Introduce findSourceLocation utility

Move the code from perfsymboltable into perfdwarfdiecache. This
simplifies the perfsymboltable code and allows reuse of this generic
code.

Change-Id: Ibeebe2312d49095adad60f2924e1be8d74d82dfe
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

3 files changed, 36 insertions, 9 deletions

diff --git a/app/perfdwarfdiecache.cpp b/app/perfdwarfdiecache.cpp
index 6f9243f..123ebac 100644
--- a/app/perfdwarfdiecache.cpp
+++ b/app/perfdwarfdiecache.cpp
@@ -259,6 +259,19 @@ QVector<Dwarf_Die> findInlineScopes(Dwarf_Die *subprogram, Dwarf_Addr offset)
     return scopes;
 }
 
+DwarfSourceLocation findSourceLocation(Dwarf_Die* cuDie, Dwarf_Addr offset)
+{
+    DwarfSourceLocation ret;
+    if (auto srcloc = dwarf_getsrc_die(cuDie, offset)) {
+        if (const char* srcfile = dwarf_linesrc(srcloc, nullptr, nullptr)) {
+            ret.file = srcfile;
+            dwarf_lineno(srcloc, &ret.line);
+            dwarf_linecol(srcloc, &ret.column);
+        }
+    }
+    return ret;
+}
+
 SubProgramDie::SubProgramDie(Dwarf_Die die)
     : m_ranges{die, {}}
 {
diff --git a/app/perfdwarfdiecache.h b/app/perfdwarfdiecache.h
index 26183b1..a268d94 100644
--- a/app/perfdwarfdiecache.h
+++ b/app/perfdwarfdiecache.h
@@ -108,6 +108,25 @@ private:
  */
 QVector<Dwarf_Die> findInlineScopes(Dwarf_Die *subprogram, Dwarf_Addr offset);
 
+struct DwarfSourceLocation
+{
+    QByteArray file;
+    int line = -1;
+    int column = -1;
+
+    explicit operator bool() const
+    {
+        return !file.isEmpty();
+    }
+};
+/**
+ * @return the file name, line number and column for the instruction at the given @p offset in @p cuDie
+ * @p cuDie CU DIE that should be queried
+ * @p offset bias-corrected address of an instruction for which the information should be found
+ * @sa CuDieRangeMapping
+ */
+DwarfSourceLocation findSourceLocation(Dwarf_Die* cuDie, Dwarf_Addr offset);
+
 /**
  * This cache makes it easily possible to find a CU DIE (i.e. Compilation Unit Debugging Information Entry)
  * based on a
diff --git a/app/perfsymboltable.cpp b/app/perfsymboltable.cpp
index 27b54ad..63eef45 100644
--- a/app/perfsymboltable.cpp
+++ b/app/perfsymboltable.cpp
@@ -841,15 +841,10 @@ int PerfSymbolTable::lookupFrame(Dwarf_Addr ip, bool isKernel,
             if (cudie) {
                 bias = cudie->bias();
                 const auto offset = addressLocation.address - bias;
-                auto srcloc = dwarf_getsrc_die(cudie->cudie(), offset);
-                if (srcloc) {
-                    const char* srcfile = dwarf_linesrc(srcloc, nullptr, nullptr);
-                    if (srcfile) {
-                        const QByteArray file = srcfile;
-                        addressLocation.file = m_unwind->resolveString(file);
-                        dwarf_lineno(srcloc, &addressLocation.line);
-                        dwarf_linecol(srcloc, &addressLocation.column);
-                    }
+                if (auto srcloc = findSourceLocation(cudie->cudie(), offset)) {
+                    addressLocation.file = m_unwind->resolveString(srcloc.file);
+                    addressLocation.line = srcloc.line;
+                    addressLocation.column = srcloc.column;
                 }
 
                 auto *subprogram = cudie->findSubprogramDie(offset);