https://github.com/jimingham created
https://github.com/llvm/llvm-project/pull/138330
None
>From aafaaa46cb5c9733451eea93be7d4a69cf88c7ad Mon Sep 17 00:00:00 2001
From: Jim Ingham <jing...@apple.com>
Date: Fri, 2 May 2025 12:40:11 -0700
Subject: [PATCH] Handle step-in over a Darwin "branch island".
---
.../MacOSX-DYLD/DynamicLoaderDarwin.cpp | 27 +++++++++++----
lldb/test/API/macosx/branch-islands/Makefile | 13 +++++++
.../branch-islands/TestBranchIslands.py | 34 +++++++++++++++++++
lldb/test/API/macosx/branch-islands/foo.c | 8 +++++
lldb/test/API/macosx/branch-islands/main.c | 6 ++++
.../test/API/macosx/branch-islands/padding1.s | 3 ++
.../test/API/macosx/branch-islands/padding2.s | 3 ++
7 files changed, 87 insertions(+), 7 deletions(-)
create mode 100644 lldb/test/API/macosx/branch-islands/Makefile
create mode 100644 lldb/test/API/macosx/branch-islands/TestBranchIslands.py
create mode 100644 lldb/test/API/macosx/branch-islands/foo.c
create mode 100644 lldb/test/API/macosx/branch-islands/main.c
create mode 100644 lldb/test/API/macosx/branch-islands/padding1.s
create mode 100644 lldb/test/API/macosx/branch-islands/padding2.s
diff --git
a/lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderDarwin.cpp
b/lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderDarwin.cpp
index e25c4ff55e408..0c5e69f47905f 100644
--- a/lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderDarwin.cpp
+++ b/lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderDarwin.cpp
@@ -26,6 +26,7 @@
#include "lldb/Target/Thread.h"
#include "lldb/Target/ThreadPlanCallFunction.h"
#include "lldb/Target/ThreadPlanRunToAddress.h"
+#include "lldb/Target/ThreadPlanStepInstruction.h"
#include "lldb/Utility/DataBuffer.h"
#include "lldb/Utility/DataBufferHeap.h"
#include "lldb/Utility/LLDBLog.h"
@@ -923,15 +924,15 @@ DynamicLoaderDarwin::GetStepThroughTrampolinePlan(Thread
&thread,
if (current_symbol != nullptr) {
std::vector<Address> addresses;
- if (current_symbol->IsTrampoline()) {
- ConstString trampoline_name =
+ ConstString current_name =
current_symbol->GetMangled().GetName(Mangled::ePreferMangled);
+ if (current_symbol->IsTrampoline()) {
- if (trampoline_name) {
+ if (current_name) {
const ModuleList &images = target_sp->GetImages();
SymbolContextList code_symbols;
- images.FindSymbolsWithNameAndType(trampoline_name, eSymbolTypeCode,
+ images.FindSymbolsWithNameAndType(current_name, eSymbolTypeCode,
code_symbols);
for (const SymbolContext &context : code_symbols) {
Address addr = context.GetFunctionOrSymbolAddress();
@@ -946,7 +947,7 @@ DynamicLoaderDarwin::GetStepThroughTrampolinePlan(Thread
&thread,
SymbolContextList reexported_symbols;
images.FindSymbolsWithNameAndType(
- trampoline_name, eSymbolTypeReExported, reexported_symbols);
+ current_name, eSymbolTypeReExported, reexported_symbols);
for (const SymbolContext &context : reexported_symbols) {
if (context.symbol) {
Symbol *actual_symbol =
@@ -968,7 +969,7 @@ DynamicLoaderDarwin::GetStepThroughTrampolinePlan(Thread
&thread,
}
SymbolContextList indirect_symbols;
- images.FindSymbolsWithNameAndType(trampoline_name, eSymbolTypeResolver,
+ images.FindSymbolsWithNameAndType(current_name, eSymbolTypeResolver,
indirect_symbols);
for (const SymbolContext &context : indirect_symbols) {
@@ -1002,7 +1003,7 @@ DynamicLoaderDarwin::GetStepThroughTrampolinePlan(Thread
&thread,
}
}
}
-
+
if (addresses.size() > 0) {
// First check whether any of the addresses point to Indirect symbols,
// and if they do, resolve them:
@@ -1028,6 +1029,18 @@ DynamicLoaderDarwin::GetStepThroughTrampolinePlan(Thread
&thread,
thread_plan_sp = std::make_shared<ThreadPlanRunToAddress>(
thread, load_addrs, stop_others);
}
+ // One more case we have to consider is "branch islands". These are
regular
+ // TEXT symbols but their names end in .island. They are to allow arm64
+ // code to branch further than the size of the address slot allows. We
+ // just need to single-instruction step in that case.
+ if (!thread_plan_sp && current_name.GetStringRef().ends_with(".island")) {
+ thread_plan_sp = std::make_shared<ThreadPlanStepInstruction>(thread,
+ /* step_over= */ false, /* stop_others */ false, eVoteNoOpinion,
+ eVoteNoOpinion);
+ LLDB_LOG(log,
+ "Stepping one instruction over branch island: '{0}'.",
+ current_name);
+ }
} else {
LLDB_LOGF(log, "Could not find symbol for step through.");
}
diff --git a/lldb/test/API/macosx/branch-islands/Makefile
b/lldb/test/API/macosx/branch-islands/Makefile
new file mode 100644
index 0000000000000..8675bbf6f85de
--- /dev/null
+++ b/lldb/test/API/macosx/branch-islands/Makefile
@@ -0,0 +1,13 @@
+C_SOURCES := main.c foo.c
+CFLAGS_EXTRAS := -std=c99
+
+include Makefile.rules
+
+a.out: main.o padding1.o padding2.o foo.o
+ ${CC} ${LDFLAGS} foo.o padding1.o padding2.o main.o -o a.out
+
+padding1.o: padding1.s
+ ${CC} -c $(SRCDIR)/padding1.s
+
+padding2.o: padding2.s
+ ${CC} -c $(SRCDIR)/padding2.s
diff --git a/lldb/test/API/macosx/branch-islands/TestBranchIslands.py
b/lldb/test/API/macosx/branch-islands/TestBranchIslands.py
new file mode 100644
index 0000000000000..b740592113619
--- /dev/null
+++ b/lldb/test/API/macosx/branch-islands/TestBranchIslands.py
@@ -0,0 +1,34 @@
+"""
+Make sure that we can step in across an arm64 branch island
+"""
+
+
+import lldb
+import lldbsuite.test.lldbutil as lldbutil
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test.decorators import *
+
+class TestBranchIslandStepping(TestBase):
+ NO_DEBUG_INFO_TESTCASE = True
+
+ @skipUnlessDarwin
+ def test_step_in_branch_island(self):
+ """Make sure we can step in across a branch island"""
+ self.build()
+ self.main_source_file = lldb.SBFileSpec("main.c")
+ self.do_test()
+
+ def do_test(self):
+ (target, process, thread, bkpt) = lldbutil.run_to_source_breakpoint(
+ self, "Set a breakpoint here", self.main_source_file
+ )
+
+ # Make sure that we did manage to generate a branch island for foo:
+ syms = target.FindSymbols("foo.island", lldb.eSymbolTypeCode)
+ self.assertEqual(len(syms), 1, "We did generate an island for foo")
+
+ thread.StepInto()
+ stop_frame = thread.frames[0]
+ self.assertIn("foo", stop_frame.name, "Stepped into foo")
+ var = stop_frame.FindVariable("a_variable_in_foo")
+ self.assertTrue(var.IsValid(), "Found the variable in foo")
diff --git a/lldb/test/API/macosx/branch-islands/foo.c
b/lldb/test/API/macosx/branch-islands/foo.c
new file mode 100644
index 0000000000000..6de2c7f36c037
--- /dev/null
+++ b/lldb/test/API/macosx/branch-islands/foo.c
@@ -0,0 +1,8 @@
+#include <stdio.h>
+
+void
+foo()
+{
+ int a_variable_in_foo = 10;
+ printf("I am foo: %d.\n", a_variable_in_foo);
+}
diff --git a/lldb/test/API/macosx/branch-islands/main.c
b/lldb/test/API/macosx/branch-islands/main.c
new file mode 100644
index 0000000000000..b5578bdd715df
--- /dev/null
+++ b/lldb/test/API/macosx/branch-islands/main.c
@@ -0,0 +1,6 @@
+extern void foo();
+
+int main() {
+ foo(); // Set a breakpoint here
+ return 0;
+}
diff --git a/lldb/test/API/macosx/branch-islands/padding1.s
b/lldb/test/API/macosx/branch-islands/padding1.s
new file mode 100644
index 0000000000000..e3bdf7007d757
--- /dev/null
+++ b/lldb/test/API/macosx/branch-islands/padding1.s
@@ -0,0 +1,3 @@
+.text
+_junk1:
+.space 120*1024*1024
diff --git a/lldb/test/API/macosx/branch-islands/padding2.s
b/lldb/test/API/macosx/branch-islands/padding2.s
new file mode 100644
index 0000000000000..187a2c3ebd117
--- /dev/null
+++ b/lldb/test/API/macosx/branch-islands/padding2.s
@@ -0,0 +1,3 @@
+.text
+_junk2:
+.space 120*1024*1024
_______________________________________________
lldb-commits mailing list
lldb-commits@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
