_back (start, end);
+	  if (entry_pc == start && blockvec.size () > 1)
+	    std::swap (blockvec[0], blockvec[blockvec.size () - 1]);
 	});
 
       BLOCK_RANGES(block) = make_blockranges (objfile, blockvec);
-- 
1.9.1