From d6bcdcdaf7c93299b741ea2cd7e983b9ac5bfef2 Mon Sep 17 00:00:00 2001
From: Roman Telezhynskyi <kroluku@gmail.com>
Date: Tue, 18 Dec 2018 16:08:14 +0200
Subject: [PATCH] Update debugbreak for support PowerPC target.

--HG--
branch : develop
---
 src/libs/vmisc/debugbreak.h | 109 +++++++++++++++++++++---------------
 1 file changed, 63 insertions(+), 46 deletions(-)

diff --git a/src/libs/vmisc/debugbreak.h b/src/libs/vmisc/debugbreak.h
index 6615dda2f..c40850901 100644
--- a/src/libs/vmisc/debugbreak.h
+++ b/src/libs/vmisc/debugbreak.h
@@ -1,4 +1,4 @@
-/* Copyright (c) 2011-2015, Scott Tsai
+/* Copyright (c) 2011-2018, Scott Tsai
  *
  * All rights reserved.
  *
@@ -33,27 +33,22 @@
 
 #else
 
-#include <signal.h>
-
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-enum {
-    /* gcc optimizers consider code after __builtin_trap() dead.
-     * Making __builtin_trap() unsuitable for breaking into the debugger */
-    DEBUG_BREAK_PREFER_BUILTIN_TRAP_TO_SIGTRAP = 0
-};
+#define DEBUG_BREAK_USE_TRAP_INSTRUCTION 1
+#define DEBUG_BREAK_USE_BULTIN_TRAP      2
+#define DEBUG_BREAK_USE_SIGTRAP          3
 
 #if defined(__i386__) || defined(__x86_64__)
-enum { HAVE_TRAP_INSTRUCTION = 1 };
-__attribute__((gnu_inline, always_inline))
+    #define DEBUG_BREAK_IMPL DEBUG_BREAK_USE_TRAP_INSTRUCTION
 __inline__ static void trap_instruction(void)
 {
     __asm__ volatile("int $0x03");
 }
 #elif defined(__thumb__)
-enum { HAVE_TRAP_INSTRUCTION = 1, };
+    #define DEBUG_BREAK_IMPL DEBUG_BREAK_USE_TRAP_INSTRUCTION
 /* FIXME: handle __THUMB_INTERWORK__ */
 __attribute__((gnu_inline, always_inline))
 __inline__ static void trap_instruction(void)
@@ -69,30 +64,37 @@ __inline__ static void trap_instruction(void)
 #endif
 
     /* Known problem:
-     * After a breakpoint hit, can't stepi, step, or continue in GDB.
-     * 'step' stuck on the same instruction.
+     * After a breakpoint hit, can't 'stepi', 'step', or 'continue' in GDB.
+     * 'step' would keep getting stuck on the same instruction.
      *
-     * Workaround: a new GDB command,
-     * 'debugbreak-step' is defined in debugbreak-gdb.py
-     * that does:
+     * Workaround: use the new GDB commands 'debugbreak-step' and
+     * 'debugbreak-continue' that become available
+     * after you source the script from GDB:
+     *
+     * $ gdb -x debugbreak-gdb.py <... USUAL ARGUMENTS ...>
+     *
+     * 'debugbreak-step' would jump over the breakpoint instruction with
+     * roughly equivalent of:
      * (gdb) set $instruction_len = 2
      * (gdb) tbreak *($pc + $instruction_len)
      * (gdb) jump   *($pc + $instruction_len)
      */
 }
 #elif defined(__arm__) && !defined(__thumb__)
-enum { HAVE_TRAP_INSTRUCTION = 1 };
+    #define DEBUG_BREAK_IMPL DEBUG_BREAK_USE_TRAP_INSTRUCTION
 __attribute__((gnu_inline, always_inline))
 __inline__ static void trap_instruction(void)
 {
     /* See 'arm-linux-tdep.c' in GDB source,
      * 'eabi_linux_arm_le_breakpoint' */
     __asm__ volatile(".inst 0xe7f001f0");
-    /* Has same known problem and workaround
-     * as Thumb mode */
+    /* Known problem:
+     * Same problem and workaround as Thumb mode */
 }
+#elif defined(__aarch64__) && defined(__APPLE__)
+    #define DEBUG_BREAK_IMPL DEBUG_BREAK_USE_BULTIN_TRAP
 #elif defined(__aarch64__)
-enum { HAVE_TRAP_INSTRUCTION = 1 };
+    #define DEBUG_BREAK_IMPL DEBUG_BREAK_USE_TRAP_INSTRUCTION
 __attribute__((gnu_inline, always_inline))
 __inline__ static void trap_instruction(void)
 {
@@ -100,42 +102,57 @@ __inline__ static void trap_instruction(void)
      * 'aarch64_default_breakpoint' */
     __asm__ volatile(".inst 0xd4200000");
 }
+#elif defined(__powerpc__)
+    /* PPC 32 or 64-bit, big or little endian */
+    #define DEBUG_BREAK_IMPL DEBUG_BREAK_USE_TRAP_INSTRUCTION
+__attribute__((gnu_inline, always_inline))
+__inline__ static void trap_instruction(void)
+{
+    /* See 'rs6000-tdep.c' in GDB source,
+     * 'rs6000_breakpoint' */
+    __asm__ volatile(".4byte 0x7d821008");
+
+    /* Known problem:
+     * After a breakpoint hit, can't 'stepi', 'step', or 'continue' in GDB.
+     * 'step' stuck on the same instruction ("twge r2,r2").
+     *
+     * The workaround is the same as ARM Thumb mode: use debugbreak-gdb.py
+     * or manually jump over the instruction. */
+}
 #else
-enum { HAVE_TRAP_INSTRUCTION = 0 };
+    #define DEBUG_BREAK_IMPL DEBUG_BREAK_USE_SIGTRAP
 #endif
 
+
+#ifndef DEBUG_BREAK_IMPL
+#error "debugbreak.h is not supported on this target"
+#elif DEBUG_BREAK_IMPL == DEBUG_BREAK_USE_TRAP_INSTRUCTION
 __attribute__((gnu_inline, always_inline))
 __inline__ static void debug_break(void)
 {
-#if defined(_WIN32) || defined(_WIN64)
-    /* SIGTRAP available only on POSIX-compliant operating systems
-     * use builtin trap instead */
-    HAVE_TRAP_INSTRUCTION ? trap_instruction() : __builtin_trap();
-#else
-    // cppcheck-suppress knownConditionTrueFalse
-    if (HAVE_TRAP_INSTRUCTION)
-    {
-        trap_instruction();
-    }
-    // cppcheck-suppress knownConditionTrueFalse
-    else if (DEBUG_BREAK_PREFER_BUILTIN_TRAP_TO_SIGTRAP)
-    {
-         /* raises SIGILL on Linux x86{,-64}, to continue in gdb:
-          * (gdb) handle SIGILL stop nopass
-          * */
-        __builtin_trap();
-    }
-    else
-    {
-        raise(SIGTRAP);
-    }
-#endif
+    trap_instruction();
 }
+#elif DEBUG_BREAK_IMPL == DEBUG_BREAK_USE_BULTIN_TRAP
+__attribute__((gnu_inline, always_inline))
+__inline__ static void debug_break(void)
+{
+    __builtin_trap();
+}
+#elif DEBUG_BREAK_IMPL == DEBUG_BREAK_USE_SIGTRAP
+#include <signal.h>
+__attribute__((gnu_inline, always_inline))
+__inline__ static void debug_break(void)
+{
+    raise(SIGTRAP);
+}
+#else
+#error "invalid DEBUG_BREAK_IMPL value"
+#endif
 
 #ifdef __cplusplus
 }
 #endif
 
-#endif
+#endif /* ifdef _MSC_VER */
 
-#endif
+#endif /* ifndef DEBUG_BREAK_H */