From 11b6db811820b28ef3abc9465ac708e31f44b5bf Mon Sep 17 00:00:00 2001
From: Pierre-Marie de Rodat <derodat@adacore.com>
Date: Mon, 20 Mar 2017 18:48:43 +0100
Subject: CV2PDB::addDWARFProc: turn uncontiguous ranges into smallest cvring
 one

This is a hack to workaround something that seems to be missing in
CodeView: lexical blocks with non-contiguous address ranges.
---
 src/dwarf2pdb.cpp | 27 ++++++++++++++++++++++++++-
 1 file changed, 26 insertions(+), 1 deletion(-)

diff --git a/src/dwarf2pdb.cpp b/src/dwarf2pdb.cpp
index f5ef586..8ba5750 100644
--- a/src/dwarf2pdb.cpp
+++ b/src/dwarf2pdb.cpp
@@ -742,7 +742,32 @@ bool CV2PDB::addDWARFProc(DWARF_InfoData& procid, DWARF_CompilationUnit* cu, DIE
 			{
 				if (id.tag == DW_TAG_lexical_block)
 				{
-					if (id.hasChild && id.pchi != id.pclo)
+					// It seems it is not possible to describe blocks with
+					// non-contiguous address ranges in CodeView. Instead,
+					// just create a range that is large enough to cover
+					// all continuous ranges.
+					if (id.hasChild && id.ranges != -1u)
+					{
+						id.pclo = -1u;
+						id.pchi = 0;
+
+						// TODO: handle base address selection
+						byte *r = (byte *)img.debug_ranges + id.ranges;
+						byte *rend = (byte *)img.debug_ranges + img.debug_ranges_length;
+						while (r < rend)
+						{
+							uint32_t pclo = RD4(r);
+							uint32_t pchi = RD4(r);
+							if (pclo == 0 && pchi == 0)
+								break;
+							if (pclo >= pchi)
+								continue;
+							id.pclo = min(id.pclo, pclo + currentBaseAddress);
+							id.pchi = max(id.pchi, pchi + currentBaseAddress);
+						}
+					}
+
+					if (id.hasChild && id.pchi > id.pclo)
 					{
 						appendLexicalBlock(id, pclo + codeSegOff);
 						DIECursor next = cursor;
-- 
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