X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/218c42a20c7eaba87e20cfb3eaac5ad8e0d0f739..706dd4584b4002e0d948b81d103dd5c4b70db077:/src/mc/DwarfExpression.cpp

diff --git a/src/mc/DwarfExpression.cpp b/src/mc/DwarfExpression.cpp
index d2de7fd838..6cdba68ae1 100644
--- a/src/mc/DwarfExpression.cpp
+++ b/src/mc/DwarfExpression.cpp
@@ -4,27 +4,26 @@
 /* This program is free software; you can redistribute it and/or modify it
  * under the terms of the license (GNU LGPL) which comes with this package. */
 
+#include <cstddef>
 #include <cstdint>
-#include <cstdarg>
 
 #include <dwarf.h>
 #include <elfutils/libdw.h>
 
-#include "mc_object_info.h"
-#include "mc_private.h"
-#include "mc/LocationList.hpp"
-#include "mc/AddressSpace.hpp"
-#include "mc/Frame.hpp"
-#include "mc/ObjectInformation.hpp"
-#include "mc/DwarfExpression.hpp"
-#include "mc_dwarf.hpp"
+#include "src/mc/mc_private.h"
+#include "src/mc/LocationList.hpp"
+#include "src/mc/AddressSpace.hpp"
+#include "src/mc/Frame.hpp"
+#include "src/mc/ObjectInformation.hpp"
+#include "src/mc/DwarfExpression.hpp"
+#include "src/mc/mc_dwarf.hpp"
 
 using simgrid::mc::remote;
 
 namespace simgrid {
 namespace dwarf {
 
-evaluation_error::~evaluation_error() {}
+evaluation_error::~evaluation_error() noexcept(true) {}
 
 void execute(
   const Dwarf_Op* ops, std::size_t n,
@@ -70,22 +69,31 @@ void execute(
     case DW_OP_breg29:
     case DW_OP_breg30:
     case DW_OP_breg31:{
+        // Push register + constant:
         int register_id = simgrid::dwarf::dwarf_register_to_libunwind(
           op->atom - DW_OP_breg0);
         unw_word_t res;
         if (!context.cursor)
-          throw evaluation_error("Missin stack context");
+          throw evaluation_error("Missing stack context");
         unw_get_reg(context.cursor, register_id, &res);
         stack.push(res + op->number);
         break;
       }
 
-      // Push the CFA (Canonical Frame Addresse):
+      // Push the CFA (Canonical Frame Address):
     case DW_OP_call_frame_cfa:
       {
-        // UNW_X86_64_CFA does not return the CFA DWARF expects
-        // (it is a synonym for UNW_X86_64_RSP) so copy the cursor,
-        // unwind it once in order to find the parent SP:
+        /* See 6.4 of DWARF4 (http://dwarfstd.org/doc/DWARF4.pdf#page=140):
+         *
+         * > Typically, the CFA is defined to be the value of the stack
+         * > pointer at the call site in the previous frame (which may be
+         * > different from its value on entry to the current frame).
+         *
+         * We need to unwind the frame in order to get the SP of the parent
+         * frame.
+         *
+         * Warning: the CFA returned by libunwind (UNW_X86_64_RSP, etc.)
+         * is the SP of the *current* frame. */
 
         if (!context.cursor)
           throw evaluation_error("Missint cursor");
@@ -109,7 +117,6 @@ void execute(
       // ***** Constants:
 
       // Short constant literals:
-      // DW_OP_lit15 pushed the 15 on the stack.
     case DW_OP_lit0:
     case DW_OP_lit1:
     case DW_OP_lit2:
@@ -142,6 +149,7 @@ void execute(
     case DW_OP_lit29:
     case DW_OP_lit30:
     case DW_OP_lit31:
+      // Push a literal/constant on the stack:
       stack.push(atom - DW_OP_lit0);
       break;
 
@@ -183,9 +191,8 @@ void execute(
       stack.pop();
       break;
 
-      // Swap the two top-most value of the stack:
     case DW_OP_swap:
-      std::swap(stack.top(), stack.top(1));
+      stack.swap();
       break;
 
       // Duplicate the value under the top of the stack: