jingham created this revision.
Herald added subscribers: lldb-commits, abidh.
"expression" is a hugely inefficient way to get the value of a local variable.
There are a few cases where "frame variable" and "expression" will produce
different results on the same expression (e.g. "foo->bar" when foo has an ->
operator overload). But in general, if you are printing a local var, "frame
var" is way more efficient. I've been trying to teach people to use 'frame
var' more when it is appropriate, and it was suggested that adding a top-level
alias for it might make the command easier to find and remember.
This patch adds two aliases:
var - frame var
vo - frame var -O
The latter is for our ObjC friends who often see the object description, rather
than the object's ivars, as the primary source of information about the object.
I also added some caveats to the frame var help page.
Repository:
rLLDB LLDB
https://reviews.llvm.org/D53010
Files:
source/Commands/CommandObjectFrame.cpp
source/Interpreter/CommandInterpreter.cpp
Index: source/Interpreter/CommandInterpreter.cpp
===================================================================
--- source/Interpreter/CommandInterpreter.cpp
+++ source/Interpreter/CommandInterpreter.cpp
@@ -386,6 +386,13 @@
if (cmd_obj_sp) {
AddAlias("rbreak", cmd_obj_sp, "--func-regex %1");
}
+
+ cmd_obj_sp = GetCommandSPExact("frame variable", false);
+ if (cmd_obj_sp) {
+ AddAlias("var", cmd_obj_sp);
+ AddAlias("vo", cmd_obj_sp, "--object-description");
+ }
+
}
void CommandInterpreter::Clear() {
Index: source/Commands/CommandObjectFrame.cpp
===================================================================
--- source/Commands/CommandObjectFrame.cpp
+++ source/Commands/CommandObjectFrame.cpp
@@ -427,7 +427,17 @@
"arguments and local variables in scope. Names of argument, "
"local, file static and file global variables can be specified. "
"Children of aggregate variables can be specified such as "
- "'var->child.x'.",
+ "'var->child.x'. The -> and [] operators in 'frame variable' do "
+ "not invoke operator overloads if they exist, but directly access "
+ "the specified element. If you want to trigger operator overloads
"
+ "use the expression command to print the variable instead."
+ "\nIt is worth noting that except for overloaded "
+ "operators, when printing local variables 'expr local_var' and "
+ "'frame var local_var' produce the same "
+ "results. However, 'frame variable' is more efficient, since it "
+ "uses debug information and memory reads directly, rather than "
+ "parsing and evaluating an expression, which may even involve "
+ "JITing and running code in the target program.",
nullptr, eCommandRequiresFrame | eCommandTryTargetAPILock |
eCommandProcessMustBeLaunched |
eCommandProcessMustBePaused |
eCommandRequiresProcess),
Index: source/Interpreter/CommandInterpreter.cpp
===================================================================
--- source/Interpreter/CommandInterpreter.cpp
+++ source/Interpreter/CommandInterpreter.cpp
@@ -386,6 +386,13 @@
if (cmd_obj_sp) {
AddAlias("rbreak", cmd_obj_sp, "--func-regex %1");
}
+
+ cmd_obj_sp = GetCommandSPExact("frame variable", false);
+ if (cmd_obj_sp) {
+ AddAlias("var", cmd_obj_sp);
+ AddAlias("vo", cmd_obj_sp, "--object-description");
+ }
+
}
void CommandInterpreter::Clear() {
Index: source/Commands/CommandObjectFrame.cpp
===================================================================
--- source/Commands/CommandObjectFrame.cpp
+++ source/Commands/CommandObjectFrame.cpp
@@ -427,7 +427,17 @@
"arguments and local variables in scope. Names of argument, "
"local, file static and file global variables can be specified. "
"Children of aggregate variables can be specified such as "
- "'var->child.x'.",
+ "'var->child.x'. The -> and [] operators in 'frame variable' do "
+ "not invoke operator overloads if they exist, but directly access "
+ "the specified element. If you want to trigger operator overloads "
+ "use the expression command to print the variable instead."
+ "\nIt is worth noting that except for overloaded "
+ "operators, when printing local variables 'expr local_var' and "
+ "'frame var local_var' produce the same "
+ "results. However, 'frame variable' is more efficient, since it "
+ "uses debug information and memory reads directly, rather than "
+ "parsing and evaluating an expression, which may even involve "
+ "JITing and running code in the target program.",
nullptr, eCommandRequiresFrame | eCommandTryTargetAPILock |
eCommandProcessMustBeLaunched |
eCommandProcessMustBePaused | eCommandRequiresProcess),
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